WO2014174014A1 - Apparatus and method for optically detecting flow movements in liquid and/or gaseous media - Google Patents

Abstract

The invention relates to a method and the apparatus for optically detecting flow movements in liquid and/or gaseous media. According to said method, a measuring volume (36) is defined in a medium and at least one measuring plane (32) is defined within the measuring volume (36), particles which move in the extent of the measuring plane (32) being optically detected. The measuring plane (32) is lighted and trans-illuminated from one side of the measuring plane (32), that is to say from an illumination side, in at least one detection area (34) by means of a beam (42) of parallel light rays emitted by an illumination unit (38), and scattered light (56) is produced by particles inside the detection area (34) of the measuring plane (32). Scattered light (56), which is emitted on a pre-scattering side opposite the illumination side, or at least a part of said light is passed, in the form of pre-scattered light, to an image recording plane (66) of a camera (68) by at least one optical light-guiding element (26). A sequence of images of the detection area (34) is recorded by the camera (68). A motion vector with respect to at least one particle is determined by means of image evaluation using the image sequence.

Description

 Apparatus and method for optical detection of

 Flowing movements in liquid and / or gaseous media

The invention relates to a device and a method for the optical detection of flow movements in liquid and / or gaseous media. In addition to the field of application of surveying, for example, groundwater flow movements in groundwater outflows in general, the invention can be used, in particular, for investigating the groundwater flow movement on dams or tunnels or planning icing measures for tunneling in the protection of a built-up frost body, for collecting data from groundwater flow models and for plausibility testing of flow models. to safeguard evidence in remediation measures and groundwater intake reaches in water management and to study for thermal aquifer storage and to monitor the flow and suspended matter of gaseous media.

The knowledge of the groundwater flow direction and speed is of great importance for the planning and preservation of evidence in a large number of projects in environmental and groundwater protection, drinking water production, civil engineering, tunneling and geothermal energy. In the Federal Republic of Germany, about 64% of the drinking water supply is covered by groundwater. Groundwater is thus a primary asset. The increasingly extensive use of groundwater, eg for water supply or as a medium for geothermal energy generation, requires increasingly precise knowledge of local flow behavior. Legislators are also calling for more in-depth investigations, especially with regard to cleanliness and sustainable management (EU Water Framework Directive). In the Federal Republic of Germany, all interventions in the groundwater - including the introduction of substances (so-called tracers) to the measuring physical quantities of groundwater - regulated by the Water Resources Act (WHG) and thus subject to authorization.

Groundwater is always in motion. From the location of groundwater recharge (infiltration of precipitation) to the discharge into a spring fill, the groundwater moves through sediment bodies and structures of the subsoil. The flow direction and speed are given by the usually unspecified structures and permeabilities of the substrate, the hydraulic pressure gradient, etc. Since these parameters are variable, the groundwater often does not move directly to the exit points.

In the run-up to projects that involve intervention in groundwater, the local groundwater flow conditions at the affected sites must be clarified via pre-installed well levels. Conventionally, the height difference of the groundwater level measured at adjacent levels is used to determine the direction of the flow gradient.

As can be seen from the above, therefore, the groundwater flow can be conventionally determined by indirect measurements, i. E. The groundwater flow direction and velocity are determined by measuring groundwater levels at adjacent well levels and using the reflectance and permeability of the subsoil. However, this indirect measurement does not always provide the required information quality and resolution, in the case of non-correlatable water levels, with extensive level networks, with an insufficient number of levels or with shallow groundwater gradients. The construction of well levels is costly and can not always be constructed in the required number and / or locations (as is the case in urban or industrial areas, for example) to obtain the desired information.

In addition to the indirect measurement of the groundwater flow movements, these can also be determined by means of "in-situ" or "single-hole measuring methods". Here, the groundwater flow is measured directly in individual groundwater outfalls such as well levels, with only one well level is required to collect this data. This direct measurement of the groundwater flow direction and velocity takes place at discrete depths of radially flowed level pipe sections.

Compared to indirect measurements, direct flow measurements at individual levels have the following advantages and disadvantages: Advantages:

 Only one well level is required to determine the local groundwater flow situation.

 For the measurement, existing well levels can be used and further well levels can be saved.

- The groundwater movement can be measured at different depths of the aquifer, this provides a detailed picture of the spatial flow conditions in the aquifer.

 The information gain is independent of / supplementary to groundwater level measurements and pumping tests.

Disadvantage:

 Almost all methods measuring directly in the well room are limited to individual measurements. Thus they do not provide sufficient data for a statistical evaluation. The results sometimes show a high variance and are therefore not always reliable.

 The measurement results reflect the flow situation at the immediate location of the well level and can only be transferred to the wider environment with knowledge of the lithological conditions.

 Changes in the flow behavior due to hydraulic events can usually not be recorded "online".

Preliminary investigations are required (level condition / removal) to check the required measurement conditions. Procedures that require the introduction of artificial tracers are usually uneconomical due to a high set-up and measuring time and are only used if no results can be achieved with conventional procedures.

Due to the majority disadvantages compared to conventional methods, the use of borehole methods is currently very limited.

The radial groundwater flow velocity at well levels ranges between 1 cm / s and 1 cm / day (five orders of magnitude). For measurements of predominantly very low flow, the addition of flow markers is required. For this purpose, in the fountain level or Brunnenringraum z. As electrolytes, dyes or radioisotopes introduced or artificially generated marker, z. B. heat pulses. Many direct methods can only map a limited speed range due to the different properties of the markers used. More recent methods, such as the PHREALOG measuring method, the "colloidal borescope" or the "darkfield probe", use the natural suspended matter contained in the groundwater as a marker. Since these are suspended with the flow movement, their drift forms the flow movement. Suspended matter is illuminated and optically recorded by CCD camera. The flow motion is then computationally calculated by PIV (Particle Image Velocimetry) on the drift of suspended solids. The optical measurement of the flow movement with the help of naturally occurring flow markers has decisive advantages over methods which use artificial markers: a) Permanent suspended solids enable a continuous, automated flow measurement with any measurement duration. This allows timely and highly resolved monitoring of flow in wells and documentation of flow changes over time. With procedures that require the use of artificial markers is an automatic monitoring is not possible or only with great effort and high costs.

b) Since fine groundwater is always present in the groundwater, which are advektiv along with the flow, no artificial marking is required, therefore

 If no use permit according to WHG is required,

 reduce sources of measurement errors (since no physico-chemical intervention takes place),

 no on-site calibration is required

 - The effort is low.

c) The ease of use and the low cost of use reduce set-up time and enable economical use.

d) Since there are no sensory elements in the measuring medium, the measuring technique is highly robust in a chemically aggressive environment.

e) A large amount of data is collected, which improves the evaluation and thus increases the accuracy of the measurement results.

f) A wide speed spectrum from 10E-2m / s to 10E-7m / s (1 cm / s to 1 cm / day) can be mapped.

g) After installation of the measuring equipment, the hydraulic stabilization can be documented.

From 1992, PHREALOG developed a measurement method (GFV) for the optical measurement of groundwater flow movement in levels. The measuring technology has been used commercially by PHREALOG since 1999 (DE 42 30 919 A1 and DE 199 45 852 A1).

A fundamental distinguishing feature compared to the known, comparable optical methods (eg colloidal borescope, dark field probe) is the illumination of the measuring field by laser.

US Pat. No. 4,206,999 describes a method by which flow movements are detected optically on the basis of the drift of microscopic particles by means of photomultipliers. Here, the considered image plane by means of a side on the Illuminated image plane incident laser beam. The laser beam is formed differently. For signal processing, the photomultiplier is followed by a pulse width analyzer. US Pat. No. 4,391,137 describes a method with which flow movements in wells can be determined by means of artificially generated temperature anomalies, wherein flow direction as well as speed are detected. For this purpose, an array of thermistors in an equidistant distance to a heating element on a circular level angeord net, wherein the heating element is positioned centrally in the circular plane. Thermistors and heating element are in a moldable, with porous Med ium or Schüttg ut, such as. As sand or glass beads, filled container installed. This arrangement is retracted into the well pipe and fixed in a defined measuring depth. The moldable container lays against the well inner wall, so that the horizontal groundwater flow flows through the porous medium. The porous medium has the task of ensuring a uniform laminar flow in the measuring space and suppressing thermal convection. Now, a heat pulse is set on the heating element, which is transported in conformity with the flow in the porous medium to the u mliegenden thermistors. From the time duration between the generation of the heat pulse and on arrival at one of the thermistors, the measure of the flow rate is determined, the direction of the radial position of the thermistor, where the H itzepuls on ^¬ , is determined. US 4 396 943 describes a method by which flow movements in pipes are detected by means of the drift of particles by means of an endoscopic device.

