JP2005266584A - Automatic focusing method and its device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase focusing speed by eliminating a waiting time before the start of a signal processing time corresponding to the integration time of analog detection signals outputted from a light receiving element. <P>SOLUTION: After having integrate-processed, in an integration circuit 30, the analog detection signals corresponding to the light amount of the luminous flux from a specimen S received by a light receiving sensor 21 through an observation optical system, the signals are converted into digital values for a constant processing time Tc by an A/D converting section 31 to conduct focusing judgement. At that time, the amount of light received is determined on the basis of digital range signals A and B corresponding to the amount of light received by the light receiving sensor 21 and setting changes are respectively made for the integration time at the integration circuit 30 and the starting time of the A/D conversion at the A/D converting section 31 based on optical amount determination signals "0", "1", ... or "5". <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an automatic focusing method and apparatus for focusing a sample in a microscope, for example.

  At present, microscopes are widely used for biological processes as well as industrial inspection processes. When using a microscope, the focusing operation is usually performed on a sample by operating a focusing handle. A high-magnification objective lens used in a microscope has a narrow focus range with a shallow depth of focus. A considerable skill is required to perform the focusing operation quickly by attaching such a high-magnification objective lens. In this case, if the operability of the microscope is poor, the production efficiency is adversely affected. In particular, in routine work such as an inspection process, it is very important to quickly perform a focusing operation to shorten the inspection time. Various autofocus (AF) apparatuses for microscopes that can automatically perform the focusing operation from such circumstances have been proposed, and many proposals for improving these have been made.

  The AF device in the industrial field detects not only the above-mentioned needs for improving the operability and throughput, but also the defect of each layer and the line width between patterns for a sample having a step such as a semiconductor wafer formed in multiple layers. -There is a need for applications that measure or measure minute steps on a sample with high accuracy. An AF apparatus having performance suitable for these inspections and measurements has also been proposed. For these reasons, the AF device in the industrial field projects light such as an infrared laser beam onto the sample in consideration of compatibility with the sample and shortening of the AF time, and detects the state of the reflected light. There are many active AF methods that perform a focusing operation.

  The biological AF device detects the contrast of the observed image because it requires a more accurate focus position and observes a transmissive sample with low reflectivity, which is impossible with the active method. Thus, the passive AF method that performs the AF operation has become the mainstream.

  In any case, what is required of the AF devices in each field is an AF operation corresponding to a wide range of sample states and an AF operation in a short time.

  In the active AF method, the intensity of the return light of the infrared laser light from the sample changes with the difference in reflectance of the sample. For example, when a high-reflectance sample or a low-magnification objective lens is attached, the intensity of laser light (observation) returning from the sample is increased. Conversely, when a low-reflectance sample or a high-magnification objective lens is attached, the intensity of the laser beam returning from the sample becomes extremely low. As a result, in the active AF method, it is necessary to be able to detect the in-focus state over a wide range of laser light intensities.

  In the passive AF method, the amount of light incident on an image sensor such as a CCD line sensor that detects contrast changes as the intensity of observation light from the sample changes. For example, when the amount of light emitted from a halogen lamp or the like is large or when a low-magnification objective lens is mounted, the incident light amount to the image sensor is large, and conversely, when the amount of observation light is small or a high-magnification objective lens is mounted Sometimes, the amount of light incident on the image sensor becomes small. Accordingly, in the passive AF method, it is necessary to be able to detect the in-focus state with respect to a wide range of incident light amounts.

  Thus, in both AF methods, it is necessary for the detection means such as an image sensor to have a wide dynamic range with respect to the amount of incident light. For example, Patent Document 1 discloses a technique for expanding the dynamic range with respect to the amount of incident light.

  This Patent Document 1 discloses a method for improving the apparent sensitivity of a light receiving element by controlling the integration time according to the brightness of reflected light when taking in observation light from a sample using an integrating light receiving element. Is disclosed. This method widens the dynamic range of light and darkness by shortening the integration time when the reflected light is bright and increasing the integration time when the reflected light is dark.

In Patent Document 2, even if the integration time when capturing observation light from a sample using a light receiving element is the same, the amount of light obtained by integration processing differs if the magnification of the objective lens is different. A method of setting the longest integration time for each is disclosed. This method cuts redundant processing that unnecessarily increases the AF supplemental range and integration time when the focal point of the sample is greatly deviated.
JP 54-45127 A JP 2001-91856 A

  However, although it is possible to widen the AF application range with respect to light and darkness of the sample using Patent Documents 1 and 2, it is not possible to increase the focusing speed, which is an important subject of AF performance. The focusing speed is closely related to a period for detecting the degree of focusing on the sample, a so-called focusing detection period (hereinafter referred to as a focusing period). In other words, if the focusing cycle is shortened, the number of times the focusing cycle is repeated increases, and this increases the amount of information that can be acquired per time, so that the focusing speed can be increased.

  As shown in FIG. 26, the focusing period is calculated from the integration time for integrating the observation light from the sample, and the signal processing time for performing the focusing control by determining the degree of focusing of the signal obtained by the integration processing. Become. When determining the degree of focus in such a focusing cycle, if the sample is bright and the amount of light from the sample increases, the integration time is shortened according to the amount of light.

  However, even if the integration time is shortened as shown in FIG. 27, since the start time of the signal processing is determined within the focusing cycle, the signal processing starts after the integration time ends. Waiting time will occur. For this reason, the focusing speed cannot be increased.

  In the present invention, the light beam from the sample is received by the light receiving element through the observation optical system while changing the distance between the sample and the observation optical system, and an analog detection signal corresponding to the amount of light received output from the light receiving element is integrated. After the processing, the integrated value is converted into a digital value in a fixed processing time, and in the automatic focusing method in which the focus is determined based on the digital value, the light receiving element uses the detection signal output from the light receiving element. This is an automatic focusing method in which the amount of received light is determined, the integration time of the detection signal is varied in accordance with the amount of received light, and the start time of conversion to a digital value is set immediately after the integration processing of the detection signal.

  The present invention integrates an analog detection signal corresponding to the amount of received light output from the light receiving element by receiving the light beam from the sample through the observation optical system while changing the mutual distance between the sample and the observation optical system. In the automatic focusing device that performs the integration process after this, converts the output of the integration circuit into a digital value in a fixed processing time by the A / D converter, and performs the focus determination based on the digital value, the received light amount of the light receiving element A light amount determination unit that determines the amount of light received by the light receiving element based on a digital value corresponding to the light amount, and an integration time of the detection signal in the integration circuit is varied according to the light reception amount determined by the light amount determination unit, and A / D The automatic focusing device includes a timing generation unit that sets a start time of A / D conversion in the conversion unit immediately after completion of integration processing in the integration circuit.

  The present invention provides an automatic focusing method and apparatus that can increase the focusing speed by eliminating the waiting time until the start of the signal processing time that occurs in accordance with the integration time of the analog detection signal output from the light receiving element. it can.

  Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is an overall configuration diagram of a microscope using an automatic focusing device. A sample S is placed on the stage 1. The stage 1 is provided with a focusing motor 2. The stage 1 moves up and down in the direction of the optical axis p ₁ by driving the focusing motor 2. The focusing motor 2 is driven by the focusing motor drive control unit 3.

An electric revolver 4 is provided above the stage 1. The electric revolver 4 includes a revolver body 6 that can be rotated and to which a plurality of objective lenses 5 can be attached, and an electric for rotating the revolver body 6 to insert an arbitrary objective lens 5 on the optical axis p _1. And a revolver hole position detector 8 for detecting an objective lens mounting position arranged on the optical axis p ₁ among a plurality of objective lens mounting positions in the revolver body 6. Have. The revolver motor 7 is driven by a revolver motor drive unit 9.

  Next, an autofocus (AF) optical system will be described. In this AF, an active pupil division method is used. The reference light source 10 used for AF uses a light source that outputs light in the visible light wavelength region such as infrared laser light. The reference light source 10 is pulsed by the laser driving unit 11 and its light intensity is driven and controlled.

