JPH09133856A - Automatic focus detecting device for microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a focusing position where the influence of surface properties of the surface of a body is small by limiting the width of a beam in a polygonal ring shape, a beam in a circular ring shape and either one beam on straight lines in mutually different directions by a limiting member. SOLUTION: Illumination light from a light source 3 lights up a slit plate 8 through a condenser lens and the beam in the circular ring shape having passed through its circulary ring-shaped aperture part 8a has its width limited by a light shield plate 10 almost to a half, so that the formed ring-shaped pattern is projected on the body surface 2. Then this light after being reflected by the body surface 2 is imaged and the image is photodetected by a photodetecting element. Further, an arithmetic part 13 calculates the radius of the ring-shaped pattern image from the radial light quantity distribution of the image according to the output signal of the photodetecting element 12, finds the direction of defocusing by regarding the calculated radius as the reference radius of a ring-shaped pattern image in the focusing state, and outputs a signal indicating the direction of defocusing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microscope automatic focus detection device used in an epi-illumination microscope.

[0002]

2. Description of the Related Art As a conventional automatic focus detecting device for a microscope, for example, one shown in FIG. 23 is known (US Pat. No. 3,721,827, JP-A-60-118814). In this automatic focus detection device, a semi-transparent mirror 100 is provided with a pattern (elongated linear slit light) for focus detection.
And a projection optical system for projecting onto the object plane 101 via the objective lens 103, and an image of the object plane 101.
And an image forming optical system for forming an image through the semi-transmissive mirror 100, and an image of the pattern provided at the image forming position of the image forming optical system and reflected by the object plane 101 is received to detect the position. And a light receiving element 108 that can be used. The projection optical system is provided with a slit plate 106 having a slit-shaped opening through which only the illumination light (invisible light) from the light source 102 passes. The slit plate 106 is provided at a position that is conjugate with the object plane 101 when focusing, with respect to the objective lens 103 and the condenser lens 105 in the projection optical system.
Further, in the projection optical system, a light shielding plate 107 that limits the width of the elongated linear slit light passing through the slit-shaped opening of the slit plate 106 to half is provided near the pupil position of the objective lens 103.

Illumination light from the light source 102 illuminates the slit plate 106 with a condenser lens (not shown). The slit light emitted from the slit plate 106 is reflected by the second-half transmission mirror 100 whose width is limited to half by the light shielding plate 107,
Further, an image is formed on the object plane 101 by the objective lens 103. The slit light reflected by the object plane 101 passes through the objective lens 103 again, passes through the semi-transmissive mirror 100, and forms an image on the light receiving element 108 by the condenser lens 104.

FIG. 23 shows a focused state in which the object plane 101 is at the in-focus position, the slit light is imaged on the light receiving element 108, and the slit light is imaged at the center of the light receiving element 108. . FIG. 24 shows a front focus state in which the object plane 101 is above the focus position, the slit light is imaged behind the light receiving element 108, and the slit light reaches the left half of the light receiving element 108. . FIG. 25 shows a rear focus state in which the object plane 101 is below the in-focus position, the slit light is imaged in front of the light receiving element 108, and the slit light reaches the right half of the light receiving element 108. . 23 to 25
, The light flux from the slit plate 106 to the object plane 10 is drawn from the object plane 101 to the light receiving element 108 with a diagonal line rising to the right.
The luminous fluxes up to are shown by diagonal lines rising to the left.

The above-described conventional automatic focus detection device is provided with the object plane 1
When 01 shifts from the in-focus position shown in FIG. 23 in the optical axis direction of the objective lens 103, the slit light shifts from the center on the light receiving element 108 in the direction orthogonal to the longitudinal direction according to this shift. The light receiving element 108
Is detected from the output signal of and the focus is achieved.

[0006]

In the above-described conventional automatic focus detection device for a microscope, focusing accuracy is good for an object surface such as a mirror surface having a small difference in light intensity distribution or a small step. However, since the slit light projected on the object plane is an elongated rectangular shape and the slit light has directionality, when the object plane has the following pattern, the focus position is determined by the surface texture of the object plane (on the object plane). The focus may be out of focus due to the influence of the level difference of a certain pattern, the difference in brightness, the degree of dust or scratches, etc., or the pattern may become unstable, resulting in a stable and highly accurate focus position. There is a problem that it cannot be detected. 26-
It will be described with reference to FIG. 26, 28, 29 and 3
In FIG. 1, reference numeral 109 indicates a field of view on the object plane 101. 27 and 30 show partial cross sections of the object. FIG. 32 shows how slit light is projected on a pattern on the object plane.

