JP2002144245A - Tool manufacturing method and optical element processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To process a lens with no error strictly in a target shape, etc. SOLUTION: An optical element is processed by a sample tool manufactured in accordance with an optical element target shape of the lens, etc., and its spherical surface shape is precisely measured with a shape measuring instrument. The shape measuring instrument has a probe 1 to scan a surface G1 of a measuring object G and computes a radius of curvature of the surface G1 from its displacement quantity in the Z axial direction. A difference of the radium of curvature is found as a relative value between the processed spherical surface shape of the optical element measured in this way and a spherical surface shape of the sample tool, and the lens, etc., is processed by using the tool having a radium of curvature from which the above difference is deducted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tool manufacturing method for manufacturing a polishing tool for processing an optical element such as a spherical lens and an optical element processing method.

[0002]

2. Description of the Related Art As a tool for machining a spherical lens or the like, a grinding tool used in a grinding process includes a pellet dish in which diamond abrasive grains are solidified with a holding agent. The pellet dish has a target shape and radius of curvature. It is manufactured by rubbing it with a casting dish made to have the shape and radius of curvature. Examples of the polishing tool used in the polishing step include a poly dish made by sticking a polyurethane sheet to a spherical surface made of cast iron or the like, and a fixed abrasive dish made by hardening an abrasive with a resin. For a fixed abrasive grain dish, first, a diamond dish (matching tool) rubbed with a casting dish made to the desired shape and radius of curvature is manufactured, and rubbed with this diamond dish to process it into the specified shape and radius of curvature. are doing.

In order for a lens to be machined into a target shape, it is necessary that the shape of the above-mentioned tool is as designed, and this is done by directly measuring the shape of the tool. That part must be corrected. However, with a simple sphere meter used at the production site,
The tool shape could not be measured directly.

More specifically, as shown in FIG. 5A, a pellet dish 401 serving as a grinding tool has a value obtained when a stylus 402 or a ring 403 of a simple sphere meter 400 hits a diamond abrasive grain 404. As shown in FIG. 5B, the difference between the value when the stylus 402 and the ring 403 of the simple sphere meter 400 do not hit the diamond abrasive grains 404 is as follows.
Since the size of the diamond abrasive grains 404 is 2 to 3 μm, the required accuracy does not reach ± 0.5 μm.

[0005] As shown in FIG. 5 (c), the ring 403 of the simple sphere meter 400 is deformed as shown by the curve A due to the elasticity of the policy 406 in the poly dish 405 which is a polishing tool. And the stylus 402 is a policy 4
The difference in the value between the case of hitting the pore 407 of the cell 06 and the case of not hitting it is several μm, which is the size of the hole 407.
m to several hundred μm, which does not reach the required accuracy of ± 1 Newton. In addition, the simple sphere meter can calculate only the radius of curvature for the point measurement, and the calculated radius of curvature is also inaccurate for the above-described reason, and the spherical shape is unknown.

[0006] A fixed abrasive dish, which is a polishing tool, has a small number of pores and can be measured with a simple sphere meter. However, as described above, only the radius of curvature can be calculated and the spherical shape cannot be known. Cannot be determined, and the appropriateness of the tool shape is unknown.

On the other hand, when a commercially available shape measuring instrument is used, the spherical shape of the above-mentioned tool can be calculated, but it is impossible to accurately measure the radius of curvature due to diamond abrasive grains or pores. There were challenges. In order to solve this problem, the present applicant has proposed a method of measuring the surface shape by correcting data avoiding diamond abrasive grains, pores, and the like (see Japanese Patent Application Laid-Open No. 08-219764). According to this, the above problem can be solved, but this method is only for the tool shape, and even if the shape of the tool is measured by this method and created according to the design value, the lens processed by this tool can be used. The relationship with the shape is unknown.

Therefore, in the conventional production site, the following 2
The tool shape was modified by one of the two measurement methods.

FIG. 6 shows a method of correcting a convex pellet dish according to a conventional example. As shown in FIG.
The casting dish 501 manufactured according to the design value is attached to a machine (not shown), and the pellet dish 5 is inserted into the recess of the casting dish 501.
02 is placed with interposed sand 503 etc.
Rotate 1 At the same time, the pellet plate 502 is swung and rotated to perform the alignment process.