US Pat. No. 4,963,019 describes an optical method which essentially corresponds to the "colloidal borescope" method, but works with a photomultiplier tube. Information on the use of cameras or corresponding optics can not be found. In US-A-5265477, the flow characteristics of a fluid are determined by introducing an electrolyte pulse at a highly localized point within the fluid without disturbing the flow field of the fluid or the shape of the pulse, and then the voltage or conductivity thereacross Point around is mapped to determine the speed and direction of fluid flow.

US-A-5 339 694 discloses a probe for determining the physical quantities of groundwater. The probe is cylindrical. On its circumferential surface, sensors are arranged uniformly on its circumference and parallel to the course of its longitudinal center axis, which sensors measure the electrical resistance values of groundwater influenced by a tracer liquid and located in the immediate vicinity of the probe. Here the use of a salt water is proposed as a tracer fluid, which must diffuse through a membrane into the ground water, which transports the conductive flues ^¬ sigkeit and produces a detectable for the sensors conductive measurement field. The extent, shape and movement size of the field are measured by the sensors. It is also possible with this device to measure vertical and horizontal flow movements and thus to determine the shape of the field and the flow velocity and direction of the groundwater. The probe and the method for its use have the disadvantage that they must be stationary in water-bearing boreholes, ie fixed, because they do not have holding or centering means such as packers. The measuring process can be performed over a large area, but the measurability of the conductive liquid moving in the groundwater is insufficiently given by the sensors. The device only provides possibilities for measuring the electrical conductivity, but not in combination with other measuring methods. US Pat. No. 5,796,679 describes a method by which flow movements in wells can be determined acoustically by means of modulated tone frequencies using the doubling method. US-B-6 227 045 discloses a probe for monitoring the velocity and direction of groundwater flow seepage comprising an electric heater and a plurality of temperature sensors arranged equidistant from the heater. The probe with the heater and the temperature sensors is inserted into a monitoring well and positioned so that it is submerged in the groundwater. Energy is supplied to the heater, and the temperature response at the temperature sensors is measured and recorded. From the measured temperature response, the groundwater flow velocity and direction are calculated and recorded. The temperature sensors may be resistive temperature detectors, thermocouples or other temperature detection devices of the prior art.

US Pat. No. 6,393,925 describes a process by means of which flow movements in wells can be determined by means of artificially generated temperature anomalies, flow direction as well as velocity being detected.

DE-B-101 49 024 describes a method for determining the physical quantities of groundwater pending in a borehole by introducing an aqueous, groundwater-diffusing solution in a predetermined space and a probe for carrying out the method. The measuring principle is based on the generation and observation of the behavior of artificially generated anomalies of conductivity and temperature. During the measuring process, the time-dependent, direction-specific changes of these two parameters are determined with adapted geoelectric arrangements and temperature sensors. Due to the parallel measurements, an increase of the accuracy is achieved and the extension of the range of application is made possible. The borehole system makes it possible to measure slow groundwater flow velocities in the range of more than 1 m / d. This goal was achieved with the development of the tracer ring space method. Thus disorders of nat are cozy groundwater flow field avoided while a rad i ^¬ al g facilitated even distributing clothes of the tracer overall as a starting condition for th e measurements guaranteed. The umenzunahme with known methods of measurement as a result of the tracer operation on ^¬ passing volume and the resulting horizontal and vertical velocity components are minimized with d iesem principle. An influence on the hydraulic conditions in the examination area by the tracer process is prevented. This forms the crucial basis for the measurement of slow groundwater movements. In addition, the design of the probe and the measuring methods used make it possible to use small amounts of tracer (<2000 ml). DE-A-42 30 919 discloses a single well method and apparatus for simultaneously detecting groundwater flow direction and velocity. The method makes it possible to replace the disadvantageous measurement of the flow characteristics over a specific time unit by a method. Preparing a formed radially tracer diffusion and also measuring the time period of the tracer transport between its input and the detection are detrimental at low Strömungsgeschwind ig ^¬ possibilities to the measured times from. However, the conditions of measuring the flow velocity and direction of the groundwater in boreholes depend as far as possible on the accurate measurement of even the smallest flow velocities. The known method concentrates deshal b on the existing groundwater flow with the lowest speeds and solves the gestel lte task characterized in that a horizontally aligned object plane illuminated in Meßabsch nitt a borehole and focused by means of optics on the image plane of a Videosensormod module and as a real Bildg product is made assessable. The solution according to DE-A-42 30 919 requires a tracer in the form of fl uorescent particles for suspending the values of the groundwater behavior to be determined, which suspended in the liquid make the flow and its direction visible. The location deviation of the tracer caused by the transport of the flow is continuously regis terized as a migration of virtual light sources on the image plane or the camera sensor surface and is evaluated directly by means of downstream image processing. The device generally has a cylindrical shape. Packers are arranged at their upper and lower ends. Forming between them an annular hollow cylinder, defined by the cylindrical surface and the bore wall, in which the device for visual and optical measurement of the properties of the groundwater takes place. The solution uses in its technical conceptions of the method and the apparatus design of the device exactly working equipment, but here an evaluation of calculable information from fast available data is not obtainable.

In DE 199 45 852 AI has a device for measuring currents in a well upper and lower terminating elements, which are net angeord at a distance from each other and between which a measuring section is formed, which can be flowed through substantially free d, wherein the termination elements M. Having means for Abd the sealing of the well, so that no vertical flows occur in the measuring ^¬ section. The apparatus is further provided with a Lichtquel le for illuminating the measurement range and with egg ^¬ nem image sensing element which innerhal captures the image of a measurement range b of the measuring portion. At least one tubular optical device is arranged between the image-sensing element and the area to be observed, with its free end projecting into the measuring section until just in front of the measuring area h and having such a shape and dimensions that the flow is substantially uninfluenced is.

In the above-mentioned measuring method using the "dark field probe", the horizontal direction of flow of the groundwater is measured by means of a camera according to the dark field principle without the introduction of artificial tracers. In dark field technology, the light emitted by a light source in the direction of the camera lens is referred to as so-called. Light traps hidden, so that in the ideal case l no light gets to the lens. The finest particles in the groundwater, whose size is far below the optical resolution of the camera, cause the light to scatter and diffract, thus reflecting the positions of these particles in the camera image. The images are recorded on video in depth-stationary measuring probes and the direction of particle motion is statistically evaluated and visualized using special software. The "darkfield probe" 1998 is a development of the University of Leoben, Austria; in cooperation with the former Fa. GECO Umwelttechnik, now FUGRO Austria GmbH (www.fugroaustria.at ^' ) and is commercially available. The method is similar to the "colloidal borescope" or consists of a conventional well inspection camera with a different optic and a light source placed below the probe in the direction of the camera.

The colloidal borescope method, also mentioned above, was reported to the Oak Ridge National Laboratory in the early 1990's (Kearl, P.M., et al., 1992): "Suggested Modifications to Groundwater Sampling Procedures Based on Observations from the Colloidal Borescope Groundwater Monitoring & Remediation (GWM R), Spring 1992 National Ground Water Association, GROUN D WATER MONITORING REVIEW; V12 N2; P155-161; Kearl, P.M. (1997): "Observation of particle movement in a monitoring well using the colloidal borescope "- Journal of Hydrology 200 (1997) 323-344, Elsevier). The instrument described in the context of the "Oak Ridge" system bears a strong similarity to a prior device which was the subject of US-A-4 963 019, the main differences being in the type of illumination (laser versus lamp) and the imaging device ("Optiram" vs. CCD camera for the versions of Foster and Fyda or Kearl). The tool consists of a down-facing camera with a microscope objective, a light source directed towards the camera, creating a "bright field" effect, a magnetometer for detecting tool alignment, holding cables, and / or a Betracher- / recording package at the head of the shaft. Once the tool has been lowered down to the target depth, video recordings are made and microscopic particles ranging in size from 2 to 10 pm are detected as dark objects; if a near-laminar flow is detected (the particles remain within the fairly thin focus plane for a majority or all of their crossing of the field of view), many particles can contribute to a single reading. Then computer software is used to detect the particles between successive frames and to calculate their speed and direction (Kearl and Roemer 1998). This Mag netometer-Ausgangssig nal is recorded at each Messtie ^¬ fenposition to ieren azimuth estimates to CORRECT, since Verd tate the tool is unavoidable when flexible cables are used for suspending the instrument.

