JPS6012035A - Eye refractive index measuring apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an eye refractive power measurement device that automatically and objectively measures the refractive power of, for example, a subject's eye.

2. Description of the Related Art Eye refractive power measurement devices that objectively measure the state of eye refraction have been known. Although most of these methods differ, the optical system is moved within the device during measurement to find a position that is conjugate with the eye to be examined, and there is a limit to the reduction in measurement time. Furthermore, most of these types of devices are of the internal viewing type, in which a fixation garment is provided within the device and the subject looks into the device. Therefore, so-called instrumental myopia is likely to occur, and in order to eliminate this, the cloud 1 method is usually adopted, in which the fixation garment is moved to the far-sighted side of the subject's eye in one measurement, and the measurement is repeated again. has been done. On the other hand, as an eye refractive power device whose internal optical system does not move during measurement, there is a
No. 6-161031 is disclosed.

The purpose of the present invention is to provide a projection optical system within the device with a simple movable part, thereby making it possible to basically perform measurements similar to those of a device without movable parts, while improving the signal-to-noise ratio of the signal during measurement. The purpose is to provide an eye refractive power measurement device that includes a projection optical system that projects a projection chart from the fundus, and a projection optical system that extracts and separates a plurality of reflected images from the fundus of the light beam projected by the projection optical element. In the eye refractive power measurement device, the projection chart or a part of the projection optical system is movable along the optical path. It is characterized by:

The present invention will be explained in detail below based on the illustrated embodiments.

In FIG. 1, l is an infrared light emitting diode, and infrared light t± emitted from this diode 1, condenser lens 2, fundus projection chart 3, relay lens 4, circular diaphragm 5, perforated mirror 6, 1 Gikroic Mirror 7
, a second guichroic mirror 8, and an objective lens 9 before proceeding to the eye E to be examined. Projection chart 3
As shown in Fig. 2, three 7) 3 a~
3C, and is movable in the optical axis direction together with the light emitting diode l. The first and second dichroic mirrors 7.8 have the characteristics of transmitting infrared light and reflecting visible light, and are arranged with a tilt angle of 1 toward the optical axis. .

On the other hand, the light th reflected by the fundus Ef passes through the original optical path and is reflected around the perforated mirror 6, and along this reflected optical path is passed through the diaphragm plate 10, the lens 11, the prism nosm 12, the reflecting mirror 13, One-dimensional photoelectric conversion elements 15 consisting of (ccp) are sequentially arranged. The aperture plate lO has six openings 10a to 10f as shown in FIG.
Elements 12a to 12f of prism 1] shown in the figure
It is designed to be separated by L. Also, it consists of three lenses 14a to 14C arranged in the meridian direction of 141±3, and 11 photoelectric conversion elements 15.
It is also composed of three solid elements 15a to 15c.
The elements 15a to 15c correspond to each other one by one.

First microscopic mirror 7&±, illumination lamp 1
Visible light emitted from 6 is made to enter,
Light from the illumination lamp 16 is incident through a fixation rate 17 and a lens 18 arranged along its optical axis. Also, the second
An observation optical system is arranged on the side of the guichroic mirror 8, and the reflected light from the guichroic mirror 8 is transmitted to a TV relay lens.

The light is received by a TV camera tube.

During the measurement, infrared light from the light emitting diode l.

The slit image of the projection chart 3 by the relay lens 4
The first,
The image is formed on the primary imaging plane F located between the second guichroic mirrors 7 and 8. This line is passed through the objective lens 9 to the subject's eye E.
It is projected from the pupil Ep of the eye and forms an image on the fundus Ef. On the other hand, the light reflected from the fundus Ef is once imaged from the periphery of the pupil Ep onto the primary imaging plane F by the objective lens 9, and then reflected from the periphery of the perforated mirror 6, and is then reflected by the diaphragm plate 10 and the lens ]l. The light passes through, is separated and deflected by a prism 12, and is imaged on a photoelectric conversion element 15 via a cylindrical lens 14.

In this case, the images formed by the apertures 10a-1Of of the aperture plate 10 are separated by the elements 12a-12f of the prism 12. Further, the diaphragm plate IO separates the incident light by focusing on the pupil Ep, and eliminates the influence of scattering within the eye E to be examined. The relationship between the photoelectric conversion elements 15 and the reflected images is such that, as shown in FIG. It's like a statue. In this case, the six openings of the aperture plate 10 are ioa
and 10d, lOb and lOe, and 10C and 1of form pairs, and each pair corresponds to three photoelectric conversion elements 15a to 15c. Therefore, the reflected images Ra and Rd are on the element 15a,
Rh and Re will be imaged on element 15b, and Rc and Rf will be imaged on element 150.

On the other hand, in the direction in which the cylindrical lenses 14a-14cj have refractive power, the apertures 10a-1of form an image on the photoelectric conversion elements 15a-15c, and have the role of reducing the image in the lateral direction and increasing the amount of light. There is.

Now, if the eye E to be examined is an emmetropic eye, the chart reflection image R projected by the infrared diode l and reflected by the fundus Ef is re-imaged on the primary imaging plane F, separated by the diaphragm plate 10, and transferred to the photoelectric conversion element. The image is formed at 15 predetermined positions. However, in a non-emmetropic eye, the fundus image is formed in front of and behind the imaging plane F.
The angle of the light beam incident on the aperture plate 10 changes and the prism 12
The deflection angle also changes, and the interval between the two reflected images R on the photoelectric conversion element 15 changes.

