JP2016132082A - Tool and tool manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tool capable of accurately processing a workpiece so that a shape error can be within an allowable value range by using a catalyst support type processing method for removing the workpiece by the chemical action of a catalyst with water without using any abrasive grains, and a manufacturing method thereof.SOLUTION: A tool 1 includes a catalyst part 2 including transition metal on a surface facing a workpiece 4, and a base part 3 for supporting the catalyst part 2. By relatively moving the catalyst part 2 in contact with or close to the workpiece 4 in the interposed state of water molecules, the workpiece 4 is processed until a curvature radius where a difference from a target curvature radius is equal to or lower than an allowable value ΔHis achieved. The tool 1 is manufactured so that a value obtained by adding together a difference ΔH between the target curvature radius and the curvature radius Rof the catalyst part of the tool and the shape error amount ΔFof the catalyst part of the tool from a true sphere having the curvature radius of the catalyst part can be equal to lower than the ΔH.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tool for processing a workpiece such as a spherical lens using a processing method that removes the workpiece by a chemical action using a catalyst and water without using abrasive grains, and a method for manufacturing the same. is there.

  Conventionally, as a polishing method of an optical element such as a spherical lens, a workpiece and a workpiece are removed by moving the tool and the workpiece in contact with each other while supplying polishing slurry containing abrasive grains to the tool surface. A loose abrasive polishing method is generally performed. By this processing operation, the surface of the workpiece is smoothed and a processed surface with a small surface roughness is obtained.

  For polishing glass used as an optical element material, cerium oxide is mainly used as abrasive grains. However, cerium oxide is a rare earth, and the price fluctuates in recent years, resulting in a problem that it cannot be stably obtained. Against the background of such problems, a catalyst-assisted processing method as shown in Patent Document 1 has been proposed as a processing method of a workpiece that does not use abrasive grains. According to the processing method of Patent Document 1, a solid oxide is used as a workpiece, a catalytic substance that assists in the generation of a decomposition product by hydrolysis is used as a processing reference plane, and the workpiece and the processing reference plane are present in the presence of water. Are placed in contact with each other or in close proximity, and the two are moved relative to each other. According to this catalyst-assisted processing method, a workpiece made of an oxide typified by optical glass can be smoothed without using abrasive grains.

  Here, the conventional example described in Patent Document 1 mainly targets a planar workpiece, and how to process a radius of curvature that is important in an optical element such as a spherical lens into a target value. Specific means are not described. In particular, the method for determining the shape of the catalyst portion of the tool to be the processing reference surface is unknown.

  On the other hand, for example, Patent Document 2 discloses a manufacturing method of a tool for processing a spherical lens by a conventional loose abrasive polishing method in which polishing is performed using abrasive grains. In the method of Patent Document 2, a sample tool having a radius of curvature equivalent to a target radius of curvature of an optical element and a radius of curvature of a lens processed by the tool are measured. And a tool is manufactured so that it may become a curvature radius which cancels the correlation value of the curvature radius of a sample tool and a lens. By using the tool manufactured by this method, a lens having a target radius of curvature can be produced.

International Publication No. 2013/084934 JP 2002-144245 A

  However, even when a lens is processed by the catalyst-assisted processing method described in Patent Document 1 with a tool whose radius of curvature is determined based on the method described in Patent Document 2, a lens having a target curvature radius is not necessarily obtained. There was no problem.

  This is because the catalyst-assisted machining method has no abrasive grains between the tool and the workpiece as in the conventional machining method, and the shape characteristics of the tool, especially its catalyst part, directly affect the machining accuracy. It is believed that there is. For example, the spherical shape formed by the envelope shape of the tool is considered to be more directly involved in forming the workpiece. And if there are individual differences in the shape factors other than the radius of curvature of the tool, the radius of curvature of the spherical surface formed by the envelope surface shape of the tool will change, and the shape error of the workpiece will exceed the allowable range Inferred.

  Accordingly, an object of the present invention is to use a catalyst-assisted machining method that removes a workpiece by a chemical action using a catalyst and water without using abrasive grains, and accurately corrects the workpiece so that a shape error is within an allowable range. It is to provide a tool that can be processed well, or a method for manufacturing the tool.

  In order to solve the above-described problem, in the tool of the present invention, the surface of the workpiece facing the workpiece has a catalyst part containing a transition metal, and a base part that supports the catalyst part, and the catalyst part has water molecules. By moving the workpiece relative to the workpiece in contact with or approaching the workpiece while being interposed, the workpiece is machined to a radius of curvature where the difference from the target radius of curvature is less than an allowable value. A difference between the target radius of curvature and the radius of curvature of the catalyst portion of the tool, and a shape error amount of the catalyst portion of the tool from a true sphere having the radius of curvature of the catalyst portion, It is characterized by a structure manufactured so that a value obtained by adding the values is equal to or less than the allowable value.

  In the present invention, not only the difference between the target radius of curvature and the radius of curvature of the catalyst portion of the tool, but also the shape error amount of the catalyst portion of the tool from the true sphere having the radius of curvature of the catalyst portion. Used to determine the dimensional conditions of the tool. For this reason, the radius of curvature of the spherical surface formed by the envelope shape of the catalyst portion of the tool is within the allowable radius of curvature of the workpiece, so that the error of the radius of curvature is surely below the allowable value by the catalyst-assisted machining method. There is an excellent effect of obtaining a tool capable of processing a workpiece.

