RU2315446C2 - Laser localizer for x-ray emitter - Google Patents

Abstract

FIELD: x-ray technologies, possible use for orientation of x-ray emitter relatively to an object.

SUBSTANCE: in accordance to the invention, introduced additionally are two identical cylindrical lenses, identically oriented and mounted at output of micro-lasers in such a way, that two flat divergent laser beams are formed, parallel to each other and forming two laser lines at distance B on the object, equal to distance between micro-lasers, semi-transparent mirror, mounted in front of first micro-laser behind cylindrical lens on its optical axis, plane of semi-transparent mirror is perpendicular to plane, formed by axes of micro-lasers, and inclined under angle of 45° to axis of first micro-laser, on the body of second micro-laser in zone of its intersection with beam axis of first micro-laser after its reflection from light-divider a flat mirror is fastened, plane of which is perpendicular to plane, formed by axes of micro-lasers, and parallel to axis of first micro-laser, on the body of first micro-laser a scale is mounted for reading linear coordinates of intersection of that scale with flat laser beam, reflected from mirror, fastened on the body of second micro-laser and, also, between main parameters of optical circuit of localizer certain ratio is maintained.

EFFECT: increased precision when measuring distance from x-ray emitter to controlled object.

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Description

The invention relates to non-destructive testing of materials and products using x-ray radiation and can be used to control objects of aerospace engineering and other industries by radiography.

Known laser centralizer for an x-ray emitter, comprising a housing with a television system located therein, consisting of a CCD matrix and a lens, the optical axis of which is parallel to the axis of the x-ray emitter, a plexiglass reflector mounted at the intersection of the x-ray beam and the optical axis of the lens of the television system perpendicular to this plane, and the video monitoring device, further comprises two microlasers, the optical axes of which are parallel to each other and the axis of the x-ray beam and are located symmetrically about this axis in a plane formed by the axes of the lens and the x-ray beam at a distance B from each other, determined from the relation B≤D _min · tg (α / 2), where D _min is the minimum distance from the x-ray emitter to the object in the operating range of these distances, α is the angular size of the X-ray beam, the size of the raster of the CCD matrix H and the focal length of the lens of the television system f are related by the relation H = 2f · tg (α / 2), where the distances from the emitter to the object are determined, a television computer and and a standard computer produces automatic calculation of the distance using the formula D = C / B ^', wherein C = B · f - constant optical centralizer system ^B' - the distance between the images of laser spots on the object in the focal plane of the television system of the lens coinciding with the plane the location of the photosensitive elements of the CCD matrix, and for this purpose a digital camera was used to record, store and transmit images of the surface of the object in the area of its transmission through x-ray radiation to a computer [1].

The disadvantages of this device are the lack of built-in means of monitoring the parallelism of the laser beams to each other, which can lead to an error in measuring the distance from the x-ray emitter to the object due to inaccurate actual distance between the laser spots on the object. The control of this distance using a linear scale located directly on the object complicates the control procedure, and is often simply impossible when examining hard-to-reach objects.

In addition, measuring the distance between images of laser spots using a CCD video camera is quite difficult due to the small diameters of these images (of the order of 100 μm at an object distance of D≥3 m), as well as the influence of the skew line passing through the centers of the laser spots, relatively line structure of the deploying system of the CCD.

The purpose of the invention is the elimination of these disadvantages.

This goal is achieved by the fact that in the laser centralizer for the x-ray emitter, comprising a housing with a digital camera located therein, consisting of a CCD matrix and a lens, the optical axis of which is parallel to the longitudinal axis of the x-ray emitter, a plexiglass reflector mounted at the intersection of the x-ray axis and the optical axis of the digital camera lens is perpendicular to this plane, and a video monitoring device, two microlasers whose optical axes are parallel to each other, and x-ray axes vskogo beam are arranged symmetrically about this axis in the plane defined by the axes of the lens and the X-ray beam at a distance B from each other, defined by the relation B≤D _min · tg (α / 2), where D _min - minimum distance from the X-ray source to the object the working range of these distances, α is the angular size of the X-ray beam, the raster size of the CCD matrix H and the focal length of the lens of the digital camera f are related by the ratio H = 2f · tg (α / 2), a television computer or a standard computer that performs automatic Calculating the distance to the object by the formula D = C / B ^', wherein C = B · f - centralizer constant optical system, ^B' - the distance between the images of laser spots on the object in the focal plane of the lens of digital camera coinciding with the plane of photosensitive elements of the CCD arrangement matrices, two identical cylindrical lenses are introduced, identically oriented and installed at the output of the microlasers in such a way that two flat diverging laser beams are formed, parallel to each other and forming on the object has two laser lines at a distance B equal to the distance between the microlasers, a translucent mirror mounted in front of the first microlaser behind a cylindrical lens on its optical axis, the plane of the semitransparent mirror is perpendicular to the plane formed by the axes of the microlasers, and is inclined at an angle of 45 ° to the axis of the first microlaser, the case of the second microlaser in the zone of its intersection with the axis of the beam of the first microlaser after it is reflected from the beam splitter, a flat mirror is fixed, the plane of which is perpendicular to the plane, formed by the axes of the microlasers, and parallel to the axis of the first microlaser, a scale is mounted on the body of the first microlaser to read the linear coordinates of the intersection of this scale with a flat laser beam reflected from a mirror mounted on the housing of the second microlaser.

