JPH06258181A - Eccentricity measuring apparatus - Google Patents

Abstract

PURPOSE:To measure the eccentric states of a plurality of the surfaces of a lens under inspection at the same time. CONSTITUTION:An objective lens 4, which projects luminous flux on a first surface 6a and a second surface 6b of a lens' under inspection, is formed of at least two or more objective lenses 4a and 4b having the same optical axis. The objective lenses 4a and 4b are provided so that the lenses can be moved singly in the direction of the optical axis. In this way, the luminous flux from a light source 1, which is transmitted through a collimate lens 2 and a beam splitter 3, is projected on the first surface 6a and the second surface 6b of the lens under inspection 6 at the same time, respectively, through the objective lenses 4a and 4b. The eccentriciy of the lens under inspection 6 is measured at the same time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eccentricity measuring device for measuring the eccentricity of a lens unit having a spherical or aspherical shape.

[0002]

2. Description of the Related Art Conventionally, as an eccentricity measuring device for measuring the eccentricity of each lens surface during or after assembling a lens to be inspected having many lens surfaces, the one disclosed in Japanese Utility Model Laid-Open No. 1-7541 is known. Has been. FIG. 8 shows the eccentricity measuring device, wherein 51 is a light source, 52 is a condenser lens, 53 is an index, 54 is a semi-transparent mirror, 55 is a collimating lens, 56 is a beam splitter, 57, 58 and 59 are mirrors, and 60 and 61. Is an objective lens, 62 is a two-dimensional sensor, 63 is an A / D converter, 64 is a microcomputer, 65 is a driving unit for the rotary stage, 66 is a holding unit for the rotary stage, and a lens 67 is a rotary stage. It is configured to be held by the holding portion 66.

When the light source 51 is turned on, the light from the light source 51 is condensed by the condenser lens 52 and illuminates the index 53. The light from the illuminated index 53 passes through the semi-transparent mirror 54 and is converted into a parallel light flux by the collimator lens 55,
This parallel light beam is split into two light beams by the beam splitter 56. One of the divided luminous fluxes travels along a path reaching the surface side of the lens 67 to be tested held by the holding unit 66 of the rotary stage, and the objective lens 60 is movably arranged in the optical axis direction on this path. ing.

The other light beam split by the beam splitter 56 is a mirror 5 forming a path forming member.
The objective lens 61 is arranged movably in the optical axis direction along the path formed by 7, 58 and 59 and reaching the back surface of the lens 67 to be inspected. Further, the test lens 67 has a plurality of lens surfaces 67a, 67b, ... 67m from the front surface side to the back surface side.

Next, the operation of the eccentricity measuring device will be described. First, the position of the objective lens 60 is adjusted so that the image of the index 53 is projected on the center of curvature P of the lens surface 67a to be tested. At this time, if the lens surface 67a is not eccentric, the center point P of curvature is located on the optical axis, but is actually displaced from the optical axis due to the eccentricity of the lens. Then, the light reflected by the lens surface 67 a moves backward through the objective lens 60, the beam splitter 56, and the collimator lens 55, and then the semitransparent mirror 5 is reached.
The reflected image P ₁ of the index 53 is imaged on the two-dimensional sensor 62 by being reflected by 4.

Further, by adjusting the position of the objective lens 61 on the optical axis, the image of the index 53 is projected to a position in the immediate vicinity of the center of curvature P, that is, the position where the center of curvature P should originally be located. To do so. At this time, the incident light beam has a lens surface of 67 m.
It is projected on the center of curvature P on the back side of the lens surface 67a by refraction of ˜67b. Then, the reflected light travels in the opposite direction of the incident path and is reflected by the semi-transparent mirror 54 to form a reflected image P ₂ of the index 53 on the two-dimensional sensor 62.

