JP6173077B2 - Method for manufacturing blazed diffraction grating and method for manufacturing mold therefor - Google Patents

Description

  The present invention relates to a blazed diffraction grating manufacturing method and a mold manufacturing method therefor.

  As shown in FIG. 1, the blazed diffraction grating 1 has an asymmetric triangular groove shape and includes a blazed surface 2 ′ on which light 7 is incident and a counter surface 3 adjacent thereto, and the blazed surface 2 ′. The counter surface 3 is inclined at a predetermined angle with respect to the lattice plane 4. In the blazed diffraction grating as described above, diffraction efficiency concentrated on a specific order is required. In order to achieve high diffraction efficiency, the shape of the blazed surface 2 'is required to be flat, and to have small unevenness and roughness. On the other hand, the flatness of the blaze surface 2 'is greatly affected by the cutting volume. When the cutting volume in one cutting process is large, as shown in FIG. 2, the blaze surface 2 'is burred and surface roughness occurs.

  Therefore, in order to reduce the stress applied to the workpiece when forming a single groove, a groove processing method is employed in which shallow cutting is repeated many times. Patent Document 1 discloses a groove processing method in which an isosceles triangular groove on a workpiece is prevented from being burred at the edge of the groove by cutting six times. In this method, cutting at a position deviated from the groove forming position to one side and cutting at a position deviated from the groove forming position to the other side are performed twice, and finally, at the groove forming position. Finishing is being done.

JP 2002-233912 A

  However, in order to manufacture one blazed diffraction grating, for example, it may be necessary to form tens of thousands of grooves. Therefore, in the conventional technique in which shallow cutting is repeated many times to form one groove, the time required for the groove processing is too long, and the manufacturing efficiency is lowered. In the method described in Patent Document 1, the cutting tool touches the blazed surface of the adjacent lattice, and burr or surface roughness may occur on the blazed surface of the adjacent lattice.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for manufacturing a blazed diffraction grating that is advantageous in terms of manufacturing efficiency and blaze surface accuracy.

In order to solve the above problems, the present invention is a method for manufacturing a blazed diffraction grating in which a plurality of grooves extending along a first direction are arranged along a second direction orthogonal to the first direction. The workpiece is cut by moving the workpiece having the first cutting edge and the second cutting edge at the first position in the second direction relative to the first direction, thereby cutting the workpiece. And a first step of forming a first groove having a first surface and a second surface respectively formed by the second cutting blade, and a lattice pitch along the second direction from the first position after the first step. The workpiece is cut by moving the bite and the workpiece relatively in the first direction at a second position separated by
A second step of forming the groove, and after the second step, tilt the first cutting edge of the cutting tool with respect to the first surface at a third position between the first position and the second position, And a third step of forming a blazed surface of the first groove by cutting the first surface with the first cutting edge by relatively moving the cutting tool and the workpiece in the first direction. And

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the blaze | braze type | mold diffraction grating advantageous at the point of the manufacturing efficiency and the precision of a blazed surface can be provided, for example.

Sectional drawing of a blaze | braze type | mold diffraction grating. The figure which shows the conventional groove processing method. The schematic diagram of the cutting machine used by the present invention. Sectional drawing of the to-be-processed object and the cutting tool in the grooving method of this invention. The figure which shows the groove processing operation | movement in the groove processing method of this invention. The figure explaining the groove processing method of this invention. The figure which shows the byte movement order in the groove processing method of this invention. The figure which shows the relative positional relationship of the byte | cutting-tool in the groove processing method of this invention. The figure which uses the grooved product formed with the groove processing method of this invention as a type | mold.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(First embodiment)

  In order to explain the present invention, an embodiment in which a blazed diffraction grating is manufactured by grooving will be described. The cutting machine used to manufacture blaze-type diffraction gratings is a high-precision machine that can control the position so that cutting can be commanded in the order of several tens of nanometers, and the tool has a sharp tip and high-precision machining transferability. Use a diamond bite that gives The material of the workpiece is selected from copper, aluminum, and electroless nickel, which are considered to have good machinability with a diamond tool.

  In FIG. 3, the outline of arrangement | positioning of the cutting machine 11, the cutting tool 12, and the workpiece 13 used by this embodiment is shown. The cutting machine 11 has a portal-shaped high-rigidity structure, is resistant to external vibrations, etc., and has specifications suitable for ultra-precise cutting capable of position control with very high resolution. In this cutting machine 11, a cutting tool 12 is attached to a structure that can slide (moves) in the Z direction (up and down direction), and a table that can slide (moves) in the X direction (left and right direction) and the Y direction (front and back direction). Mount the workpiece 13 on top.

