JP2002341234A - Automatic focusing device for microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic focusing device for a microscope, which can perform easy initial adjustment and secure sufficient automatic focusing performance. SOLUTION: This device is equipped with a 1st detecting means (13) which detects a light image from a sample S, a 1st focal length adjusting means (26) which adjusts the focal length of the light image, a light projecting means (37) which projects light on the sample S, a 2nd detecting means (17) which detects the light image reflected by the sample S, a 2nd focal length adjusting means (26) which adjusts the focal length of the light image, a 1st focusing state deciding means (26) which decides the focusing state of the sample S, a 1st focusing position adjusting means (26) which adjusts the focusing position of the sample S according to the signal of the 1st deciding means, a 2nd focusing state deciding means (26) which decides the focusing state of the sample S, and a 2nd focusing position adjusting means (26) which adjusts the focusing position of the sample S according to the signal of the 2nd deciding means; and the 2nd focal length adjusting means performs the adjustment according to both the signals from the 1st and 2nd focusing state deciding means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autofocus apparatus mounted on a microscope system having an electric focusing mechanism for adjusting a relative distance between an observation sample and an objective lens for focusing.

[0002]

2. Description of the Related Art In recent years, microscopes capable of observing a fine sample and recording an observed image as a video image have been widely used in research fields in the biological field and in inspection processes in the industrial field. When such a microscope is used, usually, a focus adjustment is performed on an observation sample by operating a focusing handle, and a focusing operation is performed.

However, when the depth of focus is small and the focusing range is narrow as in the case of a high-magnification objective lens, considerable skill is required to quickly perform the focusing operation. If this operability is poor, it has an adverse effect of fatigue of the operator and a decrease in production efficiency. Particularly in a routine work such as an inspection process, it is very important to perform this operation quickly and to reduce the inspection time.

Therefore, various autofocus (AF) devices for microscopes capable of automatically performing such a focusing operation have been proposed, and many proposals have been made for the purpose of improving them. .

The AF apparatus in the industrial field not only improves the operability and throughput as described above, but also applies to a sample having a step, such as a multi-layered semiconductor wafer.
There is a need for applications such as detection and measurement of defects in each layer and line width between patterns without omission, and measurement of minute steps on a specimen with high accuracy. Various AF devices having performances suitable for such inspection and measurement have been proposed.

In such an AF device in the industrial field, light such as an infrared laser is projected onto the sample and the state of the reflected light is detected for reasons such as compatibility with the sample and shortening the AF time. A so-called active AF method for performing a focusing operation is often used.

On the other hand, in the biological field, a more accurate focus position is required, and a transmission type specimen having a low reflectance, which is impossible with the active method, is used. A so-called passive AF method for performing an AF operation is mainly used.

[0008]

The active type AF is
Since the reflected light intensity of the light (laser light or the like) projected onto the sample is used, the focusing speed is faster than that of passive AF in which the contrast of the sample image is obtained by an image sensor (CCD or the like). In addition, a focusing operation can be performed on a sample having no contrast, such as a mirror surface, if there is reflected light. However, when the sample position on which the detection light is projected has a step or inclination, when the sample is a sample having a plurality of reflecting surfaces (such as a sample inside glass), or when the reflected light is not detected due to diffraction or the like. Then, the focusing operation becomes impossible or a malfunction occurs. Further, when a laser light source is used or the like, the focusing operation becomes unstable in a speculum method (for example, a differential interference method) in which an optical element having a polarization component is inserted into an optical path.

On the other hand, in the passive AF, there is no possibility that the AF operation is disabled due to the factors of the active AF as described above. However, the AF for a sample without contrast, which is not a problem in the active AF, is performed. Operation is disabled. In addition, if the amount of observation light is low, the focusing time is greatly increased, and the AF operation becomes impossible.

Therefore, in order to stabilize the AF operation on the sample, the AF operation is performed using both the active type and the passive type.
A so-called hybrid type AF that performs an operation has been devised, and an algorithm for compensating for the weak points of both has been proposed.

