JPH09189642A - Method and device for measuring dimension of lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To directly and precisely measure the thickness of a lens according to the holding position of the lens in a lens holding body without using a special adapter. SOLUTION: A lens holding body 1 for holding a lens R is shifted in an arrowed direction C and rotated around the axial line O of a rotating center, whereby the posture of the lens holding body 1 is regulated. After the optical axis 01 of the lens R is conformed to a measuring reference axis 02, a measuring element 15A is brought into contact with the surface of the lens R from the direction laid along the measuring reference axis 02, and the thickness of the lens R is measured on the basis of the distance between the contact position of the measuring element 15A and the reference position P0 on the measuring reference axis 02.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens dimension measuring method and apparatus for measuring lens thickness.

[0002]

2. Description of the Related Art Conventionally, as a measuring method of this kind,
As shown in FIG. 6A, there is a method of using a lens holder 1 called a recess dish capable of holding a plurality of lenses R to be polished. In the lens holder 1, a lens R is attached to each of a plurality of lens receiving portions 1A formed on a spherical surface, and the optical axes 01 of the plurality of lenses R are point P1. Is held to intersect at.
As shown in FIGS. 7A and 7B, the lens holder 1 is fixed to a fixed position on the stand 2 by being fitted into the measuring table 3 on the stand 2. And the measuring table 3
Is the reference position P0 for measurement. Stand 2
The dial gauge 4 is held at a fixed position of, and its tracing stylus 4A is in contact with the surface of the lens R from above in FIG. 6A along the measurement reference axis 02 passing through the point P1. Has become. The reference axis for measurement 02 coincides with the optical axis 01 of the lens R, which is located at the center of the lens holder 1.

At the time of measurement, as shown in FIG. 6A, the dial gauge 4 is attached to the lens R positioned on the measurement reference axis 02.
4A is applied, and the display value of the dial gauge 4, that is, the measured value of the distance between the measurement reference position P0 and the contact position of the measuring element 4A is read. And the displayed value,
Based on the known size data of the lens holder 1,
The thickness T of the lens R on the optical axis O1 is obtained.

However, with respect to the other lens R deviated from the measurement reference axis 02, the thickness T is obtained by the same method.
Is impossible to measure.

On the other hand, as shown in FIG. 6B, when the lens holder 1 holds the lens R at the same distance from the measurement reference axis O2, the block gauge 5 shown in FIG. Then, the measurement is performed using the adapter 6 made of glass or the like in FIG. 8B.

The block gauge 5 is a rectangular parallelepiped whose height is H0. Further, the adapter 6 has a flat upper surface and a lower curved surface with a radius of curvature r0, and is placed on the lens R as shown in FIG. 9B. h0
Is the height of the central portion of the adapter 6, and the total value (r0 + h0) of it and the radius of curvature r0 matches the height H0 of the block gauge 5 (H0 = r0 + h0).

In the measurement, first, as shown in FIG. 9 (a), the block gauge 5 is placed on the measuring table 3 and the gauge head 4A of the dial gauge 4 is placed on the upper surface of the block gauge 5, and the pointer of the dial gauge 4 is set. Set to "0". After that, FIG.
As shown in (b), the lens holder 1 is fixed to the measuring table 3, the adapter 6 is placed on the lens R, and the probe 4A of the dial gauge 4 is placed on the upper surface of the adapter 6.
The value displayed by the dial gauge 4 is read. The displayed value is the difference (H1-H) between the reference height H0 and the height H1.
The height H1 corresponds to the sum of the radius of curvature r0 of the adapter 6, the height h0, and the thickness Δh of the insufficient polishing amount of the lens R with respect to the target thickness for polishing the lens R. Therefore, the dial gauge 4 displays the thickness Δh of the insufficient polishing of the lens R.

[0008]

By the way, the adapter 6
In order to improve the adhesiveness between the adapter 6 and the surface of the lens R when performing the measurement using
As in (a), it is necessary to rub the contact surfaces 6A and RA in the direction of arrow A.

Therefore, when the adapter 6 is used for a long period of time, the contact surface 6A of the adapter 6 is worn and an error occurs in the measured value. In addition, the gauge head 4A of the dial gauge 4
When the contact surface 6B of the adapter 6 that contacts with is worn or damaged, an error may occur in the measured value.
It is difficult to accurately grasp the wear amount of such an adapter 6, and if it is continuously used until the wear amount reaches the limit of use, accurate measurement cannot be performed.