The theory concerning the dimensional relationship between a tool and a workpiece is shown, (a) is a sectional view of the tool, (b) is a diagram showing the amount of shape error of the catalyst part of the tool, and (c) is the workpiece. It is explanatory drawing which showed the dimension tolerance | permissible_range. It is the perspective view which showed an example of the external appearance of the tool manufactured by this invention. The surface roughness of the tool manufactured in Example 1 of this invention is shown, (a) is explanatory drawing of a surface state, (b) is the diagram which showed distribution of the height of the surface. The shape error of the surface of the tool manufactured in Example 1 of this invention is shown, (a) is explanatory drawing of a surface state, (b) is the diagram which showed the shape error. It is explanatory drawing which showed a mode that a workpiece was processed with the tool manufactured in Example 1 of this invention. It is explanatory drawing which shows the difference of the curvature radius of the workpiece processed with the tool manufactured in Example 1 of this invention. It is explanatory drawing which showed the curvature radius of the workpiece processed with the tool manufactured in Example 1 of this invention. It is explanatory drawing of the surface state of the workpiece processed with the tool manufactured in Example 1 of this invention. The processing result of the workpiece processed with the tool manufactured in Example 1 of this invention is shown, (a) is explanatory drawing of the interference fringe image of a workpiece, (b) is a cross section of a workpiece. It is explanatory drawing of this shape error profile. It is explanatory drawing which showed the curvature radius of the to-be-processed object each processed with the three tools manufactured in Example 2 of this invention. It is the flowchart figure which showed the flow of the manufacturing process which manufactures the tool which implemented this invention, or performs quality determination further. It is the block diagram which showed an example of the hardware constitutions for performing quality determination of the tool which implemented this invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. In addition, the Example mentioned later is an example to the last, For example, about the structure of a detail, those skilled in the art can change suitably in the range which does not deviate from the meaning of this invention. Moreover, the numerical value taken up by this embodiment is a reference numerical value, Comprising: This invention is not limited.

  First, the shape that should be satisfied by the catalyst portion of the tool used for machining the workpiece by the catalyst-assisted machining method will be considered. As described above, in the catalyst-assisted processing method, the catalyst portion that includes the transition metal on the surface facing the workpiece and the base portion that supports the catalyst portion, and water molecules are interposed in the catalyst portion. The workpiece is moved relative to the workpiece in contact with or close to the workpiece. As a result, the workpiece is machined to a radius of curvature at which the difference from the target radius of curvature is equal to or less than an allowable value.

  In such a catalyst-assisted processing method, there is no abrasive grain used in the conventional processing method between the tool and the workpiece. For this reason, it is considered that the accuracy of the shape of the tool, particularly the shape of the catalyst portion thereof, for example, the spherical shape formed by the envelope shape of the tool (catalyst portion), directly affects the machining accuracy.

  What can be considered as a shape factor other than the radius of curvature that can occur as individual differences between tools is, for example, the shape error amount of the true sphere having the target radius of curvature of the workpiece and the catalyst portion of the tool. Hereinafter, a dimensional accuracy range of the tool will be considered in consideration of this shape error amount as one of the conditions.

  As an example of the tool according to the present invention, FIG. 1A shows a cross section of a tool having a convex spherical shape for processing a workpiece into a concave spherical surface. In FIG. 1A, the left-right direction in the figure is the X axis, and the up-down direction is the Z axis.

In FIG. 1A, a tool 1 has a catalyst part 2 and a base part 3 that supports the catalyst part 2 on a surface facing a workpiece. Further, the outer diameter of the workpiece D _W, the radius of curvature of the target R _W of the _workpiece, the radius of curvature of the catalyst portion 2 and R _T, spherical in outer diameter D _W of the spherical surface having a curvature radius R _W The missing height is H _W , and the spherical missing height at the outer diameter D _W of the spherical surface having the radius of curvature R _T is H _T. At this time, H _W and H _T are represented by the following equations (1) and (2), respectively.

Here, the absolute value of the difference between the ball-missing heights H _W and H _T is ΔH. In this embodiment, the difference between the target curvature radius and the curvature radius of the catalyst unit 2 is defined as ΔH. From the equations (1) and (2), the difference ΔH between the target radius of curvature and the radius of curvature of the catalyst part 2 is expressed by the following equation (3).

FIG. 1B shows the shape error of the true sphere having the radius of curvature _RT and the catalyst portion 2. In FIG. 1B, the X axis (horizontal axis) coincides with FIG. 1A, but the Y axis (vertical axis) uses an interferometer or the like as described later (FIGS. 4A and 4B). It is the shape error of the catalyst part 2 measured by the above.

As in the examples described later, for example, the base portion 3 is formed by a general method so that the curvature radius _RT of the catalyst portion 2 is about several tens of millimeters, and the catalyst portion 2 is formed by film formation or the like. In this case, when the catalyst part 2 is measured using an interferometer or the like, the shape of the catalyst part 2 is not necessarily a true sphere, and the radius of curvature R _T (several tens of millimeters) of the ideal true sphere catalyst part 2 is obtained. Fluctuations are recognized in the range of about several tens of nm with respect to (order).

In the present embodiment, the difference between the maximum value and the minimum value of the shape error from the (true sphere having a radius of curvature R _T) ideal shape of the catalytic unit 2 shown in FIG. 1 (b) is defined as [Delta] F _T, the following, referred as the shape error amount [Delta] F _T of the catalyst unit 2. This embodiment, a conventional (e.g., Patent Document 2) is characterized in that the catalyst portion 2 of the shape error amount [Delta] F _T which has not been used in that used as one of the conditions for dimensional control of the tool 1.

