JPS5964022A - Method and apparatus for measuring refractivity - 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 a refractive power measuring method and a measuring device, and more particularly to one that can automatically measure refractive power without having any moving parts.

Conventionally, most of the lens meters and keratometers on the market manually measure the refractive power, which is time-consuming and complicated.

On the other hand, automatic lensmeters (2) and automatic keratometers that automatically perform measurements are known, but these have moving parts and have problems such as complexity and durability of the devices.

SUMMARY OF THE INVENTION In view of the above-mentioned points, an object of the present invention is to provide a novel refractive power measuring method and measuring device that perform measurements automatically and without any moving parts.

In order to achieve this, in the present invention, at least three beams of energy are irradiated to different positions of the element to be measured, and the energy beam that has passed through the element to be measured is directed to a two-dimensional position provided at a predetermined position in the optical axis direction. Align the element to be measured so that the sum of the deflection vectors on the detection element is zero,
An embodiment of the present invention will be described below, in which the degree of refraction in each radial direction is calculated from the vector component of the deflection vector in a predetermined radial direction. cormorant.

In FIG. 1, 1 person, 1B, and 1C are three light sources such as LEDs, which are turned on in sequence.

The diaphragm plate 2 has optical axes (
3) After being refracted by the three holes 2A, 2B, and 2C on the circumference centered on the point 2A, 2B, and 2C to be tested, the light enters the two-dimensional optical position detection element 4. The detection element 4 may be a single element such as a semiconductor device detector that outputs an analog signal, or may be an array element such as a CCD.

One light source, IB, and IC are equidistant from the optical axis 8, and the feet placed from the light source to the optical axis make an angle of 120° to each other.

The two holes 2B and 2C in the aperture plate 2 have a similar relationship, so the three light beams are parallel to each other and parallel to the optical axis 8. Here, when there is no test lens 3, the beam reaches points 4A, 4B, and 4G on the detection element 4.

When the test lens 3 enters, the beam is refracted to a point 48'.

Comes to 4B/, 4C/. Now, each point 4A, 4B,
The deviation vectors A, B, and C from 4G to points 4muf and 4BZ 4CI after refraction are the refractive power of the test lens 3, that is, the spherical power, astigmatic power, astigmatic angle, and the center of the test lens from the optical axis 8. Provides positional information regarding the deviation. Here, the angle at which the light beam is refracted by the test lens 5 is proportional to the refractive power of the test lens and the distance between the barrel beam and the lens center 0 when considered from a paraxial (4) perspective. Vector A, B, C
The size of is proportional to not only this angle but also the distance between the lens 5 to be tested and the detection element 4.

Note that if the lens surface is approximated as a paraboloid of revolution, the 2
The degree of convergence and divergence in the direction connecting two points of a beam incident on a point is independent of the incident position if the interval between the two points is constant. This allows alignment to be performed using three deviation vectors A
, B, C is expressed as zero.

In other words, one direction component of three vectors Ic, Y
The direction components should both be zep.

Mu, + Bx+ Cx= O(1) Mu, + BY+CY= O(2) Here, AI, Bx, CX are vectorum, B, C(7)
! The components, Moore, BY, CY are the Y components of the vector combs, B, and C.

By performing the alignment as shown in and, the next refractive power measurement can be made accurately. In addition, if the test lens 3 has a prism effect or if the lens is eccentrically used to intentionally produce a prism effect (5), the value on the left side of equations (1) and (2) gives the prism power at that position. .

Now, the lens to be tested generally has astigmatism, but if you calculate the refractive power in each radial direction and at least the refractive power in the triode direction for the stone, you will be able to overcome this problem.

That is, if 0 is the angle in the circumferential direction from the reference radial direction, the corresponding refractive power is expressed as a function of 0 as D(θ)=α5in2(θ+β)+γ (5).

Here, α, β, and γ are constants, and are respectively the degree of astigmatism, the angle of astigmatism,
Represents spherical power. In Figure 1, assuming that the lens surface of the lens to be tested 3 approximates a paraboloid of revolution, and using the approximate formula for Snell's law regarding refraction, we can see that after refraction of a beam that shines on two points on the lens at regular intervals, The degree of deviation is the same between any two points parallel to the direction connecting the two points.

