JPH0852112A - Ophthalmic tear film observation device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide an ophthalmic lacrimal fluid observation device capable of observing a clear tear fluid interference pattern in a wide observation visual field without interfering light without causing vignetting in the observation visual field. [Structure] The eye 1 is illuminated by a light source 7 through a lens 3, a half mirror 4, and a lens 2. Reflected light from the tear film of the eye 1 is incident on the CCD 15 of the camera for observation through the objective lens 2, the half mirror 4, and the lens 5, and the interference pattern of the tear film is observed. Since the interfering light (Pb) reflected on the back surface of the objective lens 2 is blocked and only the signal light (Pa) reflected from the tear film of the eye 1 to be examined is incident on the CCD 15, the half mirror 4 and the light source 7 are provided. Polarizing plate 12 between
A polarizing plate 13 whose polarization direction is orthogonal to the polarization direction of the polarizing plate 12 is arranged between the half mirror 4 and the CCD 15 of the camera, and the quarter wave plate 11 is provided between the eye 1 to be inspected and the objective lens 2. To place.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ophthalmic lacrimal fluid observing device, and more particularly to an ophthalmic lacrimal fluid observing device for irradiating a cornea of an eye to be examined with illumination light and observing a tear film on the cornea through an observation optical system. is there.

[0002]

2. Description of the Related Art Conventionally, for the purpose of qualitatively diagnosing the degree of progress of dry eye, the cornea of an eye to be examined is irradiated with illumination light, and the tear film on the cornea is removed through an observation system such as a CCD camera. Devices for observing are known.

FIG. 1 shows the basic construction of such an ophthalmic tear film observing apparatus. The eye 1 to be inspected is illuminated by a light source 7 (a coherent light source such as a laser light source or a white light source) via a lens 3, a half mirror 4 and an objective lens 2. Then, the reflected light from the tear film on the cornea of the eye 1 to be examined is passed through the objective lens 2, the half mirror 4, and the lens 5 to C
It leads to the camera 6 by a CD camera or the like, and the interference pattern of the tear film is observed through the camera 6.

[0004]

SUMMARY OF THE INVENTION With such a configuration,
As indicated by the solid line arrow, the illumination light is reflected by the back surface of the objective lens 2 to become interference light (Pb), which is mixed with the signal light (Pa) and is observed as flare.

In view of this problem, a configuration is known in which the optical paths of the illumination system and the observation system are separated as shown in FIG.
62-222143 etc.). In FIG. 2, the half mirror 4 of FIG.
Is replaced by a perforated mirror 4 ', and the objective lens 2 is replaced by a perforated lens 2', so that coherent illumination light passes through the peripheral part of the optical system as indicated by diagonal lines, and the eye to be examined as indicated by broken lines. It is considered that the reflected light from 1 passes through the center of the optical system.

With such a configuration, the problem of the above-mentioned interfering light can be avoided, but as shown in FIG. 3, the center of the visual field of observation is cut out (reference B) and becomes dark, and the tear fluid in the central part of the visual field cannot be observed. There is a problem. Reference numeral A in FIG. 3 indicates an interference fringe due to the tear film.

Further, as shown in FIG. 4, the light source 7, the mirror 9, and the objective lens 2 are arranged so that the illumination light passes through their peripheral portions.
A configuration in which the camera 6 is arranged is also conceivable, but this configuration also has a problem that the observation field of view cannot be made large.

An object of the present invention is to solve the above problems, and an ophthalmic lacrimal fluid observing device capable of observing a clear lacrimal fluid interference pattern without interfering light (flare) in a wide observing visual field without causing vignetting in the observing visual field. To provide.

[0009]

In order to solve the above problems, according to the present invention, an ophthalmic tear that illuminates the cornea of an eye to be examined with illumination light and observes a tear film on the cornea through an observation optical system. In the liquid observation device, an illumination light source, an objective lens that illuminates the illumination light of this illumination light source in the direction of the eye to be examined, and guides the reflected light from the tear film to the observation optical system, and the illumination light arranged in front of the illumination light source. Is arranged in front of the objective lens for converting the linearly polarized illumination light toward the subject's eye into circularly polarized light, and the circularly polarized light reflected from the tear layer of the subject's eye is incident. A 1/4 wavelength plate that converts the illumination light into linearly polarized light having a polarization direction orthogonal to the illumination light, and only the linearly polarized light reflected from the tear layer of the eye to be inspected and emitted from the 1/4 wavelength plate is the observation optical system. The configuration having the second polarizing plate that leads to

[0010]

According to the above construction, the disturbing light reflected on the back surface of the objective lens is polarized light orthogonal to the polarization direction of the linearly polarized reflected light reflected from the tear layer of the eye to be examined and emitted from the quarter-wave plate. Since it has a direction, only the signal light that does not pass through the second polarizing plate and is not incident on the observation optical system and is reflected from the tear layer of the eye to be examined can be incident on the observation optical system.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in the drawings. The same or corresponding members as those in the conventional example are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 5 shows the structure of an ophthalmic lacrimal fluid observing device to which the present invention is applied. As shown in the figure, in this embodiment, a polarizing plate 12 is arranged between the half mirror 4 and the light source 7, and a polarizing plate 13 is arranged between the half mirror 4 and the CCD 15 of the camera, and the eye 1 to be examined and the objective lens 2 are arranged. 1/4 wave plate 11 between
Has been placed.

