JPH0124251B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for automatically measuring various characteristics of an optical system, such as spherical refractive power, cylindrical refractive power, and its axial direction, prismatic refractive power, and its base direction. The principles and embodiments of the present invention described below mainly relate to the measurement of the above-mentioned characteristics of eyeglass lenses, but this invention is applicable to a so-called lens meter that measures the various characteristics of eyeglass lenses. However, the present invention is not meant to be limited to the above, and can also be used to measure the above-mentioned characteristics of lens optical systems widely used in optical instruments.

In recent years, various measurement principles and devices have been proposed for so-called automatic lens meters that automatically measure various optical properties of eyeglass lenses, such as their spherical refractive power, cylindrical refractive power, and their axial directions. . One of them is US Pat. No. 3,880,525. This device based on the U.S. patent makes parallel light incident on the lens to be tested parallel to its optical axis, and attempts to determine the optical characteristics of the lens to be tested from the polarization of the emitted light. , a mask having a point aperture is arranged so that the point aperture is located off the optical axis of the lens to be tested, a detection surface is provided a predetermined distance away from the mask in the optical axis direction, and the detection surface passes through the aperture of the mask. The coordinates of the point where the light flux reaches the detection surface are detected, and the direction and amount of deflection of the light emitted from the test lens are calculated by comparing the detected coordinates with the coordinates of the aperture on the mask. It is configured to know the optical characteristics of the detection lens. In this case, at least three openings in the mask are required to obtain the necessary information.

In the device according to this U.S. patent, it is necessary to accurately detect the point-to-point correspondence between the apertures on the mask and the arrival points on the detection surface, and each aperture must be arranged in a planar manner so that the emitted light beam is It must be made to be a non-coplanar light beam. For this purpose, a two-dimensional plane must be scanned, and the apparatus as a whole inevitably becomes expensive. Furthermore, it is necessary to solve five-dimensional simultaneous equations using coordinate information of at least three points, and the calculation mechanism becomes complicated and expensive.

There is an apparatus described in US Pat. No. 4,180,325 that can solve the enormous information processing problem associated with such two-dimensional plane detection. This device intermittently blocks multiple light beams that have passed through the mask aperture using a rotating disk with a special pattern consisting of transparent and opaque areas, and allows each light beam to arrive at the detector at different times. , is configured to eliminate the need to determine the correspondence between the aperture on the mask and the light beam on the detection surface. However, in this device, the pattern on the rotating disk is very complex, and detection of its rotational position is very important. There are major problems in terms of construction and production.

Furthermore, an attempt was made to detect whether the projected light beam transmitted through the circular mask pattern is deformed into an elliptical shape by the test lens, or whether its diameter changes while remaining circular, thereby detecting the refractive characteristics of the test lens. has already been done. For example, U.S. Pat.
No. 4007990 discloses a device that detects the refractive characteristics of a lens to be tested by rotating a projection light beam circularly and detecting changes in its radial position using a sensor that rotates in synchronization with the rotation. There is. However, in this proposed device,
The correspondence between the projected light flux and the sensor is important.
There must be precise synchronization between the rotation of the projection mask and the rotation of the sensor.

The present invention solves these problems in conventional devices, and enables detection with a linear sensor.
It is an object of the present invention to provide a refractive characteristic measuring device of an optical system with a simple configuration of a detection section.

That is, the feature of the present invention is that the light beam from the lens to be inspected is passed through a pattern consisting of a circle and at least one straight line intersecting the circle, and is projected onto a detection surface that is a predetermined distance away from the mask in the optical axis direction. At least 4 of the circular parts of the pattern
The object of the present invention is to detect at least two points, a point and a straight line, and calculate the deviation or deformation of the projected light beam based on the detected data, thereby obtaining the refractive characteristics of the lens to be tested. According to the present invention, there is no need to know which part of the mask the light beam of the detected circular part corresponds to, and the structure of the detection unit is simpler than that of conventional devices.

To explain the principle of the present invention with reference to FIG. 1, the illustrated optical system is provided with a light source L and a collimator lens CL for converting the light from the light source L into a parallel light beam. , the test lens TL is arranged so as to have an optical axis O' outside the optical axis O of the collimator lens CL. and,
Prism amounts P _H and _PV are generated by the deviation amounts E _H and _EV of these two optical axes. The test lens TL has a principal meridian having two different apex refractive powers D ₁ and D ₂ ,
One of them has an angle θ with the Xo coordinate axis of the Xo-Yo coordinate system. Behind the test lens TL, a mask pattern M having a circular opening with a diameter φ and a straight portion is arranged at a distance Δl.

