JPS6289010A - Auto-focusing device for microscope - Google Patents

Abstract

PURPOSE:To accurately detect the difference of brightness of a projected stripe pattern even if the image forming magnification is changed, by forming a strip pattern on a stripe pattern mask radially and in a ring shape and arranging photoelectric elements on image sensors in a ring shape. CONSTITUTION:A stripe pattern 3 on a stripe pattern mask 2 formed radially and in a ring shape is projected by the light from a light source 1 and is focused on the upper face of a sample 5 by an objective lens 4. The reflected light from the strip pattern is focused on light receiving faces of image sensors 9 and 10 by the lens 4. The light is focused by changing the height of a sample stage 16. A point where both contrasts of sensors 9 and 10 are equal is set to the focused surface of a sample observing image sensor 12 to detect the direction of out-of-focus by the comparison between both contrast values. In this case, the stripe pattern is detected correctly by the shape of the pattern and photoelectric elements 11 arranged in a ring shape on both sensors through the image forming magnification is different because distances from the lens 4 to sensors 9 and 10 are different from each other.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a microscope automatic focusing device, and more particularly to a microscope automatic focusing device suitable for focusing a microscope device for observing eight surfaces of an LSI sea urchin.

[Background of the invention]

As this type of conventional technology, as shown in Japanese Patent Application Laid-Open No. 58-70540 and Japanese Patent Application Laid-Open No. 58-120106,
As a focus position detection device for a microscope, a technique is known in which the focus position is detected by projecting a striped pattern onto a sample surface and detecting its contrast.

In this conventional technique, in order to determine the direction of defocus, it is necessary to provide a pair of contrast detection systems that are shifted from each other in the optical axis direction.

As a result, there is a difference in imaging magnification between the two contrast detection systems in accordance with the amount of deviation, so the dimensions of the imaging patterns of the two contrast detection systems are no longer the same. For example, when detecting a projected stripe pattern, one contrast detection system detects its line width using 6 pixels, and the other contrast detection system uses 5 pixels to detect the line width. This means that when comparing striped pattern contrast, it is difficult to make a correct comparison.

Although it is possible to add an optical system to match the imaging magnifications of both contrast detection systems, this would complicate the structure of the optical system and increase costs.

[Object of the Invention] The object of the present invention is to resolve the problems of the prior art, and to solve the problems of the prior art, even if the sample moves in the optical axis direction and the imaging magnification of the projected fringe pattern imaged on the light receiving surface of the image sensor changes. An object of the present invention is to provide a microscope automatic focusing device that can accurately detect the difference in brightness of a projected fringe pattern and has a simple structure.

[Summary of the invention]

The present invention projects a striped pattern projected from a striped pattern mask onto a sample surface through an objective lens of a microscope, and images the reflected light of the projected striped pattern reflected from the sample surface through the objective lens. When forming an image on the sensor, even if the imaging magnification changes due to the sample moving in the direction of the original axis, the dimensions of the projected fringe pattern imaged on the image sensor's light-receiving surface, that is, the line width and line spacing, do not change. In order to achieve this, the shape of the knitting pattern is radial and ring-shaped, and the image sensor H11 is characterized in that photoelectric elements are arranged in a ring-shape.

[Embodiments of the invention]

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

1 to 8 show a first embodiment of the present invention,
Figure 1 is a conceptual diagram of the configuration, Figure 2 is a diagram showing the positional relationship between the image sensor, objective lens, and focusing plane of the image sensor, and Figure 3 is a diagram showing the positional relationship between the image sensor and the striped pattern. Figure 4 is an explanatory diagram of the fringe pattern detection image signal, Figure 5 is a diagram showing the relationship between sample position and contrast, Figure 6 (αl, (bl) and Figure 7 (αI, (, 61 are the image sensor and projection, respectively). It is a figure showing the positional relationship of a striped pattern.

