JPS6017335A - Auto-lens meter - Google Patents

Abstract

PURPOSE:To measure the refractive index, axial angle and prism quantity of a lens to be tested without using a servo means or a rotary sector by processing signals on image sensors arranged on the focal surface of an image forming lens. CONSTITUTION:The lens 6 to be tested is set up on a nose piece 5 and four LEDs a-d are successively turned on by indications from a computer. Light rays from the LEDs form the optical image of a target 3 on positions A-D of two intersected image sensors 9 by an objective lens 2 through a colimate lens 4, the lens 6 to be tested and an image formation lens 7. The coordinate positions are detected by the computer and the spherical refractive index S, cylindrical surface refractive index, axial angle and prism quantity are calculated on the basis of the calculating formula and displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an auto lens meter that automatically measures power and prism elements.

B. Prior art A conventional lens meter has a collimator consisting of a collimating lens and a movable target, and coaxially with this collimator is a test lens, an objective lens for focus detection, and an imaging state at a predetermined position. A focusing plate and an eyepiece lens are provided to observe the target, and the target position is determined by moving the target in the optical axis direction relative to the collimating lens to obtain the best imaging condition on the focusing plate. The lens is read to determine the power of the lens to be tested.

In the case of a manual method, the best image position is determined by visual inspection by the measurer, which causes individual differences and has drawbacks such as the time required for measurement.

In the case of an automatic type, it is necessary to provide means for detecting the best image position and a servo mechanism for moving the target, making the structure complicated and expensive. Some automatic methods do not have a means for detecting the best image position or a servo mechanism, but this method uses a rotating sector to adjust the deflection of the measurement light due to the refractive power of the lens under test. This method detects the misalignment and calculates the refractive power of the lens through arithmetic processing, but this also requires a sector with a complicated shape and a mechanism for rotating it, which is also expensive.

OBJECT OF THE INVENTION In order to eliminate the above-mentioned drawbacks, the present invention aims to improve the image quality of a lens to be tested by processing signals on an image sensor placed on the focal plane of an imaging lens without using a sabot machine (or a rotary sector). This invention relates to an automatic lens meter that measures refractive power, axial angle, and prism angle.

20 Examples of the configuration of the invention The present invention will be explained in detail below with reference to the drawings.

FIG. 1 shows an optical system for explaining the present invention in detail, (1)
is a light emitting diode such as an LED, and the objective lens (2
) are arranged perpendicularly to the optical axis, as shown in FIG. (3) is a target plate with orthogonal slits.

The objective lens (2) and the collimating lens (4)
The slit is fixedly or movably arranged near the focal point of the slit, and the shape of the slit is as shown in Figures 3a and 3b. (5) is a nose piece on which the test lens (6) is placed, and is distributed near the focal point of the collimating lens (4) and the imaging lens (7). (8) is a half prism, and (9) is opposite to the optical axis. A target image is projected onto the image sensor as shown in FIG.

Kugera L-(3) is individually illuminated with one LED;
When there is no test lens or when the OD test lens is placed on the nosepiece (5), the LED, a,
The image sensor (
9) The target images formed above all overlap as shown in Figure 5.

When the test lens (6) has only spherical refractive power,
The position of the target image formed on the image sensor (9) is determined by the distance corresponding to the spherical refractive power of the test lens (6), as shown in Figures 2a to 3d. move on.

As is clear from the figure, the movement of the target image due to the spherical refractive power is equal to the direction of incidence of the LED light.

That is, the target images of LEDs a and c move only in the X-axis direction, and the target images of LEDs b and a move only in the Y-axis direction.

Here, the movement of the target image on the image sensor is out of focus due to the fact that the test lens is set within the optical axis, but since the incident light beam is narrow, the target image is slightly out of focus.

When the test lens (6) has only cylindrical refractive power,
The light rays incident on the cylindrical lens have refractive power acting in a direction perpendicular to (or in the same direction as) the principal axis, creating a target image on the image sensor as shown in Figures 7a to 7d. Cylindrical refraction power can be calculated from the amount of movement of the target image.

If the lens to be tested (6) has both spherical refractive power and cylindrical refractive power, the target image is formed by moving on the image sensor (9) by an amount corresponding to each refractive power value. The positional relationship ld' of images formed on the image sensor by each of one LED, a, b, c, and d, is expressed as XY coordinates in the figure. By the way, A', B
', d, r1' indicate the position according to the cylindrical refractive power, and from this position A', (IE' are in the X-axis direction, B/, DI are in the Y-axis direction,
A position shifted by one spherical power of this lens in the axial direction becomes the center of the target image formed by LEDs a, b, c, and d and on the image sensor. That is, 5. These are the positions of A, B, O, and D, and this position information is taken out as a signal. The intersection of the extension line of A' in the X-axis direction and the extension line of C' in the Y-axis direction is P, the intersection of the extension line of B' in the X-axis direction and the extension line of D' in the Y-axis direction is Q, A
The intersection of the extended line in the X-axis direction of and the extended line in the Y-axis direction of C is 〆, the intersection of the extended line in the X-axis direction of B and the extended line in the Y-axis direction of D is Q', and 49 minutes A' P is x, C2F is Af/, B'
If Q is Ax, DI Q is F, AP' total x, Dd is 15, and the spherical power is 8, then △A' d P and ΔB'I/Q are similar, so x=X-F3 V = Y-8, Ωhi shell = Yu υ- and 9, AF Y-8 spherical power 8 becomes t.