FIG. 9 shows the light receiving surface 62 of the two-dimensional sensor 62.
The reflected images P ₁ and P ₂ formed on a are shown, and in this state, the output of the two-dimensional sensor 62 is digitized by the A / D converter 63 and taken into the microcomputer 64. This data is the coordinate data of the reflection images P ₁ and P ₂ . Then, the holder 66 is rotated by the drive unit 65 of the rotary stage. Along with the rotation, the reflected images P ₁ and P ₂ on the two-dimensional sensor 62 rotate in circles centering on 0 ₁ and 0 ₂ , respectively, as shown in FIG.

The radius of gyration of this circle is proportional to the amount of eccentricity of the lens surface 67a, and its proportional constant is determined by the magnification of the optical system formed by the collimator lens 55 and the objective lens 60 or 61. Further, it is possible to know in which direction the eccentricity is occurring from the direction of the straight line formed by the point 0 ₁ and the reflected image P ₁ .

The microcomputer 64 rotates the lens 67 to be inspected by the rotating stage while reflecting the reflected image P ₁ ,
The coordinate data of P _{2 is taken in,} a predetermined calculation is performed based on the data to calculate the radius gyration, and the eccentricity of the lens surface 67a of the lens 67 to be tested is calculated based on the value.
In this way, the lens surface 67 of the lens 67 to be tested is sequentially
The eccentricity of a, 67b, 67c ... 67m is calculated. Then, the eccentricity amount of each lens surface is obtained as an average value of the eccentricity amount data of the respective front and back surfaces. As described above, the eccentricity state of each surface of the lens 67 to be tested can be measured from both front and back sides.

[0010]

However, in the above-mentioned conventional eccentricity measuring device, each lens surface 6 of the lens 67 to be inspected.
The eccentricity states of 7a, 67b, 67c, ..., 67m must be detected individually for each lens surface, so that there is a problem that it takes a lot of time for the measurement. The present invention has been made in view of the above-mentioned problems of the prior art,
An object of the present invention is to provide an eccentricity measuring device capable of simultaneously measuring eccentricity with respect to a plurality of lens surfaces of a lens to be tested.

[0011]

In order to achieve the above object, the present invention is configured such that an objective lens for projecting light onto a lens under test is divided into at least two objective lenses having the same optical axis, and Each of the divided objective lenses is provided so as to be movable independently in the optical axis direction, and light is simultaneously projected onto the lens surface of the lens to be tested for each objective lens so that the eccentricity of multiple lens surfaces can be measured at the same time. .

FIG. 1 is a block diagram schematically showing an eccentricity measuring apparatus of the present invention. A light source 1, a collimator lens 2 for collimating a light beam from the light source 1, and a light beam from the collimator lens 2 are to be tested. 6, an objective lens 4 for projecting light onto the light source 6, a beam splitter 3 arranged between the collimator lens 2 and the objective lens 4 for converting the light reflected by the lens 6 under test into a path different from the light source 1 side, and the beam splitter 3 The condenser lens 7 that condenses the light whose path has been changed by the detector 7, the detector 8 that detects the center coordinates of the point image P condensed by the condenser lens 7, and the eccentricity of the lens 6 to be detected by the signal of the detector 8 The objective lens 4 is formed by dividing one objective lens by a plane including its optical axis, and is movable independently in the optical axis direction. First surface 6a of
And a second objective lens 4b for projecting a light beam onto the second surface 6b, respectively.

[0013]

According to the above construction, the light from the light source 1 passes through the collimator lens 2 and the beam splitter 3 and enters the first objective lens 4a and the second objective lens 4b.
The first objective lens 4a is moved and arranged in the optical axis direction so that the focal position of the first objective lens 4a coincides with the center of curvature of the first surface 6a of the lens 6 to be inspected, and projects light perpendicularly to the first surface 6a. Meanwhile, the second
Objective lens 4b is moved and arranged so that the focal position thereof coincides with the center of curvature of the second surface 6b of the lens 6 to be inspected.
Light is projected perpendicularly to the surface 6b. First surface 6a, second surface 6b
Each of the reflected lights reflected by the laser light travels backward from the incident light, is reflected by the beam splitter 3 and undergoes optical path conversion, and is condensed by the condenser lens 7 on the detector 8 to form two point images P. The center coordinates of the two point images P are detected by the detection unit 8.