(1) (Patterns with large steps) Patterns A and B on the object surface 101 with large steps (FIG. 26,
26) and the slit light 110 is projected over both patterns A and B in the positional relationship shown in FIG. 26, patterns A and B are moved in the arrow direction of FIG. Then, the focus position changes gradually.

On the other hand, as shown by the solid line in FIG. 28, the longitudinal direction of the slit light 110 is substantially parallel to one side of the pattern B, and the slit light 110 has the pattern A,
When projected on the boundary portion of B, the focusing position is largely changed only by slightly displacing the slit light 110 and the patterns A and B relatively in the direction of the arrow in the figure by the movement of the microscope stage. . As a result, there is a problem that the in-focus position becomes unstable. The reason is that the slit light 110 is reflected by the object surface 101 and the light receiving element 108
Since the slit image formed on the upper part includes the part reflected by the pattern A and the part reflected by the pattern B, the ratio (area ratio) of both parts is large due to the slight displacement. This is because the light intensity of the entire slit image received by the light receiving element 108 changes significantly.

When the slit light 110 is projected on the patterns A and B as shown by the alternate long and short dash line in FIG. 28, the light intensity of the entire slit image received by the light receiving element 108 is reduced by the slight displacement. There is no problem because it does not change significantly.

(2) (Pattern with a large number of repetitions and directionality) The object plane 101 has a pattern with a large number of repetitions and directionality (for example, a pattern composed of a number of regularly arranged grooves as shown in FIG. 30). C), when the slit light 110 is projected onto the pattern C so that the longitudinal direction of the slit light 110 and the direction of the groove coincide with each other as shown by the solid line in FIG. There is a problem that the offset signal is included in the output signal from the light receiving element 108 due to the influence of the interference of the diffracted light, and the focus position is displaced by the offset signal. When the slit light 110 is projected as shown by the alternate long and short dash line in FIG. 29, the slit image includes the entire diffracted light from the groove. The light intensity of the entire received slit image does not change significantly and is not affected by the interference.

(3) (Pattern with lots of dust and scratches) When the pattern on the object surface 101 has lots of dust and scratches, and a part of the slit light 110 hits dust and scratches (FIG. 31).
However, the surface to be focused (for example, the surface of the pattern B) is out of focus and is out of focus, and the surface to be focused is out of focus. The reason is that the slit image received by the light receiving element 108 includes a portion reflected by the dust or scratch pattern A. Therefore, when the dust or scratch is bright, the peak position of the light intensity of the slit image ( Focus position is the original focus position (Pattern B)
This is because it is out of focus.

(4) (Pattern with steep slope) When the object plane 101 has the pattern D with steep slope (see FIG. 32), when the slit light 110 is projected as shown by the solid line in FIG. There is a problem that the focus position cannot be detected or the focus position becomes unstable because the amount of light reflected by both ends of 110 and received by the light receiving element 108 is insufficient. When the slit light 110 is projected as shown by the alternate long and short dash line in FIG. 32, light of the same amount is received by the light receiving element 108 from each part of the slit light 110, so there is no particular problem.

(5) (Pattern with low reflectivity) When the object surface 101 has a pattern with low reflectivity and the slit light 110 is projected on this pattern, the amount of reflected light from the pattern decreases. , The light receiving element 1
The output signal itself from 08 is small, and the entire signal is noisy. Therefore, there is a problem that the S / N ratio is poor and stable automatic focusing cannot be performed, and furthermore, the focusing position cannot be detected.

The present invention has been made in view of the above circumstances, and its problem is that it is less affected by the surface texture of the object surface and enables stable and highly accurate automatic focusing. It is to provide a device.

[0015]

In order to solve the above-mentioned problems, an automatic focus detection device for a microscope according to a first aspect of the present invention projects a focus detection pattern onto an object plane via an optical splitter. A projection optical system, and an imaging optical system that forms an image of the object plane through an objective lens and the light splitter,
Automatic focus detection for a microscope, which is provided at an image forming position of the image forming optical system, has a detecting means for receiving an image of the pattern reflected by the object surface, and detecting a focus position based on the light receiving position. In the apparatus, the pattern comprises a beam generating means for generating any one of a polygonal ring-shaped beam, a circular ring-shaped beam, and two or more linear beams whose directions are different from each other; And a light limiting member that limits the width of the beam from the generating means.