  On the optical path of the laser light output from the reference light source 10, a collimator lens 12, a light projection side stopper ST, and a polarization beam splitter 13 are arranged. The collimating lens 12 shapes the laser light output from the reference light source 10 into parallel light. The projection-side stopper ST cuts half of the beam diameter of the laser light. The polarization beam splitter 13 reflects only the P-polarized light component of the laser light cut by the light projection side stopper ST, and transmits the S-polarized light component incident from the reflected direction.

A condensing lens group 14, a chromatic aberration correction lens group 15, a λ / 4 plate 16, and a dichroic mirror 17 are disposed on the reflected light path of the polarization beam splitter 13. The condensing lens group 14 condenses the laser light from the polarization beam splitter 13. The chromatic aberration correction lens group 15 corrects chromatic aberration, and moves in the direction of the optical axis p ₂ by driving the chromatic aberration correction lens driving motor 18. The chromatic aberration correction lens driving motor 18 is driven by a chromatic aberration correction lens driving unit 19. The λ / 4 plate 16 polarizes the laser light from the chromatic aberration correction lens group 15 by 45 °. The dichroic mirror 17 reflects only the light in the infrared region of the laser light polarized by the λ / 4 plate 16 downward, and the luminous flux from the sample S side to the λ / 4 plate 16 side and an eyepiece not shown. Or it branches in two directions with the imaging device side, such as CCD. An objective lens 5 is provided below the dichroic mirror 17 on the reflected light path (optical axis p ₁ ).

A light receiving sensor 21 is provided on the transmission optical path (in the direction of the optical axis p ₂ ) of the polarization beam splitter 13 via a condenser lens group 20. The light receiving sensor 21 is a two-divided photodiode and a two-divided detector. The light receiving sensor 21 has, for example, two light receiving elements 21 a and 21 b by dividing a signal processing region by a subsequent signal processing unit 26 into two equal parts. The light receiving sensor 21, the light receiving elements 21a, placing the boundary 21b on the optical axis _{p 2.} Each of the light receiving elements 21a and 21b of the light receiving sensor 21 receives a spot imaged by the condenser lens group 20, and outputs a sensor signal corresponding to the received light intensity.

  As shown in FIGS. 2 (a) and 2 (b), the spot imaged on the light receiving sensor 21 is formed on each light receiving element 21a as long as the sample S is disposed at the in-focus position (focus position) of the objective lens 5. , 21b, the light is received in a narrow area and has a high light intensity, and the sample S is disposed on the lower side (rear pin position) from the focus position, as shown in FIGS. As shown in FIGS. 4A and 4B, if the sample S is received with an intensity distribution biased toward the light receiving element 21b and the sample S is disposed on the upper side (front pin position) from the focus position, the light receiving element 21a side is obtained. Light is received with an intensity distribution that is biased toward

The illumination light source 22 outputs illumination light for observing the sample S. A lens 23 and a half mirror 24 are provided on the optical path of the illumination light output from the illumination light source 22. The half mirror 24 is provided on the optical axis p ₁ and illuminates the sample S from above by reflecting the illumination light output from the illumination light source 22 downward.

  The control unit 25 controls the focusing operation of the microscope, and controls each of the focusing motor drive control unit 3, the revolver motor drive unit 9, the laser drive unit 11, and the chromatic aberration correction lens drive unit 19. Each signal from the signal processing unit 26, the operation unit 27, and the pulse counter 28 is input. The control unit 25 has a configuration in which a program memory, a data memory, an input / output port, and the like are connected to the CPU.

  The operation unit 27 has various operation switches so that, for example, operations such as AF start / stop and switching of the objective lens 5 can be performed by an observer. A JOG encoder 29 is connected to the pulse counter 28. Output pulses of the JOG encoder 29 are counted by the pulse counter 28 and the count value is sent to the control unit 25. Thereby, the stage 1 can be moved up and down by the JOG dial.

  The signal processing unit 26 receives the sensor signal output from the light receiving sensor 21, divides the sensor signal for each range of the two light receiving elements 21a and 21b, and each digital range signal A of the sum of the received light intensity for each range. , B are output. FIG. 5 shows the incident light intensity with respect to the vertical position (defocus) of the stage 1 for each of the range signals A and B of the light receiving elements 21a and 21b.

Each of these range signals A and B shows a symmetrical change with respect to the focus position F.

  The control unit 25 receives the digital range signals A and B output from the signal processing unit 26, and from these digital range signals A and B, the addition signal A + B shown in FIG. 6 and the focus determination signal Ef shown in FIG. {= (A−B) / (A + B)} and the light amount signal value max (A, B) are calculated, and the focusing operation is executed based on these signals. The light quantity signal value max (A, B) indicates the larger one of the digital range signals A and B.

  The control unit 25 determines the presence / absence of the sample S based on the digital range signals A and B, determines the focusing direction based on the sign of the focusing determination signal Ef, and sets the focusing determination signal Ef to “0”. A focusing operation for guiding the sample S to the focusing position is performed.

  Specifically, the signal processing unit 26 and the control unit 25 have the configuration shown in FIG. The signal processing unit 26 includes an integration circuit 30 and an A / D conversion unit 31. The integrating circuit 30 integrates each sensor signal output from each light receiving element 21a, 21b of the light receiving sensor 21. The A / D conversion unit 31 converts each integration output of the integration circuit 30 into a digital value in a certain processing time Tc.

  The calculation unit 32 of the control unit 25 takes in the digital range signals A and B corresponding to the received light amounts of the light receiving elements 21a and 21b output from the signal processing unit 26, and based on the digital range signals A and B. The addition signal A + B, the focus determination signal Ef {= (A−B) / (A + B)}, and the light amount signal value max (A, B) are calculated, and the focus determination signal Ef is calculated as the focus determination unit. To 33.

  The focus determination unit 33 determines that the sample S is in focus when the focus determination signal Ef becomes “0” for each focus cycle, and at the same time, the focus motor drive control unit A drive stop signal is sent to 3. The focus determination unit 33 determines the focus direction based on the signs “+” and “−” of the focus determination signal Ef, and controls the focus motor drive control so that the focus determination signal Ef is “0”. A focusing signal is sent to the unit 3 to guide the sample S to the focusing position.

  The light quantity determination unit 34 receives the digital range signals A and B of the received light amounts of the light receiving elements 21a and 21b from the calculation unit 32, and stores these digital range signals A and B in the light quantity determination table 35 shown in FIG. The received light amount at the light receiving sensor 21 is determined with reference to a plurality of light amount determination signals, for example, light amount determination signals “0”, “1”. The plurality of light quantity determination signals “0”, “1”... “5” are used to determine the amount of received light at a plurality of stages. For example, the initial value is “0” and the light quantity gradually increases.

  As shown in FIG. 10, the light amount determination unit 34 determines the light amount required for the AF operation when each light amount value of the digital range signal A or B is within the range of threshold TH1 ≦ max (A or B) ≦ TH0. Therefore, the corresponding digital range signal A or B is held and a light quantity determination signal is sent to the timing generator 36.

  The light amount determination unit 34 decrements the light amount determination signal of the light amount determination table 35 by 1 to increase the detected light amount when the light amount value of the digital value range signal A or B is threshold value TH1> max (A or B). Then, the light quantity determination signal “0”, “1”... Or “5” is sent to the timing generator 36.

  If the light value of the digital value range signal A or B is threshold value max (A or B)> TH0, the light amount determination unit 34 increments the light amount determination signal of the light amount determination table 35 by 1 to reduce the detected light amount. Then, the light quantity determination signal “0”, “1”... Or “5” is sent to the timing generator 36.

  The light amount determination unit 34 does not increase or decrease the light amount determination signal when the upper and lower limits of the light amount determination signal exceed the upper limit “5” and the lower limit “0” of the light amount determination signal due to increase or decrease of the light amount determination signal. Holds the current light quantity determination signal.

  The timing generator (timing generator) 36 calculates the integration time and A / D from the timing storage table 37 shown in FIG. 11 based on the light amount determination signal “0”, “1”. The conversion start time is read out, the integration time is set in the integration circuit 30, and the A / D conversion start time is set in the A / D conversion unit 31.