As shown in FIG. 1, the first embodiment shown in these figures includes a light source 1, a striped pattern mask 2 arranged in the direction of the projection source axis of the light source 10, and an objective lens of a microscope. 4, half mirrors 6, 7, 8 arranged in the direction of the imaging optical axis of the projection stripe pattern, and a first half mirror 1.4 for detecting the projection stripe pattern arranged with their positions shifted from each other in the direction of the imaging optical axis.
A second image sensor 9.10, a sample observation image sensor 12, @1. It is equipped with a defocus calculation circuit 13 to which the image sensors 9 and 10 of i2 are connected, a drive circuit 14 connected to this, and a sample stage 16 having a stage fine movement mechanism 15 connected to this drive circuit 14. 【It is configured.

The light distribution source 1 projects the striped pattern 3 of the striped pattern mask 2 onto the sample 5, and K is also used to observe the sample 5.

The striped pattern mask 2 has a radially K and ring-shaped striped pattern 3 formed thereon.

The objective lens 4 projects and images the striped pattern 3 formed on the striped pattern mask 2 onto the sample 5, and also captures the reflected light of the projected striped pattern from the sample surface. Second image sensor 9.10 and sample observation image sensor 1
It is now possible to form an image on 2.

The sample observation image sensor 12 focuses on the striped pattern imaging plane of the striped pattern mask 2.

Said 1st. In the second image sensor 9.10, photoelectric elements 11 are arranged in a ring shape corresponding to the striped pattern 3. Also, 1st. - The second image sensors 9 and 10 are arranged with their positions shifted from each other in the imaging optical axis direction of the projection stripe pattern, and as shown in FIG.
The projection stripe pattern image formation plane of the stripe pattern mask 2, that is, the position of the focusing plane of the image sensor 12 for sample observation, is sandwiched between the two and focused at a position shifted forward and backward "C" from the optical axis of the reflected light of the objective lens. The faces are now arranged.

In FIG. 2, 17, 18 and 19 are sample observation image sensors, and 1. The position of the focusing plane of the second image sensor, Sl, S, , S, is the distance from the objective lens to the focusing plane of the sample observation image sensor, the first image sensor, m2, respectively, 5; , 5t, , S
2 indicates the distance from the objective lens to the sample observation image sensor, the first image sensor, and the second image sensor, respectively.

The focus shift calculation circuit 13 is configured to operate the first . It is configured to calculate the direction of defocus from the relationship between the projection stripe patterns detected by the second image sensor 9 and 10, and output the calculation result to the drive circuit 14.

The drive circuit 14 outputs a control signal to the stage fine movement mechanism 15 based on the calculation result of the defocus calculation circuit 13.

The +m stage fine movement mechanism 15 is composed of, for example, a piezo element, and is adapted to displace the height of the sample stage 16 in response to a control signal from the drive circuit 14.

The microscope automatic focusing device according to the first embodiment of BIJ is operated and operated as follows.

The center of the circle of the striped pattern 5, the optical axis of the objective lens 4, and the first. The centers of the arrangement circles of the photoelectric elements 11 of the second image sensors 9 and 10 are made to coincide with each other.

Next, the striped pattern 5 of the striped pattern mask 2, which is formed in a radial and ring shape, is projected by the light from the light fM1, and is imaged on the upper surface of the sample 5 by the objective lens 4.

Here, the reflected light of the projected fringe pattern from the sample surface is reflected by the objective lens 4 into the first. Second image sensor 9.1
The image is formed on the light-receiving surface of the stripe pattern mask 2, and the focusing of the stripe pattern image formation surface of the stripe pattern mask 2 is performed by the first light receiving surface of the stripe pattern mask 2. This is done by determining the direction of defocus from the relationship between the projected fringe patterns detected by the second image sensor 9.10, and changing the height of the sample stage 16 according to the result.