Therefore, the refractive power in the radial direction parallel to the SB direction of the tested lens is DAB, and the refractive power in the radial direction parallel to the 3Ij5C direction and (6) 3C3 direction is respectively DBOI.
DOh, each refractive power is the corresponding vectorum,
It is expressed as the sum of the corresponding radial components of B and C. Sukawachi, D, 3=A□B +BBA (4)”B
O:B +C(5) BOCB "OA" COA 10m. (t5) Here, A□3 represents the magnitude of the 3M 3B direction component of the vectorum, and is positive when going from 3 people to 5B, and negative when going from 3B to 3M. This also applies to other codes.

Each refractive power D□ in the two radial directions determined by the above three formulas]
By substituting ``al''BOIDOA into equation (3), the degree of astigmatism α, the angle of astigmatism β, and the spherical power γ can be determined using simultaneous equations.

By the way, 3A, 3B! If iC is a point every 120° on the circumference, and the radial direction of the surface parallel to the 3B direction is the reference radial direction, the following is obtained.

DAB"MUAB+BBA=""2β+γDBO""B
O+COB ”α5in2 (120°+β)+γ(7) DoA=CoA+AAo=α5in2(240°+β)
A known automatic calculation means is used to substitute equations (4) to (6) into equation (3) and solve the simultaneous equations to obtain the unknowns α, β, and γ.

By the way, when a position detector that outputs an analog signal is used as the two-dimensional optical position detection element 4, three beams must be sequentially incident on the lens to be tested in order to detect the position irradiated by each beam.

This is because if the position detector is irradiated with a plurality of beams at the same time, the irradiation position cannot be determined, but only the averaged irradiation position can be determined.

However, if a play type element such as a COD is used as the detection element 4, it is possible to irradiate three beams at the same time, and in this case, one light source is sufficient instead of three.

Next, FIG. 2 shows a first embodiment of the refractometer according to the present invention.

11, IB, and IC are three light sources. Although IB and 1C appear to overlap on the paper, they are located symmetrically with respect to (8) on the paper as in FIG. 1.

The diaphragm plate 5 has an aperture on the optical axis 8, and the light emitted from the aperture enters the input lens 6 as a narrow beam, and thus enters the lens 3 to be examined as a parallel beam of light. Thereafter, the light is refracted by the lens 3 to be tested, passes through the light receiving lens 7, and reaches the two-dimensional optical position detection element 4.

In FIG. 2, the broken line indicates the optical path of the light beam when there is no lens 3 to be tested.

Since the detection element 4 is provided at the back focal position of the light-receiving lens 7, the magnitude of the deviation vector is constant on the focal plane, regardless of the position on the optical axis of the lens 3 to be tested, and the refractive power is stabilized. detected.

As described above, the light sources 1M, IB, and 1G are turned on sequentially, and the alignment is performed by detecting the axis deviation of the lens 3 to be tested using the vectors A, B, and C using equations (1) and (2).
The degree of refraction in each radial direction can be measured using equations 3) to (6).

FIG. 3 shows a second embodiment of the present invention, which is applied to an automatic keratometer for measuring the refractive power of the cornea of an eye to be examined.

The light emitted from one light source passes through the hole 2A of the diaphragm plate 2 shown in FIG. The reflected light from the cornea C enters the light-receiving lens 9m, is reflected by the mirror 10A, and then reaches the two-dimensional optical position detection element 4 provided at the rear focal position of the light-receiving lens 9m.

Here, the reflection angle varies depending on the corneal curvature, and the light beam position on the detection element 4 varies accordingly. The detection element 4 is provided at the rear focal position of the light receiving lens 9, and the aperture plate 2. Since the light coming from the lens is parallel to the optical axis 8, the reflection angle remains constant even if the cornea C moves on the optical axis.

Corneal astigmatism can be determined by calculating from the deviation vector.
This is the same as described in the previous embodiment. The light receiving lens and mirror are arranged in three radial directions as shown in Figure 5.
Dimensionally arranged light receiving lenses 9mm, 9B, 9C are mirrors 10mm, 10B, respectively.

2 which appears in pairs with 10C and is provided at a predetermined position in the optical axis direction.
A light beam is directed toward the dimensional optical position detection element 4.