  Specifically, the timing storage table 37 stores each integration time (μs) corresponding to each light quantity determination signal “0”, “1”... “5” and each A / D conversion start time (μs). Yes. Each integration time is set short in accordance with the increase in the amount of light received by each light receiving element 21a, 21b, that is, each light quantity determination signal “0” “1”. The start time of each A / D conversion is set to a time for starting A / D conversion immediately after the end of each integration time. For example, the integration time of the light quantity determination signal “0” is, for example, 1024 μs, and the start time of A / D conversion is 1025 μs after 1 μs after the end of the integration time.

  Next, the operation of the apparatus configured as described above will be described.

  When the reference light source 10 is pulse-lit, laser light in the visible light wavelength region such as infrared laser light is output from the reference light source 10. The intensity of the laser beam output from the reference light source 10 is controlled by the laser driving unit 11. The laser light output from the reference light source 10 is shaped into parallel light by the collimating lens 12, and half of the light beam diameter is cut by the light projecting side stopper ST. The laser light that has not been cut by the projection-side stopper ST is incident on the polarization beam splitter 13 where only the P-polarized component is reflected.

  The P-polarized component laser light reflected by the polarization beam splitter 13 is condensed by a condenser lens group 14, corrected for chromatic aberration by a chromatic aberration correction lens group 15, and polarized by 45 ° by a λ / 4 plate 16 to be dichroic mirror. Of the laser light that is incident on 17 and is polarized by the λ / 4 plate 16, only the light in the infrared region is reflected downward. The laser light reflected by the dichroic mirror 17 passes through the half mirror 24 and forms a spot-shaped image on the sample S by the objective lens 5.

  The light beam reflected by the sample S is incident on the λ / 4 plate 16 through the optical path irradiating the sample S with the laser beam and the reverse optical path, that is, the objective lens 5, the half mirror 24, and the dichroic mirror 17. It is polarized by 45 ° and polarized to the S-polarized component. The light beam polarized by the λ / 4 plate 16 passes through the chromatic aberration correction lens group 15, the condenser lens group 14, and the polarization beam splitter 13, and is condensed by the condenser lens group 20 to form an image on the light receiving sensor 21. Is done.

  Each of the light receiving elements 21a and 21b of the light receiving sensor 21 receives a spot imaged by the condenser lens group 20, and outputs a sensor signal corresponding to the received light intensity.

  On the other hand, in order to observe the sample S, illumination light is output from the illumination light source 22. This illumination light is incident on the half mirror 24 through the lens 23 and is reflected downward to illuminate the sample S from above. Reflected light (observation light) from the sample S passes through the objective lens 5, the half mirror 24, and the dichroic mirror 17 and enters an imaging device such as an eyepiece lens (not shown) or a CCD.

  Next, the AF operation will be described according to the AF flowchart shown in FIG.

  When the observer presses the AF start switch in the operation unit 27 while the sample S is away from the focus position, the control unit 25 determines in step # 1 that the AF start switch has been pressed, In the next step # 2, the threshold values TH0, TH1, and TH2 of the amount of light received by the light receiving sensor 21 are determined. The threshold value TH2 is a reference value for determining whether or not the Ef value is sufficiently close to “0”. When | Ef | <TH2, Ef = 0 is considered.

  The sensor signal output from the light receiving sensor 21 is input to the signal processing unit 26, integrated by the integration circuit 30 in the signal processing unit 26, and then digitally processed by the A / D conversion unit 31 at a certain processing time Tc. Converted to a value. As a result, the signal processing unit 26 outputs the digital range signals A and B that are the sum of the received light intensity for each range of the light receiving elements 21a and 21b of the light receiving sensor 21.

  In step # 3, the arithmetic unit 32 takes in the digital range signals A and B output from the signal processing unit 26, and calculates each light amount signal value max (A, B) based on the digital range signals A and B. To do.

  Next, the calculating part 32 compares each light quantity signal value max (A, B) with threshold value TH1 in step # 4. If the light quantity signal value max (A, B) is lower than the threshold value TH1 as a result of this comparison, the calculation unit 32 indicates that the light intensity of the light beam from the sample S is low, that is, the sample S is at a position far from the focus position. judge.

  When the light intensity of the light beam from the sample S is low in this way, the calculation unit 32 moves to step # 5, determines whether or not the entire range for searching the focus position by driving the stage 1 up and down is completed, and the entire range. If not, the process proceeds to step # 6 to issue a drive command to the in-focus motor drive control unit 3 through the in-focus determination unit 33. This calculating unit 32 searches the focus position with respect to the sample S by moving the stage 1 up and down by repeating steps # 4 to # 6. In this case, the focus position search with respect to the sample S is performed in a range where the light amount signal value max (A, B) is equal to or greater than the threshold value TH1, as shown in FIG.

  If the focus position cannot be searched even after the search of the entire range for searching the focus position is completed, the calculation unit 32 determines that AF is not possible due to the low reflectance of the sample S, for example, and in step # 7 The AF operation is interrupted.

  On the other hand, when the value of the light quantity signal value max (A, B) is higher than the threshold value TH1, the calculation unit 32 determines that the light intensity of the light beam from the sample S is sufficiently high and the sample S is in the vicinity of the focus position. Then, the process proceeds from step # 4 to step # 8 to start the fine scan.

  In this precise scanning, first, in step # 9, the arithmetic unit 32 calculates a focus determination signal Ef {= (A−B) / (A + B)} based on the digital range signals A and B, The absolute value of the focus determination signal Ef value is compared with the threshold value TH2. If the absolute value of the focus determination signal Ef value is larger than the threshold value TH2 as a result of this comparison, the calculation unit 32 moves to step # 10 and determines the drive direction of the stage 1 from the sign of the focus determination signal Ef value. The drive command in the determined drive direction is issued to the focus motor drive control unit 3 through the focus determination unit 33. Thereby, the stage 1 moves up and down.

  Next, in step # 11, the calculation unit 32 takes in the respective digital range signals A and B output from the signal processing unit 26, and again returns each light quantity signal value max (A, B) based on these digital range signals A and B. B) and the focus determination signal Ef {= (A−B) / (A + B)} are calculated.

  Thereafter, the calculation unit 32 performs the AF cycle operation by repeating Steps # 9 to # 11. When the absolute value of the focus determination signal Ef becomes smaller than the threshold value TH2 by repeating this AF cycle operation, the calculation unit 32 specifies the focus position and ends the AF operation in step # 12.

  During the above AF cycle operation, the light quantity determination unit 34 receives the respective digital range signals A and B of the respective received light amounts of the respective light receiving elements 21a and 21b from the calculation unit 32 in step # 13, and receives the light received by the light receiving sensor 21. The amount is determined with reference to each light amount determination signal “0” “1”... “5” stored in the light amount determination table 35 in advance.

  That is, as shown in FIG. 5, when the light amount value of the digital range signal A or B is within the range of threshold TH1 ≦ max (A or B) ≦ TH0, as shown in FIG. And a light amount determination signal determined in the previous AF cycle, for example, a light amount determination signal “0” is sent to the timing generator 36.

  The timing generator 36 receives a light amount determination signal determined by the light amount determination unit 34, for example, a light amount determination signal “0”, and an integration time corresponding to the light amount determination signal “0” from the timing storage table 37 shown in FIG. 1024 μs) and the A / D conversion start time (for example, 1025 μs), the integration time is set in the integration circuit 30, and the A / D conversion start time is set in the A / D conversion unit 31.

  Further, the light amount determination unit 34 decrements the light amount determination signal of the light amount determination table 35 by 1 when the light amount value of the digital value range signal A or B is threshold value TH1> max (A or B), For example, a light amount determination signal “1” decremented by 1 from the light amount determination signal “2” is sent to the timing generator 36.

  The timing generator 36 receives a light amount determination signal determined by the light amount determination unit 34, for example, a light amount determination signal “1”, and an integration time (for example, 256 μs) corresponding to the light amount determination signal “1” from the timing storage table 37 and A The / D conversion start time (for example, 257 μs) is read, and the integration time is set in the integration circuit 30 and the A / D conversion start time is set in the A / D conversion unit 31.

  Further, the light amount determination unit 34 increments the light amount determination signal of the light amount determination table 35 by 1 when the light amount value of the digital value range signal A or B is threshold value max (A or B)> TH0, For example, a light amount determination signal “1” incremented by 1 from the light amount determination signal “0” is sent to the timing generator 36.

