JPH0778419B2 - Optical sphere meter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical sphere meter for measuring the radius of curvature of a spherical surface.

[0002]

2. Description of the Related Art As an optical sphere meter for accurately measuring the radius of curvature of a spherical surface such as a Newton gauge having a relatively large spherical radius of curvature, for example, one shown in FIG. 6 is known. That is, the light beam from the light source 1 is applied to the measured spherical surface 5 to be measured through the slit 2, the semitransparent mirror 3, and the objective lens 4. Two light paths are formed, and these light paths are arranged at a constant angle. When the spherical surface 5 is arranged in the vicinity of the intersection of the two optical paths, the reflected light reflected by the spherical surface 5 via each optical path travels backward in the other optical path, respectively, and each is a semi-transmissive mirror. After being reflected by 3, the mirror 6 and the semi-transmissive mirror 7 collect them on the same optical axis passing through the eyepiece 8. Then, by adjusting the optical system so that the images of the two slits 2 are formed at the same position, it is possible to confirm that the intersection of both incident lights exists on the measured spherical surface. Next, as shown by the broken line in FIG. 6, the spherical surface 5 is moved forward, and the optical system is adjusted so that the images of the two slits 2 are formed at the same location as described above. Thereby, the intersection of the two incident light rays can be made to coincide with the center of curvature of the measured spherical surface 5. At this time, the reflected light of each incident ray travels backward in its own optical path. The radius of curvature R of the spherical surface 5 can be read by the above-mentioned movement distance on the bench.

[0003]

However, in the above-mentioned conventional optical sphere meter, as shown in FIG. 7, for example, in the case of the convex spherical surface 5A, it is moved forward by the radius of curvature R from the intersection point position of two incident light rays. Needed, and also concave spherical surface 5B
In the case of, it is necessary to move backward from the intersection position of the two incident rays by the radius of curvature R. Therefore, for example, to measure the radius of curvature of a convex Newton gauge having a radius of curvature of 2 m,
A bench with a measuring range of 2 m is required, and a bench with a length of 4 m is required to measure both Newton gauges of unevenness. As described above, the conventional optical sphere meter has a problem that the bench length required to measure a curved surface having a large radius of curvature becomes extremely long.

The present invention has been made in order to solve the above-mentioned conventional problems. Even when measuring a spherical surface having a large radius of curvature, the bench length can be greatly shortened as compared with the conventional one. It is an object of the present invention to provide an optical sphere meter that can be manufactured and can be downsized as a whole.

[0005]

An optical sphere meter according to the present invention irradiates a light beam from a light source onto a measured spherical surface through a semi-transmissive reflecting means, and at the same time transmits a light beam reflected from the measured spherical surface to the semi-transmissive surface. In an optical sphere meter provided with an optical system for forming an image on an image forming section via a reflecting means, at least a part of the light beam is arranged in an optical path from the light source to the measured spherical surface via at least two reflecting means. the two or more reflecting means with diverting moved relative to the other optical elements Te with an optical path bypassing means for varying the bypass length, the light
A path detouring means is a semi-transmissive optical means arranged in the optical path.
And is separated from the optical path by this semi-transmissive optical means.
Part of the rays are reflected at an angle of 90 °,
Three reflecting means for returning to the transparent mirror, and the three reflecting hands
Two adjacent reflecting means of the step and another reflecting hand
Variable means for varying the distance between the step and the semi-transparent mirror.
And characterized in that equipped.

[0006]

According to the present invention, the optical path detouring means is arranged in the optical path from the light source to the spherical surface to be measured, and at least two reflecting means constituting the optical path detouring means are arranged relatively to other optical elements. Since it is moved, the optical path length in the optical path detouring means can be largely changed with respect to the moving amount of the reflecting means. That is, according to the present invention, the optical path length of the entire optical system can be greatly changed with a small amount of adjustment, so that even when measuring a spherical surface having a large radius of curvature, the amount of adjustment itself is shortened to, for example, about 1/2. can do. As a result, the length of the bench can be significantly shortened compared to the conventional one.

