JPH1020186A - Automatic focus adjustment method and device - Google Patents

Abstract

(57) Abstract: The present invention adjusts the focus with high accuracy even for a specimen having a low contrast without being affected by the attached matter even if the attached matter exists in the optical system of the microscope. An image of a field stop (6) is projected onto a specimen (2p) to be observed, a defocus amount (Δa) between the image of the field stop (6) and a reference focus position is detected, and based on the defocus amount (Δa). seeking a thickness t of the specimen 2p, obtains the movement amount of the stage 1 based on the difference ΔZ in the thickness t _o of the thickness t and the reference sample of the specimen 2p, adjusts focus by moving the stage 1 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical instrument used for observing a state of a biological tissue or the like in the fields of medicine, biology, and the like, for example, an automatic focusing device in a microscope.

[0002]

2. Description of the Related Art Technologies related to focus detection of optical devices such as microscopes have been developed in various fields. One of the technologies is area division for focusing a subject with high precision. (Hereinafter, referred to as an area division method).

The area division method divides a distance measurement range into a plurality of areas, detects a focus, and controls a relative distance between a subject and an objective lens based on a calculation result of the focus detection to perform focusing. It is.

[0004] Techniques that adopt this area division method include, for example, Japanese Patent Application Laid-Open No. 2-109008 and Japanese Patent Application Laid-Open
No. 297514.

The technique disclosed in Japanese Patent Application Laid-Open No. 2-109008 is applied to, for example, a video camera or an electronic still camera, and divides a subject image taken through an image pickup optical system into a plurality of areas and focuses on each area. The focus position is selected by a majority decision among the calculation results of the focus detection, and the focus control is performed according to the focus position.

The technique disclosed in Japanese Patent Application Laid-Open No. 2-297514 is applied to, for example, an automatic focus of a camera, and divides a subject image in a distance measurement range when a subject is observed through a focus detection optical system into two images. To determine whether the output signal of each block of the photoelectric conversion element array is at a level suitable for the focus adjustment information, and output the photoelectric conversion element array determined as an appropriate level. The focus adjustment information is calculated based on the signal.

[0007]

However, the former technique is applied to a video camera or an electronic still camera, while the latter technique is applied to an automatic focusing of a camera, and these techniques are applied to a microscope. Then, there is a practically insufficient point.

That is, in the automatic focus detection for a microscope, one of the factors that lowers the focusing accuracy is dust adhering to a slide glass or a cover glass on which a sample is placed, or a condenser lens for projecting illumination on the sample. Influence.

As described above, if the sample or the slide glass has foreign matter such as dust, for example, if the image of the dust is mixed with the sample image several thousand to several hundred [μm] apart, the dust is larger than the sample. Is higher in contrast, and when auto-focusing is performed, dust is more focused on the sample than on the sample, and the focusing accuracy on the sample is significantly reduced. Note that using an apparatus for performing image processing on an unspecified sample becomes expensive.

As an improvement measure against such a decrease in focusing accuracy, it is possible to always perform focusing control by area division as described above. However, in such focusing control, the control processing becomes complicated, This affects the focusing time, which is one of the important points for the automatic focus detection performance.

Accordingly, the present invention provides an inexpensive automatic focus adjustment method capable of adjusting the focus with high accuracy even for a specimen having a low contrast without being affected by the extraneous matter, even if the extraneous substance is present in the optical system of the microscope. It is intended to provide a device.

[0012]

According to the first aspect of the present invention, there is provided an automatic focus adjusting method for adjusting focus by changing a relative position between an objective lens and a sample. This is an automatic focus adjustment method of projecting, detecting a defocus amount between the field stop image or the index image and the reference focus position to obtain a focus distance, and performing focus adjustment based on the focus distance.

According to a second aspect of the present invention, there is provided an automatic focus adjusting apparatus for adjusting a focus by changing a relative position between an objective lens and a sample, wherein an optical system for projecting a field stop image or a target image on the sample, Detecting means for detecting the defocus amount between the field stop image or index image projected on the sample and the reference in-focus position, and determining the relative position between the objective lens and the sample based on the defocus amount detected by the detecting means. An automatic focus adjustment device including focusing means for adjusting the focus to a focus position.

According to a third aspect of the present invention, in the automatic focusing apparatus according to the second aspect, the detecting means includes a field stop image or an index image when a reference sample having at least a refractive index and a thickness as a reference is used. It has a function of holding the imaging position as a reference focus position and detecting a defocus amount between the reference focus position and the field stop image or the target image projected on the sample. It has a function of calculating the thickness of the sample based on the detected defocus amount and calculating the amount of movement of the relative position between the objective lens and the sample based on the difference between the thickness of the sample and the thickness of the reference sample.

According to a fourth aspect of the present invention, there is provided an automatic focus adjustment method for irradiating illumination light to a sample through a condenser lens and adjusting a focus by changing a relative position between the objective lens and the sample. When the focal length of the condenser lens is changed in accordance with the above, an automatic focus adjustment method is employed in which a plurality of indices for focus adjustment are arranged at positions conjugate to the sample for each condenser lens.

According to a fifth aspect of the present invention, there is provided an automatic focus adjusting apparatus for irradiating a specimen with illumination light through a condenser lens and adjusting a focus by changing a relative position between the objective lens and the specimen. Condenser lens changing means for changing the focal length of the condenser lens in accordance with the following conditions; and an index for focusing adjustment at a position conjugate with the sample with respect to the condenser lens in accordance with the focal length of the condenser lens by the condenser lens changing means. This is an automatic focus adjustment device that includes an index insertion / removal unit that inserts / extracts and adjusts the focus of the objective lens sample based on the contrast of the index image on the sample surface.

According to a sixth aspect of the present invention, in the automatic focusing apparatus according to the fifth aspect, at least the focal length of the condenser lens is changed and the index is set at a position conjugate with the specimen with respect to the condenser lens during the focus adjustment operation. insert.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

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

According to the automatic focus adjustment method of the present invention, when the focus adjustment is performed by changing the relative position between the objective lens and the sample,
A field stop image or target image is projected on the specimen, a defocus amount between the field stop image or the target image and the reference focus position is detected to obtain a focus distance, and focusing is performed based on the focus distance. Adjustment is performed.

FIG. 1 is a block diagram of an automatic focus adjusting apparatus in which the automatic focus adjusting method is applied to a microscope.

A specimen 2 is mounted on a stage 1 of the microscope. The stage 1 is vertically movable along the direction of the arrow (a).

This microscope is provided with an optical system for illuminating the specimen 2. That is, on the optical path s ₁ of the illumination light emitted from the light source 3, a collector lens 4, a relay lens 5, a field stop 6 and the reflector 7 is arranged. The size of the field stop 6 is changed by the field stop driver 8.

The direction of the reflection mirror 7, i.e. on the optical path s ₂ of the illumination light directed upward by the reflecting mirror 7, a relay lens 9, is arranged 10 and the condenser lens 11 aperture stop, the condenser lens 11 Illuminates the specimen 2 uniformly.

On the other hand, above the specimen 2, the objective lens 12 placed opposite, further imaging lens on the optical beam s ₃ from the specimen 213, the optical path branching member 14 is positioned relative to the specimen 2.

The light path branching member 14 has a function to guide a part of the light beam s ₃ from the sample 2 to the eyepiece 15 and to guide the other light beam to the split prism 18 through the mirror 16 and the imaging lens 17. .

The splitting prism 18 has a function of splitting an incident light beam into two and sending the two light beams to the CCD sensor 19 in a parallel state.

The two light beams split by the split prism 18 have different optical path lengths from the exit surface of the imaging lens 17 to the light receiving surface of the CCD sensor 19.
The light receiving surface of the CCD sensor 19 is
The front and rear optically conjugate positions (the front conjugate surface and the rear conjugate surface) with respect to the predetermined image plane of the image forming optical system including the above.

Therefore, on the light receiving surface of the CCD sensor 19,
A subject image (a front focus image and a rear focus image) is projected at two conjugate positions from the predetermined imaging plane. These two subject images have the same shape when the subject is at the in-focus position.

In the first embodiment, the image of the field stop 6 projected on the sample 2 is set as a subject.

The CCD sensor 19 has a function of outputting an analog signal of a voltage level corresponding to the amount of incident light and the accumulation time of the projected light image (front focus image, rear focus image).

An output terminal of the CCD sensor 19 is connected to a memory 2 via an analog processing unit 20 and an A / D converter 21.
2 are connected.

The analog processing section 20 includes a CCD sensor 19
Has a function of separately performing analog processing such as amplification and filter processing on the front focus image and the rear focus image with respect to the analog signal output from.