Next, the target radius of curvature (R _W ) of the workpiece (4) and its allowable value (ΔH _W ) will be considered.

FIG. 1C shows a cross section of the workpiece 4. In FIG. 1 (c), the outer diameter of the workpiece 4 D _W, the curvature radius R _W of the target of the workpiece _4, the error amount of curvature allowed the [Delta] R _W. Further, the absolute value of the difference between the spherical segment height and H _W at the outer diameter D _W of the spherical surface having a curvature radius of R ± [Delta] R _W and [Delta] H _W. In the present embodiment, this ΔH _W is set as an allowable value from the target radius of curvature of the workpiece 4. The allowable value ΔH _W from the target radius of curvature of the workpiece 4 is expressed by the following equation (4).

In the present embodiment, the difference ΔH between the curvature radius of the target curvature radius R _W and the catalyst portion of the workpiece 4, a value obtained by adding the shape error amount [Delta] F _T from the true sphere of the catalyst portion 2, The tool 1 is manufactured by managing the dimensions so that the allowable value ΔH _W or less. In other words, the difference between the target curvature radius R _W and the radius of curvature of the catalyst unit [Delta] H, the relationship between the shape error amount [Delta] F _T and tolerance [Delta] H _W to produce the tool 1 so as to satisfy the equation (5) below.

That is, the difference ΔH between the target curvature radius R _W and the radius of curvature of the catalyst portion 2 of the tool 1, the shape error amount [Delta] F _T from the ideal shape of the catalyst unit 2 (true sphere having a radius of curvature of the catalyst unit), the The tool is manufactured so that the added value is equal to or less than the allowable value ΔH _W from the target radius of curvature of the workpiece 4.

  By manufacturing the tool so as to satisfy the above formula (5), the radius of curvature of the spherical surface formed by the envelope shape of the catalyst portion 2 is within the allowable radius of curvature of the workpiece.

  Here, the left side of the formula (5) may be considered as a (maximum) space range where the interface of the catalyst unit 2 that moves relative to the workpiece 4 in contact with or close to the workpiece 4 moves in and out. As described above, in the catalyst-assisted processing, since there are no abrasive grains involved in polishing, the shape of the catalyst portion 2 of the tool 1 is directly involved in the processing.

According to the dimensional control as expressed by the equation (5), the range of the space where the interface of the catalyst part 2 that moves relative to the workpiece 4 in contact with or approaches the workpiece 4 is an allowable value from the target curvature radius of the workpiece 4. It is managed to be ΔH _W or less. Therefore, it is considered that the processed surface of the workpiece 4 can be reliably prevented from exceeding the allowable range of the target curvature. That is, a spherical lens in which an error from the target radius of curvature is equal to or less than an allowable value can be processed by manufacturing a tool by performing dimension management as shown in Expression (5).

On the other hand, for example, in the technique described in Patent Document 2, in order to achieve the target curvature radius of the workpiece 4, the sample processing is repeated, and a constant value between the curvature radius of the sample tool and the curvature radius of the sample optical element is obtained. Is a relationship. In Patent Document 2, for example, the shape error of the polishing surface of the tool (corresponding to the shape error amount [Delta] F _T of the catalytic unit 2 above) such as has not been considered at all.

Therefore, in the catalyst-aided machining shape of the catalyst unit 2 is involved in the processing directly, only the technique of Patent Document 2, a large variation occurs in the shape error amount [Delta] F _T of the catalytic unit 2, readily be It is considered that the radius of curvature of the work surface of the workpiece 4 exceeds the allowable range.

  Here, a specific method for manufacturing the tool 1 will be described.

  A means for generating the catalyst part 2 in a shape satisfying the formula (5) on the base part 3 of the tool 1 is not particularly limited. For example, the catalyst part 2 may be formed by direct processing, or a method in which the base part 3 is formed and then a catalyst material is thinly coated on the base part 3 may be used.

  For the processing of the catalyst portion 2 and the base portion 3, a general method such as cutting using a diamond tool or grinding using a diamond grindstone can be used. Moreover, you may use the grinding | polishing method using abrasive grains, such as a free abrasive grain grinding | polishing process using soft abrasive grains, such as hard abrasive grains, such as diamond and silicon carbide, and cerium oxide. Further, from the viewpoint of efficiently supplying water molecules to the surface of the catalyst part 2, grooves and holes may be provided in the catalyst part 2 and the base part 3.

  Further, when the catalyst portion 2 is thin-film coated on the base portion 3, the method is not limited to the present invention, and a general film forming or coating method such as a sputtering method, a CVD method, a plating method, or a coating / drying method is used. Can be used. Furthermore, it is preferable to provide an intermediate film such as carbon between the catalyst part 2 and the base part 3 in order to increase the adhesion between the catalyst part 2 and the base part 3. The film thickness of the catalyst part 2 is not particularly limited, but is preferably, for example, 1000 nm or less from the viewpoint of not deteriorating the shape accuracy.

In addition, in the method of forming the catalyst part 2 by film formation or the like after forming the base part 3, when performing the dimension control by the above formula (5), for example, sample processing is repeated in advance, and the catalyst part 2 after the formation is formed. it is possible to actually measure the radius of curvature R _T shape error amount [Delta] F _T. Based on the actual measurement result, the radius of curvature of the base portion 3 of the tool 1, the film thickness of the catalyst portion 2, film formation control conditions, and the like can be determined so as to satisfy the equation (5).