After the joining process, as shown in FIG.
A pellet dish 502 is attached to a machine (not shown), a lens 504 to be ground is placed on the pellet dish 502, and the pellet dish 502 is rotated.
Is oscillated and rotated to perform grinding.

After the grinding, as shown in FIG.
Simple sphere meter 50 on sphere prototype 505 serving as master gauge
6 is pressed against the open portion of the ring 507 to adjust the scale of the dial gauge 508 to a zero point. Then, as shown in FIG. 6D, the open portion of the ring 507 of the simple sphere meter 506 in which the scale of the lens 504 as the object to be measured has been adjusted to zero point is replaced with the spherical prototype 505 as shown in FIG. The scale of the dial gauge 508 is read by pressing.

That is, the lens 504 corresponds to a circular section formed at the contact point 509 between the lens 504 and the ring 507.
And the height Y of the contact point 513 between the spherical prototype 505 and the probe 510 with respect to the circular section formed by the contact point 512 between the spherical prototype 505 and the ring 507. The difference Z from the height X appears on the scale of the dial gauge 508. Here, when Y−X = −Z, the concave spherical shape is large, and when Y−X = + Z, the concave spherical shape is small.

In this manner, it is determined how much the radius of curvature of the lens 504 deviates from the design value. If the radius of curvature is out of the tolerance, the radius of curvature of the pellet plate 502 is the desired radius of curvature. Judge that there is no. Therefore, in this case, the process returns to the process of FIG. 6A, and the processes of FIG. 6B, FIG. 6C, and FIG. 6D are performed again until the radius of curvature of the lens 504 falls within the tolerance of the design value. Repeat. The tool was made in this way.

On the other hand, the poly dish used in the polishing step is corrected by the step shown in FIG.

FIG. 7 (a) shows a process of aligning a diamond plate for aligning a poly plate, in which a casting plate 601 manufactured by casting as designed is mounted on a machine (not shown), Diamond plate (matching plate) 60 on the convex part of 601
2 are arranged with a sand 603 therebetween.
To rotate. At the same time, the diamond plate 602 is rocked and rotated to perform the alignment process.

When the diamond plate 602 is completed, as shown in FIG. 7B, the poly plate 604 and the above-mentioned diamond plate 6
02 to a matching machine (not shown).
02 is rotated and at the same time, the poly plate 604 arranged with water in the concave portion of the diamond plate is rocked and rotated to adjust until the amount of depletion of the poly plate 604 reaches a certain value.

After the plastic plate 604 has been aligned, as shown in FIG.
4 is attached, and the lens 605 to be polished is
Is placed on the poly plate 604 with the intermediary of the lens, and the polishing process is performed by rotating the poly plate 604 and simultaneously swinging and rotating the lens 605.

After the polishing, as shown in FIG.
The lens 605 is placed on the spherical prototype 607 serving as a master gauge. A gap B occurs when the spherical prototype 607 and the lens 605 have different radii of curvature. When the single light α is irradiated from below the spherical prototype 607, the Newton ring 608 can be observed through the lens 605 due to the relationship between the wavelength λ and the gap. One of the Newton rings is λ / 2, which indicates how much the radius of curvature of the lens 605 differs from that of the spherical prototype 607 depending on the number of Newton rings.

If the radius of curvature of the lens 605 is out of the design value tolerance, the process returns to the step (a) of FIG. 7 and the steps (b), (c), and (d) of FIG. Is repeatedly performed until the radius of curvature becomes within the tolerance of the design value. This method is the same when the polishing tool is a fixed abrasive dish.

[0020]

According to the above prior art, even if the tool shape is directly measured using a shape measuring instrument, the correlation between the lens to be machined and the tool is not known. Shows the measured values as designed, but the processed lens deviates from the designed values. In such a case, the method of manufacturing a tool by measuring the processed lens and repeating the same matching processing until the lens reaches a design value takes a long time in the process, and the cost is high. There were challenges.

The present invention has been made in view of the above-mentioned unresolved problems of the prior art, and has been made by manufacturing a tool based on a correlation value between a processed lens and a tool.
It is an object of the present invention to provide a tool manufacturing method and an optical element processing method that can significantly improve the reliability of a processing shape of a lens or the like.

[0022]

In order to achieve the above object, a tool manufacturing method according to the present invention measures a processing spherical shape of an optical element processed by a sample tool based on an optical element target shape, and calculates the processing spherical shape. And obtaining a correlation value between the sample and the spherical shape of the sample tool. The tool is manufactured based on the obtained correlation value and the target shape of the optical element.