Further, it is known to work with the aid of a so-called "scanning colloidal borescope flowmeter" (SCBFM) developed to evaluate horizontal groundwater flow directions and velocities. In the SCBFM, a charge-coupled device (CCD), a magnetometer, a light source, and a variable-focus remote-controlled lens mechanism are used to optically track particles of microscopic size. Naturally occurring colloids bewe ^¬ gen is advectively with the native groundwater flow. By recording highly sophisticated particle tracking computer software, the compass direction and advective velocity of a horizontal groundwater flow in a groundwater well (well level, well) can be evaluated. The scanning feature allows the evaluation of an approximately 50 cm high interval in the measuring volume. The scanning feature allows you to reach maybe a three-dimensional analysis of the flow so that swirling, not representative flow cells ^¬ identified and detected "fast-le flow paths" and may be characterized. The Lawrence Livermore National Laboratory's (LLN L) scanning colloidal borescope flow meter (SCBFM) flowscope adds another to the basic concept of Colloidal Boroscope instruments by Kearl and Foster and Fyda characteristic for: d ie Brennebe ^¬ ne is over a distance of almost 1/2 m away continuously adjusting bar, so that after the tool has been placed in a target depth in the peak interval of the measuring portion, an area of the image "planes "can be visualized and visualized without the tool being moved. It is believed that this allows greater flexibility in locating preferred flow motions and particles of leading regions for data collection without causing turbulence if Tool is repositioned. Because the SCBFM directly visualizes particle transport downhole, estimating velocities is done using simple calibrations of the camera lens. However, the tool is subject to the same influences as other downhole devices in that the presence of the sandpack and sieving inevitably alters the flowlines near the pit. Kearl (1997) found that colloidal boroscopic flow velocities should be reduced by a factor of one to four to derive the fluid velocities in the surrounding aquifer from the measurement results, and that the observed rates are an upper limit to true aquifer flow rates (see also Scott, J. et al. (2006): "Simulations to Verify Horizontal Flow Measurements from a Borehole Flowmeter", GROUND WATER Vol. 44, No. 3; May-June 2006; pages 394-405).

Finally, the use of an "In Situ Permeable Flow Sensor" (ISPFS) to directly measure the direction and velocity of groundwater at essentially a single point in unconsolidated, saturated bottom sediment is also known (see also Ballard, S. (1996): "The in situ permeable flow velocity meter", GROND WATER vol 34, No.2, pages 231-240). Once the ISPFS (In Situ Permeable Flow Sensor) is permanently installed in the ground, the 30 calibrated temperature sensors on its surface are activated, producing a temporally and spatially uniform heat flow around the probe. A groundwater flow past the ISPFS sensor is indicated by a change in the temperature distribution around the tool's surface, since a portion of the heat from the probe is moved around the tool by the groundwater flowing past the ISPFS sensor. The downstream side of the probe becomes relatively warm compared to the upstream side. The direction and magnitude of the flow are calculated from the measured temperature distribution at the surface of the probe. The ISPFS sensor provides unambiguous information, in particular a point estimate of the direction and velocity of groundwater flow on a scale of about one cubic meter. Under the assumption of uniform flow and uniform flow, the ISPFS sensors allow precise measurement of groundwater flow velocities in the range of lxlOE-5m / s to 5xlOE-8m / s. The ISPFS sensor provided unique information (Pun ktschätzungen the Grundwasserströ ^¬ mung vectors) to the above-mentioned demonstration points under both natural and under disturbed (d. E. Prevailing during the renovation) conditions. Measurement of groundwater flow on a small scale may be critical to optimizing the refurbishment design or developing a job-related conceptual model. ISPFS sensors provide information at extremely low cost over a longer period of time. After the sensors have been installed, the data is collected via an automatic system. Since, in particular at low flow velocities, the groundwater flow of hydrofluoric pressure fluctuations over time is variable in direction and velocity, with low flow movements there is a random distribution of the temperature mark, so that an accurate evaluation is not possible given is.

As a result of permanent installation of the probe in a bore, after termination of the test, a probe's mount is associated with great expense. Therefore, a loss of the probes is accepted insofar as they remain rich in the earth, which is ecologically unacceptable.

From EP-A-0 291 708 a device is known with which the speed of light scattering objects exposed for this purpose is measured, in which case the light of the pre-light scattering of the objects is examined.

Other devices for measuring the velocity and size of particles n are known from US-A-5 561 515 and US-A-4 026 655. DE-A-199 57 808 describes a method and a device for determining substance concentrations and / or the flow velocity in gases, aerosols and dusts by analyzing scattered light. As can be seen from the above, a variety of different methods and devices have been developed in the past, the flow parameters of Grundwasserfl ießbewegungen d by supplying markings in the form of z. As electrolytes, dyes and temperature anomalies on appro priate detectors detect the displacement of the marker with the groundwater flow. Furthermore, optical methods have also been used which use substances already contained and suspended in the groundwater as markers.

The object of the invention is to provide a method and a device for improved optical detection of flow movements in liquid and / or gaseous media, in particular in groundwater.

To solve this problem, the inventions proposed a method for the optical detection of flow movements in liquid and / or gaseous media, wherein in the method

in Med ium umen a Messvol and umens min ^¬ least one measurement plane are defined within the Messvol and

 in the extension of the measuring plane moving particles are optically detected by

 - the measuring level in at least one coverage area of the one

Side of the measuring plane, that is illuminated from a lighting side with ^{¬ means of} a light beam bundle of parallel light rays of a Be ^¬ lighting unit and is illuminated,

 By means of particles which are located within the detection range of the measurement plane, scattered light is generated,

as a Vorlichtstreuung to one of the illumination side opposite Vorlichtstrereuungsseite radiating stray light or at least a part of which is passed through at least one optical element to an image capture plane of a camera,

 from the camera a sequence of images of the detection area is recorded and

 - Based on the image sequence with respect to at least one particle by computer-aided image analysis, a motion vector is determined.

The above object is further achieved according to the invention with a device for the optical detection of flow movements in liquid and / or gaseous media, in particular for carrying out the method according to one of the aforementioned embodiments, wherein the device is provided with

 a measurement cell having or defining a measurement plane for positioning in the medium to be examined, wherein the measurement plane has at least one detection region within which particles in the medium are optically detectable,

 a lighting unit for exposing the detection area to a substantially parallel light beam,

 a camera for detecting at least a part of a light scattering resulting from the exposure of particles in the detection area as stray light,

 wherein the illumination unit and the camera are arranged on opposite sides of the measurement plane, namely on a lighting side and a Vorlichtstrereuungsseite, and

 an optical path between the detection area, ie the object plane and the camera, ie the image plane, for guiding at least part of the pre-light scattering to the camera.

In the device according to the invention, the pre-light scattering of particles to be examined is used in order to investigate their movement profile (speed, possibly speed change and flow direction and, if necessary, change in direction of flow). This concept according to the invention can be realized according to two variants. The first variant is characterized indicates that the light beam irradiates the illumination of the particles as transmitted light component in the optical path leading to a camera. In this variant, therefore, the light exit side of the illumination unit is located opposite the light entry side of the optical path. The majority of the pre-light scattering or the entire pre-light scattering is likewise coupled into the optical path.

In the second variant of the inventive concept, the light beam also penetrates the detection range of the measurement plane, but does not reach the light entry end of the optical path but is directed laterally past this. The Vorlichtstreuung is here coupled partially into the optical path. This second variant has the advantage that no transmitted light component of the light beam reaches the optical path. There is therefore no need to separate this transmitted light component from the scattered light, as is expediently carried out in the first variant.

Hereinafter, the first variant of the invention will first be described, wherein parts of this description can also refer to the second variant. According to the invention, within a measuring volume which is placed in the medium to be measured, at least one measuring plane is defined, in which there are moving particles which are optically detected. For this purpose, the measuring plane has at least one detection area, which is illuminated from one side of the measuring plane (illumination side) by means of a light beam, the light beam preferably having parallel light beams. As a result of the light scattering on illuminated particles, this exposure results in scattered light which, inter alia, also reaches the side of the measurement plane (scattered light side) opposite the illumination side, namely as a pre-light scattering. It has been found that the utilization of the light scattering due to their intensity is particularly suitable for optically detecting or localizing particles. For example, it is possible to perceive the effects of light from the naked eye by visualizing particles floating in the (sun) backlight or at an angle to it in the air. The scattering light (or at least a part thereof) radiating as a pre-light scattering to the pre-light scattering side as well as the transmitted light portion of the exposure light beam which passes the detection area of the measurement plane without being scattered, become in the first variant according to the invention d at least one optical element (i.e., along an optical path) is guided to an image pickup plane (image plane of the optically imaging system) of a camera. The camera takes a Seq uence of images of acquisition ^¬ range corresponding to the object plane of the system on. On the basis of this image sequence, a motion vector of a particle moving along the measuring plane can then be determined by the image evaluation method. In the first variant hrough the camera is erfind ungsgemäß in receiving the images d provided to filter out the transmitted light portion of the light beam bundle of BL LEVEL ^¬ processing unit before reaching the imaging plane of the camera. Thus, the camera excludes me only the Vorl ichtstreuung on.

