JP2007010941A - Optical element, its molding die, its manufacturing method, and work positioning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve positioning accuracy in the arrangement of a mirror surface in an optical device constituted by arranging a plurality of mirror surfaces comprising an aspherical surface or a spherical surface on a plane so as to be symmetric with respect to a rotation axis, and to improve accuracy in the attaching position of the optical device when it is attached to a product. <P>SOLUTION: A PSD 54 detects the position of spot light formed by condensing reflected light by a parabolic mirror part 57 previously formed on a surface 26'a forming the aspherical mirror 28 in an aspherical mirror disk blank 26' when a laser beam is made incident on the parabolic mirror part 57. By setting a perpendicular from the position of the spot light to the surface 26'a as a rotation axis in symmetry with respect to the rotation axis, the aspherical mirror 28 is positioned on the basis of the rotation axis. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a machining technique, and more particularly to a technique for positioning a workpiece in an aspherical or spherical ultraprecision cutting or ultraprecision grinding process, and is used as an optical system component such as a high-resolution video projector. In particular, the present invention relates to a plurality of reflective optical elements composed of an aspherical surface or a spherical surface arranged symmetrically with respect to a rotational axis, and a technique suitable for processing a molding die thereof.

  FIG. 10 shows a part shape related to the present invention. Here, an example of a mirror disk in which a plurality of mirror surfaces that are aspherical surfaces are arranged on a plane in a rotational axis symmetry will be shown. 10, (a) is a front view of the aspherical mirror disk 1, and (b) is a cross-sectional view taken along a cutting line indicated as P-P 'in (a).

  The aspherical mirror disk 1 has aspherical mirrors 2 which are a plurality of mirror surfaces arranged symmetrically at equal intervals with respect to the central axis A and at a radius r from the central axis A. A mounting reference hole 3 processed to be concentric with the mounting reference hole 3, a back surface 13 processed simultaneously with the mounting reference hole 3, and a fixing hole 4 for fixing the aspherical mirror disk 1 to the rotation shaft of the product body Is provided.

  When light including image information is incident on the aspherical mirror 2 while the aspherical mirror disk 1 is rotated at a high speed, the light is successively reflected by the plurality of aspherical mirrors 2. At this time, the position of the aspherical mirror 2 with respect to the central axis A is important, and in particular, submicron accuracy is required in the radial direction. By having such an accuracy, an image can be projected with a high resolution.

Conventionally, such parts have been processed by the technique shown in FIG. 11, for example.
In FIG. 11, the rotation reference shaft 8 is fixed to the position of the radius r from the rotation center axis B of the rotation main shaft 6 on the workpiece mounting plate 7 fixed to the end surface 6 a of the rotation main shaft 6 in the ultra-precision lathe 5. To do. Further, the angle indexing pin 9 is fixed at the position of the radius r from the center of the rotation reference shaft 8.

  The mounting reference hole 3 of the aspherical mirror disc blank 1 ′ and the reference counterbore 10 on the back surface of the aspherical mirror 2 are processed in advance by an ultra-precision jig borer. The index angle of the reference counterbore part 10 is the index angle of the aspherical mirror 2 to be processed, and is processed so as to be precisely fitted to the angle index pin 9.

  Here, the mounting reference hole 3 and the rotation reference shaft 8, the reference counterbore part 10 and the angle indexing pin 9 are respectively fitted, and the aspherical mirror disk blank 1 ′ is positioned on the work mounting plate 7, Secure with the bolts shown. Reference numeral 14 in the figure denotes a balance weight for balancing the rotation of the rotary spindle 6.

In such a state, the position of the diamond cutting tool 11 is controlled by the NC axis, and the aspherical mirror disk blank processing surface 1′a is subjected to ultraprecision cutting into a predetermined aspherical shape.
A plurality of aspherical mirrors 2 are processed one after another by repeatedly performing the above-described steps from setup to cutting for the number of aspherical surfaces to produce an aspherical mirror disk 1.

  When attaching the aspherical mirror disk 1 to the product, as shown in FIG. 12, the rear surface 13 of the aspherical mirror disk 1 is brought into close contact with the reference end surface portion 12a of the rotation shaft 12 on the product side and tilted. To eliminate the occurrence of Further, with respect to the shift in the radial direction, positioning is performed by fitting the reference side surface 12b of the rotating shaft 12 and the mounting reference hole 3 of the aspherical mirror disk 1.