According to a second aspect of the present invention, there is provided an automatic focus detecting device for a microscope, wherein the beam generating means has a slit plate having a circular ring-shaped opening, and a circular ring-shaped beam passing through the opening. And a light-restricting member that restricts the width of the light-receiving member, and the detection unit receives the image of the circular ring-shaped pattern formed by the slit plate and the light-restricting member; It is characterized by further comprising: an arithmetic unit that obtains the radius of the image in a plurality of directions based on the output, and that obtains a direction of positional deviation from the in-focus position based on the obtained plurality of radii.

According to a third aspect of the present invention, there is provided an automatic focus detection device for a microscope, wherein the beam generating means includes a light source for generating a circular ring-shaped beam and a light limiting member for limiting the width of the ring-shaped beam. The detecting means has a light receiving means for receiving an image of the circular ring-shaped pattern formed by the light source and the light restricting member, and a light amount in an inner area of the image based on an output from the light receiving means. Compute the sum and the sum of the light amount of the outside area and compare the two sums of light amount,
And a calculation unit that determines the direction of displacement from the in-focus position based on the comparison result.

According to a fourth aspect of the present invention, there is provided an automatic focus detection device for a microscope, wherein the detection means is configured to calculate the height of the unevenness of the object surface based on the image of the received pattern. It is characterized by

In the automatic focus detection device for a microscope according to a first aspect of the present invention, the polygonal ring-shaped beam and the circular ring-shaped beam generated by the beam generating means have different directions.
The width of any one of the two or more linear beams is limited by the light restricting member, whereby a polygonal ring-shaped pattern, a circular ring-shaped pattern, and two or more linear patterns having different directions from each other are formed. Any one pattern is formed. This pattern is projected on the object plane. The light of this pattern is reflected by the object surface and then imaged by the imaging optical system via the objective lens and the light splitter, and the imaged pattern image is received by the detection means. This pattern image is data for detecting the focus position of the object plane, and includes a plurality of focus detection data in different directions. Therefore, in the arithmetic processing by the detection means for detecting the in-focus state based on the pattern image, it is affected by the surface texture of the object surface (the level difference of the pattern on the object surface, the difference in brightness, the degree of dust or scratches, etc.). By performing processing such as removal of unnecessary data and averaging of all data, it is possible to detect a focus position that is less affected by the surface texture of the object surface.

In the microscope automatic focus detection device according to the second and third aspects, the light of the circular ring-shaped pattern is projected on the object plane, and the image of the circular ring-shaped pattern is received by the detection means. The image of this circular ring-shaped pattern is data for detecting the in-focus position of the object plane, and includes focus detection data in all directions. Therefore, it is possible to detect the in-focus position less affected by the surface texture of the object surface.

In the automatic focus detecting device for a microscope according to the present invention, the detecting means calculates the height of the unevenness of the object surface based on the image of the pattern received by the detecting means. It can be used as a distance sensor.

[0022]

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

FIG. 1 shows a schematic configuration of an automatic focus detection device for an epi-illumination microscope according to a first embodiment of the present invention.

This automatic focus detection device is a projection optical system for projecting a focus detection pattern (circular ring pattern) onto an object plane 2 via a semi-transmissive mirror (light splitter) 1 and an objective lens 5. 4, an image-forming optical system 7 for forming an image of the object plane 2 by the condenser lens 6 via the objective lens 5 and the semi-transmissive mirror 1, and an image-forming position of the image-forming optical system 7. The light receiving element 12 is provided which can receive the image of the pattern reflected by the surface 101 and detect its position.

The projection optical system 4 is provided with a slit plate 8 having a circular ring-shaped opening 8a that allows only the illumination light (invisible light) from the light source 3 to pass therethrough. This slit plate 8
Is provided in the projection optical system 4 with respect to the objective lens 5 and the condenser lens 9 at a position that is conjugate with the object plane 2 when focused. Further, the projection optical system 4 includes a slit plate 1
The light shield plate (light restricting member) 10 that limits the width of the circular ring-shaped beam that has passed through the opening 8a of 06 to approximately half (cuts the width of the inner half of the beam) is near the pupil position of the objective lens 5. It is provided in. This shading plate 10
It is a disk made of a material that blocks the illumination light.

The illumination light from the light source 3 illuminates the slit plate 8 with a condenser lens (not shown). The circular ring-shaped beam that has passed through the opening 8 a of the slit plate 8 is shielded by the light shield plate 1.
The width is limited to half by 0, and a circular ring-shaped pattern is formed. This pattern is reflected by the semi-transmissive mirror 1 and is further projected onto the object plane 2 by the objective lens 5. The circular ring-shaped light reflected by the object plane 2 passes through the objective lens 5 again, passes through the semi-transmissive mirror 1, and is focused on the light receiving element 12 by the condenser lens 6.