The light flux that has passed through the test lens TL passes through the mask pattern M with the refractive properties of that lens, so the X-Y
On a plane, the circular pattern of the mask pattern M becomes an elliptical image. By arranging the linear sensor S on this XY plane, the coordinates (X ₁ , Y ₁ ) and (X ₄ , Y ₄ ) of the two points of this elliptical image can be detected. Then, by rotating the linear sensor S and placing it at the position S',
Similarly, the coordinates (X ₂ , Y ₂ ) and (X ₃ , Y ₃ ) can be detected. Further, the slope of the linear pattern of the mask pattern M changes, so that (X ₅ , Y ₅ ) and (X ₆ , Y ₆ ) can be detected when located at the positions of the linear sensors S and S'.

A parallel light beam is made incident on the test lens TL, a mask having a circular pattern and a linear pattern with a diameter φ is placed at a position △l away from the test lens in the optical axis direction, and When the detection surface is provided at a distance l shorter than its shortest focal length in the direction, the two apex refractive powers of the test lens are D ₁ and D ₂ , the angle θ of the cylinder axis, the horizontal prism amount P _H , Assuming that the vertical prism amount is P _V , the shape of the projected pattern on the detection plane is expressed by the following equation.

{[1-(d+△d)D ₁ /1-△d・D ₁ ] ² tan ² θ+[
1-(d+△d)・D ₂ /1-△d・D ₂ 〕 ² }(x-d・P
H/100) ² + {[1-(d+△d)・D ₁ /1-△d・D ₁
] ² + [1-(d+△d)・D ₂ /1-△d・D ₂ ] ² tan ² θ
}(y-d・P _V /100) ² 2tanθ{[1-(d+△d)D ₁
/1-△d・D ₁ ] ² −[1-(d+△d)D ₂ /1-△d・D ₂ ] ² }(x-d
P _H /100) (y-dP _V /100) -(1+tan ² θ) [1-(d+△d)・D ₁ /1-△d
・D ₁ ] ² [1-(d+△d)・D ₂ /1-△d・D ₂ ] ²・(
φ/2) ² = 0...(1) Also, the relationship between the slope a of the straight line part of the mask pattern M on the mask surface (a value determined by design) and the slope a' of the projected image on the measurement plane X-Y is as follows. It is expressed by the formula.

{1-(d+△d)D ₁ /1-△d・D ₁・a-1-(d+
△d)・D ₂ /1−△d・D ₂・a′}tan ² θ + [1−(d+△d)・D ₁ /1−△d・D ₁ −1−(d
+△d)・D ₂ /1−△d・D ₂ ] (1−a・a′)tanθ +[1−(d+△d)・D ₂ /1−△d・D ₂ a′−1−
(d+△d)・D ₁ /1−△d・D ₁ a]=0……(2) Therefore, the four measured values of the circular pattern (X ₁ , Y ₁ ), ( X ₂ , Y ₂ ), (X ₃ , Y ₃ ), (X ₄ , Y ₄ )
Substituting , further, in equation (2), it is obtained from the slope a of the linear pattern on the mask surface and the measured values (X ₅ , Y ₅ ), (X ₆ , Y ₆ ) of the linear pattern on the measurement plane X-Y. inclination
By substituting a′, the unknown quantities D ₁ , D ₂ , θ, P _V , and P _H can be obtained by solving equations (1) and (2) above. In order to improve measurement accuracy, the four measurements of the circular pattern should not be concentrated on a part of the pattern, but should be taken at positions separated in the circumferential direction, and the linear pattern should intersect with the linear sensor at 45 degrees. Of course, this is preferable. In Figure 1, the center O _P of the projected image of the linear pattern and the center of the X-Y coordinate system of the detection plane where the linear sensor is placed
When O _XY matches, the center of rotation of the linear sensor and the center of the projected image of the linear pattern match,
Since two points on the straight line pattern cannot be detected, the inclination of the straight line pattern cannot be detected. This problem can be solved by using a mask M consisting of two parallel linear patterns 7a, 7b and a circular pattern 6a, as shown in FIG.
That is, a projected image of this mask is shown in FIG.
Even if the center of the image 7a' of the linear pattern 7a coincides with the rotation center of the linear sensors S and S' as shown in FIG. 8, and only the (X ₇ , Y ₇ ) coordinates can be detected,
The projected image 7b' of the linear pattern 7b parallel to this is that the linear sensor is at the position S and the (X ₉ , Y ₉ ) coordinates are
To detect the coordinates (X ₈ , Y ₈ ) at the position S′,
The inclination angle of this straight line pattern image 7b' can be determined.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, in FIG. 2, light from a light source 1 is converted into a parallel beam by a collimator lens 2 and enters a lens 3 to be tested. The test lens 3 is arranged with its optical center shifted by a predetermined distance from the optical axis of the collimator lens 2, and the incident light beam is deflected according to the refractive power of the test lens 3. Immediately after the lens 3 to be tested, a mask 4 having a circular aperture 4a and a straight portion 4b is placed as shown in FIG. 3, and selectively transmits the light beam from the lens 3 to be tested. A linear sensor 5 is arranged within the shortest focal length of the lens 3 to be tested in the optical axis direction, and immediately in front of this linear sensor 5 there are two linear slits 6a and 6b as shown in FIG. A mask 6 is placed. The linear sensor 5 is rotatable around the optical axis and is rotated by a motor 7. During its rotation, the linear sensor 5 detects three points each of the light beams that have passed through the circular aperture 4a and the linear portion 4b of the mask 4 at positions that match the slits 6a and 6b, and provides information on a total of six points. give.
The detection signal from the linear sensor 5 is applied to an arithmetic circuit 9 via an amplifier 8, and a value indicating the refractive power of the lens 3 to be tested obtained through necessary calculations is displayed on a display device 10. In order to clarify the correspondence between the detection by the linear sensor 5 and the slits 6a, 6b, the slits 6a, 6b may be provided separately, and the measurement may be performed by inserting them into the optical path in order.

