JP3187096B2 - Ophthalmic instrument with objective lens - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used, for example, in an ophthalmologic machine for measuring the refractive power of an eye to be examined from information on light reflected from the fundus, and forms an aperture in the apparatus on the pupil of the eye to be examined. Instrument having an objective lens for the same.

[0002]

2. Description of the Related Art Conventionally, an eye refraction measuring apparatus is disclosed in
No. 5529, Japanese Patent Application Laid-Open No. 61-139201, an optical system for separating a light beam by arranging a light splitting member before a light beam reflected by a fundus of an eye to be examined enters a lens system, or Japanese Patent Application Laid-Open No. 62-26045 discloses a method of separating a light beam behind an objective lens.

Since the eye refraction measuring apparatus has not only the measuring optical system but also the positioning optical system and the fixation target optical system as in the conventional example, not only the imaging performance of the reflected image of the fundus, It is necessary to sufficiently consider the imaging performance of the anterior segment of the eye to be examined. Further, it is necessary to provide an arrangement which does not affect the measurement in consideration of the reflection on the lens surface similarly to the fundus camera.

[0004]

However, in the conventional example, since the position where the light splitting member is arranged is not specified with respect to the objective lens, there is a disadvantage that the aberrations caused by these are not negligible. In particular, in the third example, since the members divided into the anterior ocular segment observation system and the fixation target optical system are both constituted by half mirrors, astigmatism caused by this becomes considerably large. In order to remove the influence of the reflection of the incident light by the lens system, the first
In the example, since the light beam incident on the eye to be examined and the light beam emitted therefrom are separated and combined by the half mirror, the loss of the light amount is large. On the other hand, the second and third examples have a disadvantage that a prism having a complicated shape is used in order to separate an index projected on the fundus on the pupil of the eye to be examined.

An object of the present invention is to provide an ophthalmic instrument having an objective lens capable of providing a good imaging relationship with a plurality of optical systems.

[0006]

An ophthalmic instrument having an objective lens according to the present invention for achieving the above-mentioned object is provided with a lens for restricting a light beam from a light source through an aperture of a perforated mirror provided near the aperture. In an ophthalmic instrument for irradiating an optometry and detecting reflected light from an eye to be inspected by an imaging means, an objective lens system including a first lens group and a second lens group for forming an image of the stop on a pupil of the eye to be inspected; The first lens group and the second lens group
A light splitting member obliquely provided between the lens groups, wherein a final surface of the first lens group and a first surface of the second lens group are formed as planes as viewed from the eye to be inspected, and a pupil of the eye to be inspected; An image formed by the first lens group is formed at an infinity point, and one of the optical paths split by the light splitting member reflects reflected light from the eye to be inspected by the second lens group and the apertured mirror. And guiding the reflected light from the eye to be inspected to the imaging unit without passing through the second lens group and the perforated mirror. Is what you do.

[0007]

An ophthalmic instrument having an objective lens having the above-described configuration projects a light beam from a pupil of an eye to be inspected to infinity by a first lens group, splits the light beam, and connects a final surface of the first lens group to a second surface. By making the first surface of the lens group flat, the reflected light of the incident light is prevented from entering the measuring optical system, and the image formed by the reflection of the first surface of the first lens group and the final surface of the second lens group. To match the position.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the illustrated embodiments. As shown in FIG. 1, the pupil of the eye to be examined is schematically shown.
Ep is imaged at an infinity point by a first lens group 1 having a focal length f1 arranged at a distance f1 and by a second lens group 2 having a focal length f2 arranged at a further distance e. An image is formed at a position E ′ that is separated from the second lens group 2 by f2.

According to such a configuration, the pupil Ep of the eye to be examined
Is parallel light between the first lens group 1 and the second lens group 2, so that astigmatism does not occur even if a light splitting member such as a half mirror is inserted into this portion. .

The surface of the first lens unit 1 on the side of the eye to be examined, that is, the first lens unit 1
The radius of curvature of the surface is r1, the final surface is a plane, and the second lens group 2 has a first surface that is a flat surface, and the radius of curvature of the final surface is r2.
It is composed of Considering that light rays emitted from the apertures arranged at the conjugate positions of the pupil Ep of the subject's eye are reflected on the respective surfaces of the lens groups 1 and 2, the light rays reflected on the final surface of the second lens group 2 are near From the axis calculation (f2 · r2) /
A virtual image is formed at a position E ′ behind (r2 + 2 · f2).
Light rays incident on the first surface of the second lens group 1 become parallel light due to the refraction of the second surface and are incident perpendicularly to the surface.
The reflected light from the first surface forms an inverted image having a paraxial lateral magnification of −1 at the position E ′, and all the reflected light returns to the aperture.

In the first lens group 1, the reflection on the last surface similarly returns to the aperture, and the reflection on the first surface is r2 / 2 in front of it.
A real image is formed at the position. Therefore, the distance d = r1 / 2
+ (R2 + 2 · f2) / (f2 · r2) When the respective lens groups 1 and 2 are arranged in a relationship of, the black point is arranged at the conjugate position B by a well-known technique, so that the first lens group 1
The reflection of the surface and the final surface of the second lens group 2 can be prevented from entering the measurement optical system.