Moreover, the dimensional condition shown in the above equation (5) can be used for quality determination of the manufactured tool. That is, actually measured radius of curvature R _T shape error amount [Delta] F _T of the catalytic unit 2 of the produced tools, the tool is judged to be good if they meet the dimensional conditions of the above equation (5), the if the condition If not, it is determined as a defective product. The tool determined to be defective is removed from the production line, for example, so as not to be used for actual machining of the workpiece. Or about the tool determined to be inferior goods, shape correction of the catalyst part 2 is carried out until the dimensional condition by the above-mentioned formula (5) is satisfied by polishing the catalyst part 2 by any of the above-described methods. It can be carried out. The configuration and process relating to the quality determination of the manufactured tool will be described later with reference to FIGS.

Further, the examples described later, verification and of the tool, especially produced to do quality determination, and the curvature radius R _T of the formed catalyst section, a shape error amount [Delta] F _T from the true sphere having a radius of curvature R _T measured There is a need to.

And these curvature radius R _T, is not particularly limited as means for measuring a shape error amount [Delta] F _T, for example, a stylus (probe) is brought into contact with the catalyst unit 2 using a stylus type profile measuring instrument, lateral and depth A method of measuring the surface shape of the catalyst unit 2 by scanning in the direction is conceivable. By calculating the measured surface shape data, it is possible to obtain a curvature of the catalyst portion 2 radius R _T and shape error amount [Delta] F _T, the condition of equation (5) is satisfied further using these measured values Can be determined.

Further, Rael from the viewpoint of improving the productivity by suppressing the time required for measurement, and the curvature radius R _T of the catalyst unit, is possible to use a Fizeau interferometer for measuring the shape error amount [Delta] F _T considered. By using the Fizeau interferometer, the shape of the interference fringes appear as a difference between the reference spherical surface can be used a method of calculating a be measured in a short time the shape error amount [Delta] F _T in the entire surface of the catalytic unit 2 it can.

Further, according to the Fizeau interferometer, the radius of curvature _RT of the catalyst portion can be measured in a short time. For example, interference fringes occur when the light emitted from the reference surface gathers at one point (usually a point called a cat's eye point) and the reflected light from the catalyst portion that is the test surface interferes with the reflected light from the reference surface. The radius of curvature R _T of the catalyst part can be measured by measuring the distance from the position where can be observed.

In addition, when the catalyst part 2 is provided with a groove or hole for drainage, in any case of the stylus type measuring machine or the Fizeau interferometer, the groove or hole is measured in advance from the measurement range. There is a need. Alternatively, performing an operation process with the exception of grooves and cavities from the shape data after measurement, it is necessary to obtain the radius of curvature R _T and shape error amount [Delta] F _T. Such control of the measuring machine or arithmetic processing for removing grooves and holes from the measured data can be executed by, for example, a CPU of a measurement system described later.

  The material of the catalyst part 2 needs to contain at least one or more transition metal elements as a catalyst substance that promotes the generation of decomposition products by hydrolysis. Examples of the transition metal element include Pt, Au, Ag, Cu, Ni, Cr, Mo, and the like. These metal elements may be single elements or alloys composed of a plurality of metal elements including transition metal elements. Good.

  Further, the material of the base portion 3 is not particularly limited, but a material having a large Young's modulus is used from the viewpoint of minimizing the deformation of the catalyst portion 2 when the workpiece is processed by contacting the catalyst portion. It is desirable to select. For example, when trying to process a workpiece having a large error from the target radius of curvature, the radius of curvature of the catalyst unit 2 may change due to the contact pressure with the workpiece. When the thickness of the catalyst part 2 is as very thin as 1000 nm or less, the Young's modulus of the base part 3 is important in reducing the deformation of the catalyst part 2 when the workpiece is processed.

Here, when the maximum displacement amount in the thickness direction of the catalyst portion 2 is δ when it is brought into contact with the workpiece, δ is less than the allowable value ΔH _W from the target curvature radius of the workpiece. It should be. In the case of a general optical element, the allowable value ΔH _W from the target curvature radius of the workpiece is often 1000 nm or less. Here, when the displacement amount δ of the catalyst unit 2 is calculated using the Hertz contact model, if the Young's modulus of the base unit 3 is 50 GPa or more, the displacement amount δ is well below 1000 nm or less. That is, it is more desirable to select a material having a Young's modulus of 50 GPa or more as the material of the base portion 3.

  Due to the tool manufacturing method as described above, the radius of curvature of the spherical surface formed by the envelope shape of the catalyst portion of the tool is within the allowable radius of curvature of the workpiece, so that the spherical lens whose curvature radius error is less than the allowable value A tool capable of machining can be obtained.

  Examples 1 and 2 are shown below as examples for verifying whether the above-described tool manufacturing method (manufacturing conditions) is appropriate.

In this embodiment, as a workpiece, the outer diameter _{D W} is 17.8 mm, the radius of curvature _{R W} having a target 63.267Mm, tolerance [Delta] H _W from the radius of curvature having a target concave is 440nm spherical lens Is assumed. In a present Example, the example at the time of manufacturing the tool 1 which processes such a workpiece is shown.