In the projection stripe pattern detection, as shown in FIG. 3, the periodic pattern of bright areas 20 and dark areas 210 is detected by the photoelectric elements 11 arranged in a ring shape, so the detection signal is as shown in FIG. It appears as the difference between the bright level and the dark level. The difference between the bright level and dark level of this detection signal, that is, the contrast, is the first. Second image sensor 9°10
Since the position of the focal plane of is shifted as shown in Figure 2,
As shown in FIG. 5, the position at which the contrast is maximum is also shifted. Therefore, for example, the point of the 11th and 2nd image sensors 9 and 10 with equal contrast values should be set to coincide with the focal plane of the sample observation image sensor 12, that is, the position 17 shown in FIG. From K.
1st. 2nd image sensor 9.10 both contrasts)
The direction of defocus can be detected by comparing fl[.

Punishment comes first. The positions of the second image sensors 9 and 10 are
As shown in FIG. 2, since the distances from the objective lens 4 are different, the magnifications are different. That is, the second image sensor 10 has a larger condensation magnification than the first image sensor 9 which is closer to the objective lens 4. This means that when the stripe pattern is parallel stripes, the output pattern dimensions of the two image sensors are different, as shown in Figure 6 (αl, (,61). ,
In the case shown in Ib1, the correspondence between the photoelectric element 22 of the image sensor and the projected fringe pattern is equal;
Correct fringe pattern contrast becomes difficult to detect.

In the present invention, the striped pattern 3 is radial and ring-shaped, and the image sensors 9 and 10 of gi and i2 have photoelectric elements 11 arranged in a ring shape. As shown in , even if the imaging magnification is different, the correspondence with the Genden element 11 is not disturbed.
It becomes possible to correctly detect the projected fringe pattern. In other words, Fig. 7 (α1 is a small imaging magnification, Fig. 7 (jl
has a large imaging magnification. Therefore, the detected projected fringe pattern is shown in FIG. 7 (in α1, the radius R1 is smaller than the radius in FIG.
The correspondence is the same in FIG. 7 (αl, [AI).

FIG. 8 shows a second embodiment of the present invention, and is a diagram showing the positional relationship between the projected stripe pattern on the sample surface and the imaging area of the sample observation image sensor.

The sample observation image sensor 12 used in the first embodiment described above is a straight-shaped one-dimensional image sensor. In this sample observation image sensor 12, it is possible to secure an observation field of view by deleting a part of the projected stripe pattern.

Therefore, in the second embodiment of the present invention, as shown in FIG.
In addition, a part of the projected striped pattern projected on the circumference is deleted to secure the sample observation area 23. In FIG. 8, reference numeral 20 indicates a bright part of the projected stripe pattern, and 21 indicates a dark part.

Regarding other configuration 1 effects of this second embodiment,
This is the same as the first embodiment.

Next, FIG. 9 is a conceptual diagram showing the configuration of a third embodiment of the present invention.

This third embodiment is different from the first embodiment in Table σ.
The difference is that two striped pattern masks 24α, 247 and one image sensor 26 are arranged.

The striped pattern masks 24α, 24b are formed in a shape in which a striped pattern arranged in a radial and ring shape is divided into two by a dividing plane in the diametrical direction, and each of the striped pattern masks 24α, 24b has a semicircular arc. striped pattern 25α,
25b is applied.

Further, the striped pattern masks 24α and 24b are arranged with their positions shifted after Ntr in the projection optical axis direction.

In the image sensor 26, photoelectric elements 27 are arranged in a ring shape.

In this third embodiment, the imaging positions of the projected stripe pattern are at positions 18 and 19 in FIG. 2, and the focal plane of the image sensor 26 is at position 1iii17.

Furthermore, as shown in Figure M7 (eLl, IbI), the fringe pattern imaged on the light-receiving surface of the image sensor 26 is projected by dividing the light-receiving surface into two, but it is not detected. The fringe pitch in the image signal is the same, and signal processing is possible regardless of the imaging magnification.