Further, as shown in FIG. 10B, the adapter 6
When the is set at an angle, the measured values will vary. For example, the radius of curvature r of the surface of the lens R is 50 mm
If the adapter 6 is tilted 1 degree, the measurement error t is 0.01
It will be about mm. Such a set error of the adapter 6,
And its wear and damage, the measurement accuracy is ± 0.
It is difficult to keep it at 03 mm. Specifically, the thickness of the 124 lenses R is measured using the adapter 6, and the result of performing polishing processing to the target thickness based on the measurement result is:
27 pieces with target thickness with 1/100 mm accuracy, +
23 of 0, 01 mm, 17 of +0.02 mm, 7 of +0.03 mm, +0.04 mm
2 of them, and 20 of −0, 01 mm, −
14 of 0.02 mm, 12 of −0.03 mm and 2 of −0.04 mm were difficult to maintain with a measurement accuracy of ± 0.03 mm.

An object of the present invention is to provide a lens dimension measuring method and apparatus capable of directly and accurately measuring the lens thickness according to the holding position of the lens in the lens holder without using a special adapter. To provide.

[0012]

In the lens dimension measuring method of the present invention, the lens is held by a lens holder, and the lens holder is moved and adjusted so that the optical axis of the lens serves as a predetermined measurement reference axis. Aligning, contact the tracing stylus to the surface of the lens from the direction along the measurement reference axis, between the contact position of the tracing stylus on the surface of the lens and the reference position on the measurement reference axis It is characterized in that the thickness of the lens is measured based on the distance.

The lens dimension measuring apparatus of the present invention comprises a lens holder capable of holding a lens and a movement adjusting means for moving and adjusting the lens holder so that the optical axis of the lens coincides with a predetermined measurement reference axis. And a tracing stylus moving means for bringing a tracing stylus into contact with the surface of the lens from a direction along the measuring reference axis, a contact position of the tracing stylus on the surface of the lens, and a reference position on the measuring reference axis. And a measuring means for measuring the thickness of the lens based on the distance between

[0014]

FIG. 1 is a block diagram showing an embodiment of the present invention.
Explanation will be made based on FIG.

FIG. 1 is a plan view of the entire apparatus, and FIG. 2 is a front view thereof. In these figures, 10 is a measuring table,
A swivel table 11 that can swivel in the direction of arrow B around the vertical axis O is provided on the upper portion thereof.
On the upper part of the turning table 11, there is provided a shift table 12 which can be shifted in the horizontal arrow C direction. The turning table 11 is turned by the driving force of the turning motor 11A or the operating force of the turning handle 11B, and the shift table 12 is slid by the driving force of the shifting motor 12A or the operating force of the shifting handle 12B.

The shift table 12 is provided with a chuck portion 13 in which the base ends of the lens holding body 1 similar to those of the conventional example described above are fitted, and is attached to the female screw portion 1B at the base end of the lens holding body 1. The lens holder 1 is positioned and fixed to the chuck portion 13 by screwing the male screw portion 14A of the tool 14 into engagement with each other.

Reference numeral 15 is a length measuring instrument having a measuring element 15A, which is supported by a length measuring instrument mounting portion 16 on the measuring stand 10. The tracing stylus 15A is movable in the horizontal arrow D direction along the measurement reference axis 02. The length measuring device 15 is configured to measure the amount of movement of the tracing stylus 15 with respect to a predetermined reference position, and the measurement data is input to the arithmetic unit 21. The arithmetic unit 21 has an arithmetic processing function, which will be described later, a control function of the motors 11A and 12A, and a function of displaying a measurement dimension or the like on the display unit 22.

The measuring reference axis 02 is orthogonal to the axis O of the turning center of the turning table 11, and the axis O is the optical axis of the plurality of lenses R held by the lens holder 1 as shown in FIG. 3 (a). The intersection point P1 of 01 is displaced by a predetermined distance L1.
The reference position P0 for measurement is the reference surface on the left side in FIG. 1 of the chuck 13 orthogonal to the axis O. FIG.
In (a), r is the same lens R as the conventional example described above.
Is the radius of curvature of the surface, and in FIG. 3 (b), d
1 is the inner diameter of the concave lens receiving portion 1A of the lens holding body 1 that positions and holds the lens R, and r0 is the distance in the optical axis O1 direction between the bottom surface of the lens receiving portion 1A and the point P1.