The A / D converter 21 has a function of digitizing the output signal of the analog processing section 20, and the memory 22 separates the digitized signal from the CCD sensor 19 into a front focus image and a rear focus image. Is to be stored.

The arithmetic circuit 23 reads out digital signals of two subject images stored in the memory 22, that is, a front focus image and a rear focus image, and uses the digital signals of the front focus image and the rear focus image to generate a front focus image. The contrast value between the image and the back focus image is calculated, and the field stop 6 is calculated from these contrast values.
Has a function of calculating a defocus amount indicating the degree of focus and transmitting the defocus signal to the CPU 24.

The CPU 24 fetches the defocus signal calculated by the arithmetic circuit 23, and determines the moving amount and the moving direction of the stage 1 for adjusting the image of the field stop 6 to the in-focus position based on the defocus signal. The driving circuit 25 has a function of transmitting the signals of the moving amount and the moving direction to the drive circuit 25.

The CPU 24 calculates the amount of movement of the stage 1 when the stage 1 is
From the field stop 6
Was calculated as the defocus amount .DELTA.a image, determine the thickness t of the specimen 2p based on the defocus amount .DELTA.a, based on the difference ΔZ in the thickness t _o of the thickness t and the reference sample of the specimen 2p It has a function of determining the amount of movement of the stage 1.

The encoder 26 has a function of generating a pulse signal corresponding to the amount of movement of the stage 1 and outputting this as a signal of the amount of movement of the stage 1.

The drive circuit 25 receives the signals of the movement amount and the movement direction sent from the CPU 24, and moves the stage 1 up and down in the direction of the arrow (a) based on the signals of the movement amount and the movement direction. It has a function to adjust focus.

The CPU 24 converts the analog signal of the subject image output from the CCD sensor 19 into the analog processing unit 2.
0 is monitored through the A / D converter 21, and when the analog signal of the subject image does not conform to the range of the analog processing unit 20, the timing generator 27 It has a function of sending a command to change the charge accumulation time at 19 to an accumulation time suitable for the range.

This timing generator 27 has a CC
A read timing signal is sent to the D sensor 19, and has a function of receiving a command from the CPU 24, changing the charge accumulation time according to the command, and sending a read timing signal to the CCD sensor 19. ing.

The CPU 24 has an external controller 2
The external controller 28 has a function of controlling the start / stop of the automatic focusing operation and the like, and a function for the speculum to specify the magnification of the objective lens 12 and the like.

Next, the operation of the above-configured apparatus will be described with reference to the operation procedure shown in FIG.

On the stage 1, the reference sample 2s is placed in step # 1. This reference sample 2s
Generally, the slide glass is formed to have a refractive index n _s and a thickness t _o .

The illumination light radiated from the light source 3 passes from the collector lens 4 to the reflecting mirror 7 through the relay lens 5 and the field stop 6, and is reflected upward by the reflecting mirror 7 to be reflected by the relay lens 9 and the bright light. The sample passes through the diaphragm 10 to the condenser lens 11 and is sampled for 2 seconds by the condenser lens 11.
Is illuminated uniformly.

The light beam s ₃ from the sample 2 s passes through the objective lens 12 and the imaging lens 13 to reach the optical path branching member 14. The optical path branching member 14 converts a part of the light beam s ₃ from the sample 2 s to an eyepiece. 15 and directs another light beam to the mirror 16,
The light is guided to the division prism 18 through the imaging lens 17.

The splitting prism 18 splits the incident light beam into two, and sends these two light beams to the CCD sensor 19 in a parallel state.

The CCD sensor 19 outputs an analog signal having a voltage level corresponding to the amount of incident light and the accumulation time of the projected light image (front focus image, rear focus image).

The analog processing section 20 includes a CCD sensor 19
The analog signals output from the CPU are separately subjected to analog processing such as amplification and filtering for the front focus image and the rear focus image.

The output signal of the analog processing section 20 is digitized by the A / D converter 21 and sent to the memory 22, where the front focus image and the rear focus image are separately stored.

The arithmetic circuit 23 reads the digital signals of the front focus image and the rear focus image stored in the memory 22 and uses the digital signals of the front focus image and the rear focus image to generate a front focus image and a rear focus image. Are calculated, and the defocus amount indicating the degree of focus of the field stop 6 is calculated from these contrast values.

The CPU 24 fetches the defocus signal calculated by the arithmetic circuit 23, and calculates the moving amount and the moving direction of the stage 1 for adjusting the image of the field stop 6 to the in-focus position based on the defocus signal. , And the signals of the movement amount and the movement direction are sent to the drive circuit 25.

As a result, stage 1 proceeds to step # 2
When the front focus image and the rear focus image projected on the light receiving surface of the CCD sensor 19 move in the vertical direction at the same shape,
The image of the field stop 6 becomes the focus position.

In step # 3, the condenser lens 11 is moved up and down to move the field stop 6 with respect to the reference sample 2s.
Focus on the image.

[0054] FIG. 3 (a) put such reference specimen 2s on the stage 1, the focal position of the objective lens 12 of the working distance WD _o, from the field stop illumination light 6 passes through the relay lens 9, a condenser lens 11 Indicates a state where the image of the field stop 6 when projected onto the reference sample 2s is at the same position. Note that, in the figure, h indicates the upper surface position of the table 1.

The position where the focal position of the objective lens 12 and the image of the field stop 6 become the same is defined as a reference focus position.

Next, in step # 4, the reference sample 2s
, The specimen 2p to be observed is placed on the stage 1.

The sample 2p is formed to have a refractive index n _s and a thickness t, for example.

When such a sample 2p is placed on the stage 1, the distance between the focal position of the objective lens 12 and the image of the field stop 6 changes due to a change in the thickness t of the sample 2p. At this time, the focal position of the objective lens 12 changes only when the sample 2p is thicker than the reference sample 2s. The position of the field stop image changes when the thickness of the sample changes.

In this state, the light beam s ₃ from the specimen 2p to be observed is moved from the objective lens 12 to the imaging lens 1 in the same manner as described above.
Through 3 reaches the optical path splitting member 14, an eyepiece part of the light beam s ₃ from the specimen 2p in this optical path splitting member 14 15
And the other light flux is guided to the split prism 18 through the mirror 16 and the imaging lens 17.

The light beam from the sample 2p is split into two by the splitting prism 18 and converted into two parallel light beams.
The image is projected onto the CD sensor 19, and is output from the CCD sensor 19 as an analog signal having a voltage level corresponding to the amount of incident light and the accumulation time of the front focus image and the rear focus image.

The analog signal is supplied to the analog processing unit 20
, The front focus image and the rear focus image are separately analog-processed, digitized by the A / D converter 21 and stored in the memory 22.

The arithmetic circuit 23 calculates the contrast value from the digital signals of the front focus image and the rear focus image stored in the memory 22, and calculates the defocus amount indicating the degree of focus of the field stop 6 from these contrast values. calculate.

When the defocus amount is detected, CP
U24 sends a signal indicating a predetermined aperture size to the field stop driver 8 so that the image of the field stop 6 can be recognized.

At this time, the size of the field stop 6 is reduced to a predetermined fixed aperture value, or a table corresponding to the magnification of the objective lens 12 and the aperture value of the field stop 6 is prepared and used in advance. An aperture value corresponding to the objective lens 12 is read out and stopped down. In the case of narrowing down to a fixed value, a size which can be detected by the objective lens 12 having the highest magnification to be used may be set.

When the detection of the defocus amount ends, the aperture value of the field stop 6 returns to the original aperture value.

The CPU 24 obtains the amount of movement and the direction of movement of the stage 1 based on the defocus signal from the arithmetic circuit 23 in step # 5, and sends the signals of the amount of movement and the direction of movement to the drive circuit 25.

As a result, the stage 1 moves in the vertical direction, and the front focus image projected on the light receiving surface of the CCD sensor 19,
When the rear focus image has the same shape, the image of the field stop 6 is at the in-focus position as shown in FIG.

At this time, the encoder 26
Is detected, and a signal indicating the amount of movement is sent to the CPU 24.

In step # 6, the CPU 24 fetches the movement amount signal from the encoder 26, sets the movement amount Δa of the stage 1 as the defocus amount Δa of the image of the field stop 6, and based on the defocus amount Δa. The thickness t of the sample 2p is determined.