  In FIG. 2, the external shape of the tool 1 manufactured in the present Example is shown. In FIG. 2, the outer diameter of the tool 1 is 35 mm (a 10 mm scale is shown in the lower right of the figure), synthetic quartz glass having a Young's modulus of about 70 GPa is used for the base portion 3, and transition metal is used for the catalyst portion 2. Pt was used.

First, the surface of the base material of the synthetic quartz glass constituting the base portion 3 of the tool 1 was processed to have a shape close to the target curvature radius (R _T ) by grinding using a diamond grindstone. Of course, at this time, the radius of curvature at the finish of processing of the base portion 3 is determined in consideration of the film thickness of the catalyst portion 2 described later. In addition, grooves 5 having a width of 1.8 mm and a depth of 1 mm were formed in a lattice shape on the surface of the base portion 3 so that water molecules can be efficiently supplied during polishing of the workpiece.

  Next, the surface of the base portion 3 was subjected to surface polishing by loose abrasive polishing using cerium oxide abrasive grains so that the shape could be measured with a Fizeau interferometer. Thereafter, Pt, which is a transition metal, as the catalyst part 2 was uniformly coated on the surface of the base part 3 with a thickness of 100 nm by sputtering.

  In FIG. 3, the result of having measured the surface roughness of the catalyst part 2 manufactured in the present Example with the scanning white interferometer (CP-300 (trade name) made by ZYGO) is shown. FIG. 3A is a height map image of a region having a size of φ0.77 mm of the catalyst portion 2. FIG. 3A shows a height map image expressed by gradation as shown in the legend on the right side of the figure. FIG. 3B shows the profile of the AA ′ cross section (vertical axis: nm unit) with the horizontal axis in the tool radial direction (mm). From this measurement result, the surface roughness of the catalyst part 2 was about 0.3 nm RMS, and it was confirmed that the surface was smooth enough to measure the shape with a Fizeau interferometer.

Then, the curvature radius _{R T} of the catalytic unit 2 using a laser interferometer (ZYGO Co. Verifire (trade name)) was measured shape error amount [Delta] F _T from the true sphere having a radius of curvature _{R T.} In this case, the groove 5 is in a state of excluding the evaluation range, to measure the radius of curvature R _T and shape error amount [Delta] F _T. Regarding the radius of curvature _RT , the position where the reflected light from the surface excluding the groove 5 (FIG. 2) interferes with the reflected light from the reference surface in the catalyst unit 2 and the light emitted from the reference surface is observed. It was measured as the distance from the points gathered at one point.

As a result, the curvature radius _{R T} of the catalytic unit 2 was the same 63.267mm curvature radius _{R W} of the target. FIG. 4 shows the result of measuring the shape error of the catalyst part 2. FIG. 4A shows an interference fringe image of the entire catalyst portion 2 (with a diameter of 35 mm) obtained by a laser interferometer. At this time, the groove 5 (FIG. 2) does not appear as interference fringes because the light is scattered and the reflected light cannot be detected. FIG. 4B shows a shape error profile of a cross section along the BB ′ line (FIG. 4A) of the catalyst unit 2 obtained from the laser interferometer.

The above results of measurement, the shape error amount [Delta] F _T of the catalyst portion 2 was 92 nm. In the present invention, the radius of curvature R _T and shape error amount [Delta] F _T of the catalyst unit 2 is required to be satisfying the above formula (5). In the case of the present embodiment, the allowable value ΔH _W from the target curvature radius of the workpiece 4 is calculated as ΔH _W = 440 nm from the above-described dimension of the workpiece and Expression (1).

Further, from the radius of curvature R _T and the shape error amount ΔF _T measured as described above, the added value of ΔH and ΔF _T is calculated as 92 nm (<ΔH _W = 440 nm). Thus, it was confirmed that the tool manufactured by the present Example satisfy | fills the above-mentioned Formula (5).

Next, with the configuration as shown in FIG. 5, the workpiece 4 is processed using the tool 1 manufactured by satisfying the dimensional condition of the above formula (5) as described above, and the processed workpiece 4 is processed. It was examined whether or not the workpiece was processed within the range of the allowable value ΔH _W from the target radius of curvature.

  In FIG. 5, lanthanum-based glass (for example, S-LAM55 (trade name) manufactured by OHARA) was used as the material of the workpiece 4. Pure water was used as the processing liquid 6 and was supplied to the surface of the catalyst portion 2 by the supply means 7 at 1000 ml / min.

  As shown in FIG. 5, the workpiece 4 was supported by the holder 8, and a load of about 2.56 N was applied to the workpiece 4 via the knurled portion 9, and the workpiece 4 and the catalyst unit 2 were brought into contact with each other. The tool 1 was rotated by the driving force of a motor (not shown), and the rotation speed was set to 60 rpm. The workpiece 4 was rotated dependently by the frictional force.

  The workpiece 4 was reciprocated and swung in a range of 2 mm in a cycle of 4 (seconds) by moving the Kanzashi 9 linearly to the left and right in the drawing. At the same time, the workpiece 4 was swung along the surface of the catalyst portion 2 by an eco-rise mechanism (not shown) provided in the holder 8. And it processed by the said method more than the time when the curvature radius of a workpiece is stabilized.

  Thereafter, the radius of curvature of the processed workpiece was measured, and the difference from the target radius of curvature was calculated. Here, a method of calculating the difference from the target curvature radius will be described with reference to FIG.