Next, the measurement procedure will be described.

First, as shown in FIG. 5 (a), the length measuring device 15 is brought into contact with the reference surface of the chuck 13, that is, the surface forming the reference position P0, and a reset button (not shown) of the arithmetic unit 21 is pressed to measure the length measuring device 15. The measured value of is set to "0".
As a result, the display device 22 displays the measured value “0”.

After that, as shown in FIG.
The lens holder 1 is positioned and fixed on the chuck 13 by. The lens holder 1 holds a plurality of lenses R as in the above-described embodiments. In the figure, an phantom spherical surface having a curvature radius r where the surface of the lens R is located is shown by a two-dot chain line.

After that, the arithmetic unit 21 controls the driving of the turning table 11 and the shift table 12 by the motors 11A and 12A according to the position of the lens R to be measured,
As shown in FIGS. 5C and 5D, the optical axis O1 of the lens R to be measured is aligned with the measurement reference axis O2. The arithmetic unit 21 recognizes the lens R having the unique number as a measurement target by inputting the unique number of the lens R, and the shift amount ΔL of the shift table 12 is based on the position data of the lens R. Then, the turning angle θ of the turning table 11 is obtained. The angle θ corresponds to the inclination angle of the optical axis O1 of the lens R from the measurement reference axis O2 as shown in FIG. 4A, and the shift amount ΔL is ΔL = (L1 · tan θ)
Is required. The shift amount ΔL and the turning angle θ are displayed on the display unit 22.

In this example, the shift table 12 is shifted by .DELTA.L as shown in FIG. 5C, and then the swivel table 11 is swung by an angle .theta. As shown in FIG. As a result, as shown in FIG. 5D, the measurement reference axis O2 and the optical axis O1 of the lens R coincide with each other, and the point P1 and the axis O are located on the measurement reference axis O2.

Then, as shown in FIG. 5 (e), the measuring element 15A of the length measuring device 15 is applied to the surface of the lens R to measure the distance LB from the reference position P0 of measurement. The measurement distance LB
Is the total value of the length r from the point P1 to the surface of the lens R and the shift amount L2 between the point P1 and the axis O, as shown in FIG. 4B, and the shift amount L2 is the turning angle. It changes according to θ and is obtained as L2 = (L1 / cos θ). The radius of curvature r of the surface of the lens R corresponds to the sum of the known distance r0 and the thickness T of the lens R. The control unit 21 obtains the thickness T of the lens R by subtracting the deviation amount L2 and the known length r0 from the measurement distance LB. The measurement result is displayed on the display device 22.

Thereafter, in the same manner, the other lens R is measured, and its optical axis O1 is made coincident with the measurement reference axis O2, whereby the thicknesses of the other lenses R are measured one by one.

Further, using the handles 11B and 12B,
It is also possible to manually perform the turning adjustment of the turning table 11 and the shift adjustment of the shift table 12. The turning angle of the turning table 11 and the shift amount of the shift table 12 are displayed on the display device 22.

On the spherical surface of the lens holder 1,
When a plurality of lenses R are held with being displaced in the circumferential direction, the mounting posture of the lens holding body 1 with respect to the chuck 13 is shifted in the circumferential direction about the axis of the female screw portion 1B of the lens holding body 1. , Its lens holder 1
It is also possible to carry out the measurement for all the lenses R which are shifted in the circumferential direction.

According to this embodiment, the thicknesses of the 124 lenses R were individually measured, and the polishing was performed to the target thickness based on the measurement results. The target thickness is the lens R
The thickness of the lens R is such that the radius of curvature r of the surface of the lens is 50 mm. As a result of measuring the thickness of the lens R after polishing with an accuracy of 1/100 mm, 27 pieces having a target thickness, +0,
26 pieces of 01 mm, 20 pieces of +0.02 mm
3 pieces with +0.03 mm, and −0,01 mm
27 pieces, -0.02 mm 17 pieces,-
4 pieces of 0.03mm, measurement accuracy ± 0.03
mm could be maintained.