The present invention also relates to a tool manufacturing method for manufacturing a mating tool used in a step of manufacturing a polishing tool, wherein the method comprises the steps of: Measure the processed spherical shape,
A tool for obtaining a correlation value between the processed spherical shape and the spherical shape of the matching sample tool, and manufacturing a matching tool based on the obtained correlation value and the optical element target shape. A manufacturing method may be used.

When the shape measuring device for measuring the spherical shape by measuring the amount of displacement of the stylus that scans the surface of the object to be measured measures the processed spherical shape of the optical element and the spherical shape of the sample tool or the combined sample tool. Good.

An optical element processing method according to the present invention is characterized in that a lens is processed using a tool manufactured by the above-described tool manufacturing method.

[0026]

In order to process an optical element according to a target design shape, the optical element is processed using a sample tool or a combined sample tool manufactured based on the target shape of the optical element, and the processed spherical shape is measured. And a curvature radius difference is calculated as a correlation value between the optical element and the target shape.

If a grinding tool or a polishing tool is manufactured by correcting the design shape so as to cancel the difference in the radius of curvature determined in advance in this way, and a lens or the like is machined using the tool,
It is possible to efficiently produce a high-quality optical element having high shape accuracy.

[0028]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 illustrates a shape measuring instrument used in one embodiment. This apparatus has a stylus 1 and
The stylus 1 is urged in a vertical direction (Z-axis direction) against a surface G1 of a plate G, which is a grinding tool, a polishing tool, or a combination tool as a measurement object, and is moved in a predetermined scanning direction (X-axis direction). (Scan direction) on the surface G1 for a predetermined scanning length L. The reading unit 2 reads the position of the stylus 1 in the X-axis direction and the displacement (vertical movement) of the stylus 1 in the Z-axis direction at that position. The calculation unit 3 reads the X of the stylus 1 from the reading unit 2.
The surface shape of the dish G is calculated by reading data in the axial direction and the Z-axis direction. The calculation result is displayed on the display unit 4,
Also, it is printed by the printer 5. The contact portion of the stylus 1 is made of diamond or sapphire, and the arithmetic unit 3, the display unit 4, and the printer 5 are controlled based on a command input to the keyboard 6.

The calculation unit 3 includes an I / O 31 for exchanging data with the reading unit 2 and a CPU for controlling and calculating.
(Central processing unit) 32, RAM (random access memory) 33 for temporarily storing various data required for processing by the CPU 32, and ROM (read only memory) 34 in which arithmetic programs and control programs are written
And an I / O 35 for transmitting a command signal from the keyboard 6 to the CPU 32, and interfaces 37 and 38 for converting the calculation progress and the result of the CPU 32 into signals for printing.

Next, a method for manufacturing a tool using the above-described apparatus will be described in detail.

First, in order to manufacture a grinding dish (pellet dish) as a grinding tool, a polishing dish (fixed abrasive dish / poly dish) as a polishing tool, or a matching dish (diamond dish) as a matching tool thereof. The casting tray is manufactured according to the design value based on the element target shape. Since the surface of the casting dish has a fine roughness, the shape can be measured with sufficient accuracy using a simple spherical meter or a shape measuring instrument, and it is easy to produce a desired shape.

[0033] A pellet dish that is fully matched with the casting dish manufactured, a combination dish (diamond dish) of a polishing dish that is sufficiently matched with the casting dish, or a polishing dish (fixed abrasive dish and poly dish) that is sufficiently matched with the diamond dish is specified. Set to the measurement position of
Is operated to move the stylus 1 to a predetermined start position.

At this time, the surface roughness and the radius of curvature of the measuring object G are roughly known, and the radius of curvature of the stylus 1 used in accordance with the shape of the measuring object is known in advance. The stylus is selected, and the scanning length L of the stylus 1 is set to be equal to or larger than the radius of curvature of the measurement object G in order to increase the accuracy.

Under these conditions, after inputting the stylus condition and scanning length of the stylus 1 and the measuring condition such as the type of the shape of the grinding / polishing dish G which is the object to be measured, the measurement is started by pressing the start key. Is sent to the CPU 32.