In FIG. 6, the outer diameter of the workpiece is D _W , the target curvature radius of the workpiece 4 is R _W , and the curvature radius of the processed workpiece is RW _′ . Furthermore, the sagittal height H _W at the outer diameter D _W of the spherical surface having a curvature radius R _{W, 'the} sagittal height at the outer diameter D _W of spherical with H _W' curvature radius R _W and. Also, the absolute value of the difference between H _W and H _{W ′} is ΔH _{W ′} . Here, the difference between the curvature radius of the workpiece and the target curvature radius is defined as ΔH _{W ′} . The difference between the radius of curvature The target, [Delta] H W _'is expressed by the following equation (6).

FIG. 7 shows the result of the difference ΔH _{W ′} between the curvature radius of the workpiece 4 and the target curvature radius for each cumulative machining time. In FIG. 7, Ar is a range in which the radius of curvature of the workpiece 4 satisfies the allowable value ΔH _W (ΔH _W = ± 440 nm) from the target radius of curvature. According to FIG. 7, ΔH _{W ′} before processing was −660 nm, but it was stabilized at 110 nm by processing for 30 minutes or more, and was processed to an allowable value ΔH _W = 440 nm or less from the target curvature radius. It was confirmed that

  In an optical element such as a lens (mirror), it is important to reduce the surface roughness and the amount of shape error from the spherical surface, in addition to making the error in the radius of curvature less than the allowable value. is there. FIG. 8 shows a scanning white interferometer (for example, CP-300 (trade name) manufactured by ZYGO) on the surface (left side) of the workpiece 4 before processing and the surface (right side) of the workpiece 4 after processing for 40 minutes. )) Shows the measurement results. FIG. 8 shows a height map image of a region having a size of φ0.77 mm obtained by a scanning white interferometer before processing (left side) and after processing for 40 minutes (right side).

  The legend of the height map image of FIG. 8 is as shown on the right side in the figure, and as shown in the figure, the surface roughness is about 70 nm RMS before processing, and about 1.1 nm RMS after 40 minutes processing, A sufficiently smooth surface is obtained as an optical element.

  Furthermore, the shape error from the spherical surface of the workpiece 4 after being processed for 40 minutes was measured using a laser interferometer (for example, Verifire (trade name) manufactured by ZYGO). The result is shown in FIG. FIG. 9A shows an interference fringe image (φ18 mm region) obtained from the workpiece 4 after being processed by a laser interferometer for 40 minutes. FIG. 9B shows the shape error profile of the cross section taken along the line CC ′ in FIG. 9A (vertical axis: unit) with the horizontal axis taken in the radial direction (unit: nm) of the workpiece 4. nm). According to FIGS. 9A and 9B, the shape error amount in the entire processing surface is 33 nm, and it was confirmed that high shape accuracy was obtained up to the outer peripheral portion of the workpiece 4.

As described above, it was proved by this example that a spherical lens in which the error in the radius of curvature is less than the allowable value can be processed with the tool manufactured so as to satisfy the above formula (5). That is, the difference ΔH between the target curvature radius R _W and the radius of curvature of the catalyst portion 2 of the tool 1, the shape error amount [Delta] F _T from the ideal shape of the catalyst unit 2 (true sphere having a radius of curvature of the catalyst unit), the The tool is manufactured so that the added value is equal to or less than the allowable value ΔH _W from the target radius of curvature of the workpiece 4. Thereby, according to the tool of the present embodiment, in the processing of the workpiece, the radius of curvature of the spherical surface formed by the envelope shape of the catalyst portion of the tool is controlled to be within the allowable curvature radius of the workpiece. The curvature radius of the workpiece 4 can be controlled within the allowable range of the target curvature radius.

In this embodiment, two different so the tool values of the shape error amount [Delta] F _T of the catalyst unit with respect to Example 1, produced (hereinafter, the sample (1) referred tools, and samples (2) Tool) The example which implemented the process similar to Example 1 using the manufactured tool is shown.

  The basic configuration of the sample (1) tool and the sample (2) tool is the same as that in FIG. Synthetic quartz glass having a Young's modulus of 70 GPa was used for the base part 3, and grooves 5 (FIG. 2) having a width of 1.8 mm and a depth of 1 mm were formed on the surface of the base part 3 in a lattice shape. Platinum (Pt), which is a transition metal, was used for the catalyst part 2, and a film was formed on the surface of the base part 3 by the same method as in Example 1. At this time, the following dimensions were obtained with the sample (1) tool and the sample (2) tool by appropriately controlling the grinding conditions of the base portion 3 and the film forming conditions of the catalyst portion 2.

Here the measurement, the sample (1) tool, the sample (2) and the curvature radius _{R T} of the catalyst portion of the tool (2), a laser interferometer shape error amount [Delta] F _T (e.g. ZYGO Co. Verifire (trade name)) did. The radius of curvature _{R T,} the sample (1) tool and a sample (2) to the tool both were 63.267Mm. Shape error amount [Delta] F _T, the sample (1) tool 47 nm, the sample (2) tool was 144 nm.

Measured sample (1) tool, from the sample (2) the radius of curvature _{R T} and shape error amount [Delta] F _T of the catalytic unit 2 of the tool, respectively the sum of ΔH and [Delta] F _T in equation (5) 47 nm, be 144nm It was confirmed that the condition of formula (5) was satisfied.