By "filtering out" in the sense of the invention is meant, in particular, a blocking, otherwise blocking, absorbing and / or diverting the transmissive portion.

Advantageously Next Image ung may be provided in the first variant of the invent ung further, that the optical element has at least one facing the Erfas ^¬ sungsbereich the measurement plane scattered light inlet end, which is provided with a material transparent to the scattered light window element. Furthermore, it may be expedient in this case if the illumination unit has at least one light beam bundle outlet end, which faces the or a He ^¬ detection area of the measurement planes and the scattered light entrance end is opposite, and if the exit end is provided with a transparent window for the light beam element ,

In the second variant of the invention, it can be expediently provided that the light beam passes through the detection area of the measuring plane and passes through the optical element is directed, wherein the scattered light or at least a part thereof by the at least one optical element to the image recording plane of the camera is ge ^¬ passes. Also in this second variant of the invention, it may be expedient if the optical element has at least one scattering light which faces the detection area of the measuring plane and which is provided with a transparent window element for the scattered light. In addition, it may be expedient in this case for the illumination unit to have at least one light beam exit end that faces the detection area or the measurement plane and faces the scattering entrance end, and that the exit end has an optical exit that allows the light beam to exit laterally Deflection element, in particular prism is provided. With the invention (according to both variants) it is possible groundwater flow velocities in a very wide speed range of 10 ^"8 m / s to 10 ^{" 3} m / s, which is the range of 8 mm / day up to 8 m / day corresponds to, in addition to the speed sel bstverständl I also the flow direction is detected.

According to the invention, several measurement levels or measurement levels can be provided with a plurality of coverage areas. The measurement levels are then superimposed. The invention is particularly suitable for one-hole drilling measurements, wherein the measuring probe, so the device is introduced into an existing hole (well level). Oberhal b and b of the unterhal eigentl cozy measurement range are Übl icherweise sogenan nth packer or Abschott ^¬ elements which prevent the measurement range between the packers or Abschottelementen d urch angularly extending flow to the measuring plane is compromised. In this way, one essentially measures horizontal currents, undisturbed. The two baffle elements are mecha ^¬ cally above about poss ichst thin, the fl ow only unwesentl I connected impairing bracing. The illumination light and the light of the light scattering should be as close as possible to the measurement plane or the measuring range of the Measuring level within the measuring volume introduced or taken ^¬ who. This is expediently achieved with as little as possible influencing of the flow through the fact that the light-conducting elements designed to guide the illumination light to the detection area and to detect the light of the pre-scattering from the detection area or the image of the light source are as thin as possible Projecting object plane. If several measuring levels or measuring levels with several detection areas are provided per measuring probe or device, there are correspondingly also a plurality of pairs of light guide elements of the kind described above and the corresponding properties.

In a further advantageous embodiment of the invent clothes can thus be provided innerhal b to define the measuring volume a plurality of measurement levels, each with Minim ^¬ least a detection area or within a measuring plane or Any artwork least one of the measured levels of a plurality of detection areas, each sensing area is exposed and urchleuchtet d and wherein the pre-light scattering generated per detection area is recorded by a sequence of images and the image evaluation taking place per image sequence for each at least one particle, a motion vector is determined.

As already indicated above, in the first variant, the filtering out of the transmission component of the light beam of the illumination unit can be carried out by reflection and / or absorption and / or extraction. For the absorption is particularly suitable an optical light suppression element such. B. a component with a black surface on which the transmitted light portion of the light beam of the illumination unit impinges, or a light absorbing hollow body, in which the transmitted light portion of the light beam bundle of Be ^¬ lighting unit enters (without the hollow body to emerge again). By a light-conducting element (light guide), the transmitted light portion of the optical path can be "out".

Suitable particles to be optically detected for determining the flow direction and velocity are, on the one hand, inherently suitable in the medium. existing particles or artificially generated or entered measuring particles (tracers), which have been introduced for the purpose of measuring the fluidic properties of the medium in this. Here, for example, special metering devices can be used with which the particles can be introduced into the well level near the measuring volume or in the measuring volume. Examples of such metering devices are described in DE-A-199 52 541, DE-A-199 52 542 and DE-C-44 43 307.

In a further advantageous embodiment of the device according to the invention (according to both variants), it may be provided that the illumination unit has a light exit surface and the optical path has a light entry surface and that both surfaces are opposite and the detection region of the measurement plane is arranged between both surfaces. In order to prevent particles from gravitationally settling on the light exit surface of the illumination unit (or, depending on the arrangement, on the light entry surface of the optical path leading to the camera for the detected pre-light scattering), it may be expedient (in the case of both variants according to the invention) , the respective light exit surface or light entry surface on which gravitational particle deposition can take place, inclined to align with the measuring plane, in which case the respective other surface, ie. the light entrance or the light exit surface, preferably can run parallel to the measurement plane. In a further advantageous embodiment of both variants of the invention may be provided in an embodiment of the method or the device with multiple detection areas within a common measurement plane or within different measurement levels,

 that the measuring level has several detection areas,

in that the illumination unit has an exposure source and a number of light exit surfaces that is the same as the number of detection areas, that a number of optical paths with entry surfaces is provided that is the same as the number of detection areas, and

 that between the exposure source and the light exit surfaces on the one hand and between the optical paths and the camera on the other hand in each case a Lichtumlenkeinheit for deflecting the light of the exposure source for sequential, in particular cyclically recurring exit from the light exit surfaces and the sequential, in particular cyclically repeating redirecting the light of the optical paths to the camera is arranged, wherein the two Lichtumlenk- units are synchronized.

This arrangement has the advantage that multiple detection areas can be sequentially or cyclically exposed to illumination light, using only a single light source is used; Likewise, with only a single camera, the pre-light scattering components can be optically detected and recorded sequentially from the individual illuminated detection areas when they are illuminated. The respective Lichtumlenkeinheiten preferably include optical prisms or the like. The individual detection areas are expediently arranged along an imaginary circular line. This can then rotary actuators on the light generation side and on the

Vorlichtstrelichtungslichtaufnahmeiteseite be synchronized or on both sides, rotating elements can be rotated by means of a central, single drive. In a further expedient continuation of the invention may be provided in both variants, that the light-guiding elements to their Lichtaustrittsbzw. Light-contact surfaces having ends tapered conically and / or have optical deflecting elements, in particular prisms. The design of a light-guiding element as an optical tube with a conical tapering towards the window surface fulfills a further purpose. On the one hand, the tapered construction does not significantly affect the flow in the vicinity of the detection area. On the other hand, this embodiment allows the light beam to completely emit the detection area. tet, the distance between the detection area and the light entry surface is low and the light beam is guided past the light entry surface. These conditions are best met when the beam of light is directed at an angle of, say, 10 °. B. 20 ° to 40 ° from the optical axis deflected incident on the plane of the detection area. The advantage is that a maximum Vorl ichtstreuung is obtained from particles in the detection area without the Durchl ichtanteil falls into the light entry surface.

In the following, various aspects of the invention and their application will be described, which are easily given to both variants of the invention.

The detection areas are ideally at measurement planes being ^¬ ord net, wherein the optical beam path of the light beam can be aligned ieser coupled Drehtel ler on the respective detection range circular bunch and bildgeben- the proportion of scattered light by means of synchronized and urch with U mlenkprismen equipped Drehtel ler d rotation d, so that only one Lichtquel le and lighting unit and only one camera for measuring the flow in several detection areas are required.

