JPH03111702A - Method and apparatus for measuring spherical surface of optical element - Google Patents

Abstract

PURPOSE:To prevent occurrence of an error in measurement and also to enable improvement of precision in measurement by providing a master lens, a spherometer, a movable device having the spherometer, and a moving means which brings the master lens and the spherometer into contact with each other. CONSTITUTION:When an arm 7 moves to a position for measurement of a lens 3 (an object of measurement), a work spindle 1 comes into contact with a spherometer 4 and a measured difference in curvature between the master lens 6 and the lens 3 is fed back to a curve generator working machine 10. When the value of the difference differs from a target value, the working machine 10 alters numerical values of a grinding spindle and the work spindle and conducts automatic correction. When measurement is ended, the spindle 1 and the arm 7 return to set positions. Subsequently, the spindle 1 lowers and comes into contact with a grinding wheel 8 and a lower spindle 12 conducts grinding and abrasion. When the spindle 1 rises and returns to the set position after a prescribed time, the lens 3 is washed. In the course of grinding and abrasion, an adaptor spindle 5 comes into contact with the spherometer 4 and first the sphere of the lens 6 is measured by a sphere measuring device 9. When the spindle 5 rises and returns to its set position afterward, the arm 7 moves to the position for measurement of the lens 3 and the measurement is conducted in the same method as the foregoing.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a spherical surface measuring method and apparatus for measuring the radius of curvature of the ground surface of an optical element, particularly when grinding or polishing an optical element, particularly a lens. It is related to.

BACKGROUND OF THE INVENTION The measurement of the spherical surface of optical elements is unique to the lens industry. In general, when measuring the spherical surface of a lens, the measurement method usually differs depending on the process (grinding, smoothing, and boring).

That is, in general, in the grinding and smoothing processes, a method based on comparison with a Newton prototype using a ring ferometer (generally referred to as a spherical meter) is often used.

In addition, air micrometers, meters, and electric micrometers are also used for the purpose of improving measurement accuracy (see Optical Element Processing Technology "84"). Furthermore, the spherical surface measurement in the smoothing process is measured and inspected using a Newtonian prototype or a laser interferometer.

A generally widely used spherical meter will be explained.

Such a spherical meter has a dial gauge attached to the center of a reference ring as shown in FIG. In the case of a convex lens, the inner diameter (R) of the ring is determined by the following formula.

In the case of a concave lens, since the lens touches the outside of the ring, D2 and h2 of the ring can be entered into the above equation.

Applying the principle of such a spherical meter at production sites, it is common for a reference spherical surface to be prepared and workers to perform relative measurements with this reference spherical surface for each process.

Further, there is a method for measuring the spherical surface described in Japanese Patent Application Laid-Open No. 62-68264, and this method is similar to the above-mentioned method.

(Problem to be solved by the invention) This conventional technique has the following problems.

Measurement of the spherical surface using a spherical meter is carried out as an important intermediate inspection for controlling the process, but it has the disadvantage that it requires a lot of man-hours because an operator must perform the inspection for each process.

Furthermore, since this is a measurement method performed by human sensation, the measurement pressure cannot be kept constant, and therefore the spherical surface of the optical element cannot be accurately measured, resulting in measurement errors.

Furthermore, it is difficult to bring the edge of the spherical meter into smooth contact with the surface of the optical element, and if the edge strongly hits a part of the surface of the optical element, scratches, chips, etc. will occur.

In addition, since dirt or fine sludge may adhere to the surface of the optical element after processing, it is necessary to wipe the surface of the optical element with a cloth, silubon paper, etc. before measuring to prevent measurement errors or scratches. Yes, the number of man-hours required increases.

SUMMARY OF THE INVENTION The object of the invention is to provide an automatic spherical surface measurement device of the type described above, suitably constructed and arranged so as to overcome the above-mentioned drawbacks.

(Means and Effects for Solving the Problems) In the method for measuring an optical element of the present invention, when measuring the spherical surface of an optical element, the curvature and curvature before processing are measured while the optical element is held on one processing axis. It is characterized by automatically measuring the curvature after processing.

The spherical surface measuring device for an optical element of the present invention includes a comparative measurement object (master lens), a spherical meter, a movable device having the spherical meter, and a moving means for bringing the master lens and the spherical meter into contact with each other, The method is characterized in that a movable device is moved to the measurement position of the optical element to perform comparative measurements between the spherical surface of the optical element and the master lens.