As another technique for processing a mold of an optical element such as a lens array in which a plurality of spherical or aspherical surfaces are arranged, for example, techniques disclosed in Patent Document 1 and Patent Document 2 are known. ing. In Patent Document 1, a slide table that is movable in a predetermined direction is provided at the center of the spindle end surface of the machining apparatus, and a workpiece is attached to the slide table, and the position is aligned with the slide table so that the workpiece machining section comes to the spindle rotation center. A technique for processing is disclosed. Further, in Patent Document 2, a work is attached to the end surface of the main shaft, a moving mechanism that is attached to the outside of the main shaft and moves the work in two directions orthogonal to the axial direction of the main shaft rotation shaft, and a rotation shaft of the main shaft. A technique for machining a workpiece with a machining tool that moves relative to the workpiece is disclosed.
JP 11-189601 A JP 2002-337043 A

  In the conventional method described with reference to FIG. 11, the position of the aspherical mirror 2 with respect to the central axis A is determined by the fitting accuracy of the attachment reference hole 3 and the rotation reference shaft 8 and the reference counterbore portion 10 and the angle indexing pin 9. The accuracy is determined. Here, if this fitting gap is made small in order to increase this accuracy, it becomes difficult to insert them, so a gap of several microns or more must be allowed. For this reason, the position accuracy of the aspherical mirror 2 with respect to the central axis A is limited to a level of several microns, and the position accuracy in the radial direction, which is particularly demanding accuracy, cannot be achieved. Further, since the position of the central axis A cannot be detected, it is not possible to correct the positional deviation.

Therefore, it is difficult to process an aspherical mirror disk having a positional accuracy of 1 micron or less, which is required by design.
Even if the aspherical mirror disk 1 having a desired design accuracy is obtained, the aspherical mirror disk 1 is obtained by aligning the rotation axis 12 of the product with the central axis A of the aspherical mirror disk 1 as shown in FIG. The shift in the radial direction at the time of positioning is determined by the fitting accuracy between the reference side surface 12b of the rotating shaft 12 and the mounting reference hole 3 of the aspherical mirror disk 1, so that a deviation corresponding to the fitting play occurs.

  The present invention has been made in view of the above-mentioned problems, and the problem to be solved is the arrangement of mirror surfaces in an optical element in which a plurality of mirror surfaces made of aspherical surfaces or spherical surfaces are arranged on a plane in a rotational axis symmetry. In addition to improving the position accuracy, the mounting position accuracy of the optical element at the time of mounting on a product is improved.

  An optical element according to one aspect of the present invention is an optical element in which a plurality of mirror surfaces made of an aspherical surface or a spherical surface are arranged on a surface in a rotational axis symmetry, and is parallel to the rotational axis in the rotational axis symmetry. A reflection mirror portion is formed on the surface on which the mirror surface is formed. The reflection mirror portion forms a spot light on the rotation axis when the laser light is incident. The above-mentioned problems are solved by the characteristics.

In the optical element according to the present invention described above, the reflection mirror unit may be a parabolic mirror.
In the optical element according to the present invention described above, the reflection mirror unit may be a diffraction grating mirror.

  An optical element production method according to another aspect of the present invention is a method of producing an optical element in which a plurality of mirror surfaces, which are aspherical or spherical, are arranged on the surface in a rotational axis symmetry, When the laser beam is incident on a reflection mirror portion that is formed in advance on the surface forming the mirror surface, the reflection mirror portion detects the position of the spot light formed by collecting the reflected light, and Using this method, the vertical line hanging from the position of the spot light to the surface is used as a rotation axis in the rotation axis symmetry, and each mirror surface is positioned based on the rotation axis. The above-described problems are solved by the characteristics of the optical element produced in this way.

  Further, a molding die that is another aspect of the present invention is an optical element molding die in which a plurality of mirror surfaces, which are aspherical or spherical, are arranged on the surface symmetrically about the rotational axis, and the rotational shaft A reflection mirror portion is formed on the surface where the mirror surface is formed so that when the laser beam is incident in parallel to the rotational axis in symmetry, the reflected light of the laser beam forms spot light on the rotational axis. The above-described problems are solved by the characteristics of the optical element produced by using this mold.

In the above-described mold according to the present invention, the reflection mirror portion may be a parabolic mirror.
In the mold according to the present invention described above, the reflection mirror portion may be a diffraction grating mirror.

  According to another aspect of the present invention, there is provided a method for producing a mold, which is a method for producing a mold for an optical element in which a plurality of mirror surfaces, which are aspherical or spherical, are arranged on the surface in a rotational axis symmetry. The position of the spot light formed when the reflection mirror part condenses the reflection light when the laser light is incident on the reflection mirror part formed in advance on the surface forming the mirror surface. , And a vertical line suspended from the position of the spot light to the surface as a rotational axis in the rotational axis symmetry, and positioning each mirror surface based on the rotational axis, The above-described problems are solved by the characteristics of the optical element produced using the mold produced using this method.