The optical elements and the electronic control (at least partially ^stabilized) may be advantageously housed in the above-mentioned packers or Abschottelementen. It is expedient to carry out the inventive image-capturing measurements of the flow movements in particular well levels in unterschiedl Ien depth positions of the well level, on the one hand, to the results obtained verg correct and statistically evaluate, and on the other hand, a comprehensive Eind jerk for the interpretation of To get results. In that regard, the invention thus also includes a multi-level embodiment of the method and the device in order to simultaneously be able to carry out measurements in several depths of a well level. In this case, preferably several measuring probes or measuring modules are then transferred to nander (and possibly mechanically coupled together) used within a well level. This refinement of the invention initially has the advantage that a measuring insert can be carried out considerably more economically than before, as operating and set-up times can be saved (the conversion of a single measuring probe or a single measuring module into different measuring depths is omitted and a hydraulic stabilization after retraction and Fixing the probe in the well level only occurs once). Another advantage is that more data is added to support the results and to support the statistical evaluation and interpretation of the measurement data.

As a result of drilling and well construction, the hydraulic boundary conditions at and in the well level are disturbed / altered and the flow lines are distorted during flow. In Stromstrom to the well there is a Stromlinienscharung, in the outflow a corresponding fanning. The speed in the well is usually higher than in the environment, the flow generally laminar.

In circular well cross sections ideally an axial symmetric flow geometry is formed, whereby the median continuous flow path best reflects the prevailing flow direction in the surrounding sediment.

The relevant flow rate of interest in the surrounding sediment can be determined as realistically as possible by knowledge of the flow path distortion and the level analysis data usually available (eg drill diameter, filter tube permeability). In practice, this distortion is determined with the aid of known formula works only from the level-expansion data (the so-called alpha factor - see, for example, Moser, H. & Rauert, W. (1980): Isotope Methods in Hydrology.- in: Matthess, G. (Ed.): Textbook of Hydrogeology, Volume 8, Berlin). However, the application of these formulas does not sufficiently take into account all of the influencing factors that occur in practice. This leads to a high variance of the calculated Flow velocity in the sediment - a reason for the subordinate application of borehole methods.

Knowing the extends transversely to the fountain-forming axis Stromlinienverzer- tion / of the flow trajectory in the fountain level is of crucial importance ^¬ tung, in order to derive the flow rate of interest in the surrounding sediment as realistic as possible.

In all flow measurement methods in well levels, a drilling or pipe section is usually hydraulically insulated up and down so that a cylindrical measuring space is formed. In all known image-receiving methods, the optical detection of the fine particles takes place at one point: in the axial center of the flow-through measuring space of a measuring probe or axially in well levels.

To Feinschwebstoffe or microscopic particles optically isolated to erfas ^¬ sen high optical resolution is required. Due to the required imaging scale, the size of the field of view considered is limited when using known, commercially available imaging sensors (CCD or CMOS optical sensors) in such a way that only a very limited section of the flow field can be detected, beyond which Measure and the symmetry of streamline distortion over the entire well cross section can be deduced. The following solution has been devised in order to be able to deduce the dimension and the symmetry of the radial streamline field over the well cross-section: it can be set up multiple, distributed over the cross section of the measurement space on ^¬ sample points which ideally posi ^¬ tioniert on the same height and on a common circular path within the measuring space are arranged.

In order to represent representatively the flow situation transverse to the well axis in the measuring room, which approximates the flow situation in the well A minimum height of the measuring room or an insulated well level section is required. This height depends, for example, on the caliber of the well pipe and the size and arrangement of the filter openings in the well pipe. The desired flow situation then naturally forms preferably in the vertical center of the measuring chamber. Ideally, the image pickup positions must therefore be positioned in the vertical center of the measurement space and thus lie at a predetermined distance from the upper and lower terminus element of the measurement space.

In order to realize a sufficiently usable image with optically isolatable particle positions as well as a sufficient illumination of the viewing plane from these image pickup positions, even at a high turbidity of the flowing medium, it is necessary, the distance between the field of view and the windows, on the one hand, light in the flowing medium introduced and on the other hand, the backscattered by the transported particles light is coupled to keep short. The distance of the optical transmission through turbid, flowing medium is then reduced. This ensures that backscattered light from individual particles can be reproduced as light points from the field of view. At the same time, the flow situation must not be significantly impaired by the proximity of optical elements.

The distal end of the upper light-guiding element is designed in the shape of a circular cone stump (cone-shaped) and the axis of the optical path runs perpendicular to the base surface of the circular truncated cone, that is to say the light entry surface, and that of the detection region.

As already noted above in this regard, it is expedient if the window openings are located distally at the ends of optical components which protrude, for example in the form of optical tubes into the measuring space and their ends are designed so that they taper towards the window surface run, wherein the size of the window area approximately iert with the Betrach ^¬ processing area.

In order to ensure an optically flawless transmission for illumination and image capture over lying window surfaces, these window surfaces are inclined relative to the horizontal plane, so that the material depositing / sedimenting at the stationary measuring position is removed along the inclined window surface. Flow modeling results show that designs which only protrude into the measurement space from one end element influence the flow geometry in the measurement space such that flow paths are deflected vertically and the designs are preferably overflowed or underflowed. The deflection of the flow paths leads to a vertical drift of the suspended solids through the viewing surfaces and overall to an asymmetrical, more complex flow geometry in the measuring chamber. This type of arrangement is detrimental effect on the measured value recording and the recon ^¬ constructive tion of the flow geometry. The requirement is to arrange components in the measurement space in such a way that, on the one hand, there is no vertical deflection of the flow paths in the measurement space and, on the other hand, to distribute the flow resistance in the measurement space given by the components such that, regardless of the direction of the flow into the flow chamber Measuring chamber is always given a horizontal, approximately identical flow behavior of the arrangement in order to allow the formation of a reconstructable flow geometry.

1. The requirement is met with the invention that components which protrude from a terminating element into the measuring space are supplemented by components which are approximately identical in shape and length, as far as possible or ideally mirror-symmetrical from the opposite terminating element projecting into the measuring room opposite. Simulation results show that these arrangements significantly less influence on the flow in the measuring cell compared to the previous arrangement. Ießbahnen vertical deflection of Fl occur for n to subordinate it forms a g leichförmigere ow ^¬ geometry in the measuring cell. It is important that the flow resistance in the vertical profile of the measuring space g is evenly distributed.

2. The invention further satisfies the requirement that the number of components arranged on circular paths, projecting into the measuring space, is odd, by a number of positions which align a preferential flow direction as a result of the shading d parallel to the flow Specify components to reduce.

The individual NEN inventive aspects with the associated requirements to be fulfilled can be summarized as follows:

First aspect

Requirement: In order from the flow velocity in the well, the Fl ießgeschwind accuracy in the surrounding sediment so real itätsnah to derive as possible, please include, knowledge of the horizontal flow geometry or Ver ^¬ distortion of the liquid is ießbahnen required. For this, the shape of the flow geometry must be made recognizable.

Solu tion: To the dimension and the symmetry of the Fl to derive ießbahnverzerrung, the image pickup and the optical detection of the liquid takes place ießbewe ^¬ g ung at several over the horizontal cross section of the measurement space distributed locations, where d hese positions ideally corresponding intervals to each other and on circular paths are angeord net and preferably lie in the vertical M itte the measuring space. By combining the flow directions and velocities determined at the discrete positions in the measurement space, the flow geometry can then be reconstructed in a model. Second aspect

Requirement: Components which only protrude into the measuring chamber from one end element cause an asymmetric flow resistance in the measuring space, which leads to a vertical deflection of the flow paths and to different flow velocities in the vertical profile of the measuring chamber. The flow situation in the measuring room becomes more complex and the formation of a representative streamline distortion on the horizontal level is impaired. The task is to arrange components in the measuring room in such a way that

 1) as far as possible, there is no vertical deflection of flow paths in the measuring space and

2) to distribute the flow resistance in the measuring space given by the components in such a way that, regardless of the direction of the radial flow into the measuring space, an approximately equal flow resistance is provided in order to influence the formation of the flow geometry by means of compo ^¬ nents low and equal to keep.

Solution: The requirement is solved by virtue of the fact that components which protrude from a terminating element into the measuring space are supplemented by components which are approximately identical in shape and length and project from the opposing terminating element, in particular ideally in mirror-symmetrical fashion, into the measuring space. The number of angeord Neten on circular paths, projecting into the measuring space components is odd in order to avoid a preferential flow direction due to the shading d äl paral lel to flow aligned components.

