JPH10253873A - Automatic focus detection control device and optical inspection machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic focus detection control device capable of preventing the occurrence of an erroneous automatic focus detecting operation under the application of simple constitution without using switches or the like. SOLUTION: Regarding an automatic focus detection control device used for an optical inspection machine and formed to obtain the image of a sample 3 on a stage 1 via an observation optical system and collect image information corresponding to the obtained image via an image processing part, and to have a motor driver for moving the stage 1 with the sample 3 placed thereon to a focused position on the basis of the collected image information, a magnet 104 is laid for identifying the sample 3 on the stage 1, together with a sample detection part using a hall element 105, and CPU 24 for controlling the execution or non-execution of the automatic focal point detecting operation of the motor driver on the basis of a detected signal about the existence or non-existence of the sample 3 via the sample detection part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic focus detection control device suitable for use in a microscope or the like and an optical inspection machine using the device.

[0002]

2. Description of the Related Art Microscopes, which are a kind of optical inspection machines, are not only used in the fields of medicine and biology, but also in the field of industrial use, such as inspection of IC wafers and magnetic heads, quality control of metal structures, etc. It is used for various purposes such as research and development. The focusing operation (focusing operation) in such a microscope is usually performed by adjusting the relative positional relationship between the objective lens and the sample to be observed. In this case, the focusing mechanism that performs the focusing operation is configured to move the stage on which the sample is placed along the optical axis direction of the objective lens.

In recent microscopes, the focusing mechanism is an electric type using a motor, an autofocus (autofocus) sensor is mounted, and the focusing mechanism is based on image information based on a detection result of the autofocus sensor. A microscope with an automatic focus detection device that drives a quasi-mechanism to automatically perform a focus detection operation has been realized.

[0004] In addition, Japanese Patent Publication No. 5-16566 discloses that
A microscope is disclosed in which an automatic focus detection start switch is operated by an external controller when performing an automatic focus detection operation.

Further, Japanese Patent Publication No. 4-35847 discloses an automatic magnification returning device for detecting a sample by a sample detector such as a microswitch and automatically setting the observation magnification of the sample.

[0006]

In a conventional automatic focus detecting device for a microscope, the electric stage is moved based on image information obtained by an autofocus sensor while moving the electric stage over almost the entire movable range. Although it is a device that moves to the focal position, the focus detection operation is performed even when there is no sample, so if there is dust or small scratches on the prism or lens near the autofocus sensor, the sample is not found (sample In general, the specimen has a higher contrast, so that there is no problem in focusing performance). However, there is a problem that dust or a scratch is mistakenly recognized as a subject to cause malfunction.

In the case of the microscope disclosed in Japanese Patent Publication No. Hei 5-16566, when performing automatic focus detection, a sample is attached to a sample holder, and then an automatic focus detection start switch of an external controller is operated, and the sample is removed. Also in this case, there is a problem that the operation becomes complicated since the removal operation must be performed after operating the automatic focus detection stop switch of the external controller.

Further, in the case of the automatic magnification returning device disclosed in Japanese Patent Publication No. 4-35847, the specimen is detected by a specimen detector such as a microswitch, and a plurality of objective lenses are switched to automatically set the observation magnification of the specimen. However, the automatic focus detection operation of a microscope having a single objective lens is not realized.

SUMMARY OF THE INVENTION The present invention has been made in view of the problems shown in the prior art, and has an automatic focus detection control device capable of preventing erroneous operation of automatic focus detection with a simple configuration not using switches and the like. An object of the present invention is to provide an optical inspection machine using the automatic focus detection control device.

[0010]

According to the first aspect of the present invention,
A stage on which the sample is mounted, an observation optical system for observing the sample on the stage, an image processing unit for obtaining image information corresponding to an image of the sample obtained by the observation optical system, and an image processing unit An automatic focus detection control device used in an optical inspection machine having an electric focusing unit for performing an automatic focus detection operation of moving the stage to a focus position based on image information, wherein the presence or absence of a sample on the stage is detected. A sample detection unit; and control means for controlling execution or non-execution of an automatic focus detection operation by the electric focusing unit based on a detection signal indicating presence or absence of a sample by the sample detection unit. It is.