For example, in Japanese Patent Application Laid-Open No. 2001-091821, an active type AF is made possible by applying an IR coating to a cover glass placed on a sample on a slide glass to increase the reflectance of infrared light. . This allows the active AF to operate at high speed up to the vicinity of the focus position, and then the passive AF to perform accurate focusing.

Japanese Patent Application Laid-Open No. 10-268198 also uses a hybrid AF to shorten the focusing time. In this proposal, in the active AF, when the focus position is out of the focus detection range, the direction is determined by image contrast detection.

In each of these proposals, an optical system dedicated to the active system and the passive system is mounted.

Incidentally, both types of AF require dedicated initial adjustment. For example, in the passive AF, the imager such as a CCD line sensor or the like is adjusted in the optical axis direction (focus direction) to obtain the same focus between the observed image and the imager. Also, in the active AF, in order to correct out-of-focus due to chromatic aberration between the laser beam and the visible light to be used, it is necessary to adjust an internal lens for chromatic aberration correction for each objective lens to be mounted and to store the position thereof. Required. These initial adjustments often require a lot of time, and in many cases, sufficient AF performance cannot be exhibited due to an incorrect setting by an observer or the like.

In the AF of the hybrid system, both the active system and the passive system must be adjusted, so that the time required for the initial adjustment is longer than that of the AF of the single system. Also, due to the AF shift between both types,
An error or the like in the focusing operation may occur.

As described above, none of the above-mentioned proposals mentions the initial adjustment, and it can be said that the AF requires difficulty in the initial adjustment.

An object of the present invention is to provide an autofocus device for a microscope that can achieve both simple initial adjustment and sufficient autofocus performance.

[0018]

SUMMARY OF THE INVENTION In order to solve the problems and achieve the objects, an autofocus apparatus for a microscope according to the present invention is configured as follows.

(1) A microscope autofocus apparatus according to the present invention is a microscope autofocus apparatus mounted on a microscope having an observation optical system for irradiating a sample with light through an objective lens and observing light from the sample. First detecting means for detecting a light image from the sample, first focal length adjusting means for adjusting a focal length of the light image formed on the first detecting means, and Light projecting means for projecting light on the sample through the objective lens, second detecting means for detecting a light image reflected by the sample by the light projecting means, and the second detecting means Second focal length adjusting means for adjusting the focal length of the light image to be formed on the first focal state, and a first focal state for determining the focal state of the sample based on an output signal from the first detecting means. Determining means;
First focus position adjustment means for adjusting the focus position of the sample based on a signal from the first focus state determination means,
A second focus state determination unit that determines a focus state of the sample based on an output signal from the second detection unit; and a second focus state determination unit that determines the focus state of the sample based on a signal from the second focus state determination unit. A second focusing position adjusting means for adjusting a focusing position, wherein the second focal length adjusting means adjusts based on both signals from the first and second focusing state determining means. I do.

(2) The autofocus apparatus for a microscope according to the present invention is the apparatus described in (1) above, and displays the in-focus state of the sample based on a signal from the first in-focus state determination means. The second focal length adjusting means, during the focusing operation by the second focus position adjusting means, sets the in-focus position based on the display of the in-focus state displaying means. adjust.

(3) The autofocus apparatus for a microscope according to the present invention is the apparatus described in (1) or (2) above, and the second focal length adjusting means is the second focusing position adjusting means. During the focusing operation, the adjustment is performed based on both signals from the first and second focusing state determination means.

As a result of taking the above-described measures, the following effects are obtained.

(1) According to the autofocus apparatus for a microscope of the present invention, in the hybrid AF, the initial adjustment error between the active AF and the passive AF can be reduced. Time can be shortened and accuracy can be improved.

(2) According to the autofocus apparatus for a microscope of the present invention, after performing the adjustment of the passive AF, the initial adjustment of the active AF can be performed while monitoring the in-focus state of the adjusted passive AF. Thus, it is possible to prevent the initial adjustment error of the active AF due to the diopter adjustment of the eyepiece and the thickness of the sample, and to perform the initial adjustment quickly and accurately.