Reference numerals 11a and 11b in FIG. 1 denote aperture stops provided in the projection optical system 4 and the imaging optical system 7, respectively.

On the light receiving element 12, light of a circular ring pattern projected on the object plane 2 and reflected by the object plane 2 is formed as a circular ring pattern image.

Further, the automatic focus detection device performs arithmetic processing for detecting the in-focus state on the basis of the output signal from the light receiving element 12 which has received the circular ring-shaped pattern image, so that the positional deviation from the in-focus position is detected. A calculation unit 13 that outputs a signal indicating a direction and a drive unit 14 that displaces one of the object plane 2 and the objective lens 5 based on the output signal from the calculation unit 13 to change the relative position of the two in the optical axis direction. I have it. The light receiving element 12, the calculation unit 13, and the drive unit 14 constitute a detection unit which is provided at the image forming position of the image forming optical system 7 and detects the focus state based on the received circular ring-shaped pattern image. ing.

Further, in the automatic focus detection apparatus according to one embodiment, the center of the light receiving element 12 coincides with the optical axis of the imaging optical system 7, and the center of the light receiving element 12 and the center of the circular ring-shaped pattern image are Are configured to match.

Next, the operation of the automatic focus detection device having the above configuration will be described.

Illumination light from the light source 3 illuminates the slit plate 8 with a condenser lens (not shown). The width of the circular ring-shaped beam that has passed through the circular ring-shaped opening 8a of the slit plate 8 is limited to approximately half by the light shielding plate 10,
A circular ring-shaped pattern is formed. This pattern includes a condenser lens 9, an aperture stop 11a, and a semitransparent mirror 1.
And projected onto the object plane 2 via the objective lens 5. The light of the circular ring-shaped pattern is reflected by the object plane 2 and then imaged through the objective lens 5, the semi-transmissive mirror 1, the aperture stop 11b and the condenser lens 6, and the imaged circular light is formed. An image of a ring-shaped pattern (hereinafter, simply referred to as a ring-shaped pattern image) is received by the light receiving element 12.

1 and 4 show a focused state in which the object plane 2 is at the focused position and the ring-shaped pattern image is formed on the light receiving element 12. FIG. 7 shows the ring-shaped pattern image 20a received by the light receiving element 12 in the focused state.

FIGS. 2 and 5 show the front focus state in which the object plane 2 is above the focus position and the ring-shaped pattern image is formed behind the light receiving element 12. FIG. 8 shows the ring-shaped pattern image 20b received by the light receiving element 12 in the front focus state.

FIGS. 3 and 6 show the rear focus state in which the object plane 2 is below the in-focus position and the ring-shaped pattern image is formed in front of the light receiving element 12. FIG. 9 shows the ring-shaped pattern image 20c received by the light receiving element 12 in the rear focus state.

As is apparent from FIGS. 4 to 9, the object plane 2
Is shifted in the optical axis direction of the objective lens 5 from the in-focus position shown in FIG. 1, the size of the ring-shaped pattern image received by the light receiving element 12 changes in accordance with this positional shift. With reference to the size (radius ra) of the ring-shaped pattern image 20a in the focused state shown in FIG. 7, the ring-shaped pattern is smaller than the ring-shaped pattern image 20a (radius rb <radius ra) in the front focus state shown in FIG. Image 20b is obtained. In the rear focus state shown in FIG. 9, a ring-shaped pattern image 20c larger than the ring-shaped pattern image 20a (radius rc> radius ra) is obtained.

The calculation unit 13 calculates the radii of the ring-shaped pattern images 20a to 20c based on the output signal of the light receiving element 12.
The defocus direction is calculated by the image calculation processing from the light amount distribution in the radial direction of the image, and the defocus direction is obtained by comparing the calculated radius with the radius ra of the ring-shaped pattern image 20a in the in-focus state serving as a reference to defocus. It outputs a signal indicating the direction of.

FIG. 10 shows the light quantity distribution in the radial direction of the ring-shaped pattern image 20a in the focused state. The distance from the center of the ring-shaped pattern image 20a to the light quantity center of gravity 20a 'is the radius ra. FIG. 11 shows the light amount distribution in the radial direction of the ring-shaped pattern image 20b in the front focus state. The center of gravity of the light amount 2 from the center of the ring-shaped pattern image 20b
The distance to 0b 'is the radius rb. FIG. 12 shows the light amount distribution in the radial direction of the ring-shaped pattern image 20c in the rear focus state. The distance from the center of the ring-shaped pattern image 20c to the light amount center of gravity 20c 'is the radius rc.