According to a second aspect of the present invention, there is provided a stage for mounting a sample, an observation optical system for observing the sample on the stage, and an image for obtaining image information corresponding to the image of the sample obtained by the observation optical system. In an optical inspection machine having a processing unit and an electric focusing unit that performs an automatic focus detection operation of moving the stage to a focus position based on image information obtained by the image processing unit, the presence or absence of a sample on the stage Automatic focus detection comprising: a sample detection unit for detecting the presence of a sample; and control means for controlling execution or non-execution of the automatic focus detection operation by the electric focusing unit based on a detection signal indicating whether or not a sample is present by the sample detection unit. It is characterized by adding a control device.

According to the automatic focus detection control device of the present invention,
By controlling the execution or non-execution of the automatic focus detection operation in accordance with the presence or absence of the sample, it is possible to prevent a malfunction in which the automatic focus detection operation is executed when there is no sample by mistake. Further, by controlling the execution or non-execution of the automatic focus detection operation in accordance with the presence or absence of the sample, switches for starting and stopping the automatic focus detection become unnecessary, and the configuration and operation can be simplified.

Further, according to the optical inspection machine of the present invention, since the automatic focus detection control device exhibiting the above operation is added, it is possible to prevent a malfunction in which the automatic focus detection operation is executed when there is no sample, and Also, there is no need to provide switches for starting and stopping the automatic focus detection, and an optical inspection machine capable of simplifying the configuration and operation can be provided.

[0014]

Embodiments of the present invention will be described below in detail.

(Embodiment 1) FIG. 1 shows the entire configuration of a microscope provided with an automatic focus detection device according to Embodiment 1 of the present invention. This microscope has a stage 1 on which a specimen 3 is placed. The stage 1 can be moved up and down by a motor driver 4 along the direction of the arrow (a) shown in FIG.

The microscope has an illumination optical system for illuminating the specimen 3. That is, the illumination optical system makes the illumination light emitted from the light source 5 incident on the reflecting mirror 9 via the collector lens 6, the relay lens 7, and the field stop 8, and reflects the illumination light upward to move the illumination light path upward. In this case, the light enters the condenser lens 12 via the relay lens 10 and the aperture stop 11, and the condenser lens 12 uniformly illuminates the sample 3 on the stage 1.

An objective lens 13 of an observation optical system is disposed above the sample 3 so as to face the same, and a light beam from the sample 3 incident on the objective lens 13 is incident on an optical path branching member 15 via an imaging lens 14. I do. The light path branching member 15 guides a part of the light beam to the eyepiece 16 and guides the remaining light beam to the relay lens 17 via the reflecting member 26.

The light beam that has passed through the relay lens 17 is split into two by the splitting prism 18, and the two split light beams become parallel light beams and enter the light receiving surface of the CCD sensor 19.

The two parallel light beams incident on the CCD sensor 19 have different optical path lengths from the structure of the splitting prism 18 to the light receiving surface of the CCD sensor 19 from the exit surface of the relay lens 17.

In the first embodiment, the light receiving surface of the CCD sensor 19 is made to coincide with the optically conjugate position before and after (the front conjugate surface and the rear conjugate surface) with respect to the predetermined imaging plane. Therefore, the image of the specimen 3 (a front focus image and a rear focus image) is projected onto the CCD sensor 19 at two conjugate positions from the predetermined image formation plane. The two images have the same shape when the sample 3 is at the in-focus position.

The CCD sensor 19 outputs an analog signal having a voltage corresponding to the amount of incident light of the projected image of the specimen 3 (the front focus image and the rear focus image) and the charge accumulation time. CCD
An analog signal from the sensor 19 is output to an analog processing unit 20.
The analog processing unit 20 separately performs analog processing such as amplification and filter processing on the analog signal from the CCD sensor 19 for the front focus image and the rear focus image, and outputs the analog signal to the A / D converter 21. I do.

The A / D converter 21 includes an analog processing unit 20
From the analog-processed signal into a digital signal,
The digitized signals are separately stored in the memory 22 corresponding to the front focus image and the rear focus image.

The contents stored in the memory 22 can be read from the arithmetic circuit 23. The arithmetic circuit 23 calculates a contrast value between the two images by using a digital signal that is image information corresponding to the two images of the sample 3 captured in the memory 22.

Then, a defocus value indicating the degree of focusing on the sample 3 is calculated from the contrast values of the two images of the sample 3, and the defocus value is sent to the CPU 24.

The CPU 24 monitors via the A / D converter 21 whether or not the analog signal based on the two images of the sample 3 output from the CCD sensor 19 matches the range of the analog processing section 20. I have.