Further, the optical path detouring means reflects the semi-transmissive optical means arranged in the optical path and a part of the light rays separated from the optical path by the semi-transmissive optical means at an angle of 90 °. Three reflecting means for returning to the semi-transmissive mirror, variable means for varying a distance between two adjacent reflecting means of the three reflecting means and another reflecting means and the semi-transmissive mirror. According to the above configuration, a part of the light rays separated by the semi-transmissive optical means is condensed at the first focus position without passing through the detour length, and the remaining light rays separated by the semi-transmissive optical means have a detour length. The light is focused at a second focus position before the first position. For this reason,
By disposing the measured spherical surface at either one of the positions, it is possible to measure the radius of curvature with almost no movement of the measured spherical surface. In this case, even if the radius of curvature of the measured spherical surface is very large, there is an advantage that a bench having a short length is sufficient.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing a first embodiment in which the present invention is applied to a one-source type optical sphere meter. That is, the light beam from the light source 11 is incident on the prism 15 as the semi-transmissive optical means through the slit 12, the prism 13 as the semi-transmissive reflection means, and the objective lens 14. A first reflecting mirror 16 is arranged at a position opposite to the objective lens 14 with respect to the prism 15. Second and third reflecting mirrors 17 and 18 are arranged at positions facing the prism 15 and the first reflecting mirror 16. The prism 15 and the reflecting mirrors 16 to 18 compose an optical path diverting means 20. The prism 15 and the reflecting mirrors 16 to 18 are mutually arranged so that the traveling direction of the incident light is sequentially changed by 90 ° so that the incident light goes around and is returned to the prism 15. They are arranged annularly at an angle of °.
The reflecting mirrors 17 and 18 are arranged in the prism 15 by the variable means 19.
Also, it is movable in the x direction in the figure with respect to the reflecting mirror 16. The light beam reflected by the prism 15 and the prism 15 are transmitted through the prism 15 and are reflected by the reflecting mirrors 16 to 18.
The rays that have passed through 5 again are condensed on the measured optical axis L, respectively. On the optical axis L to be measured, a convex mirror 21 as a spherical surface to be measured is movably held by a position adjusting mechanism (not shown). On the other hand, the light ray reflected on the surface of the convex mirror 21 reaches the prism 13 by following the path opposite to the above, is reflected by the prism 13, and is visually recognized through the slit 23 and the eyepiece lens 22. The prisms 13 and 15 may be semi-transparent mirrors, and the reflecting mirrors 16 to 18 may be corner cubes or reflecting prisms.

2 and 3 are views for explaining the operation of the present embodiment. FIG. 2 shows the case where the convex mirror 21 is measured.
Shows the case where the concave mirror 23 is measured. In FIG. 2, when the reflecting mirrors 17 and 18 are located at points E ′ and F ′, respectively, part of the light that has entered the optical path detouring means 20 from the light source 11 is reflected by the prism 15 and point A in the figure. The remaining light passes through the prism 15 and is collected at the point B ′ in the figure via the detour of the optical path detouring means 20. At this time,

[0010]

[Equation 1] CA = CDE'F'CB '

The following relationship holds. When the reflecting mirrors 17 and 18 are moved by the variable means 19 to the positions of the points E and F by the distance x, the image forming point B ′ on the measured optical axis L moves to the point B,

[0012]

[Formula 2] CA = CDEFCB

[0013] here,

[0014]

## EQU00003 ## DE = DE'-x FC = FC'-x CDE'F'CB '= CDEFCB

Therefore, BB '= 2x. That is, in this optical sphere meter, the focal position of the light beam passing through the detour route can be calculated by simply moving the reflecting mirrors 17 and 18 by the distance x.
It is possible to move the distance 2x, which is twice that. At the time of measurement, first, the convex mirror 21 is moved from the point A side to the point B side while visually recognizing the slit image through the eyepiece lens 22. When the convex mirror 21 moves from the first focus position A to a position before the radius of curvature R, one slit image is formed. Next, the reflecting mirrors 17 and 18 are moved to set the second focus position to the B ′ point. To move to point B. When the second focus position moves to the point B position, another slit image is formed. At this time, the radius of curvature R can be obtained from the following Expression 4.

[0016]

[Equation 4]

According to this embodiment, since it is not necessary to move the convex mirror 21 to the center of curvature position A, the length of the bench for movably holding the convex mirror 21 is much shorter than the radius of curvature R of the convex mirror 21. Therefore, there is an advantage that the optical sphere meter can be significantly downsized. When measuring the concave mirror 23, as shown in FIG.
The concave mirror 2 may be arranged at the focal position A and the same measurement may be performed. In this case, if the focus position A is fixed and it is necessary to measure both the concave and convex surfaces, it is necessary to arrange the convex mirror at the second focal position and the concave mirror at the first focal position. A bench having a radius of curvature R is required. Therefore, if the position of the focus A can be changed by a method such as exchanging the objective lens or using a zoom lens, it is possible to measure both the concave and convex surfaces on a short bench.

