JPH052242B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a highly sensitive and high resolution semiconductor position detector that can accurately detect the position of a light spot that emits weak light.

[Prior Art] A high-precision eye movement measurement device (Japanese Patent Application No. 198376/1983) previously proposed by the present inventors uses a television imaging tube to measure the corneal reflection of light irradiated onto the eye. However, in principle, a television camera tube cannot be expected to have a resolution higher than 1/512, and it is desired to be able to measure with even higher resolution.

In addition to measuring eye movements, when recording the movement state of various objects to be measured, such as the movement state of a part of the human body, it is possible to attach a light emitting diode to that part and detect the position of the light. However, even in such position detection, high resolution is often required.

A semiconductor position detection device (PSD:
Position Sensitive Detectors).

This semiconductor position detection element can obtain an output corresponding to the center of gravity of the electronic image or optical image formed on its surface, and has a high resolution (1/5000 or more).
It has excellent characteristics such as fast response speed (20μsec or less), small size, light weight, and high durability. Therefore, in recent years, they have come to be used in place of television image pickup tubes, which have traditionally been used for position measurement.

However, the sensitivity of semiconductor position detection elements is considerably lower than that of television image pickup tubes, and there is a limit to which they cannot be used for measuring the position of weak light.
For example, the eye movement measuring device described above measures the corneal reflected light of the light irradiated to the eye, but the reflected light is so weak that it is impossible to measure it with a semiconductor position detection element. It is.

Additionally, when using conventional semiconductor position detection elements, a light emitting diode was pasted on the object to be measured and the position of the light was measured in order to compensate for the lack of sensitivity. If so,
It is now possible to measure by pasting silver paper, etc., which is expected to not only make measurements easier, but also expand the range of applications.

[Problems to be Solved by the Invention] An object of the present invention is to increase the sensitivity of a high-resolution semiconductor position detection element that detects the position of the center of gravity of an image, and to make it possible to detect the position of the center of gravity of the image even with weak light. There is a particular thing.

[Means for Solving the Problems] In order to achieve the above object, the high-sensitivity, high-resolution semiconductor position detector of the present invention includes a photocathode, which is irradiated with light from the object to be measured, and a photocathode in the vacuum tube. an electron lens that amplifies an output according to the brightness of an image from a surface, and a semiconductor position that detects the position of the center of gravity of the output image by being directly or indirectly irradiated with the amplified output; It is configured by including a detection element.

[Operation] Even if the light irradiated on the photocathode is weak, it is electrically amplified and irradiated directly onto the semiconductor position detection element or indirectly through a fluorescent screen, etc. The position of the light is detected with high precision and high sensitivity using a high-resolution semiconductor position detection element.

[Example] The basic configuration of an example of the present invention is shown in FIG. This semiconductor position detector is located inside the vacuum tube 3.
A photocathode 4 to which light is irradiated from the measurement object 1 through the objective lens 2, and an electron lens 5 are provided as means for amplifying the output according to the brightness of the image from the photocathode 4. Furthermore, a semiconductor position detecting element 6 is provided at the position where the electron lens 5 forms an image to detect the position of the center of gravity of the electron image.

Therefore, when an image of the measurement object 1 is formed on the photocathode 4 by the objective lens 2, photoelectrons are ejected from the photocathode 4 in an amount corresponding to the brightness of the image, and the image of these photoelectrons is captured by the electron lens 5. Then, an image is formed on the surface of the semiconductor position detection element 6. The semiconductor position detection element 6 provides an output corresponding to the coordinates of the center of gravity of the electron image formed on its surface.

Here, if a voltage of about 10 kV is applied between the photocathode 4 and the semiconductor position detection element 6,
A sensitivity increase of about 1000 times can be easily obtained.

Semiconductor position detection elements are generally used to detect light points, but in principle they emit electrons upon receiving energy, and they can also be used as optical input for the input of the electronic image. It can be made to function similarly.

A semiconductor position detector having such a configuration is
Generally, the image on the photocathode 4, which has a high resolution, is simply re-imaged on the element surface of the semiconductor position detection element 6 using the electron lens 5. Since it is an element that outputs the position of the center of gravity of incident energy, there are no factors that impair the resolution, response speed, etc. of the semiconductor position detection element.
A position detector with extremely high sensitivity can be easily manufactured.

Note that during the manufacture of the semiconductor position detector, there is a risk that the characteristics of the encapsulated semiconductor position detection element 6 may deteriorate due to chemical substances generated by heating during the production of the photocathode 4; The problem can be easily solved by a commonly used method, such as enclosing a shutter that prevents chemical substances from coming into direct contact with the semiconductor position detection element 6 at high temperatures, and then opening and using the shutter after fabrication. Is possible.

FIG. 2 shows another embodiment of the present invention in which the above problem is solved by another means.

That is, in this embodiment, in order to alleviate the above-mentioned manufacturing difficulties, a fluorescent screen that is stable against chemical substances is installed in the vacuum tube 7 instead of the semiconductor position detection element 6 in the embodiment of FIG. 8 is enclosed, and a semiconductor position detection element 9 is brought into close contact with this fluorescent screen 8. It should be noted that other configurations are the same as those of the embodiment shown in FIG. 1, so the same reference numerals are given in the drawings and explanation thereof will be omitted.

In the semiconductor position detector having such a configuration, the object to be measured 1 is placed on the photocathode 4 by the objective lens 2.
When an image is formed, an image of photoelectrons from the photocathode 4 is formed on the phosphor screen 8 by the electron lens 5, and in the semiconductor position detection element 9, the center of gravity of the image of the light from the phosphor screen 8 is focused. The coordinates of the location are detected.

In the embodiment shown in FIG. 1 described above, the position of the center of gravity of the image is directly detected from the electron image formed on the surface of the semiconductor position detection element 6, but in the embodiment shown in FIG. , semiconductor detection element 9
is indirectly irradiated via the phosphor screen 8, and the phosphor screen 8
The center of gravity of the image of light from is detected. Although any of the embodiments can achieve the desired purpose, in the case of the embodiment shown in FIG. It is necessary to consider suppressing the deterioration of

[Effects of the Invention] According to the semiconductor position detector of the present invention detailed above, the sensitivity of the high-resolution semiconductor position detection element for detecting the center of gravity position of an image is increased, and even with weak light, the center of gravity position of the image can be detected. can be easily detected.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic structure of an embodiment of a high-sensitivity, high-resolution semiconductor position detector according to the present invention, and FIG. 2 is a block diagram of another embodiment. 1...Measurement object, 3, 7...Vacuum tube, 4...Photocathode,
5...Electronic lens, 6, 9...Semiconductor position detection element.

Claims (1)

[Claims] 1 A vacuum tube is equipped with a photocathode on which light from the measurement target is irradiated, and an electron lens that amplifies the output according to the brightness of the image from the photocathode, and the amplified output is directly or A high-sensitivity, high-resolution semiconductor position detector characterized by comprising a semiconductor position detection element that detects the center of gravity position of an output image by indirect irradiation.