When the analog signal does not conform to the range of the analog processing section 20, the CPU 24 sets the charge accumulation time (light receiving time) in the CCD sensor 19 to a charge accumulation time suitable for the range. To the timing generator 25.

The timing generator 25 includes a CPU 2
CCD so that the charge accumulation time according to the command from 4
A read timing signal is sent to the sensor 19. Further, the CPU 24 calculates a signal of a moving amount and a moving direction of the stage 1 for moving the sample 3 to a focus position based on the signal of the defocus value from the arithmetic circuit 23, and sends the signal to the motor driver 4. Send.

The motor driver 4 drives the stage 1 up and down in the direction of the arrow (a) based on a signal from the CPU 24 to perform an automatic focus adjustment operation of the sample 3.

Next, the stage 1 and the specimen holder 2 according to the first embodiment will be described with reference to FIGS.
The specimen holder 2 includes a thin, substantially rectangular holder body 103 for mounting and holding the specimen 3, and a holder body 10.
3, a sample holder 101 formed in a gently curved shape rotatably attached to a shaft 103a provided on one side of the sample holder 3, and arranged around the shaft 103a to constantly urge the sample holder 101 in the direction of arrow a. And a spring (coil spring) 102. Then, the long side and the short side of the sample 3 are brought into contact with a total of three convex portions 103 b provided on one end side of the holder body 103, and in this state, the sample holder 101 is pressed by the spring force of the sample 102. The sample 3 is held in pressure contact with a corner protruding outward from the sample.

A magnet 104 is attached to a portion of the sample holder 101 projecting rearward from the shaft 103. The holder body 103 holds the sample 3 toward the holder body 103 with the sample holder 101. (When the sample holder 101 is at the position shown by the solid line in FIG. 2), the Hall element 105 is attached to the position where the magnetic force of the magnet 104 acts. Magnet 104 and Hall element 1
05 constitutes a sample detection unit.

Then, such a sample detecting section and the C
The PU 24 constitutes the automatic focus detection control device according to the first embodiment.

Next, the operation of the automatic focus detection control device will be described with reference to FIG. In the state shown in FIG. 2 in which the specimen 3 is attached to the specimen holder 2 described above, the specimen holder 101 is positioned at the position shown by the solid line in FIG.
Holding. In this case, the magnetic force of the magnet 104 acts on the Hall element 105. As a result, a detection signal of the Hall element 105 indicating the presence of the sample 3 is sent to the CPU 24, and the CPU 24
And a timing generator 25 to start the automatic focus detection operation. Thus, as described above, the automatic focus detection operation in which the motor driver 4 drives the stage 1 in the direction of the arrow (a) is performed.

However, in the state shown in FIG. 3 where the specimen 3 is not attached to the specimen holder 2, the spring 10
2, the sample holder 101 moves to the position shown by the two-dot chain line in FIG.
No effect on 5. In this case, no detection signal is sent from the Hall element 105 to the CPU 24.

That is, it is determined that the sample 3 is not attached to the sample holder 2, and the CPU 24
Then, a command to stop the automatic focus detection operation is sent to the arithmetic circuit 23 and the timing generator 25.

Therefore, by detecting the presence or absence of the sample 3 at the position of the sample holder 2, when there is no sample 3, the automatic focus detection operation is stopped, and malfunction of the automatic focus detection can be prevented. Further, when the automatic focus detection operation is started when the sample 3 is attached to the sample holder 2, the start and stop of the automatic focus detection operation can be linked to the attachment and detachment of the sample 3 to and from the sample holder 2. The automatic focus detection start switch and the automatic focus detection stop switch as described above can be omitted, and the configuration can be simplified and the operation can be simplified.

(Embodiment 2) FIGS. 5 and 6 show Embodiment 2 of the present invention. The same parts as those of Embodiment 1 shown in FIGS. 2 and 3 are denoted by the same reference numerals. I have. In the case of the second embodiment, a light-shielding plate 201 is provided on the sample holder 101, and when the sample 3 is attached to the holder body 103, as shown in FIG.
When the sample 3 is not mounted, the light-emitting element and the light-receiving element are located at positions where the light is not shielded by the light-shielding plate 201 which is displaced with the rotation of the sample holder 101 in the direction of arrow a, as shown in FIG. Is provided.

