JPH05111463A - Measurement index projection optical system of eye refractive power measuring device - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the blurring of the fundus image over a wide measurement range and to enable accurate measurement. An objective lens 1 is provided so as to face an eye E to be inspected, and a plurality of indices having a light splitting mirrors 2, 3, a perforated mirror 4, an aperture stop 5, a projection relay lens 6, and a circular aperture are sequentially provided behind the objective lens 1. A light source 8 including 7b, 7a, 7c, an infrared light emitting diode and the like is arranged. A relay lens 9 and an observation image pickup device 10 for outputting to a television monitor are provided in the reflection direction of the light splitting mirror 7. Further, in the reflection direction of the perforated mirror 2, a multi-hole diaphragm 11 having openings in a plurality of radial line directions, a measurement relay lens 12, a wedge prism 13 composed of a plurality of elements corresponding to each radial line direction, an image for measurement. Element 14 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention projects a predetermined index on the fundus of the eye to be examined, and projects the light index on the fundus of the eye to calculate the refractive power of the eye from the information of the light reflected by the fundus. It relates to an optical system.

[0002]

2. Description of the Related Art As an index projection system used in an eye refractive power measuring device, as disclosed in Japanese Patent Publication No. Sho 61-41212, a measurement index is arranged substantially conjugate with the fundus of an emmetropic eye, and An optical system that ignores blurring in the fundus in the case of an emmetropic eye, or, as disclosed in JP-A-60-12035, moves a part of the optical system according to the refractive power of the eye to be examined. A method for reducing the amount of blur is known.

[0003]

However, in the former case of the above-mentioned conventional example, when the measurement range of the eye refractive power is not very wide, the structure is simple, but the strength is high. For myopia and hyperopia patients, the blurring of the index image projected on the fundus becomes large, and the S
It has a drawback that the / N ratio is deteriorated and the measurement accuracy is lowered.

The latter case has the advantage that part of the measurement index projection optical system moves during measurement to improve the S / N ratio of the measurement signal, but a drive circuit for moving the optical system, etc. Since it requires complicated additional parts, the cost is increased.

An object of the present invention is to provide an eye refractive power measuring apparatus which does not require a complicated additional component such as a driving circuit and which reduces the blurring of the fundus image in a wide measuring range and enables accurate measurement. To provide.

[0006]

An eye refractive power measuring apparatus according to the present invention for achieving the above object comprises a measurement index projection optical system for projecting a predetermined index on the fundus of an eye to be examined with infrared light,
In the eye refractive power measurement device having a measurement optical system for measuring the refractive power of the eye by projecting light reflected by the fundus of the index on the measurement element, the index is on the optical axis of the measurement index projection optical system. It is characterized in that a plurality of them are arranged.

[0007]

In the eye refracting power measuring device having the above-mentioned structure, a plurality of indices projected on the fundus of the eye are arranged at different positions to illuminate the fundus and reduce the amount of blur.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail based on the illustrated embodiments. In FIG. 1, the objective lens 1 faces the eye E to be inspected.
Is provided in the rear of it, and sequentially comprises light splitting mirrors 2, 3, a perforated mirror 4, an aperture stop 5, a projection relay lens 6, a plurality of indicators 7a, 7b, 7c having circular openings, an infrared light emitting diode, and the like. The light source 8 is arranged. A relay lens 9 and an observation image pickup device 10 for outputting to a television monitor are provided in the reflection direction of the light splitting mirror 7. Also,
In the reflection direction of the perforated mirror 2, a multi-hole diaphragm 11 having openings in a plurality of radial directions, a measurement relay lens 12, and a wedge prism 1 including a plurality of elements corresponding to the radial directions.
3. An image sensor 14 for measurement is provided. Further, in the incident direction of the light splitting mirror 3, the photographing relay lens 15,
A fixation target 16 that is movable in the optical axis direction and a light source 17 that moves together with the fixation target 16 are arranged. Here, the pupil Ep of the eye E is conjugated with the aperture of the aperture stop 5.

The infrared light emitted from the light source 8 passes through the openings of the plurality of indicators 7a, 7b, 7c formed of circular openings projected on the fundus, and is refracted by the projection relay lens 6 to open the aperture diaphragm 5. The light passes through the central hole of the perforated mirror 2 and the light splitting mirrors 3 and 7, and is further refracted by the objective lens 1 to illuminate the fundus Ef of the eye E to be examined.

The reflected light from the fundus Er returns to the original optical path and again passes through the objective lens 1 and the light splitting mirrors 2 and 3,
The light is reflected by the peripheral portion of the perforated mirror 2, passes through each aperture of the multi-hole diaphragm 11, is refracted and separated by the measurement relay lens 12 and the wedge prism 13, and reaches the image pickup device 14 for measurement. The eye refractive power is calculated by known means from the signals of the plurality of light beams separated and projected on the image sensor 14.