[0029]

As described above, according to the present invention, the position of the lens holder for holding the lens is adjusted so that the optical axis of the lens coincides with the reference axis for measurement, and then the reference axis for measurement is set. By holding the probe in contact with the surface of the lens from the direction along it, and measuring the thickness of the lens based on the distance between the contact position of the probe and the reference position on the reference axis for measurement, the lens holding Regardless of the holding position of the lens on the body, the lens can be positioned at the optimum measurement position and the thickness of the lens can be accurately measured.

Further, since the lens thickness is directly measured without interposing a special member such as an adapter as in the conventional case, a highly accurate measurement can be performed correspondingly, and a special lens for handling the adapter is required. No skill is required.

[Brief description of the drawings]

FIG. 1 is a plan view showing a configuration example of a measuring apparatus of the present invention.

FIG. 2 is a front view of the measuring device shown in FIG.

FIG. 3 is a cross-sectional view of the lens holder shown in FIG.

4A and 4B are explanatory views of a shift and a turning operation of the lens holding body shown in FIG.

5 is an explanatory diagram of a measurement procedure by the measurement device shown in FIG.

FIG. 6 is a side view of a main part for explaining a conventional measuring method.

7A is a front view of a stand on which the lens holder shown in FIG. 6 is set, and FIG. 7B is a side view of the stand.

8A is a front view of a block gauge used in a conventional measuring method, and FIG. 8B is a front view of an adapter used in a conventional measuring method.

9 is an explanatory diagram of a measurement procedure using the block gauge and the adapter shown in FIGS. 8 (a) and 8 (b).

FIG. 10 is a front view of a main part for explaining a cause of a measurement error caused by using the adapter of FIG. 8 (b).

[Explanation of symbols]

 1 Lens Holder 10 Measuring Stand 11 Swivel Table 12 Shift Table 13 Chuck 14 Fixture 15 Length Measuring Device 16 Length Measuring Device Mounting 21 Calculation Device 22 Display Device R Lens O Swing Center Axis O1 Optical Axis O2 Measurement Reference Axis

Claims (11)

[Claims] 1. A lens is held by a lens holder, and the lens holder is moved and adjusted so that the optical axis of the lens coincides with a predetermined measurement reference axis, and the lens is viewed from a direction along the measurement reference axis. A contact point on the surface of, the contact position of the probe on the surface of the lens,
A lens dimension measuring method comprising: measuring the thickness of the lens based on a distance from a reference position on the measurement reference axis. 2. The lens dimension measuring method according to claim 1, wherein a plurality of the lenses are held by the lens holding body. 3. The lens dimension measuring method according to claim 2, wherein the lens holder holds the plurality of lenses such that their optical axes intersect at one point. 4. The optical axis of the lens is measured by moving and adjusting the lens holder in a direction orthogonal to the measuring reference axis and rotating the lens holder around a point on the measuring reference axis. 4. The lens size measuring method according to claim 1, wherein the lens size is matched with the reference axis. 5. A lens holding body capable of holding a lens, a movement adjusting means for moving and adjusting the lens holding body to match an optical axis of the lens with a predetermined measurement reference axis, and the measuring reference axis. A tracing stylus moving means for bringing a tracing stylus into contact with the surface of the lens from a direction along the contacting position of the tracing stylus on the surface of the lens,
A lens dimension measuring device, comprising: a measuring unit that measures the thickness of the lens based on a distance from a reference position on the measurement reference axis. 6. The lens size measuring apparatus according to claim 5, wherein the lens holder holds a plurality of the lenses. 7. The lens size measuring device according to claim 6, wherein the lens holder holds the plurality of lenses such that their optical axes intersect at one point. 8. The movement adjusting means includes a movement adjusting portion for moving and adjusting the lens holder in a direction orthogonal to the measurement reference axis, and a rotation adjusting portion for adjusting rotation about a point on the measurement reference axis. 6. A dynamic adjustment unit is provided.
8. The lens size measuring device according to any one of 1 to 7. 9. The movement adjusting means comprises a movement adjusting portion for moving and adjusting the lens holder in a direction orthogonal to the measurement reference axis, and the optical axis deviating the lens holder from the arc center of the lens. 8. The lens size measuring device according to claim 5, further comprising a rotation adjusting unit that adjusts rotation about an upper reference position. 10. The lens size measuring device according to claim 5, wherein the measuring unit has a variable setting unit of a reference position on the measurement reference axis. 11. The lens size measuring device according to claim 5, further comprising display means for displaying a measurement result of the measuring means.