Third Aspect Requirement: In order to register the backscattered light also in the form of traceable light points from the suspended matter, whose size is less than the optical resolution of the image-sensing sensor, the illumination of the viewing area is to be monitored with high light intensity. required. At the same time, the illumination must not cause any thermal heating of the flowing medium, in order to prevent resulting convective flow movements. Solution: In order to be able to optically identify even the smallest particles and to obtain the best possible light output, according to the first variant, a 100% pre-light scattering is expedient, which is achieved only with direct counter light and shading of the incident light in the subsequent beam path can be . Therefore, the window surfaces for illumination and image transfer are opposite to the viewing surface. The viewing surface is then such ausgeleuch ^¬ tet by a laser beam that the beam path of the laser beam parallel to the optical axis of the optical path of the image and focuses the laser beam in the beam path of the image and is optically terminated at the focal point. In the second variant, the coupling of the pre-light scattering (avoiding the coupling of transmitted light) of the light beam can be realized by the angle of the light beam incident on the detection area from the light generation side to the pre-light scattering light receiving side in the range of 0 ° to 90 ° to the measurement level through the coverage area.

Fourth aspect

Requirement: At high and Trü be prolonged measuring operation can in Sus ^¬ board in flowing Med ium befindl iches material deposited on horizontal surfaces lying window. This leads to an optical shading and thus to a reduced optical transmission. In the light-coupling windows may occur due to thermal Wand ment on the deposited material undesirable convective Fl ießbewegungen on the window surface and in the viewing area.

Solution: In order to ensure the optical transmission at the windows for illumination and image acquisition, in particular for longer residence times and in continuous measurement operation, lying window surfaces are opposite to the higher windows. tilted rizontalen level so that settling / sed ententierendes material along the inclined window surface is gavatatively removed.

Fifth Aspect (applies especially to th e first variant of the invent ^clothes')

Requirement: The light beam axis is broken at the Auskoppl ung slanted windows and then no longer runs parallel to the optical axis of the measurement image. The laser light beam can not then be focused and terminated in the beam path of the measurement image axis.

Solution: In order to compensate for the deflection of the optical axis of the laser beam when coupling and decoupling in the flowing medium, opposite window surfaces are aligned parallel to each other, so that the refracted on an inclined window surface optical axis of the laser beam when reentry on the opposite window again parallel is guided to the original optical axis or to the optical axis of the measurement image.

Sixth Aspect (applies to the second variant of the invention ^') drawback of the light guide according to the fifth aspect: it is apparent that which may adversely transmission affect the optical Ü between object and image plane, the light inlet surface passing through light component in the sense that the slightest soiling on the light exit surface of the lighting ^¬ tion unit, the light entry surface and on optical elements in the beam path lead to unwanted scattered light effects, which can superimpose the image transfer and thus impair the image sharpness of the transmitted image on the image plane.

Resulting request: In order to exclude this, it is zweckmä- to provide SSIG that of the detection area passing Highness maybe share not lt in the gegenüberl iegende light entry surface become due direct ^¬ time sol l an AS POSSIBLE high Vorlichtstreuung starting from particles in the detection region obtained. become . The requirement arises that the light entering the detection area from the illumination side, on the one hand, completely illuminates the detection area and, on the other hand, does not fall into the light entry area.

Furthermore, the distance between the light exit surface and the light entry surface should be selected such that on the one hand the particles located on the object plane are reproduced with high separation even with a strong turbidity of the medium to be measured or a high particle density and on the other hand the flow movement in the detection area by the light guide projecting into the measurement volume is only slightly affected.

Alternative approach: In order to achieve this, the light bundle coming from the illumination side, typically running parallel to the axis of the light-guiding elements, is deflected immediately before reaching the detection area (the measuring plane). B. 20 ° to 40 ° deflected in the direction of the light beam from the common axis, so that the light beam to the detection area in a beam angle of z. B. 70 ° to 50 °, wherein the distance between the detection area and the light entry surface is selected so that the thus deflected light beam on the one hand completely illuminates the detection area and on the other hand is guided laterally past the light entry surface.

The deflection of the light beam, for example, by a deflection prism in the form z. As a so-called "Bauernfeind" prism, which is applied to the distal end of the lower light-guiding element, or through a window with angled light-emitting surface.

Ideally, both light-guiding elements are located axially opposite one another, but depending on the design of the light deflection of the light bundle, they can be laterally offset relative to one another. Seventh aspect

Requirement: The medium flowing through can often be cloudy due to a very high level of suspended matter. This causes the optical transmission to be restricted. Incorporated light for illuminating the viewing surface is strongly scattered when coupled out into the flowing medium, so that suspended particles can not be detected individually at some distance from the viewing surface or the contrast of the light spots backscattered by individual particles is resolved. Thus, it is not possible to obtain any images which can be evaluated for determining the flow movement.

Solution: Adequate optical detection of individual suspended matter (assignment of contrast differences) and illumination is only given directly at the object plane or viewing area to be imaged. Therefore, the window areas for the image recording and for the light extraction are positioned in the immediate vicinity of the viewing surface, so that even at high Schwebstofff aft the particles transported on the focused viewing surface are occasionally imaged. For with a high turbidity of the medium to be measured or a high particle density in the medium, it should be taken into account that the pre-scattered light used to image the particles is not completely superimposed by scattered light from other particles which are above and / or below the detection range, whereby the position detection of the particles passing through the detection area is prevented or worsened, since they are not sufficiently focused on the image plane.

Eighth aspect Requirement: In the vicinity of the viewing area, the flow conditions are negatively influenced by closely positioned window elements. Solution: In order to reduce the influence on the flow conditions at the field of view through the window elements, window elements are positioned so ^¬ resulting in that the flowing medium facing windows correspond approximately in the form and extent of the imaged viewing surface, and that the window or the window-bearing In each case, the distal window surface forms the cone tip or the window-carrying element tapers conically towards the window surface.

Ninth aspect

In the measuring volume, space-filling, stationary vortices can form in laminar flows. The formation of these vortices can fill a considerable proportion of the measurement volume and thus decisively influence the flow geometry, for example by blocking the flow in a part of the measurement volume through the formation of the stationary vortices, which leads to an increase in the flow rate in other parts of the measurement volume.

The flow movement in the measuring volume is therefore no longer uniform due to the vortex formation. The flow movements in the detection areas are therefore not representative and in this case it can not be concluded with sufficient accuracy of the flow movement in the adjacent rock / soil. There arises the requirement to prevent the formation of stationary vortices, which change a rectified, laminar flow in the measuring volume, in that the flow resistance in the measuring volume is such that the flow pattern in the measuring volume essentially corresponds to that of the laminar, rectified flow without vortex formation , The flow resistance must remain unchanged and must not change, for example as a result of gravitational settling of particles on the elements determining the flow resistance. Because the flow resistance must be a calculable quantity when determining the flow velocities.

This offers the following solution. The Messvol umen is equipped with a definable flow resistance such that from belie ^¬ biger direction of flow out the flowing Med ium an equal resistance is offered, on the one hand a uniform be ^¬ aligned with the aim that the passage of the medium d urch through this flow resistance laminar flow in the measuring volume enforces and on the other hand suppressed an "offset" to the formation of space-filling vortices.

The flow resistance is carried out in the form of several round braces, which pull the measuring volume from the upper to the lower end element d and the most possible equals uid constants distances to each other and to the light elements on the entire base surface of Abschlussele ^¬ elements distributed angeord net, said the individual struts have the same diameter as or have a smaller diameter than the light-guiding elements. Al lgemeiner ausged advances have t he optical fiber elements and the struts to each other congruent cross-sectional shapes (preferably round or streamlined), wherein the cross-sectional area of each Verstre ^¬ environment is facilitated g to or smaller than the cross-sectional area of each light-guiding element.

The invention will be explained in more detail below with reference to an embodiment and with reference to the invention. In detail, they show:

Fig. 1 schematically shows the arrangement of a measuring device erfind ungsgemäßen the example of the first variant, in a fountain level (Brun ^¬ nenbohrloch) for determining the direction and speed of a groundwater flow, Fig. FIG. 2 is a schematic representation of the optical, individual lighting components and the internal structure of the measuring device according to the first variant of the invention and FIG. 3 and 4

 two exemplary embodiments of the second variant of the invention.

Fig. 1 shows the application situation of a measuring device 10 according to the invention according to a first variant in a well level or borehole 12 in the earth region 14 in order to measure the fluidic properties (direction and speed) of the horizontal groundwater flow at a predetermined depth 16. It should be noted at this point that several measuring devices 10 according to FIG. 1 at the same time in different union depths within the borehole 12 can be angeord net.

