JP3204726B2 - Edge sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an edge sensor for detecting an edge position of a sample in a microscope or the like.

[0002]

2. Description of the Related Art Conventionally, for example, in a microscope or the like, light irradiated by transmitted illumination or the like is incident on an optical system via a sample, and light output from the optical system is received by a photodetector and photoelectrically converted. The edge position of the sample is detected based on an output signal of the subject image from the photodetector based on a predetermined threshold.

FIG. 5 is a diagram showing the configuration of a conventional edge sensor. In the optical path of light emitted from a light source (not shown), an objective lens 2, an imaging lens 3, and a prism 4 are arranged via a sample 1. Have been. A pinhole 5 is arranged at the focal position of the light imaged by the imaging lens 3, and a photodetector 6 is provided on the optical path of the light passing through the pinhole 5.

[0004] In such a configuration, for example, when illumination light is irradiated by transmission illumination, the illumination light is partly blocked by the sample and then converted into a parallel light beam by the objective lens 2. Then, the parallel light flux is incident on the prism 4 via the imaging lens 3, and the light reflected on the reflection surface 4 a of the pre-beam 4 is guided to the eyeball 7 of the observer. On the other hand, the light transmitted through the reflecting surface 4a passes through a pinhole 5 disposed at the focal position of the imaging lens 3 and passes through a photodetector 6
Is irradiated.

[0005] When a part of the transmitted light is blocked by the sample, the output signal received by the photodetector and photoelectrically converted is as shown in FIG. 6A, and as shown in FIG. Is set to 50%, the edge of the sample can be detected.

[0006]

However, in the above-described configuration, an error is included in edge position detection due to, for example, a change in light amount of a light source or a change in contrast. That is, as shown in FIG. 6B, an error occurs in the output voltage profile 61 when there is a change in the light amount, as compared with the output voltage profile 60 when the threshold value is set, and the contrast fluctuation occurs. Is also an error. Then, an error occurs between the actual edge positions 62a and 62b and the edge positions 63a and 63b in the case where the light amount fluctuates. In addition, it is conceivable to reset the threshold value for each measurement, but it takes time and the operation is troublesome. The present invention has been made in view of the above problems, and an object of the present invention is to perform edge detection with few errors without setting a threshold.

[0007]

To achieve the above object, an edge sensor according to a first aspect of the present invention comprises an optical system for guiding an object image, and an object image guided by the optical system.
Dividing the light into two optical paths,
A first pinhole disposed at a focal position where an object image is formed on one of the divided optical paths;
A second pinhole disposed at a position slightly deviated from a focal position at which the subject image is formed on the other split optical path, and receiving the subject image via the first and second pinholes, respectively. And first and second photoelectric conversion means for performing photoelectric conversion , and output signals of the first and second photoelectric conversion means .
Edge position detection means for detecting a zero-cross point from the difference to detect an edge position.

[0008] The edge sensor according to the second aspect,
An optical system for guiding the subject image;
Splitting means for splitting the object image into two optical paths,
Focus at which subject image is formed on both split optical paths
First and second pinholes respectively located at positions
And a subject image through the first and second pinholes.
First and second photoelectric conversion means for receiving and photoelectrically converting, respectively.
A step and at least one of the first and second pinholes
Means for changing contrast provided in
And the difference between the output signals of the first and second photoelectric conversion means.
Position to detect the edge position by finding the zero cross point from the
And a position detecting means.

Further, in the edge sensor according to a third aspect, the contrast changing means has different diameters of the first and second pinholes.

[0010]

[Action] That is, in accordance with the edge sensor a first aspect of the present invention, while the subject image guided by the optical system is focused
A first pinhole is arranged at a focal position on the optical path , and a second pinhole is arranged at a position slightly shifted from the focal position on the other optical path . this
The subject image is first and second photoelectrically
When the light is captured by the conversion means, both light
A zero-cross point is obtained from a difference between the output signals of the electric conversion means, and an edge position is detected.

In the edge sensor according to the second aspect , each of the optical paths divided by the dividing means is focused on the optical path.
First and second pinholes are arranged at point positions,
Contrast change that changes the contrast to at least one
Further means are provided. This change means and pinhole
The subject image is taken into the first and second photoelectric conversion means through
The output of both photoelectric conversion means by the edge position detection means
The zero-cross point is found from the signal difference and the edge position is detected.
You.

Further, in the edge sensor according to the third aspect, the diameter of each pinhole in the second aspect is made different to control.
Last is changing.

[0013]

FIG. 1 is a view showing the structure of an edge sensor according to the present invention. In FIG. 1, an objective lens 2 and an imaging lens are arranged on a light path of light emitted from a light source (not shown) via a sample 1. 3. Prisms 4a and 4b are arranged.

A pinhole 5a is arranged at the focal position of the light imaged by the imaging lens 3.
A photodetector 6a is provided on the optical path of the light passing through the pinhole 5a.

On the other hand, a photodetector 6b is provided on the optical path of the light reflected by the reflection surface 40a of the prism 4b via a pinhole 5b. The pinhole 5a is arranged at the focal position of the light imaged by the imaging lens 3, and the pinhole 5b is arranged at a position slightly shifted from the focal position.