That is, assuming that the thickness t _o of the reference sample 2 s, the working distance WD _o of the objective lens 12, and the working distance of the objective lens 12 in the case of the sample 2 p to be observed are WD, t _o + WD _o + Δa = t + WD. 1) WD _o = WD + (t−t _o ) / _ns (2)

[0071] The thickness t of the specimen 2p these formulas (1) and _{(2), t = t o + Δa /} (1-1 / n s) ... a (3). As described above, the thickness t of the sample 2p can be obtained by detecting the defocus amount Δa of the image of the field stop 6.

Next, in step # 7, the CPU 24 obtains the difference ΔZ between the thickness t of the sample 2p and the thickness to of the reference sample 2s, and obtains this as the movement amount ΔZ of the stage 1.

That is, the thickness t of the sample 2p and the reference sample 2
The difference ΔZ ΔZ = t-t _o of the thickness t _o of s ... (4) by substituting the equation (3), ΔZ = Δa / (1-1 / n s) ... Request (5).

In step # 8, the CPU 24 sets the difference ΔZ between the thickness t of the sample 2p and the thickness t _o of the reference sample 2s as the moving amount ΔZ of the stage 1 together with the moving direction.
It is sent to the drive circuit 25 again.

As a result, the stage 1 moves up and down, and focus adjustment is performed on the sample 2p as shown in FIG. 3 (c).

As described above, in the first embodiment, the image of the field stop 6 is projected onto the sample 2p to be observed, and the defocus amount Δa between the image of the field stop 6 and the reference focus position is determined. The thickness t of the sample 2p is determined based on the detected defocus amount Δa, and the movement amount of the stage 1 is determined based on the difference ΔZ between the thickness t of the sample 2p and the thickness to of the reference sample. Therefore, even if there is an attachment such as dust on the slide glass or cover glass on which the specimen 2 is mounted, or on the condenser lens 11, the contrast of the image of the field stop 6 is much higher than that of the attachment such as dust. In addition, the shape of the image of the field stop 6 is known in advance, and the automatic focus adjustment for the specimen 2 can be performed with high accuracy using only the image of the field stop 6 substantially.

Further, since image processing of the image of the field stop 6 which is an image of a specific shape may be performed, complicated image processing is not required, and an inexpensive automatic focus adjusting device for a microscope can be provided.

(2) Next, a second embodiment of the present invention will be described. The same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 4 is a configuration diagram of an automatic focus adjustment device applied to a microscope.

This microscope is provided with an epi-illumination optical system for illuminating the specimen 2. That is, on the optical path s _{4 of the} illumination light emitted from the light source 30, the collector lens 3
1, relay lens 32, brightness stop 33, field stop 34
And a half mirror 36. Among them, the field stop 34 has a field size changed by the field stop driver 8.

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

On the stage 1, a reference sample 2s is placed.

The illumination light radiated from the light source 30 is transmitted from a collector lens 31 to a relay lens 32, a brightness stop 33,
The light passes through the field stop 34 to reach the half mirror 36, is reflected downward by the half mirror 36, and uniformly illuminates the reference sample 2s by the objective lens 12.

The light beam s ₅ from the reference sample 2 s is supplied to the objective lens 12, the imaging lens 13, and the optical path branching member 1 in the same manner as described above.
Then, the light is guided to a splitting prism 18 through a mirror 16 and an image forming lens 17, where the light is split into two parallel light beams and incident on a CCD sensor 19.

Hereinafter, as in the first embodiment, C
The CD sensor 19 outputs an analog signal of a voltage level corresponding to the amount of incident light and the accumulation time of the projected light image (front focus image, rear focus image), and the analog signal is amplified by an analog processing unit 20 for amplification or the like. Analog processing is performed, and the front focus image and the rear focus image are separately stored in the memory 22.

The arithmetic circuit 23 uses the digital signals of the front focus image and the rear focus image stored in the memory 22 to calculate the defocus amount indicating the degree of focus of the field stop 6 from the contrast value.

The CPU 24 takes in the defocus signal from the arithmetic circuit 23 and uses the stage 1 for adjusting the image of the field stop 6 to the in-focus position based on the defocus signal.
The movement amount and the movement direction of the data are obtained, and signals of the movement amount and the movement direction are sent to the drive circuit 25.

As a result, the stage 1 moves up and down, and when the front focus image and the rear focus image projected on the light receiving surface of the CCD sensor 19 have the same shape, the image of the field stop 6 becomes the in-focus position. . Further, the condenser lens 11 is moved up and down to focus the image of the field stop 34 on the reference sample 2s.

Next, the sample 2p to be observed is placed on the stage 1 instead of the reference sample 2s.

When the sample 2p is placed on the stage 1, the distance between the focal position of the objective lens 12 and the image of the field stop 6 changes due to the change in the thickness t of the sample 2p.

The light beam s ₅ from the sample 2 p is supplied to the objective lens 12, the imaging lens 13, and the optical path branching member 1 in the same manner as described above.
4. Projected to a CCD sensor 19 through a mirror 16, an imaging lens 17, and a splitting prism 18, and a digital signal of a front focus image and a rear focus image is stored in a memory 22 by an analog signal output from the CCD sensor 19. Is done.

The arithmetic circuit 23 calculates the contrast value from the digital signals of the front focus image and the rear focus image stored in the memory 22, and defocuses the degree of focus of the field stop 6 from these contrast values. Calculate the amount.

The CPU 24 determines the amount of movement of the stage 1 and the direction of movement thereof based on the calculated defocus signal, and sends the signals of the amount of movement and the direction of movement to the drive circuit 25.

As a result, the stage 1 moves in the vertical direction, and the front focus image projected on the light receiving surface of the CCD sensor 19,
When the rear focus image has the same shape, the image of the field stop 34 becomes the in-focus position.

At this time, the encoder 26
Is detected, and a signal indicating the amount of movement is sent to the CPU 24.

The CPU 24 fetches the movement amount signal output from the encoder 26, sets the movement amount Δa of the stage 1 as the defocus amount Δa of the image of the field stop 6, and calculates the above equation ( 1) Obtain the thickness t of the specimen 2p according to (3).

[0097] Next CPU24, the above equation the difference ΔZ between the thickness t _o of the sample 2p thickness t and the reference sample 2s (4) and (5)
Is calculated, and this is set as the movement amount ΔZ of the stage 1.

[0098] Next CPU24, with its direction of movement a difference ΔZ between the thickness t _o of the thickness t and the reference sample 2s of the specimen 2p as the movement amount ΔZ of the stage 1, and sends to the drive circuit 25 again.

As a result, the stage 1 moves up and down, and focus adjustment is performed on the sample 2p as shown in FIG. 3 (c).

As described above, according to the second embodiment, even if the sample 2 is subjected to epi-illumination and the field stop 34 is arranged in this epi-optical system, the same as in the first embodiment described above. Even if the slide glass, cover glass, and condenser lens 11 on which the book 2 is placed have adhered substances such as dust,
The contrast of the image of the field stop 6 is much higher than that of the attached matter such as dust, and the shape of the image of the field stop 6 is known in advance.
Can be adjusted automatically.

Further, since image processing of the image of the field stop 6 which is an image having a specific shape may be performed, complicated image processing is not required, and an inexpensive automatic focus adjusting device for a microscope can be provided.

(3) Next, a third embodiment of the present invention will be described. The same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 5 is a configuration diagram of an automatic focus adjustment device applied to a microscope.

The objective lens 12 is arranged so as to be movable in the vertical direction, which is the direction of the arrow (b), by the driving of the drive circuit 40.

The encoder 41 generates a pulse signal corresponding to the amount of movement of the objective lens 12 and
Output as a movement amount signal.

The CPU 42 takes in the amount of movement of the objective lens 12 when the objective lens 12 is moved in the vertical direction from the encoder 41, and calculates the amount of movement of the objective lens 12 as the defocus amount Δa of the image of the field stop 6. Then, the thickness t of the specimen 2 is obtained based on the defocus amount Δa,
And it has a function of calculating the moving amount of the objective lens 12 based on the difference ΔZ in the thickness t _o of the thickness t and the reference sample of the specimen 2.

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

On the stage 1, a reference sample 2s is placed. The reference sample 2s has a refractive index n of the slide glass.
In _s, and is formed to a thickness t _o.

The illumination light radiated from the light source 3 passes through the collector lens 4, the relay lens 5, and the field stop 6, reaches the reflecting mirror 7, and is reflected upward by the reflecting mirror 7, and is reflected by the relay lens 9 to be bright. The reference sample 2s is uniformly illuminated through the aperture 10 and the condenser lens 11.

The light beam s ₃ from the reference sample 2 s passes through the objective lens 12 and forms the imaging lens 13 and the optical path branching member 14.
Then, the light is guided to a splitting prism 18 through a mirror 16 and an imaging lens 17, where it is split into two parallel light beams and incident on a CCD sensor 19.