  A workpiece positioning apparatus according to still another aspect of the present invention is used for production of an optical element in which a plurality of mirror surfaces, which are aspherical or spherical, are arranged on a surface in a rotational axis symmetry, or a molding die thereof. A laser beam that irradiates a workpiece attached to the rotary spindle, which is a detection unit that is a workpiece positioning device that is adjusted and positioned at an arbitrary position in the radial direction of the rotary spindle from the workpiece rotation spindle of an ultra-precision machining machine. The detection unit including a laser beam oscillation unit that excites the laser beam, and a detection unit that detects the position of the spot light formed by the reflected light from the workpiece of the irradiated laser beam, and the workpiece rotation of the ultraprecision machine A microfeed unit that is attached to a spindle end and configured to be capable of microfeeding a workpiece in a radial direction of the workpiece rotation spindle, and the microfeed mechanism And a rotary positioning unit that is attached at a predetermined position from the center of the workpiece rotation spindle and has a rotation axis parallel to the workpiece rotation spindle and is capable of positioning the workpiece at an arbitrary rotation angle. The above-described problems are solved by the characteristics of the optical element produced using this apparatus.

  According to the present invention, the positional accuracy of the arrangement of the mirror surface in the optical element in which a plurality of mirror surfaces made of an aspherical surface or a spherical surface are arranged on the plane in a rotational axis symmetry can be improved and the product can be obtained. There is an effect that the mounting position accuracy of the optical element at the time of mounting is improved.

  As an effect of the present invention,

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The present embodiment will be described with reference to FIGS.
In FIG. 1, a fine feed base 22 is fixed to an end surface 21a of a rotation spindle 21 of an ultra-precision lathe 20, and a mounting reference base 23 fixed to a fine movement stage 22a of the fine feed base 22 has a rotation reference axis. 24 is fixed at a position of a radius r from the rotation center axis B of the rotation main shaft 21. An angle indexing pin 25 is fixed at a position of a radius r from the rotation reference shaft 24. The minute feed base 22 is configured to allow minute feed in a radial plane as will be described later.

  The mounting reference hole 27 of the aspherical mirror disc blank 26 'and the reference counterbore 29 on the back surface of the aspherical mirror 28 are simultaneously processed in advance by an ultra-precision jig borer. The index angle of the reference counterbore portion 29 is an index angle of the aspherical mirror 28 that is a mirror surface to be processed, and is processed so as to be precisely fitted to the angle index pin 25 that is a rotational positioning unit.

The attachment reference hole 27 is processed so as to be precisely fitted to the rotation reference shaft 24.
Here, the attachment reference hole 27 and the rotation reference shaft 24, and the reference counterbore portion 29 and the angle indexing pin 25 are fitted, and the aspherical mirror disk blank 26 'is mounted on the fine movement stage 22a via the attachment base 23. Position and fix with bolts (not shown). In the figure, reference numeral 30 denotes a balance weight for achieving a rotational balance of the rotary spindle.

In this state, the tip position of the diamond cutting tool 31 is NC biaxially controlled, and the aspherical mirror disc blank processing surface 26'a is ultraprecision cut into a predetermined aspherical shape.
Reference numeral 32 in the figure denotes a tool holder that supports the diamond tool 31. The tool holder 32 is fixed on two NC feed stages 35 and 36 installed on the machine base 34 of the ultraprecision lathe 20. Here, the feed direction of the NC feed stage 35 is a direction perpendicular to the rotation center axis B of the rotation main shaft 21, and the feed direction of the NC feed stage 36 is a direction parallel to the rotation center axis B.

  As shown in the plan view of FIG. 2, the fine feed base 22 as a fine feed unit includes a fixed base 22b, the fine movement stage 22a, and four elastic pins 37 made of metal for elastically connecting them. Four fine feed mechanisms 38 are provided.

  FIG. 3 is a partial cross-sectional view of the micro feed base 22 taken along the cutting line indicated by A-A ′ in FIG. 2. As shown in the figure, the fixed base 22b and the fine movement stage 22a are fastened by shrinking of both end portions 37a of the elastic pin 37 at the positions of their four corners. Further, as shown in the figure, the elastic pin 37 is provided with two notches 37b on the outer peripheral portion slightly closer to the center from both end portions 37a.

  Here, a relief is provided so that a portion of the elastic pin 37 closer to the center than the notch 37b does not come into contact with either the fixed base 22b or the fine movement stage 22a. Accordingly, when a force is applied from the side of the fine movement stage 22a, the elastic pin 37 receives a shearing force through the fine movement stage 22a to cause a minute elastic deformation, and the action of the parallel spring causes the fine movement stage 22a to be minute in the plane. Can be displaced.