(3) According to the autofocus apparatus for a microscope of the present invention, after the passive AF is adjusted, the initial state of the active AF is automatically adjusted while evaluating the adjusted focusing state signal in the passive AF. The adjustment can be performed, and the microscopic person does not need to check the focus of the observation image or the like, and can perform the active AF adjustment with a simple operation at high speed and with few adjustment errors.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a view showing the entire configuration of an autofocus apparatus for a microscope according to a first embodiment of the present invention.

The electric revolver includes a revolver main body 2, a plurality of objective lenses 3 (3a, 3b), a revolver motor 18,
It comprises a revolver motor drive unit 20 and a revolver hole position detection unit 22. The revolver main body 2 is rotatable, and a plurality of objective lenses 3 can be attached thereto.
The revolver motor drive unit 20 includes a revolver motor 18.
Is electrically driven to rotate the revolver main body 2, and an arbitrary objective lens 3 is inserted into the optical path. The revolver hole position detector 22 detects which objective lens mounting hole of the revolver main body 2 is currently inserted in the optical path.

The revolver main body 2 is driven by a signal from the control unit 26. The control unit 26 controls the revolver motor drive unit 20 in response to a signal from the revolver hole position detection unit 22 indicating the objective lens mounting hole inserted in the current optical path, and controls the revolver motor 18
To rotate the revolver main body 2.

FIG. 2 is a diagram showing the configuration of the control unit 26. The control unit 26 is a well-known CPU circuit, as shown in FIG. 2, a CPU main body 30, a ROM 31 storing a program for controlling the system,
RAM 32 storing volatile data and the like necessary for control, I / O port 3 for inputting and outputting control signals
3. It is composed of well-known peripheral circuits such as an oscillator (not shown) necessary for controlling the CPU and an address decoder. These are connected by a data bus 34.
The CPU main body 30 includes a data bus 34 and an I / O port 33.
, Each peripheral device is controlled.

An observation sample (specimen) S is placed on the sample moving stage 1 and observed through the objective lens 3.
The sample moving stage 1 is moved up and down in the optical axis direction by a focusing motor 19. The focusing motor 19 is electrically driven by the focusing motor drive unit 21. The focusing motor drive unit 21 is controlled by the I / O port 3
3 to be controlled.

First, an active AF optical system will be described.

As the reference light source 4 for the active AF, a light source in the non-visible light wavelength region such as an infrared laser is used. The reference light source 4 is controlled by the laser driving unit 23. The laser drive unit 23 performs pulse lighting of the reference light source 4 and the like, and controls the intensity of the light source. The laser light from the reference light source 4 passes through a collimating lens 5 for keeping parallel light,
Half of the light beam diameter is cut by the light emitting side stopper 6.
After that, only the P-polarized light component is reflected by the PBS 7 and guided to the observation sample S side.

The light beam once collected by the condenser lens group 8 passes through the color correction lens group 9. The chromatic aberration lens group 9 includes a chromatic aberration lens driving unit 35 from the control unit 26.
By controlling the chromatic aberration lens driving motor 36 via the lens, movement in the optical axis direction, that is, correction of chromatic aberration becomes possible.

The light that has passed through the chromatic aberration lens group 9 is λ / 4
The light is polarized by 45 ° when passing through the plate 10 and enters the dichroic mirror 11. Here, since the dichroic mirror 11 reflects only the infrared region, the laser beam is reflected. The reflected light flux transmits through the half mirror 39 and forms a spot-shaped image on the observation sample S by the objective lens 3.

The light beam reflected by the observation sample S enters the dichroic mirror 11 via the objective lens 3 and the half mirror 39. The light beam reflected by the dichroic mirror 11 is further polarized by 45 ° when passing through the λ / 4 plate 10 again, and is switched to an S-polarized light component. Further, the luminous flux passes through a color correction lens group 9 and a condenser lens group 8.
And is incident on the PBS 7. Here, since the light beam is an S-polarized light component, it passes through the PBS 7 as it is and passes through the condenser lens group 12 before being imaged on the light receiving sensor 13.