The scanning length L of the stylus 1 can be set arbitrarily, and the stylus 1 is appropriately replaced with one having a different outer diameter at the tip. The stylus 1 scans on the surface G1 of the measurement object G by the measurement length L in the X-axis direction, and the reading unit 2 reads the position of the stylus 1 in the X-axis direction and the displacement in the Z-axis direction and outputs them to the CPU 32. , The CPU 32 temporarily stores the data in the RAM 33.

After the scanning, the CPU 32 calculates the surface shape of the grinding / polishing dish G based on the data stored in the RAM 33. Thereby, the display unit 4 or the printer 5
The surface shape, radius of curvature and the like of the grinding / polishing plate G are output.

Next, the lens processed by the aforementioned tool is measured in the same manner as described above, and the surface shape, radius of curvature and the like are output. The processed spherical shape of the sample tool or the sample matching tool measured in this way and the processed spherical shape of the lens processed using the same may have a relationship having correlation values as shown in FIGS. I understand.

FIG. 2 shows the results obtained by changing the processing conditions in the grinding step and measuring the spherical shapes of a grinding dish (convex pellet dish) as a sample tool and a concave lens as an optical element processed by the same method as described above. The vertical axis shows the difference in curvature radius between the grinding plate and the processed lens, and the horizontal axis shows the processing conditions. Graph 40 shows the average value of the data.
As can be seen from FIG. 2, the difference in radius of curvature between the pellet dish and the lens is approximately 0.5 μm. Here, the radius of curvature of the stylus when measuring the pellet dish and the lens in FIG. 2 is 2 mm.
It is.

As described above, since the correlation value between the pellet dish and the processed spherical shape of the lens is 0.5 μm, in order to process the lens shape as designed, the spherical shape of the pellet dish must have a radius of curvature. Is larger than the lens radius of curvature by 0.1 mm.
It may be manufactured with a difference of 5 μm.

In the actual tool manufacturing process, the combined pellet dishes are measured at the above-mentioned stylus radius of curvature, and a radius of curvature having the aforementioned correlation value, that is, a radius of curvature difference, is obtained from a desired lens radius of curvature. Adjust the radius of curvature of the pellet dish.

FIG. 3 shows that the processing conditions are changed in the polishing step, the radius of curvature between the convex poly-dish (polishing tool) as a sample tool and the concave lens processed by the same is measured by the same method as described above, and the difference in the radius of curvature is calculated. The difference between the radius of curvature of the convex lens and the processed lens is plotted on the vertical axis, and the processing conditions are plotted on the horizontal axis. Graph 41 shows the average value of the data. As can be seen from this figure, the radius of curvature difference, which is the correlation value between the convex poly-plate and the lens, is approximately 1.5 μm. Here, the radius of curvature of the stylus when measuring the convex plastic dish of FIG. 3 is 2 mm, and the radius of curvature of the stylus when measuring the lens is 0.5 mm.

Since the correlation value between the convex poly-dish and the lens measured under these measurement conditions is 1.5 μm, the shape of the convex poly-dish must be at the radius of curvature in order to process the lens shape as designed. It may be manufactured with a difference of 1.5 μm from the lens radius of curvature.

In the actual tool manufacturing process, the combined convex poly-dish is measured with the above-mentioned stylus radius of curvature, and is adjusted to have a radius of curvature having the above-mentioned correlation value difference from the desired lens radius of curvature. The curvature radius of the convex poly dish is adjusted. Then, by processing with this convex poly-dish, it is possible to manufacture a lens as designed.

FIG. 4 shows that the processing conditions are changed in the polishing process, and the radius of curvature of the diamond plate, which is a mating sample tool, the polishing plate (fixed abrasive plate), and the concave lens processed by the polishing plate are measured by the same method as described above. It was done. The vertical axis shows the difference between the radius of curvature of the diamond dish and the fixed abrasive dish, the fixed abrasive dish and the radius of curvature of the processed lens, and the horizontal axis shows the processing conditions. The graph 43 shows the data of the diamond dish-fixed abrasive dish. Shows the average value. Graph 44 shows the average value of the data of the fixed abrasive dish-lens. As can be seen from this figure, the difference in radius of curvature between the diamond plate and the fixed abrasive plate is approximately 0.5 μm. The difference in radius of curvature between the fixed abrasive dish and the lens is approximately 1.5 μm. Here, the radius of curvature of the stylus when measuring the diamond dish of FIG. 4 is 2 mm, and the radius of curvature of the stylus when measuring the fixed abrasive dish and the lens is 0.5 mm.
It is.