Hereinafter, as in the first embodiment, C
The CD sensor 19 outputs an analog signal of a voltage level corresponding to the amount of incident light and the accumulation time of the projected light image (front focus image, rear focus image), and the analog signal is amplified by an analog processing unit 20 for amplification or the like. Analog processing is performed, and the front focus image and the rear focus image are separately stored in the memory 22.

The arithmetic circuit 23 uses the digital signals of the front focus image and the rear focus image stored in the memory 22 to calculate a defocus amount indicating the degree of focus of the field stop 6 from the contrast value.

The CPU 42 obtains the moving amount and the moving direction of the objective lens 12 for adjusting the image of the field stop 6 to the in-focus position based on the defocus signal from the arithmetic circuit 23, and calculates the moving amount and the moving direction. Drive circuit 40
To send to.

As a result, the objective lens 12 moves in the vertical direction, and when the front focus image and the rear focus image projected on the light receiving surface of the CCD sensor 19 have the same shape, the image of the field stop 6 moves to the in-focus position. Become. Further, the condenser lens 11 is moved up and down to focus the image of the field stop 6 on the reference sample 2s.

FIG. 6 (a) shows the reference sample 2s placed on the stage 1, the focal position of the objective lens 12 having a working distance WDo, the illumination light passing from the field stop 6 through the relay lens 9, and the condenser lens 11 This shows a state in which the image of the field stop 6 when projected onto the reference sample 2s is at the same position, that is, a reference focus position. Note that, in the figure, f indicates the position of the lower surface of the objective lens 12.

Next, the sample 2p to be observed is placed on the stage 1 instead of the reference sample 2s.

The sample 2p is formed, for example, with a refractive index n _s and a thickness t.

When such a sample 2p is placed on the stage 1, the change in the thickness t of the sample 2p causes the change in the thickness t of FIG.
The distance between the focal position of the objective lens 12 and the image of the field stop 6 changes as shown in FIG.

In this state, the light beam s ₃ from the sample 2p to be observed is moved from the objective lens 12 to the imaging lens 1 in the same manner as described above.
3. The light is guided to the split prism 18 through the optical path branching member 14, the mirror 16, and the imaging lens 17 and is projected onto the CCD sensor 19.

The CCD sensor 19 outputs analog signals of a voltage level corresponding to the amount of incident light of the front focus image and the rear focus image and the accumulation time, and these are digitized and stored in the memory 2.
2 is stored.

The arithmetic circuit 23 calculates the amount of defocus indicating the degree of focusing of the field stop 6 from the digital signals of the front focus image and the rear focus image stored in the memory 22 based on the contrast value.

The CPU 42 obtains the moving amount and moving direction of the objective lens 12 based on the calculated defocus signal, and outputs the signals of the moving amount and moving direction to the driving circuit 4.
Send to 0.

As a result, when the objective lens 12 moves in the vertical direction and the front focus image and the rear focus image projected on the light receiving surface of the CCD sensor 19 have the same shape, the image of the field stop 6 becomes the in-focus position. .

At this time, the encoder 41 detects the movement amount Δa of the objective lens 12 and outputs the movement amount signal to the CPU 4.
Send to 2.

The CPU 42 fetches the movement amount signal output from the encoder 41, sets the movement amount Δa of the objective lens 12 as the defocus amount Δa of the image of the field stop 6, and uses the sample 2p based on the defocus amount Δa. Is determined.

[0126] That is, the thickness to the reference sample 2s, working distance WD _o of the objective lens 12, when the working distance of the objective lens 12 in the case of specimens 2p observing the WD, the specimen 2p
The thickness t of the above formulas (1) to (3), and _{t = t o + Δa / (} 1-1 / n s) ... (6).

[0127] Next CPU42 obtains a difference ΔZ between the thickness t _o of the sample 2p thickness t and the reference sample 2s, obtains this as the movement amount ΔZ of the objective lens.

That is, the thickness t of the sample 2p and the reference sample 2
The difference [Delta] Z between the thickness t _o of the s, the above formulas (4) and (5), and ΔZ = Δa / (1-1 / n s) ... (7).

[0129] CPU42, with its direction of movement a difference ΔZ between the thickness t _o of the sample 2p thickness t and the reference sample 2s as the movement amount ΔZ of the objective lens 12 again sends to the drive circuit 40.

As a result, the objective lens 12 moves up and down, and focus adjustment is performed on the sample 2p as shown in FIG. 6 (c).

As described above, in the third embodiment, the image of the field stop 6 is projected onto the sample 2p to be observed, and the defocus amount Δa between the image of the field stop 6 and the reference focus position is determined. The thickness t of the sample 2p is determined based on the defocus amount Δa, and the objective lens 12 is determined based on the difference ΔZ between the thickness t of the sample 2p and the thickness to of the reference sample.
It is needless to say that the same effect as that of the above-described first embodiment can be obtained since the movement amount is obtained.

(4) Next, a fourth embodiment of the present invention will be described. The same parts as those in FIG. 4 are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 7 is a configuration diagram of an automatic focus adjustment device applied to a microscope.

This microscope is provided with an epi-illumination system, and the objective lens 12 is movable in the vertical direction, which is the direction of the arrow (b), by the driving of the drive circuit 40.

Further, the encoder 41 has a function of generating a pulse signal corresponding to the amount of movement of the objective lens 12 and outputting this as a signal of the amount of movement of the objective lens 12.

The CPU 42 takes in the amount of movement of the objective lens 12 when the objective lens 12 is moved in the vertical direction from the encoder 41, and calculates the amount of movement of the objective lens 12 as the defocus amount Δa of the image of the field stop 6. Then, the thickness t of the specimen 2 is obtained based on the defocus amount Δa,
And it has a function of calculating the moving amount of the objective lens 12 based on the difference ΔZ in the thickness t _o of the thickness t and the reference sample of the specimen 2.

With such a configuration, when the specimen 2p to be observed is placed on the stage 1 instead of the reference specimen 2s, the change in the thickness t of the specimen 2p causes the objective lens 1p to change.
The distance between the focal position 2 and the image of the field stop 34 changes.

In this case, the arithmetic circuit 23 calculates the defocus amount indicating the degree of focus of the field stop 34 from the contrast value of the digital signal corresponding to the front focus image and the rear focus image formed on the CCD sensor 19. Then, the CPU 42 obtains the moving amount and moving direction of the objective lens 12 based on the defocus signal, moves and drives the objective lens 12, and focuses the image of the field stop 34.

At this time, the encoder 26 detects the movement amount Δa of the objective lens 12 and outputs the movement amount signal to the CPU 4.
Send to 2.

The CPU 42 fetches the movement amount signal output from the encoder 41, and uses the movement amount Δa of the stage 1 as the defocus amount Δa of the image of the field stop 34,
Seeking a thickness t of the specimen 2p according to the above formula (1) to (3) based on the defocus amount .DELTA.a, followed by the difference ΔZ between the thickness t _o of the sample 2p thickness t and the reference sample 2s Equations (4) and (5) are obtained by calculation, and this is calculated as the movement amount ΔZ of the stage 1.
And

[0141] Next CPU42, with its direction of movement a difference ΔZ between the thickness t _o of the sample 2p thickness t and the reference sample 2s as the movement amount ΔZ of the stage 1 again sends to the drive circuit 40.

As a result, the objective lens 12 moves in the vertical direction, and is adjusted to focus on the sample 2p.

As described above, according to the fourth embodiment, it goes without saying that the same effects as those of the first embodiment can be obtained.

(5) Next, a fifth embodiment of the present invention will be described. The same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 8 is a configuration diagram of an automatic focus adjustment device applied to a microscope.

On the optical path s _{1 of the} illumination light emitted from the light source 3, a collector lens 4, a relay lens 5, a field stop 6
And a half mirror 50.

[0147] reflection direction of the half mirror 50, that is, on the optical path s ₂ of the illumination light directed upward by the half mirror 50, a relay lens 9, is arranged 10 and the condenser lens 11 aperture stop, the condenser lens 11, the sample 2 is uniformly illuminated.

An indicator light source 51 is provided, and is turned on by a lighting control signal sent from an indicator light source driver 52.

An index plate 53 is arranged on the optical path of the index light emitted from the index light source 51 (coincides with the optical path s _{2 of the} illumination light).

The index plate 53 is arranged at a position conjugate with the field stop 6.