  As shown in FIG. 4, the cutting tool 12 has a first cutting edge 14 a and a second cutting edge 14 b that transfer a polygonal groove cross-sectional shape. The angle 15 formed by the tips of the first cutting blade 14a and the second cutting blade 14b is slightly smaller than the opening angle 8 (for example, 85 °) of the groove to be formed, and the tips of the first and second cutting blades 14a, 14b form. The shape should be as small as possible when viewed in an expanded range. The opening angle of the groove is preferably less than 90 degrees. The straight line accuracy of the ridge lines of the first and second cutting edges 14a and 14b is very high at both ends. When forming a reflective diffraction grating by grooving, the finish of the groove wall surface is very important.

  As shown in FIG. 5, the cutting tool 12 is lowered to the workpiece side so that the cutting amount in the Z direction (for example, 3 μm in the depth direction) is obtained at the position where the cutting tool 12 and the workpiece 13 face each other. In this state, the shape of the cutting edge of the cutting tool 12 is cut into the work piece 13 by moving the cutting tool 12 and the work piece 13 relative to each other, for example, in the Y direction by using the linear control mechanism of the cutting machine 11. Process to transfer. At this time, the actual movement may be on the cutting tool side or the workpiece side. In the cutting process, oil mist is sprayed from the back side of the rake face of the cutting tool 12 so as to remove chips and lubricate the chips while maintaining a good cutting tool transfer state.

  A method of forming a single groove by cutting the workpiece 13 using the cutting tool 12 will be described with reference to FIG. In the present embodiment, the cutting tool 12 is moved in the −X direction and positioned at the first position when the workpiece 13 is cut. After that, by moving the cutting tool 12 linearly by a predetermined length, for example, 55 mm, in the + Y direction at the first position, one groove having the first surface 2 b and the second surface 3 b and having a length of 55 mm (first Groove). The second surface 3b constitutes a counter surface of the groove, but the first surface 2b does not constitute a blaze surface as will be described later. FIG. 6A shows the workpiece 13 before forming the first groove, and the blaze surface 2 ′ formed by the cutting process so far in the + X direction from the formation position of the first groove. The groove | channel which has a and the 2nd surface (counter surface) 3a is arrange | positioned continuously. In the present embodiment, the Y direction is the first direction in which the grooves extend, and the X direction is the second direction orthogonal to the first direction in which the plurality of grooves are arranged.

  With reference to FIG. 6B, the first stage cutting process (first step) when forming the first groove will be described. In this first-stage cutting process, the cutting tool 12 is moved to a first position separated by a grid pitch, for example, 10 μm in the −X direction with respect to the previous cutting process (the first-stage cutting process for the adjacent grid). To be done. At that time, the rotation angle of the cutting tool 12 on the XZ plane is set so that the first cutting edge 14a is inclined at a predetermined angle θ1 (for example, 20 °) from the direction perpendicular to the lattice plane 4. Here, the lattice plane 4 is a plane including the first direction and the second direction. While maintaining this cutting tool angle, the cutting depth of the cutting tool in the Z direction is determined so that the second cutting edge 14b can obtain a desired width with respect to the width of the groove on the cross section. The surface cut out by the second cutting edge 14 b becomes the counter surface 3.

  With reference to FIG. 6C, the second-stage cutting (third process) for forming the first groove will be described. In this second-stage cutting, the cutting tool 12 is cut in the first-stage cutting with respect to the workpiece 13 at the third position, for example, 9.5 μm away from the first position in the + X direction with respect to the first position. Cutting is performed along the + Y direction at a depth of, for example, 0.5 μm in the −Z direction with respect to the depth. Further, the rotation angle of the cutting tool 12 on the XY plane at the third position is a predetermined angle θ2 (for example, larger than the angle θ1 at the time of cutting in the first stage from the direction perpendicular to the lattice plane 4 (for example, , 24 °). The inclination angle of the first cutting edge with respect to the direction perpendicular to the lattice plane is increased. In this second stage of cutting, the surface cut out using the first cutting edge 14a becomes a blazed surface 2a '. In this second stage cutting, the second cutting edge 14b is formed by the second surface (counter surface) 3a of the second groove formed by the first stage cutting and the groove adjacent to the + X direction. Do not contact the apex of the groove formed by the blazed surface. Therefore, in this second stage cutting, the blaze surface (not shown) of the groove formed in the + X direction adjacent to the first step is not stressed, and burr 9 generated on the blaze surface as shown in FIG. And surface roughness can be avoided. Naturally, the lattice pitch and the rotation angle of the cutting tool 12 described above are examples of the embodiment, and can be changed.

