JP3340808B2 - Calibrator for ophthalmic measurement equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a calibrator for an ophthalmologic measuring apparatus, and more particularly, to irradiating an eye to be examined with a laser beam, condensing and scanning the anterior chamber, and scattering light from cells in the anterior chamber. The present invention relates to a calibrator arranged and used at a position to be occupied by an eye to be examined with respect to an ophthalmologic measurement apparatus for performing a predetermined ophthalmological measurement by analyzing the apparatus.

[0002]

2. Description of the Related Art As an example of the above-mentioned ophthalmologic measurement apparatus, a laser beam is irradiated on an eye to be examined, focused in an anterior chamber, scanned, and scattered light from cells in the anterior chamber is received and analyzed. By
A device for measuring the cell number density in the anterior chamber is known, and the configuration of this device is as shown in FIG.

In FIG. 6, a laser beam emitted from a laser light source 41 is enlarged and parallelized by lenses 42 and 43, two-dimensionally scanned by galvanometer mirrors 44 and 45, and an eyeball of an eye to be inspected by a condenser lens 46. 54
Is collected in the anterior chamber.

[0004] When the cells existing in the anterior chamber are irradiated with laser light, the cells scatter the laser light. The scattered light is condensed by the imaging lens 47 in a direction substantially 90 ° with respect to the irradiation direction of the laser light, the optical path is split by the half mirror 48, and
3 and the examiner observes. The other is imaged on a light receiving mask 50 for limiting the visual field,
The scattered light that has passed through is converted into an electric signal by the photomultiplier tube 51, and then analyzed by the arithmetic unit 52, and the number of cells in the measurement volume in the anterior chamber is measured.

At this time, the laser beam is scanned in the observation direction of the light receiving system. In an accurate sense, an image of the laser beam is not always formed on the light receiving mask 50. There is no problem in practical use. Usually, when a cell is irradiated with a laser beam being scanned, a spike-shaped signal as indicated by an arrow in FIG. 7 is generated because the refractive index of a substance surrounding the cell is different from that of the cell. Observed. Therefore, if this spike-like signal is recognized by using any analysis technique, the number of cells in the measurement volume determined by the scanning range of the laser beam and the visual field of the light receiving mask can be counted.

[0006] Conventionally, in a final inspection in the manufacture of such an ophthalmologic measuring apparatus, a sample for modeling cells in the anterior chamber has been measured for calibration. As the sample, a sample obtained by diluting blood cells with a buffer solution or a sample obtained by diluting latex particles is used. These samples are usually measured in four-sided transparent glass cells. The cornea of an eyeball is a curved surface, whereas the surface of a glass cell is a flat surface. Therefore, when measuring a sample placed in a glass cell, an optical system for correcting the positional shift of the light-collecting point of the light projecting system and the positional shift of the light-collecting point of the light receiving system is required. A calibrator as a measurement object for calibration of the ophthalmic measurement device is configured from these optical systems and the above-described sample, and is arranged at a position to be occupied by the subject's eye with respect to the ophthalmologic measurement device and used for measurement for calibration. I was

[0007]

However, as described above, in a calibrator using blood cells or latex particles, the characteristics of the calibrator itself are largely changed over time due to a biological change or a chemical change, and are not stable. I can't say. Further, the number of blood cells or the number of particles in the measurement area is also unstable and fluctuates around a certain average value, so that the reliability of the measurement result cannot be said to be sufficient. If thin fiber or metal edge is used as the scatterer, it is considered that the change with time is small in the sense that chemical change is unlikely, but the intensity of scattered light from the scatterer largely depends on irregularities of about several μm. , Reproducibility is never high.

The calibrator of the apparatus is required to produce the same result at any time and at any time, but the calibrator according to the above-mentioned method has problems in terms of stability and reproducibility of characteristics. is there.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a calibrator used in this type of ophthalmologic measuring apparatus, which has a small change over time in characteristics and a high reproducibility.