Light shielding plate 201, photo interrupter 202
Constitutes the subject detection unit according to the second embodiment. Other configurations are the same as those of the first embodiment shown in FIGS.

The same operation and effect as those in the first embodiment can be obtained by the automatic focus detection control device using such an object detection unit.

(Embodiment 3) FIGS. 7 and 8 show Embodiment 3 of the present invention. The same parts as those of Embodiment 1 shown in FIGS. I have. In the third embodiment, as shown in FIGS. 7 and 8, the subject detection unit is configured by the microswitch 301 attached to the holder body 103 so as to face the convex portion 103a.

In the case of such an automatic focus detection control device using the object detecting section, when the sample 3 is mounted on the sample holder 103, the biasing force of the spring 102 in the direction of arrow a as shown in FIG. Is the sample 103
The sample 3 is pressed against the b side, and the sample 3 presses the actuator 302 of the microswitch 301, whereby a detection signal of the microswitch 301 indicating the presence of the sample 3 is sent to the CPU 24. As a result, the same automatic focus detection operation as that described above is performed.

On the other hand, when the specimen 3 is not attached to the specimen holder 2, the specimen 3 cannot push the actuator 302 of the micro switch 301 as shown in FIG. Not sent.

That is, it is determined that the sample 3 is not attached to the sample holder 2, and the CPU 24
Then, a command to stop the automatic focus detection operation is sent to the arithmetic circuit 23 and the timing generator 25. With this configuration, the same operation and effect as those of the first embodiment can be obtained.

(Embodiment 4) FIGS. 9 and 10 show Embodiment 4 of the present invention. The same parts as those of Embodiment 1 shown in FIGS. 2 and 3 are denoted by the same reference numerals. ing. Although the configuration of the fourth embodiment is basically the same as that of the first embodiment, as shown in FIG. 10, when the specimen 3 is not attached to the specimen holder 2, it is attached to the specimen holder 101. The Hall element 4 is located at a position where the magnetic force of the magnet 104 acts.
When the sample 3 is attached to the sample holder 2, the magnetic force of the magnet 104 does not act on the Hall element 401.

In this configuration, when the sample 3 is not attached to the sample holder 2, the sample holder 101 moves to the position shown in FIG. 10 by the urging force of the spring 102 in the direction a. And the detection signal indicating the absence of the sample 3
The CPU 24 sends a command to stop the automatic focus detection operation to the motor driver 4, the arithmetic circuit 23, and the timing generator 25 to stop the automatic focus detection operation.

On the other hand, when the specimen 3 is attached to the specimen holder 2, no detection signal is sent from the Hall element 401 to the CPU 24 because the magnetic force of the magnet 104 does not act on the Hall element 401. That is, the CPU 24 determines that the sample 3 is attached to the sample holder 2 and executes an automatic focus detection operation.

That is, in the case of the fourth embodiment, the arrangement of the Hall element 401 is changed.
24 is the reverse of the content of the detection signal to be sent.

In the first embodiment, when the size of the sample 3 changes, the position where the sample holder 101 presses the sample 3 changes, so that the Hall element 105 may not react even if the sample 3 is attached to the sample holder 2. However, according to the configuration of the fourth embodiment, the same operation and effect as those of the first embodiment can be obtained regardless of the size of the specimen 3.

When stopping the automatic focus detection operation in response to the detection signal of the Hall element 401, the CPU 2
It is also possible to configure so that the automatic focus detection operation is not started by the operation of an external switch or the like (not shown) under the control of (4).

According to the present invention described above, the following configuration can be added. (1) An image processing unit that obtains image information corresponding to an image of a subject on a stage obtained by an observation optical system, and an automatic moving unit that moves the stage to a focus position based on the image information obtained by the image processing unit In an automatic focus detection control device used for an optical inspection machine having an electric focusing unit for performing a focus detection operation, a sample detection unit for detecting the presence or absence of a sample on the stage, and a sample presence or absence by the sample detection unit Control means for controlling execution or stop of the automatic focus detection operation by the electric focusing unit based on the detection signal of the absence of the automatic focus detection. According to this configuration,
Execution and stop of the automatic focus detection operation can be controlled to prevent malfunction, and the configuration and operation can be simplified.

(2) The control of the automatic focus detection operation is as follows:
The automatic focus detection device according to claim 1, wherein the automatic focus detection operation is stopped when the sample is not at a predetermined inspection position. According to this configuration, it is possible to prevent a malfunction in which the automatic focus detection operation is performed when the sample is not at the predetermined inspection position.