In such a configuration, for example, when illumination light is irradiated by transmission illumination, the illumination light is partly cut off by the sample and then converted into a parallel light beam by the objective lens 2. Then, this parallel light beam is incident on the prism 4a via the imaging lens 3, and is reflected on the reflection surface 40 of the prism 4a.
The light reflected at a is guided to the observer's eyeball.

Further, the reflecting surface 40a of the prism 4a
Transmitted through the prism 4b is incident on the prism 4b.
The light transmitted through the reflection surface 40b of b is applied to the photodetector 6a via the pinhole 5a. Then, the light reflected by the reflection surface 40b of the prism 4b is applied to the photodetector 6b via the pinhole 5b. In the present embodiment, the difference between the output signals of the photodetectors 6a and 6b is calculated, and a zero-cross point in the calculation result is detected as an edge position.

FIG. 2 shows the photodetectors 6a and 6b.
Is a circuit example for calculating a difference between output signals from the photodetectors 6a and 6b, and current-voltage (IV) converters 20a and 20b for converting a photocurrent generated in the photodetectors 6a and 6b into a voltage.
, A zone comparator 21, a differential amplifier 22, and a zero-cross comparator 22.

In such a configuration, the photocurrents output from the photodetectors 6a and 6b are converted into voltages in the IV converters 20a and 20b, respectively.
Then, in the zone comparator 21, the above IV
From the output voltage from the converter 20a, those that fall within the range determined by the reference voltages V1 and V2 are extracted. That is, only those included in the detection zone as shown in FIG. 3A are extracted. On the other hand, the output voltages from the IV converter 20a and the IV converter 20b are also input to the differential amplifier 22, and the difference is calculated. The difference between the output voltages is shown by FIG.
, A zero cross point is calculated from the output from the differential amplifier 22. The output from the zone comparator 21 thus calculated and the zero-cross comparator 2
AND with the output from 3 to output two zero cross points indicating the edge position of the sample.

As described above in detail, according to the present invention, the difference between the output voltages of the two photodetectors is calculated without setting a threshold value as in the prior art, and the zero cross point in the detection zone determined by the reference voltage is calculated. It is calculated as the edge position of the sample. In the embodiment, transmitted illumination is described, but epi-illumination may be used.

FIGS. 4 (a), 4 (b) and 4 (c) show
Pinhole 5b at the focal position as shown
In the front of the pinhole 5b, N as shown in FIG.
The contrast can be changed by inserting a lens for changing A, a pinhole for resolution degradation as shown in FIG. 4B, and a glass plate such as frost as shown in FIG. 4C. is there.

Further, the pinholes 5a and 5b can be arranged at the focal position where the object image is formed, and the contrast can be changed by changing the hole diameter of the pinholes 5a and 5b.

[0023]

According to the present invention, it is possible to provide an edge sensor capable of detecting an edge with a small error without setting a threshold value.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an edge sensor according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of a circuit for calculating a difference between output voltages of the photodetectors 6a and 6b.

3A is a diagram illustrating output signals of the photodetectors 6a and 6b, and FIG. 3B is a diagram illustrating a difference between outputs of the photodetectors 6a and 6b.

4A shows a lens for changing the NA, FIG. 4B shows a pinhole for resolution degradation, and FIG. 4C shows a glass plate such as frost.

FIG. 5 is a diagram showing a configuration of a conventional edge sensor.

6A illustrates an output signal of the photodetector 6, and FIG. 6B illustrates a state where an output voltage changes due to a change in light amount or a change in contrast.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sample, 2 ... Objective lens, 3 ... Imaging lens, 4 ... Prism, 5 ... Pinhole, 6 ... Photodetector, 7 ... Eyeball.

Continuation of the front page (56) References JP-A-4-33603 (JP, A) JP-A-1-158303 (JP, A) JP-A-4-366705 (JP, A) JP-A-4-86514 (JP) JP-A-3-144307 (JP, A) JP-A-5-99620 (JP, A) JP-A-5-99619 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB G01B 11/00 G01C 3/06

Claims (3)

(57) [Claims] 1. An optical system for guiding a subject image , and a subject image guided by the optical system is divided into two optical paths.
Splitting means, a first pinhole disposed at a focal position where an object image is formed on one of the optical paths split by the splitting means, and a subject image on the other optical path split by the splitting means A second pinhole disposed at a position slightly deviated from a focal position at which the image is formed, and a first and second pinhole for receiving and photoelectrically converting a subject image via the first and second pinholes, respectively. From the difference between the output signals of the photoelectric conversion means and the first and second photoelectric conversion means ,
An edge sensor comprising: edge position detection means for detecting an edge position by obtaining a lo-cross point . 2. An optical system for guiding a subject image and a subject image guided by the optical system are divided into two optical paths.
A splitter, and a subject image is formed on both optical paths split by the splitter.
First and second positions respectively located at the focal position to be imaged
A pinhole, the object image through the first and second pin holes that of
First and second photoelectric conversion means for respectively receiving and photoelectrically converting
And provided in at least one of the first and second pinholes.
And a contrast changing means for changing the contrast, and a difference between the output signals of the first and second photoelectric conversion means.
Edge position detection that detects the edge position by finding the cross point
And an output unit . 3. The method according to claim 2, wherein said contrast changing means has different diameters of said first and second pinholes.
The edge sensor according to claim 2 .