FIGS. 3A and 3B show the light receiving sensor 13.
FIG. 3 is a diagram showing a state of image formation in FIG. The light receiving sensor 13 is composed of a two-division photodiode that is installed around the optical axis. When the observation sample S is in the focus position, the spot light focused on the light receiving sensor 13 has a narrow and high intensity distribution as shown in FIG. 3B, and the observation sample S is located below the focus position. In the case of (the back focus position), the observation sample S has an intensity distribution biased to the range B in the figure as shown in FIG.
Is located above the focus position (front focus position), the intensity distribution is biased toward the range A in the figure as shown in FIG. 3C, and is converted into the detection signals shown in the figure. .

FIGS. 4A and 4B are diagrams showing the intensity distribution of the signal calculated from the detection signal. The detection signal converted by the light receiving sensor 13 is divided by the signal processing unit 24 into ranges A and B shown in FIGS.
The sum of the intensities in each range is calculated. Accordingly, as shown in FIG. 4A, if the horizontal axis is the vertical direction of the stage (defocus), a signal consisting of two curves A and B symmetrical with respect to the focus position is calculated.

This signal is input to the control unit 26. The control unit 26 calculates a signal (AB) / (A + B) as shown in FIG. 4B from the input A and B signals, and performs a focusing operation based on this signal.

As described above, the laser light is controlled to be turned on, and the reflected light of the laser light beam projected on the observation sample is detected, whereby
An active AF optical system is realized.

Next, a passive AF optical system will be described.

The illumination light for observation from the illumination light source 37 passes through the lens 38, is reflected by the half mirror 39, passes through the objective lens 3, and irradiates the observation sample S from above. The reflected light from the observation sample S passes through the objective lens 3, passes through the half mirror 39, passes through the dichroic mirror 11, and the half becomes the observation light by the half mirror 14,
The other half is guided to a passive AF optical system. The light beam reflected by the half mirror 14 passes through the imaging lens 15 and then enters the passive AF optical element 16.

The passive AF optical element 16 includes a half mirror section 16a and a total reflection mirror section 16b. The light beam transmitted through the half mirror section 16a is
The half mirror section 16a and the total reflection mirror section 1
The light beams reflected by 6b are respectively incident on the portion A of the light receiving sensor 17. The position of the imaging lens 15 is
7 can be adjusted in the direction of the optical axis so that the image forming position of each light beam is immediately before and after the image forming position of the light beam immediately before entering the passive AF optical element 16.

The light receiving sensor 17 is composed of a CCD line sensor, and the signal of the received observation image is subjected to a contrast calculation in the signal processing unit 25. And active type AF
Similarly to the signal detected by the optical system, if the horizontal axis is the vertical direction (defocus) of the stage as shown in FIG. Is calculated.

This signal is input to the control unit 26. The control unit 26 calculates a signal (AB) / (A + B) as shown in FIG. 4B from the input A and B signals, and performs a focusing operation based on this signal.

The control section 26 includes an objective lens conversion switch (not shown) for rotating the revolver main body 2 to change the objective lens 3 inserted into the optical axis, an AF start switch for performing an autofocus operation, and the like. Operating unit 29 is connected. Control part 2
A JOG encoder 28 for instructing the focusing unit to move up and down is connected to 6 via a pulse counter 27. The control unit 26 reads the numerical value of the pulse counter 27, determines in which direction and how much the JOG encoder 28 has been rotated, and determines the JOG encoder 2
Each drive unit is operated in accordance with the rotation amount of 8.

The control unit 26 selects a signal from the active / passive AF optical system configured as described above, and obtains a signal from the curve as shown in FIG. The autofocus operation is performed by moving the sample moving stage 1 to a point where / (A + B)｝ = 0. That is, when the signal strength in the range A is high, the sample moving stage 1 is driven downward, and when the signal strength in the range B is high, the sample moving stage 1 is driven upward. Thus, the sample surface is focused.

