JPH0449940A - Eye refractometer - Google Patents

Abstract

PURPOSE:To enable measurement of an eye refraction value with a simple construction without use of a separation prism by receiving a reflected luminous flux from an eyegrounds on a light position detector through an objective lens and an luminous flux division member. CONSTITUTION:Luminous flux from a light source 1 travels on an optical axis 01 to be projected onto an eyeground Er of an eye E to be inspected as spot luminous flux via a lens 2, an opening 3a of a stop 3, a hole of a perforated mirror 4 and an object lens 5. The reflected luminous flux by the eyeground Er returns on the same optical path to be reflected with the perforated mirror 4 and four luminous fluxes Ma-Md are projected onto an image sensor 8 via a stop 6 and a lens 7. A diameter (d) of the reflected luminous flux from the eyeground Er differs on a plane R vertical to the optical axis 01 at a point Q according to condition of the eye E to be inspected. The diameter (d) of the luminous flux is proportional to an eye refraction, namely, a diopter value of the eye E to be inspected. Thus, an eye refraction to a longitudinal direction aligning the reflected luminous fluxes Ma and Mc of that to a longitudinal direction aligning the reflected luminous fluxes Mb and Md can be calculated from an interval between the reflected luminous fluxes Ma and Mc having an optical axis 02 therebetween or an interval between the reflected luminous fluxes Mb and Md on the image sensor 8 arranged at a position conjugated to a point Q.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an eye refractometer used, for example, in eye clinics.

[Prior art] Conventional eye refractometers project a spot-shaped light beam from the center of the pupil of the eye to be examined onto the fundus, and the light beam reflected by the fundus is extracted from the periphery of the pupil and received by a two-dimensional optical position detector. death,
It is well known to measure the refraction value from the position of the received light beam, but in order to separate the light beams on an optical position detector,
A separating prism composed of a plurality of wedge prisms is provided, and the beam reflected from the fundus of the eye is separated from the optical axis by the separating prism and then received on the optical position detector.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional example, a separation prism for separating the luminous flux is essential, and in order to use the separation prism, which is an optical member with a special and complicated configuration, the configuration of the device is difficult. becomes complicated.

An object of the present invention is to provide an ocular refractometer with a simple configuration that does not use a separating prism.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the ocular refractometer according to the present invention projects a single beam of light from a single region of the pupil plane of the eye to be examined onto the fundus of the eye through an objective lens. a projection optical system provided at a position conjugate to the pupil plane and having a transmission area including a plurality of meridians different from the single area on the pupil plane, and a two-dimensional light position provided at a position non-conjugate with the fundus. The present invention is characterized in that it has a light-receiving optical system on a detector that receives a light beam reflected by the fundus of the projection light beam through the objective lens and the light beam splitting member.

[Operation] The ocular refractometer having the above-mentioned configuration projects a single beam of light from a single region of the pupil plane onto the fundus through the objective lens, and then transmits the beam reflected by the fundus through the objective lens and the beam splitting member. The light is received on the optical position detector, and the refraction value is measured from the light receiving position.

[Example] The present invention will be explained in detail based on illustrated embodiments.

FIG. 1 shows a configuration diagram, where 1 is a light source, a lens 2 is placed on the optical axis O1 from the light source 1 to the eye E, and as shown in FIG. 3. A perforated mirror 4 and an objective lens 5 are arranged, and the optical axis 02 in the reflection direction of the perforated mirror 4 has an optical axis 0 as shown in FIG.
An image pickup device 8 consisting of a diaphragm 6 having four apertures 68 to 6d, a lens 7, a CCD, etc. is arranged at a position apart from 2.

Note that the diaphragm 3 and the diaphragm 6 are conjugate to the pupil Ep of the eye E to be examined, and the image sensor 8 is conjugate to a point Q between the myopic eye fundus conjugate point P of the eye E to be examined and the eye E to be examined. Although there is no limitation on the shape of the light source 1 in principle, it is desirable that it be a point light source.

The light beam from the light source 1 travels on the optical axis O1, passes through the lens 2, the aperture 3a of the aperture 3, the hole of the perforated mirror 4, and the objective lens 5, and is projected as a spot light beam onto the fundus Er of the eye E to be examined. The light beam reflected by Er returns along the same optical path and is reflected by the perforated mirror 4, passes through the aperture 6 and the lens 7, and is projected onto the image sensor 8 as four light beams Ma-Md as shown in FIG.

Figure 5 shows the reflected light flux from one point on the fundus Er, (a)
is when the eye E to be examined is emmetropic, fb) is when the eye is myopic, (
c) is the case of a hyperopic eye, and point Q is the conjugate position of the fundus on the myopic side, which is the measurement limit of this eye refractometer. Depending on the condition of the eye E to be examined, the diameter d of the reflected light beam from the fundus Er on the plane R perpendicular to the optical axis at the point Q varies.