The invention is illustrated by drawings (Fig.1,2,3), which shows a diagram of a centralizer.

The laser centralizer comprises a housing 2 fixed to the x-ray emitter 1, in which two identical semiconductor microlasers 3 and 3 ^{'are located} , the axes of which are parallel to each other and the axis of the x-ray beam, a digital camera containing a CCD matrix 6 and lens 5, the optical axis of which is parallel to the longitudinal the axis of the x-ray emitter, reflector 4 made of plexiglass and mounted at the intersection of the axes of the lens and the x-ray beam perpendicular to the plane formed by these axes, video monitoring device oystvo 7 and television calculator 8 ..

Microlasers form on the surface of the object 9 two luminous lines, the distance B between which remains constant at any change in the distance from the emitter to the object (Fig. 1).

Identical cylindrical lenses are arranged in front of the microlasers on their optical axes, oriented so that two flat laser diverging beams parallel to each other are formed at their output. In front of the first microlaser 3, a beam splitter 11 is installed on its optical axis behind the cylindrical lens 10, the reflecting surface of which is perpendicular to the plane formed by the axes of the microlasers 3 and 3 ′ and is located at an angle of 45 ° to the axis of the microlaser 3. Microlaser 3, a cylindrical lens 10 and a beam splitter 11 structurally rigidly interconnected and arranged in the housing 14. at the side of the housing 14 facing to the housing 15 of the second microlaser 3 ^', fixed linear scale 12. The laser light from the microlaser 3 after reflection from svetodeli ator 11 is incident on the second housing 15 microlaser 3 ^'through the opening in the housing 14 (Figure 2, type A). On the housing 15 of the microlaser 3 ′, on the side facing the housing 14, a flat mirror 13 is fixed, the surface of which is parallel to the axis of the microlaser 3 and perpendicular to the plane formed by the axes of the microlasers 3 and 3 ^' .

After reflection from this mirror 13, a planar laser beam forms a light stroke on the scale 12 (Fig. 3, a) perpendicular to this scale.

The mirror 13, the laser 3 ^{', a} cylindrical lens 10 ^{' are} rigidly fixed relative to each other in the housing 15.

The device operates as follows.

An X-ray emitter 1 with a body 2 fixed on it is aimed at object 9. An image of two laser strips parallel to each other arises on the object, the distance between which is B. The distance B between the images of these strips calculates the distance from the x-ray emitter to the object using the system consisting of a digital camera and calculator 8. Visual observation of the object 9 is carried out using an additional monitor 7. If necessary, the surface of the object is photographed digitally okameroy.

Before turning on the x-ray apparatus, the operator controls the position of the laser stroke on the scale 12 and, if it does not coincide with the desired value (Fig. 3, a, b), makes an adjustment angular rotation of the housing 14 relative to the axis passing through the intersection of the axis of the microlaser 3 and the beam splitter 11 to moment at which N = N ₀ .

The value of N _{0 is} determined by preliminary alignment of the centralizer on a standard linear measuring scale 16, length L≥B with a division price t = 1 mm, placed at the maximum distance of the x-ray emitter from the object D _max ≈ 5.0 mm perpendicular to the axes of the microlasers and the axis of the x-ray beam with error not worse than ± 5 °. The scale 16 is placed symmetrically relative to the axis of the x-ray beam and / or the rays of the microlasers 3 and 3 ′. At the same time, by rotating the case 14 relative to its axis of rotation using a standard screw mechanism (not shown in the diagram due to the well-known technical solution), the distance B between the laser lines is equal to the distance B ₀ between the centers of the microlasers 3 and 3 ′, measured in close proximity from their output ends. At the moment of equality B = B ₀ on a scale of 12 mark the value of N _{0 the} position of the laser bar on this scale.

It is significant that if, when the casing 14 is rotated as a single rigid construct at an angle γ (FIGS. 1, 2), the beam incident on the casing 15 is also deflected by the same angle γ, then after reflection from the mirror 13, the reflection angle doubles and becomes equal according to the laws of geometric optics [2]. This allows you to double the sensitivity used in the inventive device autocollimation scheme for controlling the angular deviations of the axes of microlasers 3 and 3 ′ from parallelism.