The switching between the active type and the passive type is as follows.
According to the reflectance, contrast, etc. of the observation sample, the optimum method is selected with the aim of improving the focusing accuracy, the focusing time, and the compatibility with the sample. Omitted.

Thus, a hybrid AF is realized.

FIG. 5 shows an active / passive AF
6 is a flowchart showing an initial adjustment procedure in FIG. Hereinafter, the initial adjustment in each AF will be described with reference to the flowchart shown in FIG.

First, the passive AF is adjusted.

The examiner presses an initial adjustment mode changeover switch and a passive AF adjustment mode switch (not shown) arranged in the operation section 29 (step S1). The control unit 26 receives this signal and, based on information obtained from the light receiving sensor 17 of the passive AF via the signal processing unit 25,
(AB) / (A + B) is calculated and the operation unit 29
Is turned on.

FIG. 6 is a diagram showing an example of the arrangement of LEDs on the operation unit 29. As shown in FIG. 6, four LEDs 1 to 4 are arranged on the operation unit 29. Each LED
Is based on a predetermined value: TH1 (TH1> 0), if TH1 <(AB) / (A + B), only LED1 lights up. | (AB) / (A + B) | ≦ TH1, only LED2 lights up ( If (AB) / (A + B) <-TH1, only LED3 is lit.

When only the LED 2 is turned on, it is assumed that the light receiving sensor 17 is at the focus position of the observation image. Also L
The ED 4 is turned on when the control unit 26 determines that, for example, the contrast of the observation sample is low and a signal level sufficient for determining the focus state cannot be obtained. In this case, the speculum examiner changes to a sample with high contrast or the like and performs adjustment.

Next, the observer sets the observation sample S on the stage 1, inserts the objective lens 3 having a relatively low magnification into the optical path, and then obtains a sample obtained from an eyepiece or an imaging means such as a TV camera. J to focus on the observation image of
The stage 1 is moved by rotating the OG encoder 28, and the focus is adjusted (step S2). The reason why the low-magnification objective lens is inserted into the optical path is that the thickness of the specimen has less influence on the adjustment than the high-magnification objective lens.

After focusing as described above, the imaging lens 15 is moved in the optical axis direction, and the light receiving sensor 1 is moved at the current stage position while watching the LED display described above.
Adjustment is performed so that the position 7 is the focus position (step S3). The mechanism for adjusting the imaging lens 15 may be a known mechanism that moves the imaging lens 15 attached along a guide with a lead screw, for example. And L
When the adjustment of the imaging lens 15 is completed so that only the ED 2 is turned on, the adjustment of the passive AF is completed.

Next, the process proceeds to the adjustment of the active AF.

In the active AF, as described above, a focus shift caused by a difference in wavelength between the reference light source 4 and the observation light is corrected by moving the chromatic aberration correcting lens group 9. Since the chromatic aberration differs depending on the type of the objective lens, it is necessary to perform this correction for each of the objective lenses to be mounted.

The examiner presses an active AF adjustment mode switch (not shown) arranged in the operation section 29 (step S4). The control unit 26 receives this signal, and calculates (AB) / (A + B) based on information obtained from the light receiving sensor 17 via the signal processing unit 25, as in the case of the above-described adjustment of the passive AF. At the same time, the active AF operation is performed. That is, a command is issued to the laser driving unit 23, the reference light source 4 is turned on, a laser beam is projected on the sample S, and focusing is performed based on a focusing signal calculated from a signal of the return light detected by the light receiving sensor 13. Application motor driver 2
The stage 1 is moved to the focus position by the motor 19 via the motor 1 (step S5).

At this point, since the chromatic aberration lens group 9 has not been corrected, the focusing positions of the active AF and the passive AF are not the same. That is, the AF signals of the active AF and the passive AF have signal curves having different zero cross points (focusing determination positions) as shown in FIGS. 7A and 7B. In FIG. 7, the horizontal axis represents the position of the stage in the optical axis direction (defocus amount), and the vertical axis represents the calculated (AB) / (A + B) level. Also A,
A ′ and A ″ are AF signals in active AF, respectively, and B is an AF signal in passive AF.