  The timing generator 36 receives a light amount determination signal determined by the light amount determination unit 34, for example, a light amount determination signal “1”, and an integration time (for example, 256 μs) corresponding to the light amount determination signal “1” from the timing storage table 37 and A The / D conversion start time (for example, 257 μs) is read, and the integration time is set in the integration circuit 30 and the A / D conversion start time is set in the A / D conversion unit 31.

  The light amount determination unit 34 does not increase or decrease the light amount determination signal when the upper and lower limits of the light amount determination signal exceed the upper limit “5” and the lower limit “0” of the light amount determination signal due to increase or decrease of the light amount determination signal. Holds the current light quantity determination signal.

  As a result, as shown in FIG. 13, the in-focus period includes an integration time by the integration circuit 30 and an A / D processing time (signal) in the A / D conversion unit 31 that starts immediately after the integration processing of the integration circuit 30 ends. Processing time). The A / D converter 31 digitally converts the range signals A and B of the light receiving elements 21a and 21b in a certain processing time Tc.

  Therefore, for example, in the case of the light quantity determination signal “0”, the focusing period is 1024 μs + Tc from the integration time (for example, 1024 μs) and the constant processing time Tc in the A / D conversion, and similarly, the light quantity determination signal “1”. In this case, 258 μs + Tc, and in the case of the light quantity determination signal “2”, 64 μs + Tc. That is, the focusing period is set shorter as the amount of light received by the light receiving sensor 21 increases.

  However, the integration circuit 30 receives the sensor signals output from the light receiving elements 21a and 21b of the light receiving sensor 21 at the integration time when the setting is changed, for example, the integration time 1024 μs when it is determined as the light amount determination signal “0”. Integrate. For example, the A / D conversion unit 31 performs A / D conversion at a fixed processing time Tc from the A / D conversion start time 1025 μs when it is determined as the light amount determination signal “0”.

  As described above, according to the first embodiment, the integration circuit 30 integrates the analog detection signal corresponding to the amount of light received when the light beam from the sample S is received by the light receiving sensor 21 through the observation optical system. When the / D conversion unit 31 converts the digital value into a digital value at a fixed processing time Tc and performs focus determination, the received light amount is determined based on the digital range signals A and B corresponding to the received light amount at the light receiving sensor 21. Then, based on the light quantity determination signal “0”, “1”... Or “5”, the integration time in the integration circuit 30 and the A / D conversion start time in the A / D conversion unit 31 are respectively changed.

  As a result, the focusing cycle can start signal processing immediately after the end of the integration time as shown in FIG. 13 without causing a waiting time from the end of the integration time to the start of signal processing as in the prior art. Can be variably set to an appropriate time length according to the increase or decrease in the amount of light received at. Therefore, the focusing period of the time length corresponding to the amount of light received by the light receiving sensor 21 can be quickly repeated, and the repetition period of the AF cycle is executed quickly, and as a result, high-speed focusing processing can be realized. For example, the focusing period is shortened, for example, with an increase in the amount of light received by the light receiving sensor 21, and the time until focusing is completed can be shortened.

  Next, a second embodiment of the present invention will be described with reference to the drawings. The same parts as those in FIG. 1 and FIG.

FIG. 14 is a specific configuration diagram of the signal processing unit 26 and the control unit 25. The magnification detector 40 recognizes the magnification of the objective lens 5 attached to the observation optical system. Specifically, the magnification detector 40 receives the objective lens attachment position signal output from the revolver hole position detector 8 and receives the optical axis p. The magnification of the objective lens 5 is recognized from the position of the objective lens mounted on ₁ .

  In the timing storage table 41, as shown in FIG. 15, a plurality of magnification information of the objective lens 5, for example, 5 times, 10 times, and 20 times, and the received light amounts, that is, the respective light amounts by the light receiving sensor 21 set for each magnification information. A plurality of integration times in the integration circuit 30 corresponding to the determination signal and a plurality of A / D conversion start times in the A / D conversion unit 31 are stored in advance. Among these, the integration time is set to be longer when the magnification of the objective lens 5 is higher and shorter when it is lower for the same light quantity determination signal. For example, in the light quantity determination signal “0”, the integration time is, for example, 32 μs at 5 × magnification of the objective lens 5, 243 μs at 10 × magnification of the objective lens 5, and 1024 μs at 20 × magnification of the objective lens 5.

  The timing generator 42 receives the magnification information of the objective lens 5 recognized from the magnification detection unit 40, corresponds to this magnification information, and starts integration time and A / D conversion corresponding to the light amount determination signal from the light amount determination unit 34. The time is read from the timing storage table 41 and is variably set in the integration circuit 30 and the A / D conversion unit 31, respectively.

  Next, the AF operation will be described according to the AF flowchart shown in FIG.

When the observer presses the AF start switch in the operation unit 27 while the sample S is away from the focus position, the control unit 25 determines in step # 1 that the AF start switch has been pressed, in the next step # 20, the magnification detector 40, the objective lens 5 from the objective lens mounting position receiving objective lens mounting position signal are arranged on the optical axis p ₁ output from the revolver hole position detector 8 Recognize magnification. Each magnification of the objective lens 5 to be attached to each of the objective lens mounting position of the revolver body 6, because it is set in advance by the viewer from the arranged objective lens mounting position on the optical axis p ₁ of the objective lens 5 The magnification can be recognized.

Next, the magnification detector 40, at step # 2, the threshold value set for each magnification of the objective lens 5 TH0, TH1, TH2 objective lens was actually disposed on the optical axis p ₁ from the combinations of 5 Threshold values TH0, TH1, and TH2 corresponding to the magnification of are selected and set.

  Next, in step # 21, the magnification detection unit 40 replaces the timing storage table 41 shown in FIG. 15 with a table of integration time and A / D conversion start time corresponding to the magnification of the objective lens 5. For example, when the objective lens 5 is switched from 20 times magnification to 10 times magnification, the magnification detection unit 40 is a table of integration time and A / D conversion start time corresponding to 20 times magnification of the objective lens 5 in the timing storage table 41. Are replaced with a table of integration time and A / D conversion start time corresponding to a magnification of 10 times.

  Hereinafter, the processes from Step # 3 to Step # 12 are the same as those in the first embodiment.

  Next, a setting for changing the integration time and the A / D conversion start time during the AF cycle operation will be described.

  In step # 13, the light quantity determination unit 34 receives the respective digital range signals A and B of the respective received light amounts of the respective light receiving elements 21a and 21b from the calculation unit 32 in the same manner as in the first embodiment, and receives the light receiving sensor 21. Is determined with reference to each light quantity determination signal “0” “1”... Or “5” stored in the light quantity determination table 35 in advance, and the light quantity determination signal “0” “1”. “5” is transmitted.

  The timing generator 36 receives a light amount determination signal determined by the light amount determination unit 34, for example, a light amount determination signal “0”, and uses, for example, a table of 10 × magnification of the objective lens 5 from the timing storage table 37 shown in FIG. The integration time (for example, 243 μs) corresponding to the light quantity determination signal “0” and the A / D conversion start time (for example, 244 μs) are read, and the integration time is set in the integration circuit 30 to start the A / D conversion. Time is set in the A / D converter 31.

  However, the integration circuit 30 receives each sensor signal output from each of the light receiving elements 21a and 21b of the light receiving sensor 21 at an integration time whose setting has been changed, for example, an integration time of 243 μs when it is determined that the light amount determination signal is “0”. Integrate. For example, the A / D conversion unit 31 performs A / D conversion at a fixed processing time Tc from the A / D conversion start time 244 μs when it is determined as the light amount determination signal “0”.

  As described above, according to the second embodiment, the integration time corresponding to the magnification information of the objective lens 5 recognized by the magnification detection unit 40 and the A / D conversion start time can be changed. . Thus, the amount of light received by the light receiving sensor 21 varies depending on the magnification of the objective lens 5, that is, the amount of light received by the light receiving sensor 21 decreases when the magnification of the objective lens 5 increases, and the amount of light received by the light receiving sensor 21 decreases when the magnification decreases. Therefore, an appropriate integration time corresponding to the magnification of the objective lens 5 and the start time of A / D conversion can be changed and set. Accordingly, it is possible to realize a high-speed focusing process by setting the focusing period to an appropriate time length according to the magnification of the objective lens 5 and the amount of light received by the light receiving sensor 21.