что вполне удовлетворяет требованиям технологии рентгенографического контроля.As noted above, from design considerations, B ₀ = 600 mm was adopted. When adjusting the centralizer on a scale located at a distance of D = -D _max ≅5000 m (5 m), the measurement error B is ± 1 mm (standard ruler). It is obvious that the error in measuring the scale M will be

which fully meets the requirements of the technology of radiographic control.

At the same time, if in the process of transportation, operation, and other reasons, the non-parallelism of the laser beams is only ± 1 °, then the value of B _{0 will} practically not change (B ₀ ≈600 mm ± 1 mm), and the value of B will change by ΔВ = ± D _max · tgα≈ + D _max · γ (here α = 0.02 in radian measure).

Moreover, ΔB = ± 5000 · 0.02 = ± 100 mm.

The scale error will be equal to

что уже недопустимо.

which is already unacceptable.

We estimate the error of control of parallelism using the proposed device. The maximum permissible deviation in size from the nominal ΔV ₀ = V-V ₀ (value module operate ΔV ₀ for simplicity of calculation).

The corresponding angular mismatch of the axes of the microlasers γ = ΔВ ₀ / D, where D is the distance from the x-ray emitter to the object. Express ΔB ₀ in fractions of B ₀ , i.e. ΔB ₀ = k · B ₀ , where k = 0.01 ± 0.02 is a coefficient that determines the relative error in measuring the distance between the axes of the lasers, and therefore the error in the scale of their image.

The corresponding angular displacement of the beam of the first microlaser after it is reflected from the mirror on the housing of the second microlaser is obviously equal to 2γ.

In a linear measure, this offset on the scale is placed on the housing of the first microlaser, equal to Δ = B ₀ 2γ.

In scale units (t is the scale division price) Δ = n · t, where n is the number of scale divisions attributable to this offset. Usually n = 3-5, in accordance with the rules of metrology [3].

You can finally record

и

and

Equating, we get

This equality allows you to choose the parameters of the autocollimation scheme based on the requirements for the accuracy of measuring the angular displacement of the axes of the microlasers of the current distance to the object, the distance between them and the scale division price.

Information sources

1. RF patent No. 2235447.

2. Handbook of the designer of optical-mechanical devices, ed. V.A. Panova, - L .: Engineering, 1980, - 742 p.

3. Sergeev A.G. Metrology, Moscow: Logos, 2001, 408 pp.

Claims (1)

A laser centralizer for an x-ray emitter, comprising a housing with a digital camera located in it, the optical axis of the lens of which is parallel to the longitudinal axis of the x-ray emitter, a plexiglass reflector mounted at the intersection of the axes of the digital camera lens and the x-ray beam perpendicular to the plane formed by these axes, a video monitoring device, two microlaser, the optical axis of which are parallel to each other and the axis of the x-ray beam symmetrically relative to this axis in the plane velocity formed by the axes of the digital camera lens and the x-ray beam at a distance B from each other, determined from the relation B≤D _min · tg (α / 2), where D _min is the minimum distance from the emitter to the object, α is the angular size of the x-ray beam in the working range of these distances, the focal length of the digital camera lens is related to the raster size of the CCD matrix H by the ratio f≤H / 2tg (α / 2), a television computer for measuring the distance from the emitter to the object, which automatically calculates this distance from near D = C / B ′, C = B · f is the constant of the centralizer optical system, B ′ is the distance between the images of the laser lines on the object in the focal plane of the digital camera lens, characterized in that two identical cylindrical lenses are introduced into it equally oriented and installed at the output of the microlasers in such a way that two flat diverging laser beams are formed, parallel to each other and forming two laser lines on the object at a distance B equal to the distance between the microlasers, a half-gap a mirror mounted in front of the first microlaser behind a cylindrical lens on its optical axis, the plane of the semitransparent mirror is perpendicular to the plane formed by the axes of the microlasers and tilted at an angle of 45 ° to the axis of the first microlaser, on the body of the second microlaser in the zone of its intersection with the axis of the beam of the first microlaser reflection from the beam splitter, a flat mirror is fixed, the plane of which is perpendicular to the plane formed by the axes of the microlasers and parallel to the axis of the first microlaser, on the body of the first rolazera set of linear scale for reading the coordinates of the intersection of the scale with a flat laser beam reflected from the mirror fixed to the second housing microlaser, and between the main parameters of the optical circuit form exists centralizer ratio

where n = 3 ÷ 5 is the coefficient of the metrological margin of measurement accuracy; t is the division price of the scale of the centralizer reading device, mm; In ₀ - the distance between the output ends of the microlasers, mm; K = 0,01 ÷ 0,02 - coefficient for assessing the permissible relative error of measuring the actual size of the distance between the laser lines at the object; D is the current distance from the x-ray emitter to the object, mm.

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