At the time when the focusing operation is completed by the active AF and the following operation is performed (the stage stops at the position F in the figure), the control unit 26 evaluates the signal of the passive AF. Since the passive AF signal corresponding to the position of F is P, which is smaller than -TH1 in the figure, the control unit 26 turns on the LED3.

The examiner confirms that the LED 3 is turned on (step S6), and rotates the JOG encoder 28 clockwise (step S7). The control unit 26 controls the chromatic aberration lens group 9 according to the count value of the pulse counter 27.
Is moved in the N direction. Then, the active AF signal changes from A in FIG. 7 to A ′. Along with this, the control section 26 restarts the active AF operation (follows)
Then, the stage 1 is moved to the position of F 'in FIG. The passive AF signal value at this time is P2, and is still −TH.
Since it is less than 1, the control unit 26 keeps lighting the LED3.

The speculum further turns the JOG encoder 28 clockwise (step S7). Control unit 26
Moves the chromatic aberration lens group 9 in the same direction and continues the active AF operation. The active AF signal is shown in FIG.
A ′ changes from A ′ in the middle to A ″, and the focus determination position of the active AF becomes the position of F ″ in FIG. At this time, the passive AF signal value is P3, which is within ± TH1, so that the control unit 26 turns on only the LED2.

In this manner, the position of the chromatic aberration lens group 9 at the stage position where only the LED 2 is turned on is: (focus position on the observation side) = (focus position of the passive AF) = (current objective lens of the active AF) , And each focus position adjustment is completed (step S
9).

Thereafter, the speculum operator presses an objective lens conversion switch (not shown) arranged in the operation section 29 in order to perform the same chromatic aberration lens correction for the other objective lenses (S1).
0). The control unit 26 receives this signal and stores the current position of the chromatic aberration lens group 9 in the objective lens in the internal RAM.
32.

The control section 26 rotates the revolver main body 2 via the revolver motor drive section 20 and the revolver motor 18, inserts the next objective lens 3 into the optical path, and performs the AF process again. At this time, the control unit 2
Reference numeral 6 denotes an AF according to the type of the objective lens 3 to be inserted next.
Parameters (speed, threshold value, etc.) and TH used for
The value of 1 can be selected from the ROM 31 stored in advance.

After setting the correction position of the chromatic aberration lens group 9 for all the objective lenses mounted on the revolver main body 2, the examiner returns the initial adjustment mode changeover switch of the operation unit 29 to the original position. Thus, the initial adjustment of the active AF is completed, and the microscope shifts to a normal use state (step S1).
1).

As described above, according to the first embodiment,
Conventionally, the passive AF and the active AF, which were separately performed, are adjusted.First, the passive AF is adjusted, and then the initial adjustment of the active AF is performed while monitoring the adjusted focusing state of the passive AF. By doing so, it is possible to reduce the focus shift between the two AF methods due to insufficient adjustment or adjustment error.

Further, in the active AF, the chromatic aberration correction work performed while checking the eyepiece and the image every time for each objective lens is changed to the adjustment while checking the LED. In addition, it is possible to prevent erroneous setting of chromatic aberration correction due to the thickness of the sample and the like, and to perform quick and accurate initial adjustment.

In the first embodiment, the focusing operation is performed by moving the stage. However, this operation may be realized by moving the objective lens, the revolver and the like up and down. In the first embodiment, the passive AF light-receiving sensor 17 is a CCD line sensor, but the same effect can be obtained by using an area-type CCD sensor or the like.

(Second Embodiment) The configuration of an autofocus device for a microscope according to a second embodiment of the present invention is the same as that of the first embodiment. 7 and FIG. The difference between the second embodiment and the first embodiment is the adjustment method of the active AF.

FIG. 8 shows an active / passive AF
6 is a flowchart showing an initial adjustment procedure in FIG. Hereinafter, the initial adjustment in each AF will be described with reference to the flowchart shown in FIG.

