JPH02156927A - Eye refractometer - Google Patents

Abstract

PURPOSE:To measure normally by reducing the reflection light from the glass surface when an overrefraction is generated by measuring the eye while the person to examine wears a glass, by providing a light shielding member to permeate only the central light flux selectively near an object lens. CONSTITUTION:A light shielding member 10 is inserted to the light passage by a motor only when an overrefraction is generated, and it is withdrawn from the light passage in the other conditions. By placing the light shielding member 10 with an aperture 10a near an object lens 5, almost all the reflection light A from the glass surface is shielded. And since the glass G in inclined downward more or less, almost no light flux returns to the aperture 10a. On the other hand, when the glass G is worn, the eye E to check is almost close to an emmetropia, and the measuring light reflected by the eyeground Er is not almost scattered. As a result, the measuring light passes through the central aperture 10a of the light shielding member 10 and to be radiated to a two-dimensional area sensor 9, and never shielded by the shielding member 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an eye refractometer used for measuring eye refractive power in eye clinics, opticians, and the like.

[Prior Art] Conventionally, various methods have been known for measuring the refractive power of the eye, but in all methods, the test subject's power (when measuring while wearing glasses, the eyeglass surface There are cases where reflected light from the sensor enters the photoelectric sensor, making measurement impossible.

In other words, in a boat fishing eye refractometer, the measurement light reflected from the fundus of the subject's eye diverges and spreads in hyperopic eyes, so in order to capture all of this measurement light, the objective lens facing the subject's eye must be set at a certain level or more. It must have a diameter of However, when over-refraction occurs when a test subject takes measurements while wearing glasses, the measurement incident light beam is reflected by the glasses surface, and the reflected light is significantly stronger than the fundus reflected light used for measurement. If it enters a photoelectric sensor, measurement becomes impossible. In other words, the direction of the reflected light on the glasses surface changes depending on the tilt of the glasses, but it passes through the periphery of the ζ objective lens, which has a large diameter, and enters the photoelectric sensor, disturbing the measurement.

In order to remove such reflected light, it has been proposed in the past to provide a light-shielding plate at a position that is almost conjugate to the eyeglass surface, but in this case as well, depending on the measurement method, the light-shielding plate itself may reject the measurement light. Another problem arises:

[Object of the Invention] The object of the present invention is to eliminate the reflected light from the eyeglass surface to enable normal measurement during over-reflexion that occurs when a subject takes measurements while wearing glasses. The purpose of the present invention is to provide an ocular refractometer.

[Summary of the Invention] The gist of the present invention to achieve the above-mentioned object is an eye refractometer characterized by providing a light shielding member near an objective lens that selectively transmits only a central light beam.

[Embodiments of the invention] The present invention will be explained in detail based on illustrated embodiments.

FIG. 1 shows an embodiment of an eye refractometer according to the present invention, where E indicates the eye to be examined and G indicates glasses worn by the subject. In addition, 1 is a measurement light source, and a measurement light source l is connected between it and the glasses G.
From the side, the lens 2 has an aperture 3a in the center as shown in FIG.
A central aperture stop 3, a perforated mirror 4, and an objective lens 5 are arranged, and in the direction of incidence of the perforated mirror 4, as shown in FIG.
A lens 7, a conical prism 8, and a two-dimensional area sensor 9 are arranged in this order. Further, near the objective lens E0, as shown in FIG. 4, a light shielding member 10 having a small opening 10a in the center can be inserted as desired by the operation of a motor 11.

The light beam from the measurement light source 1 passes through the lens 2, the central aperture 3, the perforated mirror 4, and the objective lens 5, enters the test subject @E, and is reflected by the fundus Er, and the reflected light from the fundus is reflected by the objective lens 5.
After being reflected by a perforated mirror 4, the light passes through an annular aperture diaphragm 6, a lens 7, and a conical prism 8, and reaches a two-dimensional area sensor 9.

FIG. 5 shows a circular fundus image 9a on the two-dimensional area sensor 9. It has been conventionally known that the spherical power is determined by the dimensions of this image, the degree of astigmatism is determined by the ellipticity, and the astigmatism angle is determined by the ellipse direction. As is known.

In the embodiment, the light shielding member 10 is inserted into the optical path by the motor 11 only during over-refraction, and is withdrawn from the optical path in other cases. Now, considering the case where this light shielding member 10 is not provided, since the objective lens 5 has a large diameter, the reflected light A from the eyeglass surface passes through the peripheral part of the objective lens 5 and enters the two-dimensional area sensor 9, and as described above, It often becomes impossible to measure.

However, if a light shielding member 10 having an aperture 10a is placed near the objective lens 5, most of the reflected light A from the eyeglass surface is blocked by the light shielding member 10. Moreover, since the glasses G are tilted somewhat downward, there is almost no light flux returning to the central aperture 10a.On the other hand, when the glasses G are worn, the subject's eye E is almost emmetropic. Therefore, the fundus Er
The measurement light reflected by the beam hardly diverges, therefore,
This measurement light enters the two-dimensional area sensor 9 through the opening 10a in the center of the light shielding member 10, and is not blocked by the light shielding member 10.

In the embodiment, the light shielding member 10 is inserted into the optical path by the motor 11 only when the over reflux 91 is activated, but the light shielding member 10 may be made of liquid crystal or the like so that such a mechanically movable part can be omitted. Moreover, the present invention can be applied to any measurement method.

[Effects of the Invention] As explained above, the eye refractometer according to the present invention is capable of performing normal measurements by preventing reflected light from the eyeglass surface from entering the measurement sensor even in the event of over reflux 91. become. Further, since the measurement light reflected from the fundus of the eye to be examined is guided to the measurement sensor through the opening in the center of the light shielding member without being diverged, there is no inconvenience that the measurement light is eclipsed by the light shielding member.

[Brief explanation of the drawing]

The drawings show an embodiment of the eye refractometer according to the present invention, in which Fig. 1 is an optical configuration diagram, Fig. 2 is a front view of the central aperture stop, and Fig. 3 is a front view of the central aperture stop.
FIG. 4 is a front view of the annular aperture stop, FIG. 4 is a front view of the light shielding member, and FIG. 5 is an explanatory diagram of the fundus image on the two-dimensional area sensor. Symbol 1 is the measurement light source, 2 is the lens, 3 is the central aperture diaphragm, 4
1 is a perforated mirror, 5 is an objective lens, 6 is an annular aperture stop, 7 is a lens, 8 is a conical prism, 9 is a two-dimensional area sensor, O is a light shielding member, 0a is an aperture, and 1 is a motor.

Claims (1)

[Claims] 1. An eye refractometer characterized by providing a light shielding member near the objective lens that selectively transmits only the central beam.