As shown in FIG. 1, the spherical surface measuring device of the present invention includes an adapter shaft 5 that holds a comparative measurement object (master lens) 6;
a spherical meter 4 and a movable arm 7 having the spherical meter 4
, a moving means for moving the master lens 6 and the spherical meter 4 using a cylinder (not shown) and bringing them into contact with each other, and the arm 7 attached to the rotating shaft of the index 20 for measuring the object to be measured (lens 3). A means for moving the lens 3 to a position by rotation of a motor (not shown) is provided, and comparative measurements are made between the lens 3 and the master lens 6. The spherical meter 4 is formed by a measuring terminal 22 and connected to a spherical measuring device 9, and is connected to a curve generator processing machine 10 and the entire device (not shown).
The system is connected to a line controller that controls the system, and is configured to perform automatic measurement and automatic correction.

On the other hand, the lens 3 is conveyed from the curve generator process to the lens holder 2 by a conveying means (not shown) and held by suction by an air suction device (not shown). At this time, comparison measurements with the master lens have been completed. When the movable arm 7 moves to the measurement position of the lens 3, the workpiece axis 1
contacts the spherical meter 4 while reducing the speed using a device that can control the speed (not shown), measures the spherical surface of the curve generator machined surface, and calculates the measured value, that is, the difference in curvature between the master lens and the measurement lens. is fed back to the curve generator processing machine 10. If the value differs from the target value, the curve generator processing machine 10 changes the numerical values of the grindstone axis and the workpiece axis to perform automatic correction. When the measurement is completed, the workpiece axis 1 rises and returns to the normal position, and the arm 7 holding the spherical meter 4 is connected to a motor (not shown).
The work shaft 1 returns to its original position by rotation, and the work shaft 1 descends and comes into contact with the grindstone 8, and the lower shaft 12 performs grinding and polishing by a swinging mechanism (not shown). After a predetermined time, the work shaft 1 rises and returns to its normal position, and then the air or city water system (not shown) is activated.
Air or city water is sprayed onto the lens 3 from the vibrator 15 to clean the lens 3.

During the grinding and polishing process, the adapter shaft 5 comes into contact with the spherical surface meter 4 held at the tip of the arm 7, and the spherical surface of the mask lens 6 is first measured by the spherical surface measuring device 9. After that, when the adapter shaft 5 rises and returns to its home position, the movable arm 7 moves to the measurement position of the lens 3 that has been ground and polished, and measures it in the same manner as the spherical surface measurement after the curve generator processing described above. conduct. Measurements are for the entire device (not shown)
If the target values are different, the difference in curvature between the master lens 6 and the measurement lens is fed back to the grinding/polishing machine, and the grinding/polishing machine changes the value on the grinding wheel axis to automatically compensate. I do. This spherical surface measurement method is used all the time or every few times.

According to the above structure or method, since the spherical surface is measured by in-process measurement, the number of man-hours is reduced, the measurement accuracy is improved, and the measurement pressure is constant, so measurement errors are prevented and dirt etc. do not occur on the lens surface. Therefore, the number of man-hours required for cleaning the lens is reduced, and defects caused by handling can be prevented.

(Example) Hereinafter, an example of the present invention will be described in detail using the drawings.

In the following invention, the same structural members as those shown in FIG. 1 are denoted by the same reference numerals.

(First Embodiment) FIG. 2 is a schematic diagram showing a first embodiment of the spherical surface measuring method and apparatus according to the present invention. The spherical surface measuring device 30 of this embodiment includes an adapter shaft 5 that holds a master lens 6,
A movable arm 7 that holds the spherical meter 4, a moving means that moves the master lens 6 and the spherical meter 4 using a cylinder (not shown) and bring them into contact, and a movable arm 7 that holds the spherical meter 4; A means for moving the lens 3 to the measurement position No. 3 by a motor shaft (not shown) is provided to perform comparative measurements between the lens 3 and the master lens 6.

The spherical meter 4 is formed by a measuring terminal 22 and is connected to a spherical measuring device 9, and is also connected to a line controller that controls a curve generator processing machine 10 and the entire device (not shown), and is connected to a line controller for controlling a curve generator processing machine 10 and the entire device (not shown), and is used for processing of a grinding and polishing processing machine. The lens spherical surface after curve generator processing and the lens spherical surface after grinding and polishing are measured on one processing axis, and automatic measurement and correction can be performed.

Next, the overall operation of the above-mentioned spherical surface measuring method and apparatus will be explained step by step.

The lens 3 is transported from the curve generator process to a processing machine for grinding and polishing processes by a transport means (not shown), and is suctioned and held in the lens holder 2 by an air suction device (not shown). Next, the movable arm 7 moves fJ[l to the measurement position on the master lens 6. On the other hand, the master lens 6 is held by the adapter shaft 5 and positioned at a normal position. When the movable arm 7 reaches the measurement position above the master lens 6, the shaft 5 of the arm 7 is lowered by a cylinder (not shown) and contacts the spherical meter 4 held at the tip of the arm 7 at a reduced speed. Then, the spherical surface of the master lens 6 is measured by the spherical surface measuring device 9.