When the lens 6 to be inspected is rotated about a reference axis in such a state, when the lens 6 to be inspected is eccentric with respect to the reference axis, there are two point images P on the detector 8. Rotate with a radius of size. The eccentricity of the first surface 6a and the second surface 6b of the lens 6 to be measured can be obtained by calculating this radius of gyration by the calculation unit 9.

[0015]

First Embodiment FIG. 2 is a schematic diagram showing a first embodiment of the present invention. The eccentricity measuring apparatus of this embodiment includes a light source 1,
A collimating lens 2 for collimating the light flux from the light source 1,
The objective lens 10 that projects the light beam from the collimator lens 2 onto the lens 6 to be inspected, and the light that is arranged between the collimator lens 2 and the objective lens 10 and reflected by the lens 6 to be inspected is on an optical path different from the light source 1 side. A beam splitter 3 for converting, a condensing lens 7 for condensing the light whose path is changed by the beam splitter 3, and a TV for receiving a point image P condensed by the condensing lens 7.
It is composed of a camera 11 and an image processing device 12 that performs image processing based on a signal from the TV camera 11 to calculate the eccentricity of the lens 6 to be inspected.

The objective lens 10 is composed of a first objective lens 10a and a second objective lens 10b which are formed by dividing one objective lens by a plane including its optical axis. The first objective lens 10a includes a first lens frame 13a.
The second objective lens 10b is attached to the second moving stage 14a that is movable in the optical axis direction of the first objective lens 10a via the second lens frame 13b.
Is attached to a second moving stage 14b that is movable in the optical axis direction of the second objective lens 10b via the lens, and any two surfaces of the lens 6 to be inspected (the first objective lens 1 in FIG.
0a is the first surface 6a, and the second objective lens 10b is the second surface 6a.
The light flux from the collimator lens 2 can be projected on each of b). The test lens 6 includes a plurality of lens groups assembled in the lens frame 15,
The outer diameter of the lens frame 15 is pressed against the reference block 16 and is held so as to be rotatable.

Next, the operation of the eccentricity measuring apparatus of this embodiment will be described. The light from the light source 1 passes through the collimator lens 2 and the beam splitter 3, and enters the first objective lens 10a and the second objective lens 10b. First objective lens 1
0a is arranged by moving the first stage 14a in the optical axis direction so that the focal position thereof matches the center of curvature of the first surface 6a of the lens 6 to be inspected, and projects light perpendicularly to the first surface 6a. . On the other hand, the second objective lens 10b is arranged by moving the second moving stage 14b in the optical axis direction so that the focal position of the second objective lens 10b matches the center of curvature of the second surface 6b of the lens 6 to be inspected. Light is projected perpendicularly to 6b.

The projected light is reflected by the first surface 6a and the second surface 6b, and the respective reflected lights travel backward in the incident optical path and are reflected by the beam splitter 3 to be converted into an optical path. Two point images P collected by the camera 11
To form. Then, the signals of the TV camera 11 are subjected to image processing by the image processing device 12, whereby the center coordinates of each of the two point images P are obtained.

In this state, when the lens under test 6 is rotated while pressing the outer diameter of the lens frame 15 against the reference block 16, the first surface 6a and the second surface 6b of the lens under test 6 are centered on the lens frame 15. When decentered with respect to the axis, the two point images P on the TV camera 11 rotate with a certain radius. This turning radius is used as the image processing device 12.
By the above, the eccentricity of the first surface 6a and the second surface 6b of the lens 6 to be inspected can be obtained at the same time.

Similarly, the first objective lens 10a is
The first stage 14a is moved so that the focal position thereof coincides with the center of curvature of the third surface 6c of the lens 6 to be inspected.
The light is projected perpendicularly to c and the second objective lens 1
0b is moved by moving the second moving stage 14b so that the focal position thereof coincides with the center of curvature of the fourth surface 6d of the lens 6 to be inspected to project light perpendicularly to the fourth surface 6d. The eccentric states of the third surface 6c and the fourth surface 6d of 6 are simultaneously obtained. By sequentially measuring in this manner, the eccentricity of each surface of the lens 6 under test having a plurality of surfaces can be obtained.