The measuring device 10 has a first upper Abschott- or packer element 18 and a lower second packer element 20, which seal off the measuring volume forming a section between the two packer elements 18,20 insofar as vertically through the borehole 12 flowing groundwater the Ho or not substantially affected. The two Abschott- or packer elements 18,20 are connected by struts 22 with each other. Of the Abschott- or packer elements 18,20 stand tubular or rod-shaped optical light guide 24,26 of lichtleitendem material (eg., Full material) or each as a window tube 25, 27 formed from their structure and function in combination with other elements the measuring device 10 below with reference to FIG. 2 will be explained in more detail.

The measuring device 10 has a plurality of pairs of preferably along a circular line angeord Neten light-guiding elements 24,26, ie, with the ends 28,30 of their window tubes 25, 27 facing each other (in the figure n. Only two pairs are Lich shown). Each Fenstertu bus 25, 27 has at its end 28, 30 a window member 29, 31. Between these ends 28,30 is the measuring plane 32 and each a detection area 34, which in turn are arranged within the measuring volume 36 between the two Abschott- or packer elements 18,20. Within the measurement level 32, groundwater flows with natural or artificial particles that need to be optically detected, in the form of sequences of images with the aid of a camera, which will be explained in more detail below.

In this embodiment, the lower Abschott- or packer element 20 has a lighting unit 38 which is formed as an exposure source 40 in the form of a laser light source for emitting a light beam 42 with parallel light beams 44. So that the light of the illumination source 40 can be guided sequentially to the light-guiding elements 24, it is deflected radially outward by a prism 48 located centrally on a turntable 46, from there by another prism 50 through an opening 52 in the turntable 46 to the light entrance side 53 the light guide 24 to be deflected. The light passes through the light-guiding element 24 (window tube 25) and exits via a slightly bevelled light exit side 54 of its window element 29. The exiting light passes through the focused detection area 34 and is partially scattered there on particles. This pre-scattered light is shown at 56.

The preliminary scattered light 56 passes through the light entrance side 57 on the window element 31 of the light guide 26 in its window tube 27 and out of its light exit side 58 to another deflection prism 59, which is disposed behind an opening 60 of another turntable 62, which in the upper first Abschott- or packer element 18 is located. The deflecting prism

59 directs the received light radially inwardly toward the center of the turntable 62, where it passes from a deflecting prism 64 arranged there in the direction of the image recording plane 66 of a camera 68. The exposure of a detection area or each detection area takes place over a certain period; During this time, a sequence of images from the pre-scattered light is recorded with the camera. By evaluating the images of this sequence, the direction vector and the velocity of individual particles n, which have moved through the detection area 34 within the measurement plane 32 during the exposure time, can be determined. Thereafter, then the Drehtel ler 46 step by step until the next pair of light guide 24,26 rehers. Serves a rotary drive 70, which is in this embodiment in rotary drive engagement with the Drehtel ler 46 in the lower Abschott- or packer element 20 angeord net, but just as well in the upper Abschott- or packer element 18 for d rehenden drive there befindl ichen Drehtel lers 62 angeord net can be. Both turntables 46, 62 are synchronized with respect to their rotation, which is done in this embodiment by a mechanical coupling rod 72, but also by a correspondingly synchronized activation of two separate drives for the turntables 46, 62 could be realized.

As shown in FIG. 2, the portion 34 of the light beam 42 that does not scatter on particles also enters through the detection area 34. This transmitted light component is denoted by the reference numeral 74 and would, if it were detected by the camera 68, disturb the image evaluation and image information. Therefore, it is provided according to the invention to filter out this transmitted light component 74 d by means of an optical undershield element 76. This may be a component with a black surface or else a coupling-out optical conductor 78. The extraction of the partial light component 74 is possible by using a corresponding lens system, such as the use of achromats 80, 81 in the optical path 82 between the detection area 34 and the camera 68 and in particular before the deflection of the pre-scattered light 56, d. H . before exiting the light guide 26 through t he two achromatic lenses 80, 81, the magnification and the focal points of the image plane and Abbil ^¬ d ungsebene (image pickup plane 66) to (32 d. e. reference) set. In the variant of the invention described here having a plurality of detection regions 34, these are ideally arranged along a circular line in the measurement plane 32, the optical beam path of the light beam 42 and transmitted light component 74 and the imaging preliminary scattered light 56 being synchronized with one another. rotatable and equipped with deflecting prisms 50 Drehtel ler 46, 62 d urch rotation of these coupled Drehtel ler on the respective detection area 34 can be aligned so that only one light source 40 and lighting unit 38 and only one camera 68 for measuring the flow in several detection areas 34 erforderl I am.

In Fig. FIG. 3 shows a further exemplary embodiment as a second variant of the device 10 ^{according to the} invention. As far as the elements of this device 10 'construction and / or functionally identical to the respective elements of the device 10 of FIG. 2, they are in Fig. 3 provided with the same reference numerals.

The difference between the devices 10 and 10 'is in the manner of coupling the pre-scattering light 56 and preventing the transmission of the transmitting portion 74 of the light beam 42, which, after penetrating the detection area 34, is laterally attached to the window member 31 of FIG Light guide 26 is directed past. For this purpose, a deflecting prism 84 is mounted on the window element 29, which is designed as Vollzyl indians. The light exit surface 54 of the deflection prism 84 is inclined by 30 ° to the axis of the light guide elements 24, 26. The light beam bundle 42 is completely guided through the detection area 34 by 60 °, but guided past the light entry surface 57. At the same time, tilting of the light exit surface 54 prevents gravitational settling of suspended matter on the light exit surface 54. With the attached deflection prism 84, the deflection of the light beam bundle 42 can be realized such that the light guide elements 24, 26 lie parallel to one another.

The advantage of the solution with attached deflecting prisms 84 is that the light-guiding elements 24, 26 can be arranged symmetrically opposite one another and the flow conditions in the vertical profile of the measuring volume 36 are uniform. The course of flow in the measuring volume 36 is not impaired by asymmetrical arrangements of structural units. It is, however Additional cozy optical components (deflection prisms) and related structure ^¬ steps required to realize the light beam deflection.

Fig. 4 shows a second exemplary embodiment of the second variant of the measuring device 10 "according to the invention. If their elements in each case resemble those of the measuring devices 10 and 10 'of FIGS. 2 and 3 (in construction and / or function), they are shown in FIG. 2 and 3. The difference of the measuring device 10 "to the measuring device 10 'can be seen in the realization of the deflection of the light beam bundle 42, which is realized by the window element 29 of the light guiding element 24 becomes . Due to the steep (60 °) radiation angle for illuminating the detection region 34, a maximum Vorlichtstreuung is achieved without the light beam bundle 42 falls into the light entrance surface 57.

The upper end of the window member 29 (laser beam outlet) is divided into two FLAE ^¬ surfaces which are inclined to each other by 18 ° and 30 °. The inclined by 18 ° surface is the (mirrored) reflecting surface for deflecting the light beam 42 and the inclined at 30 ° surface of the light exit surface 54 will follow the light beam 42 by 60 ° entirely d urch the Erfas ^¬ sungsbereich 34 Hindu rch, however, guided past the light entry surface 57. At the same time, tilting of the light exit surface 54 prevents gravitational settling of suspended matter on the light exit surface 54.

The light guide elements 24, 26 are in the embodiment with inclined window surfaces not parallel opposite but laterally offset in order to be able to sieren the light guide real. This offset can be done by avoiding the positioning of the light guide 24 on a Kreisl inie with g rößerem radius (as shown in Fig. 4), on which the lower light guide 24 are positio ^¬ ned, or even by an offset on the common position wheel ius of upper and lower light-guiding elements 24, 26. The advantage of the solution with windows is that no further optical components are required and the light beam deflection can be advantageously realized only with a modified window element 29. The light guide elements 24, 26 are not arranged symmetrically opposite, which may adversely affect the flow situation in the measuring volume 36.