  Next, a third embodiment of the present invention will be described.

  First, the relationship between the driving speed of the stage 1 and the amount of light reflected from the sample S will be described. The basic speed of the stage 1 is determined for each objective lens 5. This basic speed will be described with reference to FIG. In FIG. 10, the horizontal axis represents the stage coordinates, and the vertical axis represents the intensity of the laser light reflected from the sample S. The figure shows a laser intensity distribution of the reflectance R (= 3%) of the sample S, for example, glass, and a laser intensity distribution of the reflectance R (= 100%), for example, of a mirror. When the reflectance of the sample S is low, the reflected laser light intensity is lower than the laser light intensity projected onto the sample S.

  The threshold value TH1 is set in consideration of so-called noise components such as dark output of a light receiving sensor (for example, a two-divided photodiode, two-divided detector) 21 that detects reflected laser light from the sample S. When the reflected laser beam intensity is greater than or equal to the threshold TH1, it is determined that the sample S exists, and scanning for focusing on the sample S is performed as described in the first embodiment. Note that the moving range (elevating range) of the stage 1 at which the reflected laser light intensity is equal to or higher than the threshold TH1 varies depending on the reflectance of the sample S. For example, if the sample S has a reflectance of 3%, Zb shown in FIG. In the case of the sample S having a reflectance of 100%, for example, it is Za shown in FIG.

The search speed when performing the focusing scan on the sample S is determined by the moving range of the stage 1. In this case, since the reflectance of the sample S is unknown at the start of AF, the speed must be set so that the moving range Zb of the narrower stage 1 can be detected with a reflectance of 3%, for example. However, the search speed is
Search speed = Zb / focusing cycle. If the sample S is focused at such a search speed, the movement range Zb of the stage 1 is surely detected, and the presence or absence of the sample S can be detected regardless of the reflectance of the sample S.

  On the other hand, when the sample S has a high reflectance, the moving range Za of the stage 1 that can detect the sample S is wider than the moving range Zb. As a result, the sample S can be detected even when the search speed is high. However, in the third embodiment, when the amount of reflected light from the sample S is large, the driving speed of the stage 1 is increased.

  This will be specifically described below. FIG. 17 is a specific configuration diagram of the signal processing unit 26 and the control unit 25. The same parts as those in FIG. 1 and FIG.

  In the speed table 50, a plurality of speed signals corresponding to the amount of light received by the light receiving sensor 21 are stored in advance. Specifically, in the speed table 50, as shown in FIG. 18, speed signals “4”, “6”, and “12” corresponding to the light quantity determination signals “0”, “1”, and “5” are stored in advance. Yes. These speed signals “4”, “6”,..., “12” are set so as to increase as the amount of light received by the light receiving sensor 21 increases and to decrease as the amount of received light decreases.

  The speed control unit 51 drives the focusing motor drive control unit 3 to change the driving speed for moving the sample S to the in-focus position of the observation optical system. The received light amount determined by the light amount determination unit 34, that is, The speed signals “4”, “6”,..., Or “12” corresponding to the light quantity determination signals “0”, “1”,..., “5” are read from the speed table 50 and variably set in the focusing motor drive control unit 3.

  Next, change setting between the integration time and the A / D conversion start time during the AF cycle operation will be described with reference to an AF flowchart shown in FIG. The processing from step # 1 to # 12 is the same as that in the first embodiment.

  In step # 13, the light quantity determination unit 34 receives the respective digital range signals A and B of the respective received light amounts of the respective light receiving elements 21a and 21b from the calculation unit 32 in the same manner as in the first embodiment, and receives the light receiving sensor 21. Is determined with reference to each light quantity determination signal “0” “1”... Or “5” stored in the light quantity determination table 35 in advance, and the light quantity determination signal “0” “1”. “5” is transmitted. For example, when the light quantity determination unit 34 is in the state of sending the light quantity judgment signal “1” and the amount of light received by the light receiving sensor 21 is increased, the light quantity judgment signal “1” is changed to “2” and sent. To do.

  Next, when the light amount determination signal sent from the light amount determination unit 34 changes from “1” to “2” in step # 30, the speed control unit 51 changes the speed signal read from the speed table 50 from “6” to “ Change to 8 ”.

  Next, in step # 31, the speed control unit 51 variably sets the speed signal “8” read from the speed table 50 in the focusing motor drive control unit 3. Thereby, the focusing motor drive control unit 3 moves the stage 1 up and down at a driving speed according to the speed signal “8”.

  At the same time, the timing generator 42 receives the light amount determination signal determined by the light amount determination unit 34, for example, the light amount determination signal “2”, and corresponds to the light amount determination signal “2” from the timing storage table 37 shown in FIG. An integration time (for example, 64 μs) and an A / D conversion start time (for example, 65 μs) are read, and the integration time is set in the integration circuit 30 and the A / D conversion start time is set in the A / D conversion unit 31.

  However, the stage 1 is moved up and down at a driving speed according to the speed signal “8”, and the integration circuit 30 together with this, the integration time when the setting is changed, for example, the integration time 243 μs when determined as the light quantity determination signal “0”. Then, each sensor signal output from each of the light receiving elements 21a and 21b of the light receiving sensor 21 is integrated, and the A / D conversion unit 31 starts A / D conversion when it is determined that the light amount determination signal is “0”, for example. A / D conversion is performed at a constant processing time Tc from time 244 μs.

  As described above, according to the third embodiment, the integration time in the integration circuit 30 and the start time of the A / D conversion in the A / D conversion unit 31 are variable according to the amount of light received by the light receiving sensor 21. In addition to setting, the driving speed of the stage 1 is variably set according to the amount of light received by the light receiving sensor 21. As a result, the focusing period can be shortened, and the time required to reach the in-focus position by increasing the driving speed of the stage 1 can be shortened. As a result, the focusing speed can be increased.

  Next, a fourth embodiment of the present invention will be described with reference to the drawings. The same parts as those in FIG. 14 are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 20 is a specific configuration diagram of the signal processing unit 26 and the control unit 25.

Magnification detection unit 40 receives the objective lens mounting position signal outputted from the revolver hole position detector 8 recognizes the magnification of the objective lens 5 from the objective lens mounting position disposed on the optical axis p _1.

  In the timing storage table 41, as shown in FIG. 15, a plurality of magnification information of the objective lens 5, for example, 5 times, 10 times, and 20 times, and the received light amounts, that is, the respective light amounts by the light receiving sensor 21 set for each magnification information. A plurality of integration times in the integration circuit 30 corresponding to the determination signal and a plurality of A / D conversion start times in the A / D conversion unit 31 are stored in advance.

  The timing generator 42 receives the magnification information of the objective lens 5 recognized from the magnification detection unit 40, corresponds to this magnification information, and starts integration time and A / D conversion corresponding to the light amount determination signal from the light amount determination unit 34. The time is read from the timing storage table 41 and is variably set in the integration circuit 30 and the A / D conversion unit 31, respectively.

  In the speed table 60, speed signals for the magnification information of the objective lens 5 recognized by the magnification detection unit 40 are stored in advance. Specifically, as shown in FIG. 21, the speed table 60 includes speed signals “16”, “12”, and “4” corresponding to the magnifications “5 times”, “10 times”, and “20 times” of the objective lens 5. Stored. These speed signals “16”, “12”,..., “4” are set to lower speeds as the magnifications “5 times”, “10 times”, “20 times” of the objective lens 5 become higher.

  The speed control unit 61 receives the magnification information of the objective lens 5 recognized from the magnification detection unit 40, reads the speed signal “16”, “12”... Or “4” corresponding to the magnification information from the speed table 60. The read speed signal “16”, “12”... Or “4” is variably set in the focusing motor drive control unit 3.

  Next, the setting for changing the integration time, the A / D conversion start time, and the driving speed of the stage 1 during the AF cycle operation will be described.