Since the diameter d of this light beam is proportional to the eye refractive power, that is, the diopter value of the eye E to be examined, the distance between the reflected light beams Ma and Mc that sandwich the optical axis 02 on the image sensor 8 arranged at a position conjugate to the point Q is Or from the interval between the reflected light fluxes Mb and Md, the reflected light flux Ma
It is possible to calculate the eye refractive power in the meridian direction connecting the reflected light beams Mb and Md or the eye refractive power in the meridian direction connecting the reflected light beams Mb and Md. Further, assuming that the change in the eye refractive power in the meridian direction has a sinusoidal relationship with the meridian direction, the spherical power, astigmatism angle, and degree of astigmatism of the eye E to be examined can also be calculated.

In this way, the pupil E is adjusted using the aperture 3 and the perforated mirror 4.
By inputting the light beam only into a single region p, and using the diaphragm 6 to receive light from a region including multiple meridians different from the projected light beam position of the reflected light beam from the fundus Er, the received light beam on the image sensor 8 is It can be separated from axis 02. Therefore, the purpose of the aperture 3a of the diaphragm 3 is to make the light beam enter only a single area of the pupil Ep, so instead of the diaphragm 3, an aperture 3b is provided at a position off the optical axis O1 as shown in FIG. An aperture of 3° may be used. In addition, since the purpose of the diaphragm 6 is to receive light from a region including multiple meridians of the reflected light flux from the fundus Er, two diaphragms are installed in place of the diaphragm 6 at a position off the optical axis O1 as shown in FIG. A 6° diaphragm having openings 6e and 6f or a diaphragm 6'' having an annular opening 6g as shown in FIG. 8 may be used.

When apertures of 3° and 6° are used, two reflected light beams Me and Mf as shown in FIG. 9 are projected onto the image sensor 8, connecting the apertures 3b and 6e at the pupil Ep. The eye refractive power in the meridian direction, the meridian direction connecting the aperture 3b and the aperture 6f, and the meridian direction connecting the aperture 6e and the aperture 6f can be calculated from the positional relationship of the light beams Me and Mf in each meridian direction. When using an aperture of 6", an annular beam of light is projected onto the image sensor 8, but if the subject's eye E has astigmatism, the beam of light becomes an ellipse, so by calculating this ellipse, Perform refraction value measurement.

It is convenient to perform the above calculation after A/D converting the signal captured by the image sensor 8 and storing it in the memory, and the light flux projected onto the image sensor 8 is always from the position of the image sensor 8. Although it is blurred, there is no problem if the center position of the light beam is calculated and used. Note that since the lens 7 is provided to change the magnification of the light beam on the image sensor 8, it can be omitted depending on the magnification. In addition, although the optical position detector was provided at the conjugate position on the myopic side in the embodiment, it may be placed on the hyperopic eye side.

[Effects of the Invention] As explained above, the ocular refractometer according to the present invention projects a single beam of light from a single region of the pupil plane onto the fundus through the objective lens, and divides the beam reflected by the fundus through the light splitting member. By using this method, the light is extracted from an area including multiple meridians different from the photographing light beam position on the pupil plane and received on the optical position detector, and the refraction value is measured from the light reception position, so the refraction value can be measured without using a separation prism. The measurement light flux can be separated from the optical axis.

[Brief explanation of drawings]

The drawings show an embodiment of the eye refractometer according to the present invention, in which FIG. 1 is a configuration diagram, FIGS. 2 and 3 are front views of the aperture, FIG. 4 is an explanatory diagram of the light flux on the image sensor, and FIG. Figure (al (b)
fcl is an explanatory diagram of a light flux reflected by the fundus of the eye, FIGS. 6, 7, and 8 are front views of apertures according to other embodiments, and FIG. 9 is an explanatory diagram of a luminous flux on an image sensor. The symbol 1 is a light source, 3.6 is an aperture, 4 is an aperture lens, 5 is an objective lens, and 8 is an image sensor. Patent applicant Canon Co., Ltd. Figure 1 Figure 6 Figure 8

Claims (1)

[Claims] 1. A projection optical system that projects a single beam of light from a single area on the pupil plane of the subject's eye onto the fundus through an objective lens; A beam splitting member having a transmission region including a meridian, and a two-dimensional optical position detector provided at a position non-conjugate with the fundus, receive the reflected beam of the projected light beam by the fundus via the objective lens and the beam splitting member. An eye refractometer characterized by having a light receiving optical system.