E N G L I S H E S T E

10 measuring device

10 'measuring device

10 "measuring device

 12 borehole

 14 soil

 16 depth

 18 packer element / sealing element

20 packer element / Abschottelement

 22 struts

 24 (illumination) light guide

 25 window tubus

 26 light guide

27 window tube

 28 light beam exit end

 29 window element

 30 stray light entering end

 31 window element

32 measuring level

 34 coverage area

 36 measuring volumes

 38 lighting unit

 40 exposure source

42 light beam

 44 light beams

 46 turntable

 48 deflecting prism

 50 deflection prisms

52 opening

 53 light entry side

 54 light exit surface

 56 stray light

 57 light entry surface

58 light exit side

 59 deflecting prism

 60 opening

62 turntable

 64 deflecting prism

66 image acquisition level

 68 camera

 70 rotary drive

 72 coupling rod

 74 transmitted light component

76 suppression element

 78 output optical fiber

 80 achromats

 81 achromats

 82 Path

84 deflection prism, prism

Claims

Method for the optical detection of flow movements in liquid and / or gaseous media, wherein in the method  in the medium, a measuring volume (36) and within the measuring volume (36) at least one measuring plane (32) are defined and in the extension of the measuring plane (32) moving particles are optically detected by  the measuring plane (32) is illuminated and illuminated in at least one detection region (34) from one side of the measuring plane (32), ie from one illumination side, by means of a light beam (42) of parallel light beams of a lighting unit (38),  scattered light (56) is produced by particles which are located within the detection area (34) of the measurement plane (32), as scattering light scattering (56) or at least a part thereof by at least one optical light guide element (26) as a pre-light scattering to a pre-light scattering side opposite the illumination side ) is directed to an image acquisition plane (66) of a camera (68),  from the camera (68) a sequence of images of the detection area (34) is recorded and Based on the image sequence with respect to at least one particle by computer-aided image analysis, a motion vector is determined. A method according to claim 1, characterized in that within the measuring volume (36) a plurality of measuring planes (32) with at least one detection area (34) or within a measuring plane (32) or at least one of the measuring planes (32) a plurality of detection areas (34) are defined , wherein each detection area (34) is exposed and illuminated, and wherein the scattered light (56) generated per detection area (34) is taken by a sequence of images and represented by per Image sequence taking place image evaluation for each at least one particle, a motion vector is determined. A method according to claim 1 or 2, characterized in that the light beam (42) is directed in the direction of the light guide (26) and that the scattered light (56) as Vorlichtstreuung emitting scattered light (56) or at least a part thereof and a transmitted light component ( 74) of the light beam (42) of the illumination unit (38), which passes the detection area (34) of the measurement plane (32) without being scattered, by the at least one light guide (26) to the image acquisition plane (66) of the camera (68 ), wherein the transmitted light portion (74) of the light beam (42) of the illumination unit (38) is filtered out before reaching the image recording plane (66) of the camera (68). Method according to Claim 3, characterized in that the light-guiding element (26) has at least one scattered-light entry end (30) facing the detection area (34) of the measuring plane (32) and provided with a window element (31) transparent to the scattered light (56) is. Method according to Claim 4, characterized in that the illumination unit (38) has at least one light beam exit end (28) which faces the or a detection region (34) of the measurement planes (32) and faces the scattered light entry end (30), and that the light beam exit end (28) is provided with a window element (29) transparent to the light beam (42). Method according to one of claims 3 to 5, characterized in that the transmitted light portion (74) of the light beam (42) of the illumination unit (38) is filtered out by reflection and / or absorption and / or decoupling. 7. The method according to claim 1 or 2, characterized in that the light beam (42) through the detection area (34) of the measuring plane (32) and its transmitted light component (74) is laterally directed to the light guide (26) over, wherein the stray light (56) or at least part of which is passed through the at least one light-guiding element (26) to the image-recording plane (66) of the camera (68). 8. The method according to claim 7, characterized in that the light-guiding element (26) has at least one scattered light entry end (30) facing the detection area (34) of the measuring plane (32), which is provided with a transparent window element (31) for the scattered light (56) ) is provided. 9. The method according to claim 8, characterized in that the illumination unit (38) has at least one light beam exit end (28) facing the or a detection area (34) of the measurement plane (32) and the scattered light entrance end (30) and that the light beam exit end (28) is provided with an optical deflecting element, in particular prism (84), which allows the light beam (42) to exit laterally. 10. The method according to any one of claims 1 to 9, characterized in that in the medium, the movement of particles is detected, which are inherently present in the medium particles or for the purpose of measuring introduced into the medium measuring particles suspended be carried in the medium to be measured. 11. An apparatus for the optical detection of flow movements in liquid and / or gaseous media, in particular for carrying out the method according to one of the preceding claims, with a measurement volume (36) having or defining a measurement plane (32) for positioning in the medium to be examined, the measurement plane (32) having at least one acquisition range (34) within which particles in the medium are optically detectable,  a lighting unit (38) for exposing the detection area (34) to a substantially parallel light beam (42),  a camera (68) for detecting at least a portion of a scattered light (56) arising from the exposure of particles in the detection area (34),  wherein the illumination unit (38) and the camera (68) are arranged on opposite sides of the measurement plane (32), on a lighting side and a Vorlichtstrereuungsseite, and an optical path (82) between the detection area (34) and the camera (68 ) for directing at least a portion of the pre-light scattering to the camera (68). 12. The device according to claim 11, characterized in that the illumination unit (38) at least one light exit surface (54) and the optical path (82) at least one light entrance surface (57) and that in each case a light exit surface (54) and a light entry surface (57 ) and between these two surfaces (54,57) a detection area (34) of the measuring plane (32) is arranged. 13. The apparatus of claim 11 or 12, characterized in that the light exit surface (54) of the illumination unit (38) to the measuring plane (32) is inclined and the light entry surface (57) of the optical path (82) parallel to the measuring plane (32). 14. Device according to one of claims 11 to 13, characterized in that the light beam (42) irradiates in the optical path (82), wherein the optical path (82) has a suppression element (76) for suppressing the transmission of a detection area (34 ) of the measuring plane (32) without scattering passing transmitted light portion (74) of the light beam (42) of the illumination unit (38). 15. The apparatus according to claim 14, characterized in that the suppression element (76) comprises a light-absorbing component such. B. a component with a black surface on which the transmitted light portion (74) of the light beam (42) of the illumination unit (38) impinges, or is a light-absorbing hollow body, in which the transmitted light portion (74) of the light beam (42) of the illumination unit (38) occurs or a light receiving component such as a light guide. 16. The device according to claim 11, characterized in that the illumination unit (38) has at least one light exit surface (54) and the optical path (82) at least one light entry surface (57) and that in each case a light exit surface (54) offset laterally to a light entry surface (54). 57) and in a region between these two surfaces (54, 57) a detection region (34) of the measuring plane (32) is arranged, wherein the transmitted light portion (74) of the light beam (42) laterally on the optical path (82) is directed past. 17. The apparatus according to claim 16, characterized in that the light exit surface (54) is a surface of an optical deflection element, in particular a prism (84). 18. Device according to one of claims 11 to 17, characterized  in that the measurement plane (32) has a plurality of detection regions (34), that the illumination unit (38) has an exposure source (40) and a number of light exit surfaces (54) that is equal to the number of detection regions (34),  in that a number of optical paths (82) with light entry surfaces (57) that are the same as the number of detection regions (34) are provided, and in that between the exposure source (40) and the light exit surfaces (54) on the one hand and between the optical paths (82) and the Camera (68) on the other hand in each case a Lichtumlenkeinheit (48,50,59,64) for deflecting the light of the exposure source (40) for sequential, in particular cyclically recurring exit from the light exit surfaces (54) and for sequential, in particular cyclically repeating Diverting the light from the optical paths (82) to the camera (68) is arranged, wherein the two Lichtumlenkeinheiten (48,50,59,64) are synchronized. Device according to one of claims 11 to 18, characterized in that the measuring volume (36) on the exposure side and on the Vorlichtstrereuungsseite the measuring plane (32) of a respective Abschottelement (18,20) for suppressing an angle to the measuring plane (32) directed Störströmungen is limited. Apparatus according to claim 19, characterized in that from the first Abschottelement (20) for each detection area (34) of the measuring plane (32) projects a first Beleuchtungslichtleitelement (24) with a light exit surface (54) for guiding a light beam (42) and that of the second Abschottelement (18) for each detection area (34) a second light guide (26) protrudes that a light entrance surface (57) for scattered light (56) and possibly unscattered light of the light beam (42) from the respective detection area (34) and forms at least a portion of the optical path (82) leading to the camera (68), wherein the light exit surfaces (57) and the light entry surfaces (54) are positioned in a region between each of them by arranging a respective detection region (34). Apparatus according to claim 19, characterized in that the light-guiding elements (24, 26) have a conically tapering towards their ends (28, 30) having light exit surfaces (54, 57) and / or optical deflecting elements, in particular prisms ( 84). Device according to one of claims 19 to 21, characterized in that the illumination unit (38) is arranged in or on the one Abschottelement (20) and that the camera (68), the optical path (82) and the suppression element (76) in or are arranged or formed on the other Abschottelement (18).