In this case, as further comparative examples, by appropriately controlling the grinding conditions and the film formation conditions of the catalytic unit 2 of the base portion 3, the third tool shape error amount [Delta] F _T does not satisfy the condition of formula (5) (Hereinafter referred to as sample (3) tool). The sample (3) tools, although the radius of curvature _{R T} is the same 63.267Mm, shape error amount [Delta] F _T is 1080 nm, which depart from the condition of Equation (5).

Using the sample (1) tool, the sample (2) tool, and the sample (3) tool manufactured as described above, using the same configuration as in FIG. processed. As a result, the difference ΔH _{W ′} between the curvature radius of the obtained workpiece and the target curvature radius is shown in FIG.

The vertical axis in FIG. 10 represents the difference ΔH _{W ′} between the curvature radius of the workpiece and the target curvature radius, and the horizontal axis represents the target curvature radius R of the sample (1) tool, the sample (2) tool, and the sample (3) tool. the sum of the difference ΔH and shape error amount [Delta] F _T of the curvature radius of the _W and the catalyst unit K1, shows K2, K3.

As shown in FIG. 10, the difference ΔH _{W ′ from} the target radius of curvature is 0 mm for the workpiece processed with the sample (1) tool and 110 nm for the workpiece processed with the sample (2) tool. That is, sample (1) tool, and sample (2) the difference between [Delta] H W of the target curvature radius R _W of the workpiece that is machined by a tool _'is inside the range of ± 440 nm is an allowable value of the target curvature radius A4 It was confirmed that it was processed to fit in

On the other hand, a sample of a comparative example having a shape error amount ΔF _T (1080 nm) that deviates from the condition of Expression (5) (3) ΔH _{W ′} of a workpiece processed with a tool is 660 mm, and is based on a target radius of curvature. The allowable value of is exceeded.

  As described above, according to the present embodiment as well, according to the tool manufactured so as to satisfy the above formula (5), it is possible to process a workpiece (for example, a spherical lens) so that the error in the radius of curvature is less than the allowable value. Has been demonstrated. In addition, with a tool that does not satisfy the above formula (5), the workpiece cannot be machined so that the error in the radius of curvature is less than the allowable value.

That is, the difference ΔH between the target curvature radius R _W and the radius of curvature of the catalyst portion 2 of the tool 1, the shape error amount [Delta] F _T from the ideal shape of the catalyst unit 2 (true sphere having a radius of curvature of the catalyst unit), the The tool is manufactured so that the added value is equal to or less than the allowable value ΔH _W from the target radius of curvature of the workpiece 4. Thereby, the curvature radius of the spherical surface formed by the envelope shape of the catalyst portion of the tool is controlled to be within the allowable curvature radius of the workpiece, and the curvature radius of the workpiece 4 is controlled within the allowable range of the target curvature radius. It has been demonstrated that it can.

  The tool manufacturing method (manufacturing conditions) described at the beginning of the embodiment can also be used to determine the quality of manufactured tools. In the present embodiment, a configuration and a determination method for determining the quality of a manufactured tool will be described. In this example, the quality of the tool is determined according to whether or not the manufactured tool satisfies the dimensional condition shown in the expression (5) at the beginning of the embodiment.

  FIG. 12 shows a configuration example of a control system for performing the above-described pass / fail determination for at least a manufactured tool. The control system shown in FIG. 12 includes a CPU 201 composed of a general-purpose microprocessor, a ROM 202, a RAM 203, a measurement unit 204, and an output unit 205. It should be noted that the shape of the processed workpiece (or further quality determination) can also be performed using the same control system configuration.

  The ROM 202 can be used, for example, for storing a quality determination program (FIG. 11) and control data described later. Note that the storage area for updating the quality determination program and control data stored in the ROM 202 may be constituted by an E (E) PROM or various types of flash memories. Such a rewritable part of the ROM 202 can also be constituted by a removable storage device (flash memory or the like). Such a detachable computer-readable recording medium can be used, for example, for installing or updating a control program constituting a part of the present invention. In this case, various detachable computer-readable recording media store the control program constituting the present invention, and the recording medium itself also constitutes the present invention. It should be noted that a network communication via a network interface (not shown) constituting the present invention may be performed so that a control program constituting the present invention can be installed or updated.

  The RAM 203 is composed of a DRAM element or the like, and is used as a work area for the CPU 201 to execute various controls and processes. A function related to pass / fail judgment control to be described later is realized by the CPU 201 executing the access control program of this embodiment. The CPU 201 executes firmware and pass / fail judgment control programs stored in the ROM 202 (or an external storage device such as an HDD (not shown)).

  In FIG. 12, a measuring unit 204 is for measuring the shape of a (provisionally) manufactured tool (or machined by it), for example, the above-described interferometer (scanning white interferometer, Fizeau interference). Meter) and a stylus type shape measuring machine. The CPU 201 reads the measurement value of the measurement unit 204 via a serial / parallel interface (not shown) or a network interface.

  The measurement unit 204 can output measurement data in a digital data format that allows the CPU 201 to process the analog measurement value. For example, in the case of an interferometer or the like, a digital camera that captures an interference fringe image is provided and configured to output captured image data at a constant frame rate. In this case, the photographed image data is output in a data format such as JPEG / MPEG, and the CPU 201 can easily access the photographed image data received via various serial / parallel interfaces or network interfaces.