Figure 6 is the third fruit (10) of the measuring device according to the present invention. This example is applied to an automatic eye refractometer.

The light emitted from one light source goes through lens 16, aperture 11, and lens 1.
5, is reflected by the peripheral reflection part of the perforated mirror 12,
The light passes through the objective lens 15 parallel to the optical axis 8, enters from the periphery of the pupil Kp of the eye E, and reaches the fundus Er, as shown in FIG.

The light reflected from the fundus Br is at the center of the pupil Kp 1! ! 2 through the hole in the perforated mirror 12 and through the lens 14.
This leads to the dimensional optical position detection element 4.

There, there is one light source, 1B, 1C, perforated mirror 12, and pupil E.
p is optically conjugate; on the other hand, the diaphragm 11 and the objective lens 1
The right focal position of No. 5, the fundus 11ir of the emmetropic eye, and the detection element 4 are optically conjugate. That is, the detection element 4 is provided at a position conjugate with the right focal position of the objective lens 15. If the eye to be examined is emmetropic, the incident light reaches the optical axis at the fundus, and the reflected light returns along the optical axis 8 and reaches the center of the detection element 4.

If the eye to be examined is an ametropic eye, the light is reflected in a direction inclined to the optical axis 8, as shown by the solid line in the figure, and reaches a point away from the center of the detection element 4.

(11) The deviation of the irradiation position on the detection element 4 is defined as the light source iA.

By calculating in the three radial directions corresponding to 1B and 1C, alignment is performed as described above, and the eye E
Find the eye refractive power.

In this embodiment, the light flux is taken out from the pupil center EO, but it may be taken out from the pupil center symmetry point of the incident point. In that case, the perforated mirror 12 needs to be provided with three light transmitting parts.

As described above, according to the present invention, there are no moving parts at all,
Furthermore, automatic refractive power measurement is possible using the electrical output from the detection element. Note that in the present invention, the measurement directions are not limited to three directions, and it is expected that the measurement accuracy will be improved by using more information.

Further, in the above embodiment, a visible light beam was described, but the beam is not limited to this, and general energy beams such as ultraviolet light, infrared light, and electron beams can be used. For example, it is also possible to measure the refractive power of an electron lens. .

[Brief explanation of the drawing]

(12) Figure 1 is a detailed explanatory diagram of the present invention, Figure 2 is a diagram of the first embodiment of the refractometer according to the present invention, and Figure 3 is the second embodiment, applied to an automatic keratometer. Figure 4 is a diagram of the aperture plate, Figure 5 is a spatial layout diagram viewed from the optical axis direction, and Figure 6 is a diagram of the diaphragm plate.
A diagram of the third embodiment applied to an automatic refractometer. Figure 7 is an explanatory diagram of the beam irradiation position on the eye to be examined viewed from the optical axis direction. In the diagram, IA, 1B, 1C... light source 2... aperture Diameter plates 2A, 2B, 2G...Aperture 3...Test lens 4...Two-dimensional optical position detection element 5...Aperture plate 6...Incoming lens 7.9mm, 9B, 9G... ...Light receiving lens (13) 10A 10B 10C...(Two 12...Perforated mirror 15...Objective lens applicant Canon Co., Ltd. (14) Mar 135-d

Claims (1)

[Claims] A step of receiving the energy beam that has passed through the element on a two-dimensional position detection element, and performing shear alignment when the sum of the deflection vectors is zep; A refractive power measuring method comprising the step of calculating the refractive power in each radial direction as well as the vector component. A refractive power measuring method according to claim 1. & Means for irradiating at least three parallel energy beams onto the element to be measured, and a light receiving lens that receives the energy beams that have passed through the element to be measured, (1) installed at the rear focal position of the light receiving lens or at its conjugate position A refraction measuring device comprising: two-dimensional position detection means; and means for calculating a refraction degree in each radial direction from a vector component of a deviation vector in a predetermined radial direction. 4. A refractive power measuring device according to claim 3, which measures the refractive power of a lens to be tested. 5. Stone for measuring the refractive power of the cornea of the eye to be examined Patent Claim No. 3
Refractometer as described in Section 1. 6. The refractive power measuring device according to claim 3, which measures the refractive power of an eye to be examined.