[0010]

According to the present invention, in order to solve the above-mentioned problems, a laser beam is applied to an eye to be inspected, and the laser beam is condensed and scanned in the anterior chamber. A calibrator used as a measurement target for calibration of an ophthalmologic measurement apparatus that performs scattered light and performs a predetermined ophthalmic measurement, the calibration apparatus being disposed at a position to be occupied by an eye to be examined with respect to the apparatus, A lens for shifting the position of the focal point of the laser light emitted from the light projecting system to the light projecting system side by a predetermined distance,
A slit plate disposed at the position of the focal point of the laser light shifted by the lens, and provided so that a slit exists within the scanning range of the laser light; and a laser light passing through the slit of the slit plate. A diffuser for diffusing the light, and a reflecting member for reflecting the laser light diffused by the diffuser to a light receiving system side of the ophthalmologic measurement apparatus, when the laser light is scanned on the slit plate. By adopting a configuration in which light observed by the light receiving system is regarded as scattered light from cells in the anterior chamber, measurement for calibration of the ophthalmologic measuring apparatus can be performed.

[0011]

According to the above arrangement, at the time of measurement using the calibrator, the laser light emitted from the light projecting system of the ophthalmologic measuring device is projected from the original converging point (the position of the anterior chamber of the eye to be examined). The light is condensed at a position shifted by a predetermined distance to the side, and scans on the slit of the slit plate disposed at that position. The laser light transmitted through the slit is diffused by the diffusion plate, reflected by the reflection member, and received by the light receiving system of the ophthalmologic measurement apparatus. By regarding the light observed by the light receiving system as scattered light from cells in the anterior chamber, measurement for calibration of the ophthalmologic measuring apparatus can be performed.

[0012]

An embodiment of the present invention will be described below with reference to FIGS.

First, the principle of the calibrator of the present invention will be described.
While the intensity of scattered light from an edge from a thin fiber or metal is easily affected by irregularities of the fiber or the edge, the intensity of light transmitted through the slit 2a of the slit plate 2 as shown in FIG. Is hardly affected by the unevenness of the edge of the slit 2a. Now, the slit width is set to be approximately the same as the size of the cells in the anterior chamber, and the slit plate 2 is placed at the position of the focal point of the laser beam to be irradiated in the above-mentioned ophthalmologic measurement apparatus, as shown in FIG. Next, when the laser beam is scanned on the slit plate 2 so that the slit 2a exists within the scanning range of the laser beam, and the intensity of the light passing through the slit 2a is observed, it is observed as shown in FIG.

The time width of the transmitted light intensity observed at this time can be converted from the scanning speed of the laser light into a space width, and the space width is obtained by folding the beam diameter and the slit width at the laser light focusing point. It is expressed by the integral integral. Therefore,
If the slit width is set to be about the same as the size of the cells in the anterior chamber, the signal shown in FIG. 4 will be the cells observed when the cells are irradiated with the laser light that is being scanned in the anterior chamber. It becomes similar to the signal of the scattered light from. Therefore, it is possible to configure a calibrator of an ophthalmologic measuring apparatus that quantitatively measures the cell number density in the anterior chamber using the slit plate, and it is possible to configure a stable calibrator with high reproducibility and little change over time.

However, in order to observe the transmitted light from the slit using the optical system of the ophthalmologic measuring apparatus shown in FIG. 6, the position of the converging point of the light projecting system of the ophthalmic measuring apparatus and the position of the light receiving system Since the positions of the imaging points coincide, it is necessary to devise an optical system for observing the transmitted light from the slit. FIG. 1 shows a configuration of an embodiment of a calibrator devising this.

The calibrator 10 shown in FIG. 1 is used in the ophthalmologic measuring apparatus shown in FIG. 6 at a position to be occupied by the eyeball 54 of the eye to be examined at the time of ordinary ophthalmologic measurement.

In the calibrator 10, the condenser lens 1 is located behind the condenser lens 46 of the light projecting system of the ophthalmologic measuring apparatus.
As shown in FIGS. 5A and 5B, the focal length is shortened by a predetermined distance, and the focal point P of the laser beam by the condenser lens 46 is reduced.
Is shifted from the original position by a predetermined distance toward the near side (light projection system side).

In the configuration shown in FIG. 1, the above-mentioned slit plate 2 is disposed at the position of the converging point shifted to the near side by the converging lens 1, and as described above, it is located within the scanning range of the laser beam. Is installed such that the slit 2a exists in the first position. Further, a diffusion plate 3, a neutral density filter 4, and a beam splitter 5 are sequentially arranged behind the slit plate 2.

The light passing through the slits 2a of the slit plate 2 is diffused by the diffusion plate 3, adjusted to an appropriate intensity by the neutral density filter 4, and reflected by the beam splitter 5 to bend the optical path by 90 °. Then, the light is received by a light receiving system below the imaging lens 47 of the ophthalmologic measuring apparatus.