FIG. 5 shows another embodiment of the present invention,
The linear sensor 5 is placed apart from the mask 4, and between them are relay lenses 11 and 12 for placing the linear sensor 5 equivalently within the shortest focal length of the lens 3 to be tested, as shown by 5'. An image rotator 13 is arranged between the relay lenses 11 and 12 to rotate the projected image around the optical axis. In this example, by placing the image rotator 13 at at least two different rotational positions and performing measurements, it is possible to detect projected images at at least six locations.

FIG. 6 shows still another embodiment of the present invention, in which the light source 1 consists of two light emitting diodes 1a and 1b with different emission wavelengths, and the light from these light emitting diodes 1a and 1b is wavelength-selected. It is directed toward the collimator lens 2 by a half mirror 14a having a characteristic. Further, the optical path between the mask 4 and the linear sensor 5 is divided into two optical paths by a half mirror 15a having wavelength selection characteristics, and further combined by a similar half mirror 16a to reach the linear sensor 5. Relay lenses 11 and 12 are arranged in each of the divided optical paths, and an image rotator 13 is arranged in one of the optical paths to rotate the projected image by different angles around the optical axis. . In this arrangement, by sequentially lighting up the light emitting diodes 1a and 1b, it is possible to perform measurements similar to those in the above embodiment.

[Brief explanation of drawings]

Fig. 1 is a perspective view of an optical system for explaining the principle of the present invention, Fig. 2 is a schematic diagram showing an embodiment of the invention, and Figs. 3 and 4 are used for the embodiment of Fig. 2. FIGS. 5 and 6 are views similar to FIG. 2 showing different embodiments of the present invention, FIG. 7 is a front view of a mask according to another embodiment, and FIG.
The figure is a projected image of the mask shown in FIG. 1...Light source, 3...Test lens, 4, 6...Mask, 5...Linear sensor.

Claims (1)

[Scope of Claims] 1. A light source for projecting a light beam onto a test optical system, a collimator means for converting light from the light source into a parallel light beam, a mask disposed perpendicular to the optical axis of the collimator means, means for arranging a test optical system between the collimator means and the mask; a detection device disposed a predetermined distance apart from the mask in the optical axis direction; and calculating information obtained by the detection device. the mask has a mask pattern that selectively transmits the light beam that has passed through the test optical system, and the mask pattern includes a circle and at least a circle that intersects with the The detection device includes a linear sensor that detects the mask projection pattern in at least two mutually intersecting axes on a plane perpendicular to the optical axis, and A refractive characteristic measuring device for an optical system, wherein the projection image is detected at at least four points on the circular portion and at least two points on the straight line portion, and the detected information is provided to the arithmetic unit. 2. In the above item 1, between the mask and the detection device, there is provided an optical path splitter that splits the light beam from the mask into at least two parts, and an optical path that recombines the split optical path and guides it to the detection device. A refractive characteristic measuring device for an optical system, which is provided with a splitter and an image rotator that rotates a projection pattern around an optical axis on one side of the split optical path. 3. In the above item 2, the optical path splitter is a refractive characteristic measuring device of an optical system having wavelength selection characteristics. 4. A refractive characteristic measuring device for an optical system according to any one of Items 1 to 3, wherein the light source includes at least two light emitting devices with different emission wavelengths and an optical path splitter having wavelength selection characteristics. 5. In any one of the above items 1 to 4, the detection device is an optical system refractive property measuring device having a self-scanning linear sensor fixedly arranged.