This measured value is input into the sphere measuring device 9. When the measurement is completed, the adapter shaft 5 is raised by a cylinder (not shown), and when it returns to the normal position before lowering, the arm 7 attached to the rotating shaft of the index 20 is moved by the motor (
It comes to a fixed position on the work shaft 1 by rotation of the workpiece (not shown).

Thereafter, the workpiece shaft 1 descends while reducing its speed using a speed control device (not shown), contacts the spherical meter 4, and is then held by the lens holder 2 and processed by the curve cinerator processing machine 10. The spherical surface measuring device 9 automatically measures the difference between the measured value of the master lens inputted to the spherical surface measuring device 9 that measures the spherical surface of the surface, and feeds the measured value back to the curve generator processing machine 10.

If the value differs from the target value, the curve generator processing machine 10 changes the numerical values of the grindstone axis and the workpiece axis to perform automatic correction. When the measurement of the machined surface machined by the curve generator processing machine 10 is completed, the work shaft 1 rises and returns to the normal position, and the arm 7 returns to the normal position by rotation of the motor. After that, the work shaft 1 descends and comes into contact with the grindstone 8,
The lower shaft 12 performs grinding and polishing using a rotating mechanism and a swinging mechanism (not shown). After a predetermined period of time, the work shaft 1 rises and returns to its home position, and then air or city water is sprayed onto the lens 3 from the vibrator 15 by an air or city water device (not shown) to clean the lens 3. During this time, the rotation and rocking of the grinding and polishing machine are also stopped.

During the above-mentioned grinding and polishing process, the adapter shaft 5 is lowered by a cylinder (not shown), contacts the spherical meter 4 held at the tip of the arm 7 at a reduced speed, and the master lens 6 is detected by the spherical meter 9. Measure the spherical surface of The spherical surface measuring device 9 measures the curve generator machined surface as described above.
Input the measured values of master lens 6. When the measurement is completed, the adapter shaft 5 rises and returns to the normal position, and when the movable arm 7 moves to the measurement position of the lens 3 that has been ground and polished, it is measured in the same manner as the spherical surface measurement after the curve generator processing described above. Perform spherical measurements.

The measured value is controlled by a line controller that controls the entire device (not shown), and if the target value differs, the difference in curvature between the master lens 6 and the measurement lens is fed back to the grinding/polishing machine, and the grinding/polishing process is performed. The processing machine automatically makes corrections by changing the values on the grinding wheel axis. Such spherical surface measurements are performed all the time or every few times.

According to this embodiment, it is possible to significantly reduce costs due to in-process measurement, and measurement errors can be prevented, so measurement accuracy is further improved and spherical surface measurement can be performed efficiently under the same conditions.

Further, by constantly performing automatic correction, the quality of each process is stabilized, and therefore, the final process (polishing process) can stabilize the high quality of NR and prevent quality defects.

Furthermore, by performing the measurement while holding the optical element on the processing axis, it becomes possible to shorten the measurement time and simplify the equipment of the spherical surface measuring device, thereby reducing costs.

(Second Embodiment) FIG. 3 is a schematic diagram showing a second embodiment of the spherical surface measuring method and apparatus of the present invention.

In this embodiment, an apparatus for carrying out a workpiece measurement method is configured so that water 31 such as grinding fluid attached to the lens 3 can be removed after grinding and polishing. Therefore, the measurement accuracy of the lens 3 can be further improved.

In the example shown in FIG. 3, after the grinding and polishing processes are completed, the lens 3 is cleaned by spraying air or city water onto the lens 3 from a pipe 15 using an air or city water device (not shown). After that, the work shaft 1 rises and returns to the position before descending, and the water absorption tool 13 stops rotating by the rotation mechanism (not shown), and then the rotating arm 14 rotates and returns to the fixed position on the work shaft 1. (Then, when the work shaft 1 descends and comes into contact with the water absorbing tool 13, the water absorbing tool 13 starts rotating by a rotating mechanism (not shown), removes moisture and dirt, etc., and after a predetermined period of time, stops rotating and the work shaft 1 starts to rise and returns to the normal position. Also, water absorbing tool 1
3 is positioned at a fixed position before rotation by the rotating arm 14. The other configurations, ie, the spherical surface measurement method and apparatus, are the same as those in the first embodiment, so their explanation will be omitted.

According to this embodiment, the same effects as in the first embodiment can be achieved, and measurement errors can be reduced by performing spherical surface measurement after removing moisture, chips, dirt, etc. adhering to the lens 3. It is possible to further improve the prevention of scratches that occur during measurement.

(Third Embodiment) FIG. 4 is a schematic diagram showing a third embodiment of the spherical surface measuring method and apparatus of the present invention.