The signal of the photoelectric conversion element 15 becomes as shown in FIG.
By measuring the interval between the two peaks, the refractive power in the longitudinal direction of the photoelectric conversion element can be measured. Further, the diopter of the eye to be examined changes depending on the angle, and the refractive power Dθ in the θ direction can be expressed in the form: Dθ=AB, ) * 5in2 (θ10.). Note that A is a value related to the spherical power Sph of the eye E to be examined, Bo is a value related to the astigmatic power CYI,
θ0 is a value related to the astigmatic angle Ax. Therefore, Sph
, Cyl, and All, it is sufficient to find the refractive power in the three meridian directions.

As shown in FIG.
a-15c in the predetermined meridian direction, 3ph, Cy
This is to calculate l and Ax.

In actual measurement, the subject looks at the internal fixation garment 17 that is illuminated by the illumination lamp 16, but this is done via the dichroic mirror 7 and the lens 18. In order to eliminate instrument myopia, the actual measurement procedure is that when the measurement switch is pressed, the fixation garment 17 remains in its initial setting.
Take the second measurement. Here, Sph, Cyl, and Ax are calculated, and according to the refractive power of the eye E, the projection chart 3,
The condenser lens 2 and the light source 1 are moved from the initially set locations, and the chart 3 is made almost conjugate with the fundus Ef of the eye E to be examined. At the same time, the illumination lamp 16 and the fixation garment 17 are moved in accordance with a predetermined routine to create fog and a second measurement is performed. In this cloud, visible light emitted by the illumination lamp 16 enters from the first dichroic mirror 7, forms an image on the primary imaging plane F, and projects it onto the anterior segment of the eye E to be examined via the objective lens 9. Then, the reflected light is reflected by the second dichroic mirror 8 toward the observation optical system, and while being observed on a TV monitor (not shown) through the TV camera tube 20,
This is done by moving the illumination lamp 16 and fixation garment 17 back and forth.

In the first measurement, the chart 3 is placed at the initial setting position, so the farther the eye E is from emmetropia, the more
The chart image projected onto the fundus Ef is blurred, and the seventh
As shown by the solid line in the figure, the two peaks cannot be separated sufficiently, but after the second measurement, the chart 3 moves by the amount of the refraction peak obtained in the first measurement, so the reflected image becomes clear and the photoelectric conversion element 15 is also reduced, and as shown by the broken line in FIG. 7, the peak becomes larger and the S/N ratio improves.

Further, in order to optically change the image position of the projection chart 3, the relay lens 4 may be moved without moving the chart 3 itself, and an example thereof is shown in FIG. In this case,
The relay lens 4 is moved so that the chart 3 is projected from the same position as the refractive power obtained in the first measurement.

Furthermore, regarding the movement method, in addition to pressing the measurement switch and moving based on the first information, you can also leave the instrument in constant measurement mode so that the light enters the pupil conveniently and outputs a predetermined signal. By moving the chart position at that time, the measurement time can be shortened.

As explained above, the eye refractive power measuring device according to the present invention includes:
By making the projection chart or a part of the chart projection optical system movable, it is possible to improve the S/N ratio of the signal without moving the optical system during measurement, allowing for more accurate measurement.

In addition, in the present invention, the fog method can also be used as explained in the examples.

[Brief explanation of the drawing]

The drawings show an embodiment of the eye refractive power measuring device according to the present invention,
Figure 1 is its configuration diagram, Figure 2 is a front view of the projection chart,
Figure 3 is a front view of the aperture plate, Figure 4 is a front view of the prism,
The fifth part is an explanatory diagram of the relationship between the fundus reflection image and the photoelectric conversion element,
6 and 7 are output waveform diagrams of the photoelectric conversion element, and FIG. 8 is a configuration diagram of another embodiment. The encoder is an infrared diode, 3 is a projection chart, 4 is a relay lens, 5 is a circular aperture, 6 is a perforated mirror, 7.8 is a dichroic mirror, 9 is an objective lens, 10 is an aperture plate, 12 is a prism, 14 is a cylindrical lens, 1
5 is a photoelectric conversion element, 16 is an illumination lamp, 17 is a fixation garment,
20 is a TV image pickup tube, E is the eye to be examined, Ef is the fundus, and EP is the pupil. Patent applicant: Canon Co., Ltd. No. 411 Figure 6 vl IS Figure 4c No. 70

Claims (1)

[Scope of Claims] 1. A projection optical system for projecting a projection chart onto the fundus, an extraction means for extracting and separating a plurality of reflected images from the fundus of the light beam projected by the projection optical system, and extraction by the extraction means. An eye refractive power measuring device comprising a photoelectric conversion element for detecting the imaging position of a light beam, characterized in that a part of the projection chart or the projection optical system is movable along the optical path. Device. 2. The photoelectric conversion element is arranged at a position substantially conjugate to the fundus of an emmetropic silver eye, and the projection chart is moved to a position substantially conjugate to the fundus of the subject for measurement. The eye refractive power measuring device described in Section 1.