The arithmetic circuit 54 obtains only the image of the index plate 53 from the deviation between the output signal of the CCD sensor 19 for the reference sample 2s stored in the memory 22 and the output signal of the CCD sensor 19 for the sample 2p to be observed. Has a function.

The arithmetic circuit reads out digital signals of the front focus image and the rear focus image for the image of the index plate 53 stored in the memory 22, and uses the digital signals of the front focus image and the rear focus image. It has a function of calculating a contrast value between the front focus image and the rear focus image, and calculating a defocus amount indicating the degree of focus of the index plate 53 from these contrast values.

The CPU 55 takes in the defocus signal from the arithmetic circuit 54, obtains the moving amount and the moving direction of the stage 1 for adjusting the image on the index plate 53 to the in-focus position based on the defocus signal. It has a function of sending a signal of the movement amount and the movement direction to the drive circuit 25.

The CPU 55 calculates the amount of movement of the stage 1 when the stage 1 is
And the movement amount of the stage 1 is
Was calculated as the defocus amount .DELTA.a image, determine the thickness t of the specimen 2p based on the defocus amount .DELTA.a, based on the difference ΔZ in the thickness t _o of the thickness t and the reference sample of the specimen 2p It has a function of determining the amount of movement of the stage 1.

The timing generator 56 has a CPU 5
5 has a function of sending a readout timing signal to the CCD sensor 19 based on the timing signal from the CPU 5.

The indicator light source driver 52 outputs a lighting control signal based on a timing signal from the CPU 55 to the indicator light source 5.
1 to control the lighting.

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

On the stage 1, a reference sample 2s is placed.

The illumination light emitted from the light source 3 passes from the collector lens 4 through the relay lens 5 and the field stop 6 to the half mirror 50, where it is reflected upward and is reflected by the relay lens 9 and the brightness stop 10 Through the condenser lens 11, and the condenser lens 11 uniformly illuminates the reference sample 2s.

The light beam s ₃ from the reference sample 2 s passes through the objective lens 12 and the imaging lens 13 and passes through the optical path branching member 14.
Then, the light is guided to a splitting prism 18 through a mirror 16 and an imaging lens 17, where it is converted into two parallel light beams.
The light is divided and incident on the CCD sensor 19.

Since the CCD sensor 19 outputs an analog signal having a voltage level corresponding to the amount of incident light of the projected light image and the accumulation time, the analog signal is amplified and filtered by an analog processing section 20, and the like. The data is digitized by the A / D converter 21 and stored in the memory 22.

At this time, the CCD stored in the memory 22
The digital output signal of the sensor 19 is obtained by irradiating only the illumination light to the reference sample 2s, and its waveform is shown in FIG. 9, for example.

Next, when the index light source 51 is turned on, the index light emitted from the index light source 51 passes through the index plate 53 to become an index image, and this index image is formed by the half mirror 50, the relay lens 9, and the brightness. The light reaches the condenser lens 11 through the aperture 10 and is projected onto the reference sample 2s by the condenser lens 11.

Then, the reference sample 2s on which the index image is projected
Light beam s ₃ from the objective lens 12, reaches the optical path splitting member 14 through the imaging lens 13 is guided to the split prism 18 further through the mirror 16, an imaging lens 17, 2 wherein the two parallel light beams The light is divided and incident on the CCD sensor 19.

Since the CCD sensor 19 outputs an analog signal having a voltage level corresponding to the amount of incident light of the light image including the index image and the storage time, the analog signal is amplified and filtered by the analog processing section 20. A / D
The data is digitized by the converter 21 and stored in the memory 22.

At this time, the CCD stored in the memory 22
The digital output signal of the sensor 19 is obtained by projecting an index image onto the reference sample 2s, and its waveform is shown in FIG. 10, for example.

The arithmetic circuit 54 generates a signal of only the index image shown in FIG. 11 from the deviation between the output signal of each CCD sensor 19 when the index image is projected onto the reference sample 2s stored in the memory 22 and when it is not projected. Ask.

The index image incident on the CCD sensor 19 is split into two parallel light beams by the splitting prism 18.
Since the image is divided, a front focus image and a rear focus image for the target image are formed.

Therefore, the arithmetic circuit reads out the digital signals of the front focus image and the rear focus image of the target image, and uses the digital signals of the front focus image and the rear focus image to form the front focus image and the rear focus image. Contrast values are calculated, and a defocus amount indicating the degree of focus of the index plate 53 is calculated from these contrast values.

The CPU 24 fetches the defocus signal from the arithmetic circuit 54, obtains the moving amount and the moving direction of the stage 1 for adjusting the image on the index plate 53 to the in-focus position based on the defocus signal. The signal of the movement amount and the movement direction is sent to the drive circuit 25.

As a result, the stage 1 moves up and down, the front focus image and the rear focus image projected on the light receiving surface of the CCD sensor 19 have the same shape, and the index image is at the in-focus position.

Next, the sample 2p to be observed is placed on the stage 1 instead of the reference sample 2s.

When the sample 2p is placed on the stage 1, the distance between the focus position of the objective lens 12 and the index image changes due to a change in the thickness t of the sample 2p.

However, as described above, the sample 2p to be observed
C when the target image is not projected and when the target image is projected
Each digital output signal of the CD sensor 19 is stored in the memory 22.

The arithmetic circuit 54 obtains a signal of only the index image from the deviation between the output signal of each CCD sensor 19 when the index image is projected onto the sample 2p stored in the memory 22 and when it is not projected.

Next, the arithmetic circuit reads out the digital signals of the front focus image and the rear focus image of the target image, and uses the digital signals of the front focus image and the rear focus image to form the front focus image and the rear focus image. Contrast values are calculated, and a defocus amount indicating the degree of focus of the index plate 53 is calculated from these contrast values.

The CPU 24 fetches the defocus signal from the arithmetic circuit 54, obtains the moving amount and the moving direction of the stage 1 for adjusting the image on the index plate 53 to the in-focus position based on the defocus signal. The signal of the movement amount and the movement direction is sent to the drive circuit 25.

As a result, the stage 1 moves up and down, and the target image projected on the sample 2p is at the in-focus position.

At this time, the encoder 26
Is detected, and the movement amount signal is sent to the CPU 55.

The CPU 55 fetches the movement amount signal output from the encoder 26, sets the movement amount Δa of the stage 1 as the defocus amount Δa of the index image, and based on the defocus amount Δa, The thickness t of the sample 2p is obtained according to (3).

[0181] Next CPU55, the above equation the difference ΔZ between the thickness t _o of the sample 2p thickness t and the reference sample 2s (4) and (5)
Is calculated, and this is set as the movement amount ΔZ of the stage 1.

[0182] Next CPU55, with its direction of movement a difference ΔZ between the thickness t _o of the thickness t and the reference sample 2s of the specimen 2p as the movement amount ΔZ of the stage 1, and sends to the drive circuit 25 again.

As a result, the stage 1 moves up and down, and focus adjustment is performed on the sample 2p.

As described above, according to the fifth embodiment, the target image is projected onto the sample 2p to be observed, and the defocus amount Δa between the target image and the reference focus position is detected. The thickness t of the sample 2p is obtained based on the defocus amount Δa, and the movement amount of the stage 1 is obtained based on the difference ΔZ between the thickness t of the sample 2p and the thickness t _o of the reference sample 2s. Needless to say, the same effects as those of the first embodiment can be obtained, and it is not necessary to adjust the aperture of the field stop 6.

(6) Next, a sixth embodiment of the present invention will be described. The same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

As a microscope for switching the observation magnification of the objective lens, there is one having a configuration shown in FIG.

On the optical path s _{1 of the} illumination light emitted from the light source 3, a collector lens 4, a field stop (FS) 6, and a reflecting mirror 7 are arranged.

The optical path s of the illumination light in the reflection direction of the reflecting mirror 7
₂ , a relay lens 9, a brightness stop 10, a condenser lens 11a and its front lens 11b (condenser lens 11) are arranged.

[0189] On the other hand, on the light beam s ₃ from the specimen 2, a plurality of objective lenses 61a provided on the revolver 60, 61b
Among them, for example, the objective lens 61a is inserted.

The revolver 60 includes a revolver driving device 6
It is driven by 2 with a plurality of objective lenses 61a, which is intended to insertion and removal of one of the objective lens 61a or 61b of 61b on the light beam s _3.

[0191] However, CPU 24 is the magnification of the objective lens 61a or 61b is inserted on the optical beam s _3, drives the condenser lens driving device 63 according to the NA (numerical aperture), illuminating the top lens 11b of the condenser lens 11 The light is inserted into and removed from the optical path s ₂ of the light, the focal length of the condenser lens 11 is changed, and appropriate illumination is projected onto the sample 2.