According to this embodiment, since the objective lens 10 is divided into the first and second objective lenses 10a and 10b, the eccentricity of the two surfaces of the lens 6 to be tested can be measured at the same time. . Further, since the image processing device 12 obtains the center coordinates of the point image P, flare light which adversely affects the measurement can be cut by the image processing, and thus the measurement can be performed with higher accuracy.

[0022]

Second Embodiment FIG. 3 is a schematic diagram showing a second embodiment of the present invention. The eccentricity measuring apparatus of this embodiment includes a light source 1,
A collimating lens 2 for collimating the light flux from the light source 1,
The objective lens 20 that projects the light beam from the collimator lens 2 onto the test lens 6, and the light reflected by the test lens 6 that is arranged between the collimator lens 2 and the objective lens 20 is provided on an optical path different from the light source 1 side. A beam splitter 3 for converting, a condensing lens 7 for condensing the light whose optical path is converted by the beam splitter 3, an optical position detecting element 21 for detecting the central coordinates of the point image P condensed by the condensing lens 7, and a light The signal processing unit 22 processes the signal from the position detection element 21 to calculate the eccentricity of the lens 6 to be inspected.

The objective lens 20 includes a first objective lens 20a, a second objective lens 20b, and a third objective lens 20c which are formed by dividing one objective lens into two planes parallel to the optical axis thereof. It consists of 1st, 2nd, 3rd
The objective lenses 20a, 20b, 20c of Example 1 are the same as those in the first embodiment.
Are mounted on movable stages (not shown) that are movable in the optical axis direction, respectively, so that the light flux from the collimator lens 2 can be projected onto any three surfaces 6a, 6b, 6c of the lens 6 under test. It has become.

A liquid crystal shutter 23 is arranged between the beam splitter 3 and the condenser lens 7. As shown in FIG. 4, the liquid crystal shutter 23 is provided with the signal processing unit 232 so that the reflected light that has passed through the first, second, and third objective lenses 20a, 20b, and 20c can individually pass and be blocked. 23a capable of arbitrarily blocking light rays by controlling
Section, 23b section, and 23c section are provided. Further, the lens 6 to be inspected has three surfaces 6a, 6b and 6c, and the surface 6b
It is a cemented lens made up of two lenses with the cemented surface as a cemented surface, and is held on the rotary spindle 24.

Next, the operation of the eccentricity measuring device of this embodiment will be described. The light from the light source 1 passes through the collimator lens 2 and the beam splitter 3, and the first objective lens 20a,
It is incident on the second objective lens 20b and the third objective lens 20c. The first lens 20a is arranged so that its focal position matches the center of curvature of the first surface 6a of the lens 6 to be inspected, and projects light perpendicularly to the first surface 6a. On the other hand, the second objective lens 20b is arranged so that the focal position thereof coincides with the center of curvature of the second surface 6b which is the cemented surface of the lens 6 to be inspected, and projects light perpendicularly to the second surface 6b. In addition, the focal position of the third objective lens 20c is the third objective lens 20c.
The third surface 6c is arranged so as to match the center of curvature of the surface 6c.
The light is projected vertically to. Then, the projected light is the first surface 6
a, the second surface 6b, and the third surface 6c are reflected, and the respective reflected lights travel backward in the incident optical path and are reflected by the beam splitter 3 to undergo optical path conversion.