Note that the other configuration 1 effect of this fifth embodiment is the above-mentioned first
This is similar to the embodiment.

〔Effect of the invention〕

According to the invention described above, the striped pattern is formed in a radial and ring shape on the striped pattern mask, and the photoelectric elements are arranged in a ring on the image sensor, so that the sample moves in the optical axis direction. Even if the imaging magnification of the projected fringe pattern formed on the light-receiving surface of the image sensor changes, the correspondence between the photoelectric element and the projection fringe pattern position is not affected by the imaging magnification, so the brightness difference of the projected fringe pattern is correct. can be detected, and therefore, there is an effect that focusing can be performed with high precision.

Furthermore, according to the present invention, as described above, it is sufficient to form a striped pattern in a radial and ring-shaped pattern on the striped pattern mask, and to arrange photoelectric elements in a ring-shaped pattern on the image sensor, which simplifies the structure. There are also effects that can be achieved.

[Brief explanation of drawings]

1 to 8 show a first embodiment of the present invention,
Figure 1 is a conceptual diagram of the configuration, Figure 2 is a diagram showing the positional relationship between the image sensor, objective lens, and focusing plane of the image sensor, Figure w13 is a diagram showing the positional relationship between the image sensor and the striped pattern, and Figure 4 The figure is an explanatory diagram of the striped pattern detection image signal.
Figure 5 shows the relationship between sample position and contrast, Figure 6
Figures (αl, (bl) and Figure 7 (αl, (Al
8 shows the positional relationship between the image sensor and the projection stripe pattern, respectively, and FIG. 8 shows the second embodiment of the present invention. FIG. 9, a diagram showing the relationship, is a conceptual diagram showing the configuration of a third embodiment of the present invention. 1... Light source 2... Striped pattern mask 3
...Fringe pattern 4...Microscope objective lens 5...Sample 9.10...First lens for detecting the projected fringe pattern. Second image sensor 11...first. f! of the second image sensor! Element 12... Image sensor for sample observation 13... Focus shift calculation circuit 16... Sample stage 17.1
ε, 19...Positions 20, 21... of the focusing planes of the sample observation image sensor, the first and second image sensors, 20, 21...
Bright part of projected fringe pattern, @ part 23...sample observation area 24α, 24b...stripe pattern mask 25cL, 25
b... Striped pattern 26... Image sensor 27 for detecting the projected striped pattern
...Photoelectric element edition 1 Figure 2 Figure 3 Figure 4 Kokuhaku 5 Figure ''M4iL placement (Z) Figure 6 Figure 7 (c?') (P) Go 8 Figure

Claims (1)

[Claims] 1. A striped pattern projected from a striped pattern mask is projected onto a sample surface through an objective lens of a microscope, and the projected striped pattern reflected from the sample surface is transmitted through the objective lens to a photoelectric element. A microscope automatic focusing device that focuses an image on an array of image sensors, obtains brightness information of the projected fringe pattern from the image signal captured by the image sensor, and detects the positional relationship between the sample surface and the focal plane of the microscope based on the brightness difference. The microscope automatic focusing device according to the invention, wherein a striped pattern is formed in a radial and ring shape on the striped pattern mask, and photoelectric elements are arranged in a ring shape on the image sensor. 2. Claim 1 is characterized in that one striped pattern mask is disposed, and two image sensors are disposed with their positions shifted back and forth in the optical axis direction of the reflected light of the objective lens. Microscope autofocus device. 3. In claim 1, the striped pattern mask is arranged such that the striped pattern arranged in a ring shape is divided into two by a dividing plane in the diametrical direction, and the positions are shifted from each other in the direction of the projection optical axis. , A microscope automatic focusing device characterized in that one of the image sensors described above is arranged. 4. The microscope automatic focusing device according to claim 1, characterized in that the projection stripe pattern in the sample observation area is deleted.