Here, the illumination optical system based on the optical paths s ₁ and s ₂ of the illumination light will be described in detail with reference to FIG.
Illumination light emitted from the light source 3 is collected by the collector lens 4 and the relay lens 9,
The image of the light source 3 is projected on the surface of the aperture stop 10 at the entrance pupil position.

On the other hand, the illumination light illuminated by the light source 3 and the collector lens 4 and emitted from the field stop 6
, Is collimated by the relay lens 9, condensed on the surface of the sample 2 by the condenser lens 11, and the image of the field stop 6 is projected, so-called Koehler illumination is performed.

That is, the condenser lens 11 is an imaging lens for projecting the field stop 6 on the surface of the sample 2. For example, the objective lenses 61a and 61b are switched to illuminate a wide field with a low magnification objective lens. For this purpose, it is necessary to increase the focal length of the condenser lens 11 and increase the projection magnification of the field stop 6.

However, with one condenser lens, the position of the aperture stop 10 serving as the entrance pupil is not changed, and the rear focal position serving as the projection plane of the field stop 6 is kept on the surface of the sample 2. It is difficult to change only the focal length of the lens, and even if it is realized, the number of lenses increases and the cost increases.

[0196] From such a fact, by removing the top lens 11b of the condenser lens 11 as shown in FIG. 14 from the optical path s _2, although a longer focal length of the condenser lens 11, which in the complete Kohler illumination In many cases, the field stop 6 is not projected on the surface of the specimen 2 in many cases.

This is not limited to the case where optimal illumination is performed from a low-magnification objective lens to a high-magnification objective lens with a single condenser lens, but optimal illumination is performed for an extremely low-magnification objective lens such as a 1 × objective lens. Even in this case, the focal length of the condenser lens becomes longer, whereby the condenser lens approaches the relay lens 9 and the reflecting mirror 7, and the field stop 6 is often not projected on the two surfaces of the sample due to space restrictions.

Therefore, even if the contrast of the image (FS image) of the field stop 6 is detected and the automatic focus adjustment is performed, the image of the field stop 6 cannot be focused on the surface of the sample 2.

A sixth embodiment in which the contrast can be detected and the automatic focus adjustment can be performed even when the image of the field stop 6 cannot be projected on the sample 2 based on such a situation will be described below.

When the focal length of the condenser lens 11 is changed in accordance with the observation magnification of the objective lens 61a or 61b as shown in FIGS. An index 70 for focus adjustment is arranged at a position conjugate with the sample 2.

[0201] That is, FIG. 15 is an overall configuration diagram of a microscope according to the according autofocus adjustment method, 16 when opening the top lens 11b of the condenser lens in the low-magnification objective lens illumination in the microscope from the optical path s ₂ 1 is a configuration diagram of a transmission illumination optical system including a condenser lens 11a of FIG.

The first lens 11b of the condenser lens has an optical path s ₂
In the state of being inserted into, although the image of the field stop 6 is projected on two surfaces specimen, when the top lens 11b is removed from the optical path s _2, the focal length of the condenser lens 11 is increased, the image of the field stop 6 Is above the specimen 2, that is, the objective lens 61
It is projected on the side of a or 61b, and is not projected on the surface of the specimen 2.

[0203] In a state where the top lens 11b is removed from the optical path s ₂ is the focal length of the condenser lens 11 is increased, the sample 2 and the conjugate plane is a position of the collector lens 4 side than the field stop 6.

Therefore, the index 7 is located at a position conjugate with the sample 2.
When 0 is arranged, the image of the index 70 is projected on the surface of the sample 2, and the contrast of the image of the index 70 is detected to perform automatic focus adjustment, and the sample 2 can be focused.

Here, the index 70 has a shape projected onto the periphery of the visual field of the specimen 2 such as a circle, and
1b even if the condenser lens 11 is inserted in the optical path s ₂ becomes illumination for the high-magnification objective lens, does not enable light for illumination is blocked by vignetting by indicator 70.

[0206] Also, even when the previous ball 11b is out of the optical path s _2, if the indicator image 70 is projected at a sufficiently such size of the observation magnification CCD sensor 19 for automatic focusing, the index 70, in a fixed position, or in a state of being always inserted into the optical path s _2.

However, an effective ray for illumination when the front lens 11b is inserted into the optical path s ₂ is blurred by the index 70, or the size of the projected image of the index 70 is
When it does not cover the D sensor 19, the objective lens 16a
Or the one that insertion and removal of the indicator 70 from the optical path s ₂ in accordance with a change in observation magnification by 16b.

The mechanism for inserting and removing the index 70 according to the change in the observation magnification by the objective lens 16a or 16b will be described below with reference to the overall configuration diagram of the microscope shown in FIG.

The CPU 71 receives a selection signal of the type and magnification of the objective lens 61a or 61b sent from the external controller 28, and sends a signal of objective lens conversion to the resolver driving device 62 based on the selection signal. It has a function as a changing means.

The CPU 71 sends the objective lens conversion signal to the revolver driving device 62, and determines whether the front lens 11b of the condenser lens 11 is inserted or removed according to the observation magnification of the objective lens 61a or 61b, ie, a high magnification. It sends a determination signal for inserting a lensed 11b in the optical path s ₂ to the condenser lens driving device 63 in the case of the objective lens, also the condenser lens driving determination signal to remove the lensed 11b from the optical path s ₂ in the case of low magnification objective lens It has a function of sending it to the device 63.

Further, the CPU 71 replaces the objective lens, inserts and removes the front lens 11b, and sets the first lens 1 of the condenser lens 11 together.
1b is sent a signal to remove the indicator 70 from the optical path s ₁ to the index drive 72 when it is inserted into the optical path s _2, Matasakidama 11b optical path s ₁ the indicator 70 when is out of the optical path s ₂ Has a function as index insertion / removal means for transmitting a signal to be inserted into the index driving device 72.

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

When the observation magnification by the objective lens is changed, the external controller 28 selects the objective lens 61a or 61b suitable for the desired observation magnification.

The external controller 28 sends the CPU 71
On the other hand, when a selection signal for the type and magnification of the selected objective lens 61a or 61b is sent, the CPU 71 sends a signal for objective lens conversion to the revolver driving device 62 based on the selection signal, for example, if the magnification is high, the objective Objective lens conversion signal of lens 61a, objective lens 61b if low magnification
Is transmitted.

Thus, the objective lens 6 having a desired observation magnification can be obtained.
1a or 61b is disposed on the light beam s ₃ by the operation of the revolver 60 by driving the revolver drive 62.

At the same time, when the high-magnification objective lens 61a is selected, the CPU 71
Determination signal to be inserted into the optical path s ₂ and 1b, also sends a decision signal to remove the lensed 11b from the optical path s ₂ if you select the low-magnification objective lens 61b to the condenser lens driving device 63.

[0217] Thus, the hemispherically 11b of the condenser lens 11 is inserted into the optical path s ₂ in the case of high-magnification objective lens 61a by driving the condenser lens driving device 63, and the optical path s ₂ in the case of low magnification objective lens 61b Removed.

[0218] In addition, CPU 71 is replace the objective lens, with insertion and removal of the front lens 11b, an indicator if the front lens 11b of the condenser lens 11 is inserted into the optical path s ₂ 70
Signal to remove from the optical path s _1, Matasakidama 11b sends out a signal to insert the index 70 in the optical path s ₁ if you are out of the optical path s ₂ in the index drive 72.

As a result, the index 70 is changed to the index driving device 72.
Of being removed from the optical path s ₁ in the case of high-magnification objective lens 61a by the drive, also is inserted into the optical path s ₁ in the case of low magnification objective lens 61b.

[0220] Therefore, when a high magnification of the objective lens 61a is selected, the indicator 70 is removed from the optical path s ₁ with the top lens 11b of the condenser lens 11 is inserted into the optical path s _2, as shown in FIG. 13 The image of field stop 6 is sample 2
Projected onto the surface.

The light beam s ₃ from the sample 2 reaches the optical path branching member 14 through the objective lens 61 a and the imaging lens 13, and a part of the light beam s ₃ from the sample 2 is converted into an eyepiece by the optical path branching member 14. 15 and another light beam is guided to a split prism 18 through a mirror 16 and an imaging lens 17.

The splitting prism 18 splits the incident light beam into two, and sends the two light beams to the CCD sensor 19 in a parallel state.

The CCD sensor 19 outputs an analog signal having a voltage level according to the amount of incident light and the accumulation time of the projected light image (front focus image, rear focus image).