In this state, the signal processing unit 22 controls the liquid crystal shutter 23 to allow only the light of the portion 23a through which the reflected light of the first surface 6a passes and block the light of the portions 23b and 23c. Only the reflected light from the first surface 6a is condensed by the condenser lens 7 on the optical position detecting element 21, and the point image P is formed. At this time, the signal processing unit 22 obtains the center coordinates of the point image P by the reflected light of the first surface 6a. Therefore, the lens 6 to be inspected is rotated by the rotary spindle 24, and the 21a and 21b parts of the liquid crystal shutter 23 are
The center coordinates of the point image P are obtained by the signal processing unit 22 while sequentially opening any one of the parts 21c, so that the rotary spindle 24 of each of the first surface 6a, the second surface 6b, and the third surface 6c of the lens 6 to be tested. The eccentricity with respect to the rotation axis of is required. Furthermore, after that, the first surface 6a of the lens 6 to be inspected,
The eccentricity of the joint surface 6b can be obtained by calculating with the axis connecting the centers of curvature of the third surfaces 6c as a reference. As described above, according to the present embodiment, the cemented surface 6 of the cemented lens that is the lens 6 to be inspected.
The eccentricity of b can be measured in a short time.

[0027]

Third Embodiment FIG. 5 is a schematic diagram showing a third embodiment of the present invention. The eccentricity measuring apparatus of this embodiment includes a light source 1,
A collimating lens 2 for collimating the light flux from the light source 1,
The objective lens 30 which projects the light flux from the collimator lens 2 onto the lens 6 to be inspected, and the light which is arranged between the collimator lens 2 and the objective lens 30 and reflected by the lens 6 to be inspected, is provided on an optical path different from the light source 1 side. First beam splitter 3 for conversion
1, a second objective lens 32 that splits the light whose optical path has been changed by the first beam splitter 31, into two, a first condensing lens 33a that condenses one of the two halved lights, and a first collective lens 33a. First to detect the center coordinates of the point image P condensed by the optical lens 33a
Optical position detecting element 34a and the second condenser lens 32
A reflection mirror 35 that reflects the other light divided by
Second condenser lens 3 for condensing the light from the reflection mirror 35
3b, a second light position detecting element 34b for detecting the center coordinates of the point image P condensed by the second condenser lens 33b, the first light position detecting element 34a and the second light position detecting element. Three
4b, and a calculation unit 36 that calculates the eccentricity of the lens 6 to be inspected.

The objective lens 30 has a cylindrical first objective lens 30a and an annular second objective lens 30a formed by dividing one objective lens by a cylindrical surface centered on the optical axis as shown in FIG. It is composed of an objective lens 30b.

First and second objective lenses 30a and 30b
Are provided so as to be movable in the optical axis direction, and the first objective lens 30a is located at the central portion 6g of the first surface 6a of the lens 6 to be tested, and the second objective lens 30b is located at the first surface 6a.
The luminous fluxes from the collimator lens 2 can be projected onto the peripheral portions 6h of each.

Between the second beam splitter 32 and the first condenser lens 33a and between the reflection mirror 35 and the second
Between the condenser lenses 33b of the
A first light blocking plate 37a that blocks the light reflected by h and a light blocking plate 37b that blocks the light reflected by the central portion 6g of the lens 6 to be tested are arranged. 7 (A) and 7 (B)
[Fig. 4] is a perspective view showing a first light blocking plate 37a and a second light blocking plate 37b. The lens 6 to be inspected is a single-sided non-inspection lens in which the radius of curvature of the central portion 6g of the first surface 6a and the radius of curvature of the peripheral portion 67 are different, and is held on the rotary spindle 24 with the spherical surface side 6b facing downward. Has been done.

Next, the operation of the eccentricity measuring device of this embodiment will be described. The light from the light source 1 is the first light of the collimator lens 2.
After passing through the beam splitter 31, the beam enters the first objective lens 30a and the second objective lens 30b. The focus position of the first objective lens 30a is the first of the lens 6 to be inspected.
It is arranged so as to match the center of curvature of the central portion 6g of the surface 6a and projects perpendicularly to the central portion 6g. On the other hand, the focal point of the second objective lens 30b is the first surface 6 of the lens 6 to be inspected.
It is arranged so as to match the center of curvature of the peripheral portion 61h of a,
Light is projected vertically to the peripheral portion 6h.