The measurement method of this embodiment is a means of measuring two points on the spherical surface of the lens and measuring the spherical accuracy based on the height difference, whereas the first and second embodiments are comparative measurement methods using a master lens.

The spherical surface measuring device of this embodiment uses a sensor 17.18 for measuring the curvature of the lens 3, and the measuring sensor 17.18 is fixed at one end and moved to the workpiece axis 1. It is formed from a rotating arm 7. The measurement sensors 17 and 18 are connected to the spherical surface measuring device 9 and connected to a line controller that controls the curve generator processing machine 10 and the entire device (not shown), so that automatic measurement and automatic correction can be performed. . On the other hand, the lens 3 is held by the lens holder 2, and is configured so that the work shaft 1 can descend and come into contact with the grindstone 8, and at the same time, the lower shaft 12 can rotate and perform processing.

Next, the overall operation of the spherical surface measuring method and apparatus of this example will be explained step by step. After the lens 3 is processed by the curve generator, it is held in the lens holder 2 by a conveying means (not shown) during the grinding and polishing steps. The measurement sensors 17 and 18 are fixed to the tip of the rotating arm 7, and are connected to a rotating mechanism (not shown).
As a result, the rotary arm 7 rotates and is located at a fixed position on the work shaft 1.

Thereafter, the work shaft 1 descends and comes into contact with the measurement sensors 17, 18, and the spherical surface measuring device 9 starts measuring.

At this time, the difference in curvature of the lens 3 is input into the measuring device in advance. The measuring instrument calculates the difference in curvature and feeds the measurement back to the curve generator processing machine 10. Also, if the target value is exceeded, automatic correction is performed. When the measurement is completed, the workpiece shaft 1 descends and contacts the grindstone 8 fixed to the lower shaft 12, and the lower shaft 12 rotates and swings (
(not shown), a grinding and polishing machine processes the lens 3.

After a predetermined period of time, the work shaft 1 rises and reaches a fixed position, and then the pipe 15 is
When air or city water is sprayed onto the lens 3 to wash (clean) the surface of the lens 3, the rotation and swing mechanisms of the grinding and polishing machine also stop.

Thereafter, the rotating arm 7 is positioned at a fixed position on the work shaft 1 by the rotation of the motor by a rotating mechanism (not shown). After that, work axis 1 has a function that can control the speed (
(not shown), the lens descends at a reduced speed, contacts the measurement sensors 17 and 18, and measures the curvature of the lens 3 after grinding and polishing using the spherical surface measuring device 9. The details of the measurement will be omitted because they are the same after the curve generator processing described above.

According to this embodiment, the same effects as those of the first and second embodiments can be achieved, and the equipment (master lens, adapter shaft, etc.) of the first and second embodiments is unnecessary.

Furthermore, since the measurement method of this embodiment does not require a master lens, it can be applied to a wide variety of lens shapes.

(Effects of the Invention) As described above, according to the present invention, automatic measurement can significantly reduce costs.

Moreover, by changing from human measurement to mechanical measurement, measurement errors can be prevented and measurement accuracy can be further improved.

Furthermore, poor handling (burrs, scratches, etc.) can be prevented.

Since automatic correction is always performed, the quality of each process is stabilized, and therefore the NR quality of the final process (polishing process) can be stabilized and quality defects can be prevented.

[Brief Description of the Drawings] Fig. 1 is an explanatory diagram showing the concept of the spherical surface measurement method of the present invention, Fig. 2 is a configuration explanatory diagram showing a first embodiment of an apparatus for carrying out the spherical surface measurement method of the present invention, and Fig. 3 4 is a configuration explanatory diagram showing a second embodiment of an apparatus for implementing the spherical surface measurement method of the present invention, FIG. 4 is a configuration explanatory diagram showing a third embodiment of the apparatus for implementing the spherical surface measurement method of the present invention, and FIG. FIG. 2 is a configuration explanatory diagram showing a spherical surface measuring device. Work axis Lens holder Measured object (lens) Spherical meter adapter Axial comparison measured object (master lens) Arm grinding wheel Spherical measuring instrument Curve generator Processing machine Lower shaft Water absorber Rotating arm pipe... Measurement sensor Index measuring terminal Spherical measuring device

Claims (1)

[Claims] 1. When measuring the spherical surface of an optical element, the optical element is
A method for measuring the spherical surface of an optical element, characterized in that the curvature before processing and the curvature after processing are automatically measured while the optical element is held on two processing axes. 2. A spherical surface measuring device for an optical element, comprising a comparative measurement object (master lens), a spherical meter, a movable device having the spherical meter, and a moving means for bringing the master lens and the spherical meter into contact, An optical element spherical surface measuring device characterized in that the movable device is moved to a measurement position of the optical element to perform comparative measurements between the optical element spherical surface and a master lens.