The ring-shaped pattern images 20a to 20c received by the light receiving element 12 include data for detecting the in-focus position of the object plane 2 and focus detection data in all directions. Therefore, in the image calculation processing based on the output signal of the light receiving element 12 that receives the ring-shaped pattern images 20a to 20c, the calculation unit 13 determines the surface texture of the object surface 2 (steps of the pattern on the object surface 2 and difference in brightness). The direction of displacement from the in-focus position is obtained by performing processing such as removal of unnecessary data affected by dust or scratches, averaging of data, and the like, and a signal indicating this direction is output to the drive unit 14 Output to.

That is, the arithmetic unit 13 obtains the radii of the ring-shaped pattern images 20a to 20c in a plurality of directions in the image arithmetic processing and obtains a plurality of obtained data (radii of the ring-shaped pattern images 20a to 20c). , The unnecessary data affected by the surface texture of the object surface 2 is removed, the data is averaged, and the like to determine the direction of the positional deviation.
Output to 4. Regarding data removal, specifically, data having a large difference from data in other directions is removed according to a certain standard.

The drive unit 14 displaces one of the object plane 2 and the objective lens 5 based on a signal indicating the direction of positional deviation output from the arithmetic unit 13 to change the relative position of the two in the optical axis direction. This makes it possible to perform stable and highly accurate automatic focusing without being easily affected by the surface texture of the object surface 2. About this advantage, FIG.
This will be specifically described with reference to FIG. These figures show that the light on the object plane 2 has a circular ring-shaped pattern.
Is projected. 13 to 16, reference numeral 31 indicates a field of view on the object plane 2.

(1) (Pattern with a large step) As shown in FIG. 13, the object plane 2 has patterns A and B with a large step (the pattern A is lower than the pattern B as in FIG. 27) and has a circular shape. When the ring-shaped pattern of light 30 is projected over both patterns A and B, the calculation unit 13
In the image calculation process, the radius of the ring-shaped pattern images 20a to 20c received by the light receiving element 12 is set in a plurality of directions of the circular ring-shaped pattern light 30 (directions indicated by solid lines and broken line arrows in FIG. 13). The directions corresponding to are obtained. Of the focus detection data (radius) obtained in a plurality of directions, the data corresponding to the direction indicated by the broken line in FIG. 13 is the movement of the microscope stage (not shown) as in the slit light 110 indicated by the solid line in FIG. The patterns A and B and the circular ring-shaped pattern light 30 are slightly displaced relatively in the direction of the arrow in FIG. 13 due to the influence of the step or the difference in brightness between the patterns A and B (difference in reflectance). This is unnecessary data because the in-focus position largely shifts in response to this.

Therefore, the calculation unit 13 is affected by the surface texture of the object plane 2 (here, the step difference between the patterns A and B and the difference in brightness) among the obtained focus detection data (radius) in a plurality of directions. Perform processing to remove unnecessary data.
As a result, it is possible to detect an in-focus state with high accuracy that is less affected by the surface texture of the object surface 2.

(2) (Pattern with a large number of repetitions and directionality) The object plane 2 has a pattern with a large number of repetitions and directionality (for example, a pattern composed of a number of regularly arranged grooves as shown in FIG. 30). C) (see FIG. 14), the calculation unit 13 uses the light receiving element 12 in the image calculation process.
The radii of the ring-shaped pattern images 20a to 20c received at are obtained with respect to the respective directions corresponding to the plurality of directions of the light 30 of the circular ring-shaped pattern (directions indicated by solid lines and broken line arrows in FIG. 14). Of the focus detection data (radius) obtained in a plurality of directions, the data corresponding to the direction indicated by the broken line in FIG. 14 is the same as the slit light 110 indicated by the solid line in FIG. This is unnecessary data because an offset signal due to the influence of light interference is included in the output signal from the light receiving element 12, and the focus position shifts by the offset signal.

Therefore, the calculation unit 13 has an influence of the surface texture of the object plane 2 (here, the pattern C consisting of a number of regularly arranged grooves) in the obtained focus detection data (radius) in a plurality of directions. The process of removing the unnecessary data is performed. As a result, it is possible to detect a stable focused state that is less affected by the surface texture of the object surface 2. Instead of performing the process of removing the unnecessary data, a process of averaging all data may be performed.