The projected light is reflected by the central portion 6g and the peripheral portion 6h of the first surface, and the respective reflected light travels in the reverse direction of the incident optical path and is reflected by the first beam splitter 31 to change the optical path. Then, the beam is split into two by the second beam splitter 32. The light transmitted through the second beam splitter 32 has its peripheral portion blocked by the light shielding plate 37a, and only the reflected light at the central portion 6g is condensed by the first condenser lens 33a to form a point image P. Then, the center coordinates of the point image P are detected by the first light position detecting element 34a. On the other hand, the light reflected by the second beam splitter 40 on an optical path different from that on the first beam splitter 32 side is reflected again by the reflection mirror 41 and the optical path is changed, and the central portion thereof is blocked by the light shielding plate 37b. As a result, only the reflected light at the peripheral portion 6h is condensed by the second condenser lens 33b to form a point image P, and the center coordinates of the point image P is determined by the second light position detection element 34b. To be detected.

In this state, when the lens 6 to be inspected is rotated by the rotary spindle 24, the central portion 6g and the peripheral portion 6h of the first surface 6a of the lens 6 to be inspected are eccentric with respect to the rotation axis of the rotary spindle 24. In this case, the point images P on the first light position detecting element 34a and the second light position detecting element 34b rotate with a certain radius.
By calculating this radius of gyration by the calculation unit 36, the eccentricity of the central portion 6g and the peripheral portion 6h of the first surface 6a of the lens 6 under test can be determined. Furthermore, the eccentricity of the aspherical surface is obtained by calculating the eccentricity of the peripheral portion 6h with the central portion 6g as a reference. Thus, according to this embodiment,
The decentering of the aspherical axis of the aspherical lens, which is the lens 6 to be inspected, can be measured in a short time.

[0034]

As described above, according to the present invention, the objective lens is divided into a plurality of objective lenses, and the divided objective lenses can be individually moved in the optical axis direction so that the luminous flux of the subject lens can be changed. Since the light can be projected onto each lens surface, the eccentricity of a plurality of surfaces of the lens to be inspected and a plurality of portions of one surface can be measured simultaneously, and the eccentricity measurement can be performed in a short time.

[Brief description of drawings]

FIG. 1 is a configuration diagram schematically showing an eccentricity measuring device of the present invention.

FIG. 2 is a configuration diagram schematically showing a first embodiment of the present invention.

FIG. 3 is a configuration diagram schematically showing a second embodiment of the present invention.

FIG. 4 is a diagram illustrating a liquid crystal shutter according to a second embodiment.

FIG. 5 is a configuration diagram schematically showing a third embodiment of the present invention.

FIG. 6 is a perspective view showing an objective lens in Example 3;

FIG. 7 is a perspective view showing a light shielding plate according to a third embodiment.

FIG. 8 is a configuration diagram schematically showing a conventional eccentricity measuring device.

FIG. 9 is an explanatory diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 light source 2 collimator lens 3 beam splitter 4,10,20 objective lens 6 test lens 7, 33a, 33b condensing lens 8 detection part 9 calculation part 11 TV camera 12 image processing device 21, 34a, 34b optical position detection element 22 Signal processing unit 36 Calculation unit

Claims (1)

[Claims] 1. A light source, a collimator lens for collimating a light flux from the light source, an objective lens for projecting light transmitted through the collimator lens onto a lens under test, and a lens under test arranged between the collimator lens and the objective lens. A beam splitter that converts the light reflected by the optical path to a different optical path from the light source side, a condensing lens that condenses the light whose path is changed by the beam splitter, and the center coordinates of the point image that is condensed by the condensing lens is detected. In the eccentricity measuring device including a detecting unit for calculating the eccentricity of the lens to be inspected by a signal from the detecting unit, the objective lens is divided into at least two objective lenses having the same optical axis, and An eccentricity measuring device, wherein each of the divided objective lenses is provided so as to be independently movable in the optical axis direction.