With such a configuration, the laser beam emitted from the light projecting system of the ophthalmologic measuring device and diffused through the slit of the slit plate 2 is received by the light receiving system of the ophthalmologic measuring device, and is used for calibration. A measurement can be made.

According to the calibrator of the present embodiment, since the constituent members such as the slit plate 2 do not have a biological change or a chemical change, the characteristic change with time is small and the light is received by the ophthalmologic measuring device. The light is transmitted light from the slit 2a and has a sufficient intensity, so that the influence of minute structures such as scratches on the surface of each optical component can be neglected, so that a calibrator with high reproducibility can be obtained.

The number of the slits 2a of the slit plate 2 is not limited to one, but may be plural. However, the slit interval is made larger than the laser beam diameter. Further, instead of the beam splitter 5, another reflecting member such as a mirror or a prism may be used. The neutral density filter 4 reduces the light diffused by the diffusion plate 3 to protect the photomultiplier tube 51 of the light receiving system of the ophthalmologic measuring apparatus. Then, the dimming filter 4
May not be provided. Further, the neutral density filter 4 may be provided near the imaging lens 47 side of the beam splitter 5 instead of between the diffusion plate 3 and the beam splitter 5.

[0023]

As is apparent from the above description, according to the present invention, the subject's eye is irradiated with laser light, condensed and scanned in the anterior chamber, and scattered light from cells in the anterior chamber is obtained. As a measurement object for calibration of an ophthalmologic measurement apparatus that performs a predetermined ophthalmic measurement by analyzing, a calibrator that is used by being arranged at a position to be occupied by the subject's eye with respect to the apparatus, using a slit plate, By performing measurement using the light transmitted through the slit, there is no biological or chemical change in the constituent members, so that changes over time in the characteristics are small, and the light received by the ophthalmic measurement device is transmitted through the slit. Since it is light and has sufficient intensity, the influence of minute structures such as scratches on the surface of each optical component can be neglected, and an excellent effect of providing a reproducible calibrator can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a plan view of a slit plate used in the calibrator.

FIG. 3 is an explanatory view showing scanning of a laser beam on the slit plate.

FIG. 4 is a diagram showing transmitted light intensity observed when a laser beam is scanned on the slit plate.

FIG. 5 is an explanatory diagram showing movement of a focal point of laser light by a lens 1 in FIG. 1;

FIG. 6 is an explanatory diagram showing a configuration of an ophthalmologic measurement apparatus using a calibrator.

FIG. 7 is a diagram showing a signal of the intensity of scattered light due to cells in the anterior chamber observed by the ophthalmic measurement apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 lens for shifting the focal point 2 slit plate 3 diffusion plate 4 extinction filter 5 beam splitter 10 calibrator 41 laser light source 42, 43, 46, 47, 49, 53 lens 44, 45 galvanometer mirror 48 half mirror 51 photoelectron Multiplier tube 52 arithmetic unit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) A61B 3/10-3/18

Claims (3)

(57) [Claims] 1. An ophthalmologic measuring apparatus for irradiating a laser beam to a subject's eye, converging and scanning in an anterior chamber, analyzing scattered light from cells in the anterior chamber, and performing a predetermined ophthalmic measurement. As a measurement target for, a calibrator arranged and used at the position to be occupied by the eye to be examined with respect to the device, the position of the focal point of the laser light emitted from the light projecting system of the ophthalmic measurement device A lens for shifting a predetermined distance toward the light projecting system side, and a lens arranged at a position of a condensing point of the laser light shifted by the lens, and installed such that a slit exists in a scanning range of the laser light. A slit plate, a diffusion plate for diffusing the laser light passing through the slit of the slit plate, and a reflecting member for reflecting the laser light diffused by the diffusion plate to a light receiving system side of the ophthalmologic measurement apparatus. The laser beam On when scanning in Tsu door plate,
A calibrator for an ophthalmologic measuring apparatus, characterized in that the light observed by the light receiving system is regarded as scattered light from cells in the anterior chamber, so that measurement for calibration of the ophthalmologic measuring apparatus can be performed. . 2. A light-reducing filter for adjusting the intensity of laser light diffused by the diffusion plate is provided between the diffusion plate and the reflection member or in the vicinity of the light-receiving system side of the reflection member. The calibrator for an ophthalmologic measurement apparatus according to claim 1, wherein 3. The calibrator according to claim 1, wherein a width of the slit of the slit plate is substantially equal to a size of a cell in an anterior chamber of an eye to be inspected.