(3) (Pattern with lots of dust and scratches) When the pattern on the object surface 2 has lots of dust and scratches, and a part of the circular ring-shaped light 30 hits the dust 32 and scratches (Fig. 15), the calculation unit 13 sets the radii of the ring-shaped pattern images 20a to 20c received by the light-receiving element 12 in a plurality of directions of the circular ring-shaped light 30 in the image calculation processing (solid line in FIG. 15). And directions indicated by broken line arrows). Of the obtained focus detection data in a plurality of directions, the data corresponding to the direction indicated by the broken line in FIG. 15 has the focus position affected by dust 32 or scratches, as in the slit light 110 shown in FIG. It is unnecessary data because it is displaced.

Therefore, the calculation unit 13 removes the unnecessary data affected by the surface texture (here, the degree of dust or scratches) of the object surface 2 from the obtained focus detection data in a plurality of directions. Perform processing. As a result, it is possible to detect an in-focus state with high accuracy that is less affected by the surface texture of the object surface 2.

Instead of performing the process of removing the unnecessary data, a process of averaging all data may be performed.

(4) (Pattern with a steep slope) When the object plane 2 has a pattern with a steep slope (see FIG. 32), the calculation section 13 causes the light receiving element 12 to receive a ring shape in the image calculation processing. Pattern images 20a-20
The radius of c is calculated for each of the directions corresponding to the plurality of directions of the light 30 having the circular ring-shaped pattern. Of the obtained focus detection data in a plurality of directions, the data in the direction along the slope in FIG. 32 is the slit light 11 shown by the solid line in FIG.
As in the case of 0, this is unnecessary data because the focus position cannot be detected or the focus position becomes unstable because the amount of light received by the light receiving element 12 is insufficient.

Therefore, the calculation unit 13 removes the unnecessary data, which is affected by the surface texture of the object plane 2 (here, a pattern having a steep slope), from the obtained focus detection data in a plurality of directions. Do. As a result, it is possible to detect a stable focused state that is less affected by the surface texture of the object surface 2. Alternatively, also in this case, instead of performing the process of removing the unnecessary data, a process of averaging all data may be performed.

(5) (Pattern of low reflectance) When the object plane 2 has the pattern A of low reflectance, and the light 30 having a circular ring pattern is projected on the pattern A (see FIG. 16), In the image calculation processing, the calculation unit 13 receives the ring-shaped pattern image 2 received by the light receiving element 12.
The radius of 0a to 20c, the light 3 of the circular ring pattern
The directions corresponding to a plurality of 0 directions (directions indicated by solid arrows in FIG. 16) are obtained, and the focus detection data in all the obtained directions are integrated, and the integrated values are averaged. As a result, the noise included in each data is canceled out, the S / N ratio is improved, and a highly accurate in-focus state detection that is less affected by the surface texture of the object surface 2 (here, a pattern with low reflectance) can be detected. Can be done.

As described above, according to the first embodiment, it is possible to perform stable and highly accurate automatic focusing without being easily influenced by the surface texture of the object surface 2.

Further, according to the first embodiment, when the microscope stage is moved, the focus position does not change abruptly, and the offset signal due to the influence of the interference of the diffracted light is output from the light receiving element 12. Since it is not included in the signal, it is possible to detect the in-focus position with high accuracy, and it is possible to detect the in-focus position with a sufficient light amount and a good S / N ratio.

Next, an automatic focus detection device for an epi-illumination type microscope according to a second embodiment of the present invention will be described with reference to FIGS.

FIG. 17 shows the light receiving element 12 in the focused state.
The ring-shaped pattern image 20a received is shown in FIG.
FIG. 20 shows a light amount sum 51 of an inner region 41 and a light amount sum 52 of an outer region 42 of the ring-shaped pattern image 20a in the focused state shown in FIG.

FIG. 18 shows the light receiving element 1 in the front pin state.
2 shows the received ring-shaped pattern image 20a. FIG. 21 shows the sum 51 of the light amount of the area 41 inside the ring-shaped pattern image 20b in the front focus state shown in FIG.
The light intensity sum 52 of the area 42 outside thereof is shown.

FIG. 19 shows the light receiving element 1 in the rear pin state.
2 shows the received ring-shaped pattern image 20a. FIG. 22 shows the sum 51 of the light amount of the area 41 inside the ring-shaped pattern image 20c in the rear focus state shown in FIG.
The light intensity sum 52 of the area 42 outside thereof is shown.

As is clear from FIGS. 20 to 22, in the focused state (light amount sum 51 = light amount sum 52), in the front focus state (light amount sum 51> light amount sum 52), in the rear focus state (light amount sum). The sum 51 <sum of light intensity 52).