Here, as shown by the arrow and arrowhead symbols, the direction of the lattice of the polarizing plate 12 is parallel to the plane of the paper, the direction of the lattice of the polarizing plate 13 is perpendicular to the plane of the paper, and they are orthogonal to each other. Reference numeral 7'denotes a condenser lens.

Focusing on the signal light (Pa), the polarizing plate 12
The illumination light that has become linearly polarized light parallel to the paper surface is reflected by the half mirror 4, passes through the objective lens 2, and is circularly polarized (for example, clockwise) by the ¼ wavelength plate 11. When this illuminating light is reflected by the tear film of the eye 1 to be inspected, the direction of rotation is reversed and circularly polarized (for example, counterclockwise), and becomes 1/4.
When the light passes through the wave plate 11 again, it becomes linearly polarized light, but at this time, the polarization direction is perpendicular to the paper surface.

On the other hand, the interfering light (Pb) reflected on the back surface of the objective lens 2 does not pass through the quarter-wave plate 11 and therefore passes through the half mirror 4 as it is as linearly polarized light. The polarization direction of this interference light is parallel to the paper surface.

Both the signal light (Pa) and the interfering light (Pb) pass through the lens 5 and enter the polarizing plate 13.
Since the direction of the grating of 3 is perpendicular to the paper surface, the signal light (Pa) passes through as it is without being attenuated, but the interfering light (Pb) has the same polarization direction and the grating direction of the polarizing plate 13. Because it does not, it can hardly pass.

Therefore, the intensities of the signal light (Pa) and the interfering light (Pb) entering the CCD 15 are Pa >> Pb, and the interfering light hardly enters the CCD 15 and flare does not occur. That is, the SN ratio can be greatly improved.

Moreover, according to this structure, the center and the peripheral portion of the optical system can be used for illumination and observation.
Without vignetting in the field of view unlike conventional devices,
A clear tear interference pattern can be observed in a wide observation field.

[0019]

As is apparent from the above, according to the present invention, the interfering light reflected by the back surface of the objective lens is reflected by the tear film of the eye to be examined and is reflected by the linearly polarized light emitted from the ¼ wavelength plate. Since it has a polarization direction orthogonal to the polarization direction of light, only the signal light that does not pass through the second polarizing plate and does not enter the observation optical system and is reflected from the tear layer of the eye to be observed is input to the observation optical system. (EN) An excellent ophthalmic lacrimal fluid observing device that can be incident and can observe a clear tear fluid interference pattern without interfering light (flare) in a wide observation visual field without causing vignetting in the observation visual field. it can.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a basic configuration of a conventional ophthalmic lacrimal fluid observation device.

FIG. 2 is an explanatory diagram showing a configuration example of a conventional ophthalmic lacrimal fluid observation device.

FIG. 3 is an explanatory diagram showing a problem of the apparatus of FIG.

FIG. 4 is an explanatory diagram showing a different configuration example of a conventional ophthalmic lacrimal fluid observation device.

FIG. 5 is an explanatory diagram showing the configuration of an ophthalmic lacrimal fluid observing device adopting the present invention.

[Explanation of symbols]

 1 Eye to be inspected 2 Objective lens 3 Lens 4 Half mirror 6 Camera 7 Light source 11 Quarter wave plate 12 Polarizing plate 13 Polarizing plate 15 CCD

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeru Takimoto 13-35 Miyanari-cho, Gamagori-shi, Aichi Prefecture Kowa Stock Company Electric Optics Division Gamagori Factory

Claims (1)

[Claims] 1. An ophthalmic lacrimal fluid observing device for irradiating a cornea of an eye to be inspected with illumination light and observing a tear film on the cornea via an observation optical system, comprising: an illumination light source; and illumination light of the illumination light source. The objective lens that irradiates light in a direction and guides the reflected light from the tear film to the observation optical system, the first polarizing plate that is placed in front of the illumination light source and converts the illumination light into linearly polarized light, and is placed in front of the objective lens. A quarter-wave plate that converts linearly polarized illumination light directed to the eye to be examined into circularly polarized light and converts circularly polarized light reflected from the tear layer of the subject eye into linearly polarized light whose polarization direction is orthogonal to that of the incident illumination light. And an ophthalmic lacrimal fluid observation, comprising a second polarizing plate that guides only linearly polarized reflected light emitted from the quarter-wave plate that is reflected from the tear layer of the eye to be examined to the observation optical system. apparatus.