First, the passive AF is adjusted.

The examiner presses an unillustrated initial adjustment mode changeover switch and a passive AF adjustment mode switch, which are arranged in the operation section 29 (step S21). Passive A
The initial adjustment method in F is the same as that in the first embodiment, and a description thereof will be omitted (steps S22 and S2).
3). When the initial adjustment of the passive AF is completed, the focus position on the observation side and the focus position of the passive AF are the same.

Next, the process proceeds to the adjustment of the active AF.

The examiner presses an active AF adjustment mode switch (not shown) arranged in the operation section 29 (step S24). The control unit 26 receives this signal,
As in the case of the passive AF adjustment described above, the light receiving sensor 17
The active AF operation is performed at the same time as calculating the above (AB) / (A + B) based on the information obtained through the signal processing unit 25 (step S25). That is,
A command is issued to the laser driving unit 23, the reference light source 4 is turned on, the laser light is projected on the sample S, and based on the focusing signal calculated from the signal of the return light detected by the light receiving sensor 13,
The stage 1 is moved to the focus position by the motor 19 via the focusing motor drive unit 21.

At this point, as in the first embodiment, since the chromatic aberration lens group 9 has not been corrected, the in-focus positions of the active AF and the passive AF are not the same. That is, A of each of the active AF and the passive AF
The F signal has different zero cross points (focus determination positions) as shown in FIGS. 7A and 7B.

When the focusing operation is completed by the active AF (step S26), and after the tracking operation (the stage 1 stops at the position F in the figure), the control unit 26 evaluates the signal of the passive AF. (Step S27). The passive AF signal corresponding to the position of F is P, which is smaller than -TH1 in FIG. Therefore, the control unit 26
Chromatic aberration lens driving unit 35 and aberration lens driving motor 3
The chromatic aberration lens group 9 is moved by a predetermined amount in the direction N in FIG.

Then, the active AF signal changes from A in FIG. 7 to A ′. Along with this, the control section 26 restarts (follows) the active AF operation, and moves the stage 1 to the position F 'in FIG. At this time, the passive AF signal value is P2, and ± TH1 shown in FIG.
, The control unit 26 further drives the chromatic aberration lens group 9 in the same direction, and continues the active AF operation (step S28).

In such a sequence, at the stage position F ″ where the passive AF signal (P3) becomes ± TH1 or less,
Chromatic aberration lens group 9 so that active AF determines that it is in focus
Is driven, the control unit 26 determines that the chromatic aberration correction of the active AF in the current objective lens has been completed, and stores the current lens position (step S30).

Thereafter, the control section 26 rotates the revolver main body 2 via the revolver motor drive section 20 and the revolver motor 18, inserts the next objective lens 3 into the optical path, and performs the AF operation (step S32). ). At this time, the control unit 26 stores in advance a parameter (speed, threshold value, etc.) used for AF and a value of TH1 in the ROM according to the type of the objective lens 3 to be inserted next.
You can select from 31.

Thereafter, the above-described sequence (steps S26 to S32) is similarly applied, correction of chromatic aberration and storage of lens positions are performed for all objective lenses (step S31), and initial adjustment is completed. The microscope shifts to a normal use state (step S33).

As described above, according to the second embodiment,
Conventionally, the passive AF and the active AF, which were separately performed, are adjusted. After the passive AF is first adjusted, the active AF is automatically adjusted while evaluating the adjusted focus state signal in the passive AF. By performing the initial adjustment (correction of the chromatic aberration lens), the observer can perform the active AF adjustment at high speed and with few adjustment errors only by pressing the adjustment start switch without confirming the focus of the observation image.

Further, similarly to the first embodiment, by comparing and adjusting the focusing state of both the active and passive systems, it is possible to reduce the out-of-focus between the two systems due to the adjustment misalignment.

In the second embodiment, the focusing operation is performed by moving the stage. However, the focusing operation may be realized by moving the objective lens and the revolver up and down. In the second embodiment, the passive AF light-receiving sensor 17 is a CCD line sensor, but the same effect can be obtained by using an area-type CCD sensor or the like.