FIGS. 4 and 5 show a second embodiment in which the present invention is applied to a two-light source type optical sphere meter effective for highly accurate measurement when the radius of curvature to be measured is very large. FIG. 4 is a front view and FIG. 5 is a plan view. Light source 31
The light beam from the light enters the prisms 35a and 35b as the semi-transmissive reflection means through the right-angle prisms 32a and 32b, the condenser lenses 33a and 33b, and the slits 34a and 34b. The light rays that have respectively passed through the prisms 35a and 35b pass through the reflecting prisms 36a and 36b, and are applied to the convex mirror 40 as the measured spherical surface through the objective lenses 37a and 37b, the reflecting mirrors 38a and 38b, and the optical path detouring means 39. . The light reflected by the convex mirror 40 follows the opposite path to the prisms 35a, 35b, and is reflected here and is observed by the prism 41, the prism 42 as the semi-transmissive combining means, and the eyepiece lens 43. In addition,
The right angle prisms 32a and 32b are mirrors and a prism 35.
A and 35b may be semi-transparent mirrors, prism 41 may be a mirror, and prism 42 may be a semi-transparent mirror.

The optical path detouring means 39, as shown in FIG.
A prism 51 as semi-transmissive optical means and three reflecting mirrors 5
2, 53 and 54 are arranged so that the optical path makes one round, and the reflecting mirrors 53 and 54 move relative to other optical elements. Also in this embodiment, the same effect as described above can be obtained. In addition, in the above-mentioned embodiment, the detour that the optical path makes one round is formed as the optical path detouring means, but the detour that exceeds the optical path by two rounds or more may be formed. Further, as described above, as the semi-transmissive optical means cited as an example of the optical path detouring means, a semi-transparent mirror may be used in addition to the prism, and the reflecting means may be a so-called corner cube or a reflecting prism of an optical system. May be used.

[0020]

As described above, according to the present invention, the optical path detouring means is arranged in the optical path from the light source to the spherical surface to be measured, and at least two reflecting means constituting the optical path detouring means are provided in another optical path. Since the optical element is moved relative to the optical element, the optical path length of the optical system can be changed at least twice with respect to the small relative movement amount of the reflecting means. Therefore, even when measuring a spherical surface having a large radius of curvature, the length of the bench can be significantly shortened compared to the conventional case. By using a semitransparent prism (or a semitransparent mirror) at the entrance of the optical path detouring means, the objective lens 14 → prism 15 → optical path of point A and the objective lens 14 → prism 15 → reflecting mirror 16 → reflecting mirror 17 → reflection Since the optical path from the mirror 18 to the focal point B is taken, there is a great effect that it is possible to perform the measurement without moving the measured spherical surface on the bench.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an optical sphere meter according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining an operation when a convex mirror is measured by the spherical meter.

FIG. 3 is a diagram for explaining an operation when a concave mirror is measured by the spherical meter.

FIG. 4 is a side view of an optical sphere meter according to a second embodiment of the present invention.

FIG. 5 is a plan view of the same optical sphere meter.

FIG. 6 is a diagram showing a configuration of a conventional optical sphere meter.

FIG. 7 is a diagram for explaining a bench movement distance when measuring a concave mirror and a convex mirror with a conventional optical sphere meter.

[Explanation of symbols]

1, 11, 31 ... Light source, 2, 12, 34a, 34b ... Pickle, 19 ... Variable means, 20, 39 ... Optical path detouring means.

Claims (1)

[Claims] 1. An optical system which irradiates a light beam from a light source onto a spherical surface to be measured through a semi-transmissive reflecting means and forms an image of a light beam reflected from the measured spherical surface onto an image forming portion via the semi-transmissive reflecting means. In an optical sphere meter including a system, at least a part of the light beam is arranged in an optical path from the light source to the measured spherical surface, and at least a part of the light beam is diverted through at least two reflecting means, and at least two reflecting means are provided by another optical means. An optical path detouring unit that moves the detour length relative to the element to change the detouring length is provided , and the optical path detouring unit is a semi-transmissive light beam disposed in the optical path.
And Manabu means one which is separated from the optical path by the semitransparent optical means
The semi-transparent mirror by reflecting the light rays of each part at an angle of 90 °
And three adjoining reflecting means of the three reflecting means.
Variable distance between another semi-transparent mirror and the semi-transparent mirror
Optical spherical meter, characterized in that is obtained by and a varying means for.