  In order not to give stress to the previously formed blaze surface, the second cutting edge 14b is adjacent to the second surface 3b formed by the first stage cutting of the groove adjacent to the + X direction and adjacent to the + X direction. The second stage of cutting is performed without contacting the apex 6 of the groove formed by the blaze surface of the groove to be formed. Therefore, the blaze surface formed by the method of the present invention is flat without burr. Therefore, the positional relationship between the previously formed groove and the cutting tool at the second stage is very important. The positioning accuracy of the cutting tool depends on the accuracy of the processing machine, but when the number of grooves is large, the entire processing time may exceed one week, and errors due to environmental fluctuations such as temperature cannot be ignored. A first-stage cutting process (first step) for forming the first groove at the first position is performed, and then the second groove is formed at the second position separated from the first position by the lattice pitch. A first stage cutting process (second process) is performed. Immediately after performing the first-stage cutting for forming the second groove, the first groove for forming the first groove at the third position between the first position and the second position. It has been found that performing two-stage cutting (third step) is effective for obtaining a flat blazed surface. The blazed diffraction grating or the mold for manufacturing the diffraction grating is manufactured by repeating the first and second cutting processes in the −X direction a predetermined number of times, for example, 33500 times. The amount of burr or surface roughness on the blazed surface of the blazed diffraction grating produced by the method of the present invention is smaller than that produced by the conventional method. Furthermore, since only two cutting operations are required to form one groove, a blazed diffraction grating having a flat blazed surface or a mold for the same is required as compared with the prior art described in Patent Document 1. It can be manufactured efficiently.

  FIG. 7 shows the movement of the position of the cutting tool 12 when the cutting process is repeated with a single cutting tool. In this figure, the direction of groove formation is from right to left. First, in S1, the first stage of cutting is performed at the first position to form the counter surface of the first groove. Subsequently, at S2, the cutting tool 12 is shifted in the advancing direction (−X direction) by the lattice pitch, and the first stage cutting is performed at the second position to form the counter surface of the second groove. After that, in S3, at the position where the cutting tool 12 is returned to the X direction by an amount smaller than the lattice pitch (third position), the cutting tool 12 is tilted in the traveling direction rather than the angle of the cutting tool 12 at the first stage, and the second stage. Cutting is performed to form a blazed surface of the first groove. Then, before forming the blazed surface of the second groove, in S4, the angle of the cutting tool 12 is returned to the angle at the first stage of cutting, and the first position is advanced by one lattice pitch from the second position. A stepped cutting process is performed to form the counter surface of the third groove. In S5, the second stage cutting for forming the blaze surface for the second groove, in S6, the first stage cutting for forming the counter surface of the fourth groove, and in S7 the third groove A second stage of cutting is performed to form the blaze surface. Thereafter, a number of grooves are formed by sequentially repeating such steps.

FIG. 8 is a diagram for explaining the relative relationship between the position of the first-stage cutting and the position of the second-stage cutting according to the lattice pitch. A first-stage cutting position P _n-1 (first position) for forming a counter surface of the (n-1) -th groove of S1 and a counter surface of the n-th groove of S2 are formed. The distance from the first-stage cutting position P _n (second position) is the lattice pitch d. The position S _n (third position) of the second stage cutting for forming the blazed surface of the (n−1) -th groove is the position P _n−1 (first position) and the position P _n ( 2nd position). Then, at the time of the second-stage cutting performed in S3, the cutting tool 12 is tilted in the traveling direction of the cutting tool 12 so that the angle θ2 is larger than the angle θ1 of the cutting tool 12 at the first-stage cutting.

  A blazed diffraction grating composed of a groove having a highly accurate blazed surface manufactured by such a method is used as a wavelength selection element of an excimer laser which is a light source in the ultraviolet band.