First, the magnification detection unit 40 receives the objective lens mounting position signal output from the revolver hole position detection unit 8 and receives the magnification of the objective lens 5 from the objective lens mounting position arranged on the optical axis p ₁ , for example, a magnification of 10 A double objective lens 5 is recognized. In the same manner as described above, the magnification detection unit 40 replaces the timing storage table 41 shown in FIG. 15 with a table of integration time and A / D conversion start time corresponding to the objective lens 5 having a magnification of 10 times.

  On the other hand, the light quantity determination unit 34 receives the digital range signals A and B of the light reception amounts of the light receiving elements 21 a and 21 b from the calculation unit 32 in the same manner as in the first embodiment, and receives the light received by the light receiving sensor 21. The amount is determined with reference to each light amount determination signal “0” “1”... Or “5” stored in the light amount determination table 35 in advance, and the light amount determination signal “0” “1”. Is sent out.

  The timing generator 42 receives the light amount determination signal determined by the light amount determination unit 34, for example, the light amount determination signal “0”, and uses, for example, the table of the objective lens 5 having a magnification of 10 times from the timing storage table 37 shown in FIG. The integration time (for example, 243 μs) corresponding to the light quantity determination signal “0” and the A / D conversion start time (for example, 244 μs) are read, the integration time is set in the integration circuit 30, and the A / D conversion start time is set. Is set in the A / D converter 31.

  At the same time, the speed controller 61 receives the magnification information of the objective lens 5 having a magnification of, for example, 10 recognized from the magnification detector 40, and the speed table “60” corresponding to the magnification information is shown in the speed table 60 shown in FIG. The read speed signal “12” is variably set in the focusing motor drive control unit 3.

  However, the stage 1 moves up and down at a driving speed according to the speed signal “12”, and the integration circuit 30 simultaneously with the integration time from the respective light receiving elements 21a and 21b of the light receiving sensor 21 with the integration time changed, for example, the integration time 243 μs. Each of the output sensor signals is integrated, and the A / D conversion unit 31 performs A / D conversion at a constant processing time Tc from, for example, A / D conversion start time 244 μs.

  As described above, according to the fourth embodiment, the integration time in the integration circuit 30 and the A / D conversion unit 31 correspond to the magnification information of the objective lens 5 and correspond to the amount of light received by the light receiving sensor 21. A / D conversion start time is variably set, and the drive speed of the stage 1 is variably set in accordance with the magnification information of the objective lens 5 and in accordance with the amount of light received by the light receiving sensor 21. As a result, it is possible to change and set an appropriate integration time corresponding to the magnification of the objective lens 5 and an A / D conversion start time, and to variably set an appropriate driving speed of the stage 1 corresponding to the magnification of the objective lens 5. As a result, the focusing cycle can be shortened, and the time required to reach the in-focus position by increasing the driving speed of the stage 1 can be shortened to increase the focusing speed.

  Next, a fifth embodiment of the present invention will be described with reference to the drawings. 17 identical to those in FIG. 17 are assigned the same reference codes as in FIG.

FIG. 22 is a specific configuration diagram of the signal processing unit 26 and the control unit 25. Magnification detection unit 40 receives the objective lens mounting position signal outputted from the revolver hole position detector 8 recognizes the magnification of the objective lens 5 from the objective lens mounting position disposed on the optical axis p _1.

  In the speed table 70, as shown in FIG. 23, each light quantity determination signal “0” “1”... “5” determined by the light quantity determination unit 34 and each magnification of the objective lens 5 recognized by the magnification detection unit 40, For example, the driving speeds of a plurality of stages 1 corresponding to the magnifications “5 times”, “20 times”, and “100 times” are stored in advance. The driving speed of the stage 1 is set faster with an increase in the amount of light received by the light receiving sensor 21, that is, with each light quantity determination signal “0”, “1”... “5”, and faster as the magnification of the objective lens 5 increases. Is set.

  The speed control unit 71 receives the magnification information of the objective lens 5 recognized by the magnification detection unit 40 and receives the light amount determination signal “0”, “1”... A speed signal “4”, “6”, or “30” corresponding to the magnification of the objective lens 5 and the light amount determination signal “0”, “1”, or “5” from the table 70 is sent to the focusing motor drive control unit 3. Variable setting.

  Next, the setting for changing the integration time, the A / D conversion start time, and the driving speed of the stage 1 during the AF cycle operation will be described.

First, the magnification detection unit 40 receives the objective lens attachment position signal output from the revolver hole position detection unit 8 and receives the magnification of the objective lens 5 from the objective lens attachment position disposed on the optical axis p ₁ , for example, the magnification 5. A double objective lens 5 is recognized.

  On the other hand, the light quantity determination unit 34 receives the digital range signals A and B of the light reception amounts of the light receiving elements 21 a and 21 b from the calculation unit 32 in the same manner as in the first embodiment, and receives the light received by the light receiving sensor 21. The light amount determination signal stored in advance in the light amount determination table 35, for example, a light amount determination signal “0” is determined, and the light amount determination signal “0” is transmitted.

  The timing generator 42 receives, for example, the light amount determination signal “0” determined by the light amount determination unit 34, and uses the table of the objective lens 5 having a magnification of 5 times, for example, from the timing storage table 41 shown in FIG. The integration time corresponding to “0” (for example, 32 μs) and the A / D conversion start time (for example, 33 μs) are read, the integration time is set in the integration circuit 30, and the A / D conversion start time is set to A / D. Set in the conversion unit 31.

  At the same time, the speed controller 71 receives the magnification information of the objective lens 5 having a magnification of, for example, 5 recognized from the magnification detector 40, and also receives the light amount determination signal “0” sent from the light amount determiner 34. For example, the speed signal “16” corresponding to the light quantity determination signal “0” and the objective lens 5 having a magnification of 5 times is variably set in the focusing motor drive controller 3 from the speed table 70 shown in FIG.

  However, the stage 1 moves up and down at the driving speed according to the speed signal “16”, and the integration circuit 30 simultaneously with the integration time from the light receiving elements 21a and 21b of the light receiving sensor 21 with the integration time changed, for example, the integration time 33 μs. Each of the output sensor signals is integrated, and the A / D conversion unit 31 performs A / D conversion at a constant processing time Tc from, for example, 34 μs of A / D conversion start time.

  As described above, in the fifth embodiment, as in the fourth embodiment, an appropriate integration time corresponding to the magnification of the objective lens 5 and the start time of A / D conversion can be changed and set. The driving speed of the stage 1 can be variably set according to the magnification of the objective lens 5. As a result, the focusing cycle can be shortened, and the time required to reach the in-focus position by increasing the driving speed of the stage 1 can be reduced. It can be shortened to increase the focusing speed.

  Next, a sixth embodiment of the present invention will be described with reference to the drawings. The same parts as those in FIG. 8 are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 24 is a specific configuration diagram of the signal processing unit 26 and the control unit 25. When the focusing determination unit 33 determines that the sample S is focused for each focusing cycle, it sends a drive stop signal to the focusing motor drive control unit 3 and simultaneously with this, the counter 80 is sent to the counter 80. An increment signal for incrementing by one is sent.

  The counter 80 receives the increment signal sent from the in-focus determination unit 33 for each in-focus period and performs a counting operation to count the in-focus frequency.

  In the focusing number setting table 81, the number of focusing determinations corresponding to the amount of light received by the light receiving sensor 21 is stored in advance. Specifically, in the focusing number setting table 81, as shown in FIG. 25, each focusing number value “1” corresponding to the light amount determination signal “0” “1”. “1”... “5” are stored. These focusing frequency values “1”, “1”... “5” are set to be larger as the amount of light received by the light receiving sensor 21 increases.

  The focusing number setting unit 82 receives the light amount determination signals “0”, “1”,..., Or “5” sent from the light amount determination unit 34 for each focusing period, and the light amount determination signals “0”, “1”,. The focus count value corresponding to “5” is read from the focus count setting table 81 and sent to the focus completion determination unit 83.

  The in-focus completion determination unit compares the in-focus number value sent from the in-focus number setting unit 82 for each in-focus period with the in-focus number of the counter 80, and the in-focus number of the counter 80 becomes the in-focus number value. When it arrives, it is determined that focusing is complete.