Thereby, the CPU 201 can perform image analysis processing on the received captured image data (interference fringe image). Accordingly, CPU 201, for example the radius of curvature and the catalyst portion 2 of the tool 1, is possible to obtain a shape error amount [Delta] F _T from the ideal shape of each part of the catalyst portion 2 (true sphere having a radius of curvature of the catalytic unit) it can. Further, the CPU 201 can determine the quality of the tool according to whether or not the dimensional condition shown in the expression (5) at the beginning of the embodiment is satisfied. In the case of measuring a workpiece, shape measurement (or further quality determination) can be performed by analyzing the interference fringe image.

  Even when the measurement unit 204 is a stylus type shape measuring machine, the CPU 201 can easily receive the measurement data when the measurement data is transmitted in an appropriate digital data format from the stylus type shape measuring machine as described above. Can be accessed. Then, the CPU 201 can acquire the shape or dimension data of the measurement target (the catalyst part 2 of the tool 1 or the workpiece) based on the measurement data expressed by the displacement amount of the probe.

  The output unit 205 is an output device that outputs measurement results, and can be configured by output devices having various output formats. The output unit 205 can be configured by, for example, a display device (printer) that displays (prints) the measurement result of the measured tool 1 or the measurement result of the measurement unit 204 expressed in numerical values or images.

  Alternatively, the output unit 205 may include an interface that outputs conveyance control data for performing conveyance control of a tool (or workpiece) manufacturing (machining) line. Such a conveyance control interface can be arranged on the production line of the tool 1 (or the workpiece). And based on the quality determination of the target object (the processed tool 1 or the workpiece), for example, transport control data for controlling whether the target object is transported to a manufacturing line that handles non-defective products or a manufacturing line that handles defective products is output. be able to.

  FIG. 11 shows an example of the quality determination process for the tool 1 performed by the control system of FIG. The illustrated control procedure can be stored in, for example, the ROM 202 as a control program executed by the CPU 201.

  In step S11 of FIG. 11, the tool 1 is created by the technique shown in the first or second embodiment. The production process of the tool 1 includes a base part forming process for grinding the base part 3 and a catalyst part forming process for forming the catalyst part 2 on the base part by film formation.

In step S <b> 12, the CPU 201 uses the measuring unit 204 to measure the shape of the catalyst surface of the tool 1. Here, CPU 201 analyzes the measured data received from the measurement unit 204 measures the radius of curvature R _T of the tool 1 with (measurement step), the shape error amount [Delta] F _T from the true sphere having a radius of curvature R _T Measure (error measurement process).

In step S13, CPU 201 determines whether the radius of curvature _{R T} and shape error amount [Delta] F _T of the catalyst unit 2 satisfies the condition of the above equation (5). If the determination in step S13 is affirmative, the process proceeds to step S14, and it is determined that the tool is a non-defective product. If the determination in step S13 is negative, the process proceeds to step S15, and it is determined that the tool is defective.

  If it is determined in step S15 that the tool is a defective product, as indicated by a broken line in FIG. 11, the process proceeds to step S16 and the tool determined as a defective product, particularly the tool. You may make it perform correction processing of a catalyst surface. For example, the above-described arbitrary technique can be used as a technique for correcting the tool (catalyst surface). For example, a technique such as a cutting process using a diamond bite or a grinding process using a diamond grindstone can be used. A polishing method using abrasive grains such as free abrasive polishing using hard abrasive grains such as diamond or silicon carbide or soft abrasive grains such as cerium oxide may be used.

  After performing the correction process in step S16, the process returns to step S12 as indicated by the broken line, and the quality determination for the tool subjected to the correction process can be performed again.

  As described above, according to the present example, the quality of the tool can be determined according to whether or not the manufactured tool satisfies the dimensional condition shown in the expression (5) at the beginning of the embodiment. . Alternatively, it is possible to obtain a tool that satisfies the dimensional condition shown in the equation (5) by repeating the correction processing for the tool determined to be defective.

  DESCRIPTION OF SYMBOLS 1 ... Tool, 2 ... Catalyst part, 3 ... Base | substrate part, 4 ... Workpiece, 5 ... Groove part, 6 ... Processing liquid, 7 ... Supply means, 8 ... Holder, 9 ... Kanzashi.

Claims (4)

It has a catalyst part containing a transition metal on the surface facing the work piece, and a base part that supports the catalyst part, and the catalyst part is in contact with or close to the work piece with water molecules interposed therebetween. A tool for processing the workpiece up to a radius of curvature at which a difference from a target radius of curvature is less than or equal to an allowable value by relatively moving in a state in which
A value obtained by adding the difference between the target radius of curvature and the radius of curvature of the catalyst portion of the tool and the shape error amount of the catalyst portion of the tool from a true sphere having the radius of curvature of the catalyst portion is A tool manufactured to be equal to or less than the allowable value.   2. The tool according to claim 1, wherein the Young's modulus of the base portion is 50 GPa or more.   An optical element processed by the tool according to claim 1. In the manufacturing method of the tool which manufactures the tool according to claim 1 or 2, a base part forming process which forms the base part,
A catalyst part forming step of forming the catalyst part on the molded base part;
A measuring step of measuring a radius of curvature of the catalyst part formed on the base part;
An error measuring step of measuring the shape error amount of the true sphere having the target radius of curvature and the catalyst part formed on the base part;
A value obtained by adding the difference between the target radius of curvature and the radius of curvature of the catalyst portion measured in the measurement step and the shape error amount of the catalyst portion measured in the error measurement step is the allowable value. A tool manufacturing method, wherein the quality of the tool is determined according to whether or not the following is true.