The analog processing section 20 includes a CCD sensor 19
The analog signals output from the CPU are separately subjected to analog processing such as amplification and filtering for the front focus image and the rear focus image.

The output signal of the analog processing section 20 is digitized by the A / D converter 21 and sent to the memory 22, where the front focus image and the rear focus image are separately stored.

The arithmetic circuit 23 reads out the digital signals of the front focus image and the rear focus image stored in the memory 22, and uses the digital signals of the front focus image and the rear focus image to generate the front focus image and the rear focus image. Are calculated, and the defocus amount indicating the degree of focus of the field stop 6 is calculated from these contrast values.

The CPU 24 fetches the defocus signal calculated by the arithmetic circuit 23, and calculates the moving amount and the moving direction of the stage 1 for adjusting the image of the field stop 6 to the in-focus position based on the defocus signal. , And the signals of the movement amount and the movement direction are sent to the drive circuit 25.

As a result, the stage 1 moves up and down, and when the front focus image and the rear focus image projected on the light receiving surface of the CCD sensor 19 have the same shape, the image of the field stop 6 becomes the in-focus position. .

On the other hand, when the low-magnification objective lens 61b is selected, the front lens 11b of the condenser lens 11 is connected to the optical path s.
Since the index 70 together are removed from the ₂ is inserted into the optical path s _1, the indicator image 70 is projected on the two surfaces specimen as shown in FIG. 16.

The light beam s ₃ from the sample 2 is supplied to the objective lens 61a in the same manner as the high-magnification objective lens 61a.
Then, the light passes through the imaging lens 13, passes through the imaging lens 17, and is guided to the splitting prism 18, where it is split into two and enters the CCD sensor 19.

The CCD sensor 19 outputs an analog signal having a voltage level corresponding to the amount of incident light and the accumulation time of the projected light image (front focus image, rear focus image). Digital signals of the pin image and the back focus image are separately stored in the memory.

The arithmetic circuit 23 calculates the contrast value between the front focus image and the rear focus image using the digital signals of the front focus image and the rear focus image, and indicates the degree of focus of the field stop 6 from these contrast values. Calculate the defocus amount.

The CPU 24 fetches the defocus signal calculated by the arithmetic circuit 23, and obtains the moving amount and the moving direction of the stage 1 for adjusting the image of the field stop 6 to the in-focus position based on the defocus signal. The stage 1 moves up and down, and sends a signal indicating the amount of movement and the direction of movement to the drive circuit 25.
When the front focus image and the rear focus image projected on the light receiving surface 9 have the same shape, the image of the index 70 becomes the in-focus position.

In the field stop 6, the front lens 11b has the optical path s.
_{When the} lens is inserted into the optical path s ₂ , it is set to an appropriate size by driving the field stop driver 8 based on a command from the CPU 71 in accordance with the observation magnification of the objective lens 61a. If the effective light of the illumination light is cut off and blocked by the field stop 6 in a state where
In conjunction with the switching of the objective lens, the field stop 6 may be expanded to a size at which the effective light of the illumination light cannot be cut.

[0235] Also, when the top lens 11b is in the way the image is observed indicator 70 in a state that has entered the optical path s ₂ is linked to the start / stop signal of the automatic focusing operation is input from the external controller 28 to, may be as automatic focus adjusting operation only when the index 70 via the CPU71 and the index drive 72 is inserted in the optical path s _1.

Here, the index 70 is inserted into and removed from the optical path s ₁ via the CPU 71 and the index driving device 72 in conjunction with various operations. The index 70 is, for example, an open / close type index whose diameter is approximately circular. When the index 70 is unnecessary, the diameter may be increased so as to deviate from the effective light beam.

As described above, in the sixth embodiment, the index 70 is arranged at a position conjugate with the surface of the sample 2 with respect to the condenser lenses 11 having different focal lengths. Even when the condenser lens 11 cannot be projected onto the surface of the specimen 2, by projecting the image of the index 70 onto the surface of the sample 2 and detecting the contrast thereof, automatic focusing can be performed from low-magnification observation to high-magnification observation.

Also, in conjunction with switching of the objective lenses 61a and 61b, insertion and removal of the front lens 11b of the condenser lens 11,
Since the opening and closing of the diameter of the field stop 6 and the insertion and removal of the index 70 are performed, optimal illumination can be obtained from low-magnification observation to high-magnification observation without obstructing the effective light beam of the illumination to the index 70 or the field stop 6, and operation. Can be simplified and complicated operations can be eliminated, and the user can concentrate on microscopy of microscope images.

Further, since the projection optical system of the index 70 does not require a dedicated optical path and is coaxial with the transmission illumination optical system, optical elements such as mirrors and lenses are inserted during the automatic focus adjustment operation. There is no need to remove it, the configuration is simple, and a single light source 3 can be configured at low cost.

Further, since it is not necessary to guide the dedicated target projection optical system coaxially with the transmitted illumination optical system by a half mirror or the like,
Both the image of the index 70 and the observation image have no loss of brightness, the illumination efficiency is good, and a bright index image and observation image can be obtained.

(7) Next, a seventh embodiment of the present invention will be described. The same parts as those of the entire configuration of the microscope shown in FIG. 15 are denoted by the same reference numerals, and detailed description thereof will be omitted.
The following description focuses on each component of the index projection and transmission illumination optical system including the condenser lens 11 which is a feature of the present invention.

FIGS. 17 and 18 are views showing the configuration of a seventh embodiment of a target projection and transmission illumination optical system in a microscope to which an automatic focus adjustment device is applied, and FIG. 17 illuminates a low-magnification objective lens 61b. FIG. 18 shows a case of illumination suitable for the high-magnification objective lens 61a.

As shown in FIG. 17, from the light source 3 to the aperture stop 10, Koehler illumination having the same configuration as the microscope shown in FIG. 15 is used.

The condenser lens 11 includes a condenser lens 11a of a convex lens and a front lens 11c of a concave lens, of which the front lens 11c is an objective lens 61a, 61b.
Has a removably with respect to the optical path s ₂ according to the observation magnification.

As shown in FIG. 17, the low-magnification objective lens 61b
In the case where the top lens 11c is inserted into the optical path s _2, light source 3, the field stop 6 image of illuminated by the collector lens 4 is projected onto the specimen 2 sides, similar to the embodiment of the sixth By detecting the contrast of the image of the field stop 6, automatic focus adjustment can be performed.

[0246] On the other hand, shows a state in which the front lens 11c upon lighting of the low magnification objective lens 61b is out of the optical path s ₂ from the state of being inserted into the optical path s ₂ as shown in FIG. 18.

Since the front lens 11c is a concave lens, the optical path s ₂
Is out of the range, the focal length of the condenser lens 11 is shortened, and critical illumination suitable for a high-magnification objective lens is obtained.

In this case, a plane optically conjugate with the specimen 2 coincides with the aperture stop 10, and an image of the aperture stop 10 is projected on the specimen 2.

Therefore, the image of the aperture stop 10 is
Since the image is projected on the surface, the automatic focus adjustment can be performed by detecting the contrast of the image of the aperture stop 10 as described above, and the sample 2 is brought into focus.

As described above, in the seventh embodiment, the two indices, ie, the field stop 6 and the brightness stop 10, are placed at positions conjugate with the sample 2 with respect to the condenser lens 11 having two different focal lengths. Since the condenser lens 11 is disposed, the condenser lens 11 is composed of a condenser lens 11a of a convex lens and a front lens 11c of a concave lens. 2 and can be focused on the specimen 2.

In addition, since the field stop 6 or the brightness stop 10 is used as an index, there is no need to provide a dedicated index for projecting the index, and the configuration can be made inexpensively.

In the seventh embodiment of the present invention, the objective lens 6 can be used if necessary, as in the sixth embodiment.
The insertion and removal of the front lens 11c and the opening and closing of the field stop 6 and the brightness stop 10 may be performed in conjunction with the switching between 1a and 61b.

As a result, optimal illumination can be obtained from low-magnification observation to high-magnification observation, and the operation is simplified, and complicated operation is eliminated.

(8) Next, an eighth embodiment of the present invention will be described. The same parts as those of the entire configuration of the microscope shown in FIG. 15 are denoted by the same reference numerals, and detailed description thereof will be omitted.
The following description focuses on each component of the index projection and transmission illumination optical system including the condenser lens 11 which is a feature of the present invention.

FIGS. 19 and 20 are configuration diagrams showing an eighth embodiment of a target projection and transmission illumination optical system in a microscope to which the automatic focus adjustment device is applied. FIG. 19 shows a case where the front lens is removed. FIG. 20 shows a case where the front ball is inserted.