(3) The control of the automatic focus detection operation is as follows:
The automatic focus detection device according to claim 1, wherein the automatic focus detection operation is started when the sample is at a predetermined inspection position. According to this configuration, the automatic focus detection operation can be reliably performed when the specimen is at the predetermined inspection position.

(4) An additional feature that the automatic focus detection operation is not started by an external operation when the automatic focus detection operation is stopped in response to the signal from the sample detection unit. Automatic focus detection device. According to this configuration, it is possible to prevent an erroneous operation in which the automatic focus detection operation is executed by an external operation when the sample is not at the predetermined inspection position.

(5) When the automatic focus detection operation is stopped,
3. The automatic focus detection device according to claim 1, wherein the stage is stopped by the electric focusing unit. According to this configuration, it is possible to prevent an erroneous operation in which the automatic focus detection operation is performed due to the movement of the stage when the sample is not at the predetermined inspection position.

(6) The automatic focus detecting device according to appendix 1 or 2, wherein the sample detecting section is a sample fixing device. According to this configuration, it is possible to prevent a malfunction in which the automatic focus detection operation is performed using the sample fixing device.

(7) The automatic focus detection device according to appendix 1 or 2, wherein the sample detection section detects the presence or absence of the sample by reacting according to a change in the holding position of the sample holder. According to this configuration, the execution and stop of the automatic focus detection operation can be controlled using the change in the holding position of the sample holder.

[0056]

According to the present invention, it is possible to provide an automatic focus detection control device which can control the execution and non-execution of the automatic focus detection operation to prevent erroneous operation and simplify the configuration and operation.

Further, according to the present invention, it is possible to prevent a malfunction in which the automatic focus detection operation is executed when there is no sample, and
There is no need to provide switches for starting and stopping the automatic focus detection, and it is possible to provide an optical inspection machine whose configuration and operation can be simplified.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an automatic focus detection control device according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a stage, a specimen holder, a specimen, and a specimen holder according to the first embodiment of the present invention.

FIG. 3 is a plan view showing a displacement state of a specimen holder according to the first embodiment of the present invention.

FIG. 4 is a side view showing a stage, a specimen holder, a specimen, and a specimen holder according to the first embodiment of the present invention.

FIG. 5 is a plan view showing a stage, a specimen holder, a specimen, and a specimen holder according to Embodiment 2 of the present invention.

FIG. 6 is a plan view illustrating a displacement state of a specimen holder according to the second embodiment of the present invention.

FIG. 7 is a plan view showing a stage, a specimen holder, a specimen, and a specimen holder according to Embodiment 3 of the present invention.

FIG. 8 is a plan view showing a displacement state of a specimen holder according to the third embodiment of the present invention.

FIG. 9 is a plan view showing a stage, a specimen holder, a specimen, and a specimen holder according to Embodiment 4 of the present invention.

FIG. 10 is a plan view illustrating a displacement state of a specimen holder according to the fourth embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 stage 2 sample holder 3 sample 4 motor driver 13 objective lens 19 CCD sensor 20 analog processing unit 21 A / D converter 22 memory 24 CPU 25 timing generator 101 sample holder 102 spring 103 holder body 104 magnet 105 Hall element

Claims (2)

[Claims] 1. A stage on which a sample is placed, an observation optical system for observing the sample on the stage, an image processing unit for obtaining image information corresponding to an image of the sample obtained by the observation optical system, An automatic focus detection control device used in an optical inspection machine having an electric focusing unit that performs an automatic focus detection operation of moving the stage to a focus position based on image information obtained by a processing unit, And a control means for controlling execution or non-execution of the automatic focus detection operation by the electric focusing unit based on a detection signal indicating presence or absence of a sample by the sample detection unit. An automatic focus detection control device. 2. A stage on which a sample is mounted, an observation optical system for observing the sample on the stage, an image processing unit for obtaining image information corresponding to an image of the sample obtained by the observation optical system, A motorized focusing unit that performs an automatic focus detection operation of moving the stage to an in-focus position based on image information obtained by a processing unit, wherein a sample detection unit that detects the presence or absence of a sample on the stage When,
An automatic focus detection control device comprising control means for controlling execution or non-execution of the automatic focus detection operation by the electric focusing unit based on a sample presence / absence detection signal from the sample detection unit is added. And optical inspection machine.