The correlation value between the fixed abrasive dish and the lens measured under these measurement conditions is 1.5 μm (the radius of curvature of the fixed abrasive dish is larger than the radius of curvature of the lens). The correlation value with the dish is 0.5 μm (the radius of curvature of the fixed abrasive dish is larger than the radius of curvature of the diamond dish). That is, when the sizes of the radius of curvature of the diamond plate, the fixed abrasive plate, and the lens are compared with each other on the basis of the lens, the fixed abrasive plate is 1.5 μm larger than the lens, and the diamond plate is 1.0 μm larger than the lens. . Therefore, when processing the lens shape according to the design value, if the shape of the diamond dish is manufactured with a difference of 1.0 μm from the lens curvature radius at the radius of curvature, the shape of the fixed abrasive dish will be the lens dish at the radius of curvature. Is 1.5 μm different from the radius of curvature of the lens, and the radius of curvature of the polished lens eventually becomes the designed value.

In the actual tool manufacturing process, the combined diamond plate is measured at the above-mentioned stylus curvature radius, and the diamond radius is adjusted so as to have a curvature radius having a difference between the desired lens curvature radius and the above-described correlation value. Adjust the radius of curvature of the dish. Then, the fixed abrasive dish adjusted by the diamond dish has a radius of curvature having the above-described correlation value.

Although the above description has been made by selecting a certain radius of curvature for improving the accuracy of the stylus curvature, sufficient accuracy is possible with a stylus curvature radius other than this radius of curvature. In this case, the radius of curvature of the object to be measured is different depending on the radius of curvature of the stylus, and the correlation value between the tool and the lens is different. Therefore, in this case, the tool may be manufactured according to the correlation value by checking the correlation value once beforehand.

[0049]

Since the present invention is configured as described above, the following effects can be obtained.

A correlation value between the spherical shape of a tool such as a grinding tool or a polishing tool or a matching tool and an optical element such as a lens processed by the tool is determined in advance, and a spherical shape tool or a matching tool taking this correlation value into consideration. Is manufactured and used for processing an optical element.

At the time of manufacturing a tool, it is only necessary to add a correction based on the above correlation value to a design value. Therefore, a lens or the like is actually processed to obtain a shape error, and then the spherical shape of the tool is corrected and processed. Compared with the case, the time and cost required for tool manufacturing can be greatly reduced, and a high-quality lens or the like having the same design value without a shape error can be efficiently produced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a shape measuring instrument used in an embodiment.

FIG. 2 is a graph showing a graph for obtaining a correlation value between a grinding plate and a lens.

FIG. 3 is a diagram showing a graph for calculating a polishing plate-lens correlation value.

FIG. 4 is a diagram showing a graph for calculating a correlation value between a combination dish and a polishing dish-lens.

FIG. 5 is a diagram showing a conventional measurement method using a simple sphere meter.

FIG. 6 is a diagram showing a grinding plate manufacturing process according to a conventional example.

FIG. 7 is a view showing a polishing dish manufacturing process according to another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Touch probe 2 Reading part 3 Operation part 4 Display part 5 Printer 6 Keyboard 31, 35 I / O 32 CPU 33 RAM 34 ROM 36 VRAM 37, 38 Interface

Claims (5)

[Claims] 1. A processing spherical shape of an optical element processed by a sample tool based on an optical element target shape is measured.
Obtaining a correlation value between the processed spherical shape and the spherical shape of the sample tool, and manufacturing a tool based on the obtained correlation value and the optical element target shape. . 2. The method according to claim 1, wherein the tool is a grinding tool or a polishing tool. 3. A tool manufacturing method for manufacturing a mating tool used in a step of manufacturing a polishing tool, comprising the steps of: Measuring the processing spherical shape and obtaining a correlation value between the processing spherical shape and the spherical shape of the matching sample tool, and manufacturing a matching tool based on the obtained correlation value and the optical element target shape. A method for producing a tool. 4. A shape measuring device for measuring a spherical shape by measuring a displacement amount of a stylus for scanning a surface of a measuring object, thereby forming a processed spherical shape of an optical element and a spherical shape of a sample tool or a combined sample tool. The tool manufacturing method according to claim 1, wherein the measurement is performed. 5. An optical element processing method, wherein a lens is processed using a tool manufactured by the tool manufacturing method according to any one of claims 1 to 4.