Further, the objective lens 1 forms an image of the light beam reflected by the light splitting mirror 7 on the anterior segment of the eye E to be examined on the image pickup device 10 for observation through the relay lens 9 for observation, and the light source 17 is provided. The fixation target 16 illuminated by the relay lens 15
It has a function of projecting the image of the fixation target 16 onto the fundus Ef of the eye E through the eye. The television signal from the image pickup device 10 for observation is sent to a television monitor (not shown) to display the anterior segment image of the eye E, and the examiner observes the television monitor and, while observing the television monitor, the eye E to be inspected by a sliding mechanism (not shown). And align the device.

In FIG. 2, the luminous flux emitted from the light source 8 is the projection index 7
It shows the state of the light rays when the positions and sizes of b, 7a, and 7c are adjusted to the optimum ones. The light source 8 has a finite certain area from which light is emitted from each of the indicators 7c, 7a,
The light passing through the edge portion of 7b is arranged so as to enter the pupil Ep of the eye E to be inspected. The edge of the index 7a is illuminated by the part between the rays r1 and r2 represented by a straight line, the edge of the index 7b is illuminated by the part between the ray r2 and the ray r ⁻ represented by the dotted line, and the edge of the index 7c. Is illuminated in the portion between the ray r1 and the ray r ⁺ represented by the chain double-dashed line.

Here, it suffices that the entire range from the ray r ⁺ to the ray r ⁻ can pass through the pupil Ep of the eye E and illuminate the fundus Ef. Furthermore, the luminous flux from the light source 8 is reflected by each index 7
If the aperture diameter is determined so that the illuminance for illuminating the edge of the eye is the same, it is possible to illuminate with a minimum change in the contrast of the aperture image projected on the fundus Ef. For example, if the index 7a is arranged at the conjugate position of the fundus of the emmetropic eye, the image of the index 7a is clearly projected on the fundus when the eye E is emmetropic.
The indicators 7b and 7c are -10 diopters and +1 respectively.
Assuming that it is placed in the fundus conjugate of 0 diopter, -1
In the eye E of 0 diopter, the aperture image of the index 7b is +10
In the eye E of the diopter, the aperture image of the index 7c is clearly projected on the fundus Er. Even in other refraction states, the light fluxes limited by the respective indexes 7a, 7b, 7c illuminate the fundus Ef, so that the blur amount decreases.

FIG. 3 schematically shows the change in the contrast of the index image according to the refractive power of the eye E to be examined. This is 0 diopter (still eye), -10 diopter, +1 as described above.
The figure shows a state in which the index 7 is arranged at 0 diopter and all the index edges are illuminated in the same state.

In the present embodiment, the description has been given with the number of the indexes 7 being three, but the size and position of the indexes 7 are optimized as described above, and the luminous flux from the light source 8 is always all the indexes 7a ,.
By arranging so as to illuminate the edge portions of 7b and 7c,
It is possible to increase the number and it works effectively for a wider measuring range.

FIG. 4 shows another embodiment in which beam splitters 20 and 21 and a total reflection mirror 22 are provided on the optical axis.
Infrared light sources 23, 24, 25 are arranged in the respective incident directions, and the infrared light sources 23, 24, 25 serve as an index.

In this case, the three infrared light sources 23, 2
In order to make 4 and 25 have the same brightness, the beam splitter 20 is 30% reflective / 70% transmissive, and the beam splitter 21
Has characteristics of 50% reflection and 50% transmission.

[0018]

As described above, the measurement index projection optical system of the eye refractive power measuring device according to the present invention has a simple configuration in which a plurality of indexes to be projected on the fundus of the eye to be examined are arranged on the optical axis. Since the blurring of the index image on the fundus can be reduced over a wide measurement range, the measurement signal S / N can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an optical system.

FIG. 2 is a schematic diagram showing how a light beam emitted from the optical axis is restricted by each index.

FIG. 3 is an explanatory diagram of a relationship between a contrast of an index and a refractive power on a fundus.

FIG. 4 is a configuration diagram of another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 objective lens 2, 3 light splitting mirror 4 aperture mirror 5 diaphragm 7a, 7b, 7c measurement index 8, 17 light source 10 observation image sensor 11 multi-hole diaphragm 13 wedge prism 14 measurement image sensor 20, 21, 22 beam Splitter 23, 24, 25 Infrared light source

Claims (4)

[Claims] 1. A measurement index projection optical system for projecting a predetermined index on the fundus of an eye to be examined with infrared light, and light reflected by the fundus of the index on a measuring element to measure the refractive power of the eye to be examined. An eye refractive power measuring device having a measuring optical system, wherein a plurality of the indexes are arranged on an optical axis of the measuring index projecting optical system. 2. The eye refractive power measuring device according to claim 1, wherein the plurality of measurement indices are arranged at positions conjugate with the emmetropic eye and before and after the position. 3. The eye refractive power measuring device according to claim 1, wherein the plurality of measurement indexes are adjusted in position and size so that a light flux passing through an edge of the opening of the index reaches the fundus of the eye to be inspected. .. 4. The eye refractive power measurement device according to claim 1, wherein the index is an infrared light source.