This microscope uses an illumination system for a very low magnification objective lens such as a 1 × objective lens.

The structure from the light source 3 to the aperture stop 10 is the same as that of the seventh embodiment.

Since the condenser lens 11 is dedicated to extremely low magnification illumination, it has a one-group structure and a very long focal length. The projected image of the field stop 6 is located above the sample 2 (objective lens) as shown in FIG. Side).

A field stop projection lens (hereinafter, referred to as an FS projection lens) 71 is disposed so as to be insertable into and removable from the optical path s ₂ above the condenser lens 11.

In the state where the FS projection lens 71 is inserted into the optical path s ₂ as shown in FIG.
The field stop 6 is projected on the surface of the sample 2.

The FS projection lens 71 is connected to the optical path s ₂
In this state, the illumination performance does not necessarily need to be maintained, and the image of the field stop 6 may be clearly projected on the surface of the sample 2.

With such a configuration, during normal microscopy, as shown in FIG. 19, the FS projection lens 71 moves the optical path s _2.
And maintains sufficient illumination performance to satisfy the illumination field NA of the extremely low magnification objective lens.

As shown in FIG. 20, only during the automatic focus adjustment operation, the FS projection lens 7
1 is inserted into the optical path s ₂ , the image of the field stop 6 is projected onto the sample 2 by the FS projection lens 71, and the automatic focus adjustment is performed by detecting the contrast of the image of the field stop 6.

[0264] When the automatic focus adjustment is completed, FS projection lens 71 becomes disengaged from the optical path s ₂ again, the normal observation is performed.

As described above, in the eighth embodiment, the FS projection lens 71 of the illumination system is inserted into and removed from the optical path s ₂ in conjunction with the automatic focus adjustment operation, and the field stop 6 is opened only during the automatic focus adjustment operation. Since the image is projected on the surface of the sample 2 and the contrast of the image of the field stop 6 is detected to perform the automatic focus adjustment operation, sufficient illumination performance can be maintained during normal observation, and the sample 2 can be maintained. Even if the index is arranged at a position conjugate with the sample, even if the index cannot be arranged at a desired position due to a space problem or a position conjugate to the sample 2 near the light source 3 and a problem of damage due to heat, the FS projection lens The image of the field stop 6 is projected onto the surface of the sample 2 by inserting / removing the 71, and the position of the index is arranged at a desired position by a combination of the position and the power of the FS projection lens 71 to be inserted / removed. Projected on Can.

Further, since the insertion / removal of the FS projection lens 71 is linked with the automatic focus adjustment operation, the observation of the sample 2 by the condenser lens 11 in the state of the automatic focus adjustment operation is prevented by mistake.

[0267]

As described above in detail, according to the present invention, even if there is an adhering substance in the optical system of the microscope, focus adjustment can be performed with high accuracy even for a sample having a low contrast without being affected by the adhering substance. It is possible to provide an inexpensive automatic focus adjustment method and a device therefor.

According to the present invention, even when the field stop cannot be projected on the sample surface when condenser lenses having different focal lengths are used, the image of the target is projected on the sample surface, and the contrast is changed. By detecting, it is possible to provide an automatic focus adjustment method and an automatic focus adjustment method capable of performing automatic focus adjustment from low magnification observation to high magnification observation.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing an operation procedure of automatic focus adjustment.

FIG. 3 is a diagram showing the operation of automatic focus adjustment.

FIG. 4 is a configuration diagram showing a second embodiment of the automatic focus adjustment device according to the present invention.

FIG. 5 is a configuration diagram showing a third embodiment of the automatic focus adjustment device according to the present invention.

FIG. 6 is a view showing the operation of automatic focus adjustment.

FIG. 7 is a configuration diagram showing a fourth embodiment of the automatic focus adjustment device according to the present invention.

FIG. 8 is a configuration diagram showing a fifth embodiment of the automatic focus adjustment device according to the present invention.

FIG. 9 is a diagram showing an output of a CCD sensor when an index image is not projected on a sample.

FIG. 10 is a diagram showing a CCD sensor output when an index image is projected on a sample.

FIG. 11 is a diagram showing a CCD sensor output of only an index image.

FIG. 12 is a configuration diagram of a microscope that switches an observation magnification of an objective lens.

FIG. 13 is an enlarged configuration diagram of an illumination optical system of the microscope.

FIG. 14 is an enlarged configuration diagram of an illumination optical system in which a front sphere is removed.

FIG. 15 is a configuration diagram showing a sixth embodiment of a microscope to which the automatic focus adjustment device according to the present invention is applied.

FIG. 16 is a configuration diagram of a transmission illumination optical system in which a front lens of a condenser lens is removed during illumination of a low-magnification objective lens.

FIG. 17 is a configuration diagram showing a seventh embodiment in the case of a low-magnification objective lens of a microscope to which the automatic focus adjustment device according to the present invention is applied.

FIG. 18 is a configuration diagram of the microscope in the case of a high-magnification objective lens.

FIG. 19 is a configuration diagram showing an eighth embodiment of a 1 × objective lens of a microscope to which the automatic focus adjustment device according to the present invention is applied.

FIG. 20 is a view showing a state where a front lens is inserted in the microscope.

[Explanation of symbols]

 Reference Signs List 1 ... stage, 2 ... sample (reference sample 2s, observation sample 2p), 3,30 ... light source, 6,34 ... field stop, 10 ... brightness stop, 11 ... condenser lens, 11b, 11c ... front lens, 12 , 61a, 61b: Objective lens, 19: CCD sensor, 23, 54: Arithmetic circuit, 24, 42, 55, 71: CPU, 26, 41: Encoder, 51: Index light source, 53: Index plate. 60: Revolver, 70: Index, 71: FS projection lens.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nobuyuki Nagasawa 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Industrial Co., Ltd. (72) Hideaki Endo 2-43-2 Hatagaya, Shibuya-ku, Tokyo Within Olympus Optical Co., Ltd. (72) Minoru Kojima 2-43-2 Hatagaya, Shibuya-ku, Tokyo Within Olympus Optical Co., Ltd. Atsuhiro Tsuchiya 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd.

Claims (6)

[Claims] 1. An automatic focus adjustment method for adjusting focus by changing a relative position between an objective lens and a specimen, wherein a field stop image or a target image is projected on the sample, and the field stop image or the target image is projected. An autofocus adjustment method comprising: detecting a defocus amount between a reference focus position and a reference focus position to obtain a focus distance; and performing focus adjustment based on the focus distance. 2. An automatic focus adjustment device for adjusting focus by changing a relative position between an objective lens and a sample, wherein: an optical system for projecting a field stop image or an index image on the sample; Detecting means for detecting a defocus amount between the obtained field stop image or index image and a reference in-focus position; and a relative position between the objective lens and the sample based on the defocus amount detected by the detecting means. An autofocusing device, comprising: focusing means for adjusting a position to a focus position. 3. The detection means holds an imaging position of the field stop image or the index image when a reference sample having at least a refractive index and a thickness serving as a reference is used as a reference focus position. A function of detecting a defocus amount between the reference in-focus position and the field stop image or the index image projected on the specimen, wherein the focusing unit adjusts the defocus amount detected by the detection unit. A function of calculating a relative position movement amount between the objective lens and the sample based on a difference between the thickness of the sample and the thickness of the sample based on the thickness of the sample. 3. The automatic focusing device according to claim 2, wherein 4. An automatic focus adjustment method for irradiating illumination light onto a sample through a condenser lens and changing a relative position between the objective lens and the sample to perform focusing adjustment, wherein the focus adjustment is performed according to an observation magnification of the objective lens. When the focal length of the condenser lens is changed, a plurality of indices for focus adjustment are arranged at positions conjugate to the specimen with respect to each condenser lens. 5. An automatic focus adjustment device for irradiating illumination light onto a sample through a condenser lens and changing a relative position between an objective lens and the sample to perform focusing adjustment, according to an observation magnification of the objective lens. Condenser lens changing means for changing the focal length of the condenser lens; and an index for focusing adjustment at a position conjugate with the sample with respect to the condenser lens according to the focal length of the condenser lens by the condenser lens changing means. And an index insertion / removal means for inserting / removing the objective lens, and adjusting the focus of the objective lens on the specimen based on the contrast of the index image on the specimen surface. 6. The focusing apparatus according to claim 5, wherein at the time of a focus adjustment operation, at least a focal length of the condenser lens is changed, and the index is inserted at a position conjugate with the specimen with respect to the condenser lens. Automatic focus adjustment device.