Therefore, in the second embodiment, the calculation unit 1
3 is a ring-shaped pattern image 2 received by the light receiving element 12.
The light amount sum 51 of the inner region 41 and the light amount sum 52 of the outer region 42 of 0a to 20c are calculated, and the light amount sum 51 is calculated.
And the light amount sum 52 are compared, the direction of the positional deviation from the in-focus position is obtained based on the comparison result, and a signal indicating the direction is output to the drive unit 14.

As described above, according to the second embodiment,
The ring-shaped pattern images 20a to 20c are not removed without removing unnecessary data affected by the surface texture of the object plane 2.
Since the light amount sum 51 of the inner region 41 and the light amount sum 52 of the outer region 42 are compared to determine the direction of the positional deviation, there is little influence of unnecessary data, that is, the influence of the surface texture of the object surface, and stable accuracy is obtained. A high degree of automatic focusing can be performed. Moreover, since it is not necessary to remove unnecessary data affected by the surface texture of the object surface 2, the processing speed can be increased.

In the first embodiment, the slit plate 8 has a circular shape that allows only the illumination light (invisible light) from the light source 3 to pass through in order to project the light in the circular ring pattern onto the object plane 2. Although the ring-shaped opening (circular ring-shaped pattern) 8a is provided, the shape of the opening of the slit plate 8 is not limited to the circular ring-shaped pattern. Other than this pattern, an elliptical ring-shaped pattern, a polygonal ring-shaped pattern including a triangle or a quadrangle, and a linear pattern in two or more different directions can be used. When using an elliptical ring-shaped pattern or a polygonal ring-shaped pattern,
The light shield plate 10 may be configured to limit the width of the light of the ring-shaped pattern that has passed through the opening of the slit plate 8 to approximately half. When the linear pattern is used, two or more light-shielding plates that limit the width of the linear pattern in each direction may be arranged.

Further, in each of the above embodiments, the arithmetic unit 1
The automatic focus detection device can be used as a distance sensor for measuring the shape of the object plane 2 by configuring the height of the unevenness of the object plane 2 based on the output signal from the light receiving element 12. it can.

In the first embodiment, the light source 3 and
The slit plate 8 and the light shield plate 10 constitute a beam generating means for generating a circular ring-shaped beam.
The beam generating means may be composed of a self-luminous element such as an LED and the light shielding plate 10. In this case, many LEs
D is arranged so as to generate a beam similar to a circular ring-shaped beam formed by passing through the opening 8a of the slit plate 8.

[0064]

As described above, according to the automatic focus detection apparatus for a microscope of the first aspect of the present invention, the polygonal ring-shaped beam and the circular ring-shaped beam generated by the beam generator are generated. The width of one of the two or more linear beams having different directions is limited by the light restricting member, whereby a polygonal ring-shaped pattern,
Either one of a circular ring-shaped pattern and two or more linear patterns whose directions are different from each other is formed. This pattern is projected on the object plane. The light of this pattern is reflected by the object surface and then imaged by the imaging optical system via the objective lens and the light splitter, and the imaged pattern image is received by the detection means. This pattern image is data for detecting the focus position of the object plane, and includes a plurality of focus detection data in different directions. Therefore, in the arithmetic processing by the detection means for detecting the in-focus state based on the pattern image, it is affected by the surface texture of the object surface (the level difference of the pattern on the object surface, the difference in brightness, the degree of dust or scratches, etc.). By performing processing such as removal of unnecessary data and averaging of all data, it is possible to detect a focus position that is less affected by the surface texture of the object surface. Therefore, it is less affected by the surface texture of the object surface, and stable and highly accurate automatic focusing can be performed.

According to the microscope automatic focus detection device of the second and third aspects, the light of the circular ring-shaped pattern is projected on the object plane, and the image of the circular ring-shaped pattern is received by the detection means. The image of this circular ring-shaped pattern is data for detecting the in-focus position of the object plane, and includes focus detection data in all directions. Therefore, it is possible to detect the in-focus position less affected by the surface texture of the object surface.

According to another aspect of the automatic focus detection apparatus for a microscope of the present invention, the detecting means calculates the height of the unevenness of the object surface based on the pattern image received by the detecting means. Can be used as a distance sensor.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an automatic focus detection device for an epi-illumination microscope according to a first embodiment of the present invention, showing a focused state.

FIG. 2 is a configuration diagram similar to FIG. 1, showing a front pin state.

FIG. 3 is a configuration diagram similar to FIG. 1, showing a rear pin state.

FIG. 4 is an enlarged view of part of FIG. 1.

5 is an enlarged view of part of FIG. 2. FIG.