Here, X, Y, Ajc, and Ay are all signals that can be extracted from the image sensor.

Ha Ha The cylindrical frequency is the sum of the line segments A/c/ and B/D/.

Therefore, the spherical refractive power CYL is CY　L-r-stone/Tenbutsu t'' + As It's summer.

Since the axis angle has a value of <A'C'P or <, B' m Q, the axis angle 0 becomes θ=tan-Xfu or jan.

The amount of prism is the amount of movement from the origin, and therefore, the coordinates of the center of this lens to be tested can be determined from the coordinates of the measured points A, B, C, and D, and the distance from the origin can be determined. Now q
The coordinates of the point are A(XA, YA).

13 (XB, YB), C (XC, YC), D (X
D, YD) Torto, its center coordinates are.

becomes. Therefore, prism eating △ is becomes.

FIG. 7 is a block diagram of the electrical system according to the present invention, and QO is the LE for sequentially lighting up the number of light sources.
D driver, 01) is a drive circuit that captures the signal on the image sensor, 02 is a clock counter, 0 is a clock generation circuit, and α chrysanthemum is a peak that holds the peak voltage of the signal sent from 01). Hold circuit, αQ
OQ is a comparator that outputs a strobe signal by comparing the voltage between the signal from the drive circuit and the signal converted to the peak voltage 7 through the peak circuit α comparator σ force. power converter,
(19H/, converter.

FIG. 70 shows waveforms showing a state in which the target image is formed on the image sensor.

With the above configuration, the lens to be tested (6)
When set on the nosepiece (5), the LED driver 00 operates according to instructions from the computer αη, and one LED a, ' b, c, d 7)E
ll (I lights up. The light from the LED passes through the objective lens (
2), the optical image of Googet (3) is formed on two orthogonal image sensors (9) via a collimating lens (4), a test lens (6), and an imaging lens (7). , the signals are transmitted to the two drive circuits 01). The signal from the drive circuit On is transmitted to the comparator αO and the peak hold circuit 04. The peak voltage detected by the peak hold circuit is 1/
The signal is converted into a digital signal by the converter and then input to the computer.

The digital signal of the peak voltage outputted by αη is converted into a direct voltage signal of the peak voltage by the converter (11) and input to the comparator α sieve. This signal and the signal directly input to the comparator αG The strobe signal is output by comparing the peak voltage i with the signal from the image sensor input a cycle ago.
The signal enters the launch Q, and at that time, the positions of the bright and dark edges can be read from the waveform shown in FIG. The waveform in FIG. 1O is information from the target (3) shown in FIG. 3a, and the intermediate value of the waveforms from two orthogonal image sensors becomes the coordinate position to be detected.

The computer a71 detects this coordinate position, calculates the spherical pressure contact degree, cylindrical refraction degree, axial angle, and prism amount based on the above-mentioned calculation formula, and displays the values digitally.

E.2 Effects of the Invention As is clear from the above description, the present invention has no mechanically driven parts, so the structure is simple and there is less risk of failure.

[Brief explanation of drawings]

FIG. 1 is an optical system layout diagram explaining the details of this invention, and FIG.
The figure is a layout diagram of the LED, Figure 3 is a plan view showing the target plate, Figures 1 to 7 are layout diagrams showing the state in which the target image is formed on the image sensor, and Figure g is the layout diagram showing the state in which the target image is formed on the image sensor. XY coordinates indicating the state in which the target image is formed;
Figure 2 is a block diagram, and Figure 70 is a waveform showing a signal from the image sensor. (1)...LED (3)...Target plate (6)...Test lens (9)...Image sensor 00...LED driver (c)...Counter αυ...Comparator 0O...Latch αη...Computer patent applicant Nidetsu Co., Ltd.

Claims (1)

[Claims] A point light source perpendicular to the optical axis, a slit-shaped target illuminated through an objective lens with a transparent part orthogonal to it, a collimating lens that images the point light source on the tip of the nose pin, and an imaging lens. 2 perpendicular to the focal point
An image sensor is installed, and the null image formed on the image sensor by each of the point light sources generated by the refractive power of the test lens inserted between the collimating lens and the imaging lens is deflected and deflected. An automatic lens meter configured to measure the refractive power (spherical surface, cylindrical surface), axial angle, and prism axis of a test lens from the axial direction.