  Next, the focusing operation during the AF cycle operation will be described. The change setting operation between the integration time and the A / D conversion start time during the AF cycle operation is the same as that in the first embodiment.

  When the focus determination unit 33 determines that the sample S is in focus because the focus determination signal Ef becomes “0” for each focus cycle, the focus determination unit 33 determines that the focus motor drive control unit 3 is in focus. Then, a drive stop signal is sent, and at the same time, an increment signal is sent to the counter 80.

  The counter 80 receives the increment signal sent from the focus determination unit 33 and counts up by 1 to count the number of focus times.

  At this time, the stage 1 is not moving up and down because a drive stop signal is sent from the focus determination unit 33 to the focus motor drive control unit 3. In this state, the AF cycle proceeds repeatedly.

  In this state, when the focus on the sample S is deviated, the normal AF cycle is resumed, and the focus determination unit 33 determines the focus direction based on the signs “+” and “−” of the focus determination signal Ef, and A focusing operation is performed to send the control signal to the focusing motor drive control unit 3 so as to set the focusing determination signal Ef to “0” and lead the sample S to the focusing position.

  Thereafter, when the sample S is focused, the focus determination unit 33 determines again that the sample S is focused and stops driving the focusing motor drive control unit 3. At the same time, an increment signal is sent to the counter 80. The counter 80 receives the increment signal sent from the focus determination unit 33 and counts up by 1 to count the number of focus times.

  On the other hand, similarly to the first embodiment, the light quantity determination unit 34 receives the respective digital range signals A and B of the respective received light amounts of the respective light receiving elements 21a and 21b from the calculation unit 32 for each focusing period, and receives the light. The amount of light received by the sensor 21 is determined as a light amount determination signal stored in the light amount determination table 35 in advance, for example, a light amount determination signal “0”, and the light amount determination signal “0” is transmitted.

  The focusing number setting unit 82 receives the light amount determination signal “0” sent from the light amount determination unit 34 for each focusing cycle, and focuses the focusing number value “1” corresponding to the light amount determination signal “0”. It is read from the number-of-times setting table 81 and sent to the in-focus completion determination unit 83.

  The in-focus completion determination unit compares the in-focus number value “1” sent from the in-focus number setting unit 82 for each in-focus period with the in-focus number of the counter 80. As a result of this comparison, when the in-focus count of the counter 80 reaches the in-focus count value, the in-focus completion determination unit determines that in-focus is complete. In this case, it is determined that focusing is completed based on the number of focusings that increases as the amount of light received by the light receiving sensor 21 increases. When focusing is completed, the AF cycle stops.

  As described above, according to the sixth embodiment, the counter 80 counts the number of focusing times, compares the number of focusing times with the focusing number value corresponding to the amount of light received by the light receiving sensor 21, and determines the counter 80. When the in-focus count reaches the in-focus count value, it is determined that focusing is complete. Since the focusing period is variably set according to the amount of light received by the light receiving sensor 21, the focusing determination value for determining completion of focusing can be varied according to the focusing period. For example, when the amount of light received by the light receiving sensor 21 is large, the focusing cycle is shortened. At the same time, by increasing the in-focus determination value, the period for determining in-focus can be increased. Thereby, for example, when the microscope main body vibrates due to camera shake or the like, and this vibration is transmitted to the sample S via the stage 1, the number of in-focus times of the counter 80 reaches the in-focus number value. It is possible to eliminate vibration in the meantime, complete focusing without being affected by camera shake or the like, and prevent a focus determination error.

  In this way, the number of focusing is counted by the counter 80, the number of focusing is compared with the number of focusing according to the amount of light received by the light receiving sensor 21, and the number of focusing of the counter 80 reaches the number of focusing. The method for determining that the in-focus state has been completed can be applied to the first to fifth embodiments.

  Note that the present invention is not limited to the first to sixth embodiments as they are, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage.

  For example, the adjustment of the distance between the sample S and the objective lens 5 is not limited to the stage 1 being driven up and down, and for example, a mechanism that moves the revolver body 6 to which the objective lens 5 is attached in the vertical direction may be used.

  The AF operation is not limited to the so-called active AF in which the sample S is irradiated with the laser light and the AF operation is performed based on the reflected light. The image of the sample S is detected by, for example, a CCD line sensor, and the contrast of the image data is detected. The present invention can also be applied to a so-called passive AF operation that performs an AF operation based on a value.

  In the active AF, the threshold value TH1 used for determining whether or not it is near the in-focus position is set with respect to the intensity max (A, B) of the laser beam. In the passive AF, a CCD line sensor or the like is used. An AF operation can be performed by setting the threshold value TH1 for the total contrast value of the detected image of the sample S.

  Operations such as start / stop of AF operation and switching of the objective lens 5 are performed by a switch provided in the operation unit 27. However, the operation is not limited to this, and for example, a communication command by a host personal computer connected to the control unit 25 A method of setting by may be used.

The block diagram which shows the microscope using 1st Embodiment of the automatic focusing apparatus which concerns on this invention. The figure which shows intensity distribution of the spot imaged on the light reception sensor when the sample in the same apparatus is arrange | positioned in a focus position. The figure which shows intensity distribution of the spot imaged on the light reception sensor when the sample in the same apparatus is arrange | positioned in a back focus position. The figure which shows intensity distribution of the spot imaged on the light reception sensor when the sample in the same apparatus is arrange | positioned in a front focus position. The figure which shows each range signal of the incident light intensity according to each range in the light reception sensor in the same apparatus. The figure which shows the addition signal A + B of each range signal in the same apparatus. The figure which shows the focus determination signal Ef value in the same apparatus. The specific block diagram of the signal processing part and control part in the apparatus. The schematic diagram of the light quantity determination table in the same apparatus. The figure for demonstrating the effect | action of the light quantity determination part in the apparatus. The schematic diagram of the timing storage table in the same apparatus. An AF flowchart in the apparatus. The figure which shows the focusing period in the same apparatus. The specific block diagram of the signal processing part and control part in 2nd Embodiment of the automatic focusing apparatus which concerns on this invention. The schematic diagram of the timing storage table in the same apparatus. An AF flowchart in the apparatus. The specific block diagram of the signal processing part and control part in 3rd Embodiment of the automatic focusing apparatus which concerns on this invention. The schematic diagram of the speed table in the same apparatus. An AF flowchart in the apparatus. The specific block diagram of the signal processing part and control part in 4th Embodiment of the automatic focusing apparatus which concerns on this invention. The schematic diagram of the speed table in the same apparatus. The specific block diagram of the signal processing part in the 5th Embodiment of the automatic focusing apparatus which concerns on this invention, and a control part. The schematic diagram of the speed table in the same apparatus. The specific block diagram of the signal processing part in the 6th Embodiment of the automatic focusing apparatus which concerns on this invention, and a control part. The schematic diagram of the focusing frequency setting table in the same apparatus. The figure which shows the focusing period which detects the focus degree with respect to a sample. The figure which shows the case where waiting time arises in the focusing period which detects the focus degree with respect to a sample.

Explanation of symbols

  S: Sample, 1: Stage, 2: Focusing motor, 3: Focusing motor drive unit, 4: Electric revolver, 5: Objective lens, 6: Revolver body, 7: Revolver motor, 8: Revolver hole position detection , 9: Revolver motor drive unit, 10: Reference light source, 11: Laser drive unit, 12: Collimator lens, ST: Projection side stopper, 13: Polarizing beam splitter, 14: Condensing lens group, 15: Color correction Lens group, 16: λ / 4 plate, 17: Dichroic mirror, 18: Motor for driving chromatic aberration lens, 19: Chromatic lens driving unit, 20: Condensing lens group, 21: Light receiving sensor, 21a, 21b: Light receiving element, 22 : Light source for illumination, 23: Lens, 24: Half mirror, 25: Control unit, 26: Signal processing unit, 27: Operation unit, 28: Pulse counter, 29: JOG encoder, 3 : Integration circuit, 31: A / D conversion unit, 32: calculation unit, 33: focus determination unit, 34: light amount determination unit, 35: light amount determination table, 36: timing generator, 37: timing storage table, 40: magnification Detection unit, 41: Timing storage table, 42: Timing generator, 50: Speed table, 51: Speed control unit, 60: Speed table, 61: Speed control unit, 70: Speed table, 71: Speed control unit, 80: Counter 81: Focusing number setting table 82: Focusing number setting unit.