  A method for manufacturing a blazed diffraction grating using a diffraction grating formed by cutting described in this embodiment as a mold will be described with reference to FIG. As shown in FIG. 9, the epoxy resin layer 92 cured by filling the mold 91 formed by cutting with an epoxy resin and stacking the base material 93 supporting the resin and then curing the epoxy resin is formed on the base material 93. In close contact. Thereafter, as shown in FIG. 9, by separating the base material 93 from the mold 91, the grating shape of the mold 91 is transferred to the resin layer 92, and a blazed diffraction grating 92 made of epoxy resin is obtained. Since the surface corresponding to the blazed surface of the mold 91 is flat without burrs, the blazed surface of the blazed diffraction grating 92 manufactured using the mold 91 is flat.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

2 'Blaze surface 3 Counter surface 12 Diamond tool 13 Work piece 14a Tool bit ridge line first cutting edge 14b Tool bit ridge line second cutting edge

Claims (7)

A method of manufacturing a blazed diffraction grating in which a plurality of grooves extending along a first direction are arranged along a second direction orthogonal to the first direction,
The workpiece is cut by moving the workpiece having the first cutting edge and the second cutting edge at the first position in the second direction relative to the workpiece in the first direction to cut the workpiece. A first step of forming a first groove having a first surface and a second surface respectively formed by one cutting edge and the second cutting edge;
After the first step, the cutting tool and the workpiece are relatively moved in the first direction at a second position separated from the first position by a lattice pitch along the second direction. A second step of cutting the workpiece to form a second groove,
After the second step, at a third position between the first position and the second position, the first cutting edge of the cutting tool is inclined with respect to the first surface, and the cutting tool and the cutting tool a third step of forming a pre-Symbol blazed surface of the first groove by cutting said first surface by said first cutting edge by moving the workpiece relative the first direction,
A method characterized by comprising: The method according to claim 1 , wherein the third step is performed without performing another cutting after the second step of forming the second groove adjacent to the first groove. .   The method according to claim 1 or 2, wherein an opening angle of the groove formed by the blazed surface and the second surface is less than 90 degrees. And characterized by forming a blazed surface of the through Rukoto tilting the bytes in the second direction in the third step, the first cutting edge of the said inclined with respect to the first surface a first groove of the byte The method according to any one of claims 1 to 3. The angle of the first cutting edge with respect to a direction perpendicular to the plane including the first direction and the second direction, the angle of the first cutting edge in the third step, and the first cutting edge in the first step . The method according to any one of claims 1 to 4, wherein the angle is larger than the angle . A method of manufacturing a mold for manufacturing a blazed diffraction grating, wherein a plurality of grooves each extending along a first direction are arranged along a second direction orthogonal to the first direction,
The workpiece is cut by moving the workpiece having the first cutting edge and the second cutting edge at the first position in the second direction relative to the workpiece in the first direction to cut the workpiece. A first step of forming a first groove having a first surface and a second surface respectively formed by one cutting edge and the second cutting edge;
After the first step, the cutting tool and the workpiece are relatively moved in the first direction at a second position separated from the first position by a lattice pitch along the second direction. A second step of cutting the workpiece to form a second groove,
After the second step, at a third position between the first position and the second position, the first cutting edge of the cutting tool is inclined with respect to the first surface, and the cutting tool and the cutting tool A surface corresponding to the blazed surface of the blazed diffraction grating in the first groove by cutting the first surface by the first cutting edge by relatively moving the workpiece in the first direction. a third step that form the,
A method characterized by comprising: A method of manufacturing a blazed diffraction grating in which a plurality of grooves extending along a first direction are arranged along a second direction orthogonal to the first direction, using a mold,
The mold is
The workpiece is cut by moving the workpiece having the first cutting edge and the second cutting edge at the first position in the second direction relative to the workpiece in the first direction to cut the workpiece. A first step of forming a first groove having a first surface and a second surface respectively formed by one cutting edge and the second cutting edge;
After the first step, the cutting tool and the workpiece are relatively moved in the first direction at a second position separated from the first position by a lattice pitch along the second direction. A second step of cutting the workpiece to form a second groove,
After the second step, at a third position between the first position and the second position, the first cutting edge of the cutting tool is inclined with respect to the first surface, and the cutting tool and the cutting tool A surface corresponding to the blazed surface of the blazed diffraction grating in the first groove by cutting the first surface by the first cutting edge by relatively moving the workpiece in the first direction. Manufactured by the third step of forming
A method of manufacturing a blazed diffraction grating, comprising the step of manufacturing the blazed diffraction grating using the mold.

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