The present invention is not limited to the above embodiments, but can be implemented with appropriate modifications without departing from the scope of the invention.

[0087]

According to the present invention, simple initial adjustment and sufficient autofocus performance can be achieved by reducing the time and initial adjustment error in a hybrid AF using both an active AF and a passive AF. It is possible to provide an autofocus device for a microscope capable of ensuring both of the above.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a microscope autofocus device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a control unit according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a state of image formation by the light receiving sensor according to the first embodiment of the present invention.

FIG. 4 is a diagram showing an intensity distribution of a signal calculated from a detection signal according to the first embodiment of the present invention.

FIG. 5 is a flowchart showing an initial adjustment procedure in an active / passive AF according to the first embodiment of the present invention.

FIG. 6 is a view showing an example of the arrangement of LEDs in the operation unit according to the first embodiment of the present invention.

FIG. 7 shows an active A according to the first embodiment of the present invention.
FIG. 4 is a diagram showing AF signals of F and passive AF.

FIG. 8 is a flowchart showing an initial adjustment procedure in an active / passive AF according to the first embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Sample moving stage 2 ... Revolver main body 3 ... Objective lens 4 ... Reference light source 5 ... Collimating lens 6 ... Projection side stopper 7 ... PBS 8 ... Condensing lens group 9 ... Color correction lens group 10 ... λ / 4 plate 11 ... Dichroic mirror 12 ... Condensing lens group 13 ... Light receiving sensor 14 ... Half mirror 15 ... Imaging lens 16 ... Optical element for passive AF 16a ... Half mirror section 16b ... Total reflection mirror section 17 ... Light receiving sensor 18 ... Motor for revolver 19 ... Focusing motor 20 ... Revolver motor driver 21 ... Focusing motor driver 22 ... Revolver hole position detector 23 ... Laser driver 24 ... Signal processor 25 ... Signal processor 26 ... Control unit 27 ... Pulse counter 28 ... JOG Encoder 29 Operation unit 30 CPU main body 31 ROM 32 RAM 33 I / O port 34 ... Data bus 35 ... Chromatic aberration lens drive unit 36 ... Aberration lens drive motor 37 ... Illumination light source 38 ... Lens 39 ... Half mirror S ... Observation sample (sample)

Claims (3)

[Claims] 1. A microscope autofocus device mounted on a microscope having an observation optical system for irradiating a sample with light through an objective lens and observing light from the sample, wherein a light image from the sample is detected. One detecting means, a first focal length adjusting means for adjusting a focal length of the light image formed on the first detecting means, and a projection means for projecting the sample through the objective lens in the observation optical system. A light projecting unit that emits light, a second detecting unit that detects a light image reflected by the sample by the light projecting by the projecting unit, and a focal length of the light image that is formed on the second detecting unit. Second focal length adjustment means for adjusting; first focus state determination means for determining a focus state of the sample based on an output signal from the first detection means; and the first focus state Based on the signal from the determination means, A first focus position adjusting unit that adjusts a focus position; a second focus state determination unit that determines a focus state of the sample based on an output signal from the second detection unit; A second focusing position adjusting unit that adjusts a focusing position of the sample based on a signal from the focusing state determining unit, wherein the second focal length adjusting unit includes the first and second focal length adjusting units. An autofocus apparatus for a microscope, wherein the adjustment is performed based on both signals from two focus state determination means. 2. The apparatus according to claim 2, further comprising a focus state display means for displaying a focus state of said sample based on a signal from said first focus state determination means, wherein said second focal length adjustment means comprises: 2. The autofocus apparatus for a microscope according to claim 1, wherein a focus position is adjusted based on a display of said focus state display means during a focus operation by said focus position adjustment means. 3. The second focal length adjusting means, during a focusing operation by the second focusing position adjusting means, based on both signals from the first and second focusing state determining means. The autofocus device for a microscope according to claim 1, wherein adjustment is performed.