FIG. 2 shows an embodiment in which the present invention is applied to an eye refraction measuring apparatus. Reference numeral 3 denotes an infrared light source. A black spot 4, a projection lens 5, a stop 6, a perforated mirror 7, a second lens group 2, a light splitting mirror 8, a first light source 4 are arranged along an optical path of infrared light emitted from the light source 3. The lens groups 1 are sequentially arranged. Note that the first lens group 1 and the second lens group 2 have the same arrangement as in FIG. Further, a mirror 9 is arranged behind the light splitting member 7, and a photosynthetic mirror 10, a relay lens group 11, and an image pickup device 12 are arranged in the reflection direction. Further, between the perforated mirror 7 and the photosynthetic mirror 10, a multi-hole aperture 13 having a plurality of radial openings, a measuring lens group 1
4. A wedge prism 15 composed of a plurality of elements corresponding to the aperture of the stop 13 is provided.

The infrared light emitted from the light source 3 is transmitted to a projection lens 5, a stop 6, a central portion of a perforated mirror 7, and a second lens group 2.
Are reflected by the light splitting mirror 8 and further illuminate the first lens group 1 and the fundus oculi Ef of the eye E to be inspected. Here, the stop 6 forms an image on the pupil Ep of the eye E by the objective lens including the first lens group 1 and the second lens group 2.

The infrared light reflected by the fundus Ef of the eye E is
Again, the first lens group 1, the light splitting mirror 8, the second lens group 2
After being refracted and reflected by the aperture mirror 7, it is reflected by the perforated mirror 7, passes through the apertures of the multi-hole aperture 13, passes through the measuring lens group 14, is further separated by the wedge prism 15, is reflected by the photosynthetic mirror 10, and is relayed. The image is projected onto the image sensor 12 via the lens group 11. A known technique may be applied to a method of measuring the eye refractive power from signals of a plurality of light beams separated and projected on the image sensor 12.

The black spot 4 is located at a position conjugate with the image reflected by the first surface of the first lens unit 1 of the stop 6 and the final surface of the second lens unit 2 as described above. A part of the light beam is blocked so that the reflected light does not enter the opening of the multi-hole aperture 13.

The observation optical system for aligning the apparatus with the eye E to be inspected has a configuration in which light from the pupil Ep of the eye to be inspected is converted into parallel light by the first lens group 1 and passes through the light splitting mirror 8. , A mirror 9 and a photosynthetic mirror 10, and an image is formed on an image sensor 12 by a relay lens group 11.

In this optical system, both the light splitting mirror 8 and the photosynthetic mirror 10 are arranged in a portion where the light beam from the pupil of the eye E to be inspected is a parallel light, so that the optical system is formed of a parallel flat plate obliquely provided. The effect of astigmatism and the like caused by the light splitting mirror 8 and the light combining mirror 10 is removed, and a good image can be formed on the image sensor 12.

Although the embodiment has been described with reference to an eye refraction measuring apparatus, it can be easily applied to a fundus observation apparatus such as a fundus camera. Further, each of the lens groups 1 and 2 does not have to have a plurality of lenses, and may be composed of one lens.

[0019]

As described above, an ophthalmologic instrument having an objective lens according to the present invention can be used to illuminate the fundus of a subject's eye via a perforated mirror and an objective lens, and to receive reflected light through the eye fundus. The light splitting member can be provided in the parallel light while minimizing the influence of the surface reflection of the objective lens. That is, even if the number of surfaces increases with two objective lenses,
Since the reflection on the plane returns to the illumination system and does not enter the light receiving system, it becomes the same as in the case of the first lens group, and the reflection of the lens can be easily removed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a lens system.

FIG. 2 is a configuration diagram applied to an eye refraction measuring apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st lens 2 2nd lens 3 Light source 4 Black point 5 Projection lens 6 Aperture 7 Perforated mirror 8 Light splitting mirror 9 Mirror 10 Photosynthesis mirror 12 Image sensor 13 Multi-hole aperture 15 Wedge prism

Claims (2)

(57) [Claims] 1. A diaphragm for reducing a light beam from a light source and a vicinity of the diaphragm.
Irradiates the eye to be examined through the aperture of the apertured mirror provided in
In an ophthalmic instrument for detecting reflected light from an optometry by an imaging means, an objective lens system including a first lens group and a second lens group for forming an image of the stop on a pupil of the eye to be inspected;
Light splitting member obliquely provided between a lens group and the second lens group
Wherein the last surface of the first lens group and the first surface of the second lens group are formed as planes as viewed from the eye to be inspected , and the image of the pupil of the eye to be inspected by the first lens group is at infinity. One of the lights split by the light splitting member so as to form an image at a point.
The path reflects light reflected from the subject's eye to the second lens group and the hole.
The light is reflected by an open mirror and guided to the imaging means, and the light is split.
The other optical path transmitted through the member transmits the reflected light from the subject's eye.
Without passing through the second lens group and the perforated mirror,
Eye having an objective lens, which is directed to an imaging means
Departmental instruments . 2. The method according to claim 1, further comprising:
The distance d to the final surface of the lens group is the first lens group,
Assuming that the respective radii of curvature of the second lens group are r1 and r2 and the focal lengths are f1 and f2, d = (r1 / 2) + (f2 · r2) / (r2 + 2 · f2). d is (r1 / 2) vs. (f2 · r2)
2. The pair according to claim 1, wherein a black point having a light-shielding portion is arranged at a position optically conjugate to a position internally divided into / (r2 + 2 · f2) .
Ophthalmic instrument with object lens .