FIG. 6 is an enlarged view of a part of FIG. 3.

FIG. 7 is a diagram showing how a circular ring-shaped pattern image is received by a light receiving element in a focused state.

FIG. 8 is a view similar to FIG. 7, showing a front pin state.

FIG. 9 is a view similar to FIG. 7, showing the rear pin state.

FIG. 10 is a diagram showing a light quantity distribution of a circular ring-shaped pattern image in a focused state.

11 is a view similar to FIG. 10, showing a front pin state.

FIG. 12 is a view similar to FIG. 10, showing a rear pin state.

FIG. 13 is an operation explanatory diagram of the first embodiment.

FIG. 14 is an operation explanatory diagram of the first embodiment.

FIG. 15 is an operation explanatory diagram of the first embodiment.

FIG. 16 is an operation explanatory diagram of the first embodiment.

FIG. 17 is an explanatory diagram for the second embodiment,
It is a figure which shows a mode that the circular ring-shaped pattern image is received by the light receiving element in the focused state.

FIG. 18 is an explanatory view similar to FIG. 17, and is a view showing a state where a circular ring-shaped pattern image is received by the light receiving element in the front focus state.

19 is an explanatory view similar to FIG. 17, and is a view showing a state where a circular ring-shaped pattern image is received by the light receiving element in the rear focus state.

FIG. 20 is an explanatory diagram for the second embodiment,
It is a figure which shows the light amount sum in a focus state.

FIG. 21 is an explanatory diagram for the second embodiment,
It is a figure which shows the light amount sum in a front focus state.

FIG. 22 is an explanatory diagram for the second embodiment,
It is a figure which shows the light amount sum in a back focus state.

FIG. 23 is a schematic configuration diagram showing a conventional microscope automatic focus detection device, and is a diagram showing a focused state.

FIG. 24 is a configuration diagram similar to FIG. 23, showing a front pin state.

FIG. 25 is a configuration diagram similar to FIG. 23, showing a rear pin state.

FIG. 26 is an operation explanatory diagram for a conventional automatic focus detection device for a microscope.

27 is a cross-sectional view of the object plane shown in FIG.

FIG. 28 is an operation explanatory diagram similar to FIG. 26.

FIG. 29 is an operation explanatory diagram similar to FIG. 26.

FIG. 30 is a sectional view of the object plane shown in FIG. 29.

FIG. 31 is an operation explanatory diagram similar to FIG. 26.

32 is an operation explanatory diagram similar to FIG. 26;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semi-transmissive mirror (light splitter) 2 Object plane 4 Projection optical system 7 Imaging optical system 8 Slit plate 10 Light-shielding plate (light limiting member) 12 Light receiving element (detection means) 13 Arithmetic section (detection means) 14 Driving section ( Detection means)

Claims (4)

[Claims] 1. A projection optical system for projecting a pattern for focus detection onto an object plane through a light splitter, and an imaging for forming an image of the object plane through an objective lens and the light splitter. A microscope provided with an optical system and a detection unit which is provided at an image forming position of the image forming optical system, receives an image of the pattern reflected by the object surface, and detects a focus position based on the light receiving position. In the automatic focus detection device for use with the above-mentioned pattern, the pattern is a beam generating means for generating any one of a polygonal ring-shaped beam, a circular ring-shaped beam, and two or more linear beams whose directions are different from each other. And an optical limiting member for limiting the width of the beam from the beam generating means. 2. The beam generating means includes a slit plate having a circular ring-shaped opening formed therein, and a light limiting member for limiting a width of the circular ring-shaped beam passing through the opening. The detecting means detects the image of the circular ring-shaped pattern formed by the slit plate and the light limiting member, and the radius of the image in a plurality of directions based on the output from the light receiving means. The automatic focus detection device for a microscope according to claim 1, further comprising: a calculation unit that obtains a direction of displacement from a focus position based on the obtained plurality of radii. 3. The beam generating means includes a light source that generates a circular ring-shaped beam and a light limiting member that limits the width of the ring-shaped beam, and the detection means includes the light source and the light limiting member. A light receiving means for receiving the image of the circular ring-shaped pattern formed by a member, and a light quantity sum of the inner area of the image and a light quantity sum of the outer area of the image based on the output from the light receiving means. Compare the light intensity sum,
The automatic focus detection device for a microscope according to claim 1, further comprising a calculation unit that obtains a direction of displacement from a focus position based on the comparison result. 4. The detection means is configured to calculate the height of the unevenness of the object surface based on the received image of the pattern. The automatic focus detection device described.