Claims (26)

While changing the distance between the sample and the observation optical system, the light beam from the sample is received by the light receiving element through the observation optical system, and the analog detection signal corresponding to the amount of light received output from the light receiving element is integrated. Later, in the automatic focusing method in which the integral value is converted into a digital value in a fixed processing time, and the focusing determination is performed based on the digital value,
The amount of light received by the light receiving element is determined based on the detection signal output from the light receiving element, the integration time of the detection signal is varied according to the amount of received light, and immediately after the integration processing of the detection signal is completed. To set the start time of the conversion to the digital value,
An automatic focusing method characterized by that. 2. The automatic focusing method according to claim 1, wherein the integration time of the detection signal varies short when the amount of light received by the light receiving element increases, and varies long when the amount of received light decreases. The focusing determination is performed by repeating a focusing cycle consisting of the integration processing of the analog detection signal and the conversion processing to the digital value immediately after the integration processing,
2. The automatic focusing method according to claim 1, wherein when the integration time corresponding to the amount of received light is obtained, the integration time is varied in a focusing period next to the focusing period for which the integration time is obtained. . The automatic focusing method according to claim 1, wherein the integration time of the detection signal varies according to magnification information of the observation optical system. 5. The automatic focusing method according to claim 4, wherein the integration time of the detection signal is changed long when the magnification of the observation optical system is high, and short when the magnification is low. 2. The automatic focusing method according to claim 1, wherein a driving speed for changing a distance between the sample and the observation optical system is varied in accordance with the determined amount of received light. The driving speed for changing the distance between the sample and the observation optical system is varied rapidly when the amount of light received by the light receiving element is increased, and is varied slowly when the amount of received light is decreased. 6. The automatic focusing method according to 6. 2. The automatic focusing according to claim 1, wherein the magnification information of the observation optical system is recognized, and the driving speed for varying the distance between the sample and the observation optical system is varied according to the magnification information. Method. 9. The driving speed for changing the interval between the sample and the observation optical system is varied slowly when the magnification information of the observation optical system is high, and is varied rapidly when the magnification information is low. Automatic focusing method. According to the determined amount of received light, the observation optical system varies the in-focus determination number of times to focus on the sample,
Based on the digital value after integration processing of the analog detection signal, the number of focusing is counted for each focusing cycle for performing the focusing determination, and when the count value reaches the focusing determination number, the focusing is completed. judge,
The automatic focusing method according to claim 1, wherein: 11. The automatic focusing method according to claim 10, wherein the number of focusing determinations is varied as the amount of light received by the light receiving element increases, and varies as the amount of received light decreases. While changing the distance between the sample and the observation optical system, the light beam from the sample is received by the light receiving element through the observation optical system, and an analog detection signal corresponding to the amount of light received output from the light receiving element is received by the integration circuit. In an automatic focusing device that performs integration processing, and thereafter converts the output of the integration circuit into a digital value in a predetermined processing time by an A / D converter, and performs focusing determination based on the digital value.
A light amount determination unit that determines the amount of light received by the light receiving element based on the digital value corresponding to the amount of light received by the light receiving element;
The integration time of the detection signal in the integration circuit is varied in accordance with the amount of received light determined by the light quantity determination unit, and the start time of the A / D conversion in the A / D conversion unit is changed in the integration circuit. A timing generator to be set immediately after completion of the integration process;
An automatic focusing device characterized by comprising: A timing storage table that stores in advance a plurality of the integration times corresponding to the amount of light received by the light receiving element and a plurality of the start times in the A / D conversion;
The timing generation unit reads the integration time corresponding to the amount of received light determined by the light amount determination unit and the start time of the A / D conversion from the timing storage table, and the integration circuit and the A / D respectively. Variably set in the converter,
The automatic focusing device according to claim 12, wherein: The timing storage table is shortened in accordance with an increase in the amount of received light at the light receiving element set for each of the light amount determination data and a plurality of levels of light amount determination data corresponding to the amount of received light determined by the light amount determination unit. 14. The automatic focusing device according to claim 13, wherein a plurality of the integration times and a plurality of the start times of the A / D conversion set immediately after the integration times are ended are stored. The observation optical system can be attached with a plurality of objective lenses each having a different magnification.
A magnification detector that recognizes the magnification of the objective lens attached to the observation optical system;
The timing generation unit variably sets the integration time in the integration circuit according to magnification information of the objective lens recognized by the magnification detection unit;
The automatic focusing device according to claim 12, wherein: A plurality of magnification information of the objective lens, a plurality of integration times corresponding to the amount of light received by the light receiving element set for each magnification information, and a plurality of the start times of the A / D conversion are stored in advance. Timing storage table
The timing generation unit corresponds to the magnification information of the objective lens and indicates the integration time corresponding to the received light amount determined by the light amount determination unit and the start time of the A / D conversion in the timing storage table. Are variably set in the integration circuit and the A / D conversion unit, respectively.
The automatic focusing device according to claim 12, wherein: 17. The automatic focusing apparatus according to claim 16, wherein the timing storage table stores the integration time that is longer when the magnification of the objective lens is higher and shorter when the magnification is lower. A stage on which the sample is placed;
A stage driving unit for raising and lowering the stage;
A speed control unit that drives the stage driving unit to vary the driving speed for moving the sample to the in-focus position of the observation optical system;
13. The automatic focusing device according to claim 12, further comprising: A speed table in which a plurality of the speed signals corresponding to the amount of light received by the light receiving element are stored in advance;
The speed control unit reads the speed signal according to the received light amount determined by the light amount determination unit from the speed table and variably sets the stage driving unit;
The automatic focusing device according to claim 18, wherein: 20. The automatic focusing apparatus according to claim 19, wherein the speed table stores the speed signal that increases when the amount of light received by the light receiving element increases and decreases when the amount of received light decreases. A stage on which the sample is placed;
A stage driving unit for raising and lowering the stage;
A magnification detector for recognizing the magnification information of the observation optical system;
A speed control unit that drives the stage driving unit based on the magnification information recognized by the magnification detection unit to vary a driving speed for moving the sample to a focusing position of the observation optical system;
13. The automatic focusing device according to claim 12, further comprising: Having a speed table pre-stored with a plurality of speed signals according to a plurality of magnification information;
The speed control unit reads the speed signal according to the magnification information recognized by the magnification detection unit from the speed table and variably sets the stage driving unit;
The automatic focusing device according to claim 21, wherein 23. The automatic focusing apparatus according to claim 22, wherein the speed table stores the speed signal that is slow when the magnification information is high and is fast when the magnification information is low. A stage on which the sample is placed;
A stage driving unit for raising and lowering the stage;
A magnification detector for recognizing the magnification information of the observation optical system;
A speed table that stores in advance the received light amount determined by the light amount determination unit, a plurality of pieces of magnification information of the objective lens, and a speed signal of the stage driving unit set for each piece of magnification information;
A speed controller corresponding to the magnification information of the objective lens and reading the speed signal according to the amount of received light determined by the light quantity determination unit from the speed table and variably setting the stage drive unit;
13. The automatic focusing device according to claim 12, further comprising: An in-focus determination unit that performs the in-focus determination based on the A / D converted digital value after integrating the analog detection signal output from the light receiving element;
A counter that counts the number of in-focus times determined to be in focus at each in-focus period by the in-focus determination unit;
A focusing number setting table that stores in advance the number of focusing determinations according to the amount of light received by the light receiving element;
Read the in-focus determination number according to the received light amount determined by the light amount determination unit from the in-focus number setting table, and when the in-focus number of the counter reaches the in-focus determination number A focus completion determination unit for determining,
13. The automatic focusing device according to claim 12, further comprising: 26. The in-focus count setting table stores the in-focus determination count that increases as the amount of light received by the light receiving element increases and decreases as the amount of received light decreases. Automatic focusing device.

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