  FIG. 4 is a partial cross-sectional view of the micro feed base 22 along the cutting line indicated by B-B ′ in FIG. 2, and shows a cross section of the micro feeding mechanism 38 along the cutting line. In the figure, a feed screw 39 is rotatably attached to the fixed base 22b via bearings 42 and 43 built in support members 40 and 41.

  In the vicinity of the center of the feed screw 39, a pressing member 44 screwed to the feed screw 39 is provided, and the feed screw 39 is finely fed in the screw direction on the fixed base 22b. The end surface 44a (see FIG. 2) of the pressing member 44 on the fine movement stage 22a side is a flat surface having a taper angle. An abutting member 46 having an end surface 46a having the same taper angle and in contact with the end surface 44a is fixed to the side surface portion 22c of the fine movement stage 22a. In addition, 45 in FIG. 4 is a spring for preventing screwing backlash.

  The fine feed mechanism 38 configured as described above is provided at four positions on the side of the fine movement stage 22a on the fixed base 22b. When force is applied from the side of the fine movement stage 22a, the fine movement stage 22a is thereby activated. It can be finely displaced in two orthogonal directions in the plane.

  Reference numeral 47 in FIG. 1 denotes a spot light detection unit fixed to the machine base 34. Among these, the detection unit box 48 is supported by the support member 49 in a state in which the opening 48a is directed in the direction of the processed surface 26′a of the aspherical mirror disc blank 26 ′ attached to the rotary spindle end surface 21a. .

  In the detection unit box 48, a laser oscillator 50, a collimator lens 51 that makes the oscillated laser light parallel light, a beam splitter 52 that branches the parallel light in two directions at right angles, and reflected and converged light from the beam splitter 52 , And a PSD (Position Sensing Device) 54 that can accurately detect the position of the spot light converged through the magnifying lens 53. The parallel light transmitted through the beam splitter 52 is guided out of the detection unit box 48 through the opening 48a, and is irradiated perpendicularly to the processing surface 26'a of the aspherical mirror disk blank 26 '. The laser beams reflected at right angles by the beam splitter 52 are guided to the PSD 54 so that the positions can be detected.

  A signal related to the position information of the spot light detected by the PSD 54 is input to the computer 55. The computer 55 performs a process of calculating a distance from a preset position reference based on an input signal by executing a predetermined control program, and a process of displaying the position of the spot light on the monitor television 56.

The details of the procedure and operation for manufacturing an aspherical mirror disk using the super-precision lathe 20 having the above-described configuration will be described.
As the aspherical mirror disk blank 26 ′, an aluminum base surface is coated with an electroless nickel coating, and the coating is used as a cutting layer. A concave paraboloid mirror portion 57 is cut in advance at the center position of the aspherical mirror disk blank 26 '. As will be described later, the parabolic mirror portion 57 is for reflecting incident parallel laser light to form spot light, so that the amount of deviation from the design shape is within λ / 4. It is desirable to process.

  Next, the aspherical mirror disk blank 26 'is positioned by the rotation reference shaft 24 and the angle indexing pin 25 as described above, and then attached to the mounting base 23 attached to the ultraprecision lathe 20 (not shown). fix it with bolts.

  Next, the laser light is excited by the laser oscillator 50 of the spot light detection unit 47, and the laser light is irradiated as parallel light from the opening 48a toward the paraboloid mirror part 57. The laser beam reflected by the paraboloid mirror portion 57 becomes spot light of about 1 micrometer at a focal position determined by the design shape of the paraboloid of the paraboloid mirror portion 57 and the focal length of the magnifying lens 53. Focus.

  Here, the position of the spot light detection unit 47 is finely adjusted by a position adjustment mechanism (not shown) so that the PSD 54 can detect the position of the spot light, and an image of the spot light is displayed on the monitor television 56. At this time, an instruction is given to the computer, and the intersection of the cross lines displayed on the monitor television 56 is moved to coincide with the spot light position. The position of this intersection is used as a reference position for subsequent processing of the aspherical surface.

  Subsequently, the rotary spindle 21 is rotated, and the tip position of the diamond tool 31 is NC2 controlled so that the processing surface 26′a of the aspherical mirror disk blank 26 ′ centered on the rotation center axis B has a predetermined shape. The aspherical mirror 28 is subjected to ultraprecision cutting.

  Prior to this cutting process, it is desirable to adjust the weight of the balance weight 30 to adjust the rotational balance, thereby preventing the surface roughness and shape accuracy of the cut surface from being deteriorated due to rotational vibrations. The occurrence of displacement of the micro feed base 22 due to the bias of the centrifugal force is prevented.

Thereafter, the aspherical mirror disk blank 26 ′ is temporarily removed, and the adjacent reference counterbore portion 29 and the angle indexing pin 25 are fitted and fixed to the mounting base 23 again.
Since the reference counterbore part 29 is processed at a predetermined angle by an ultra-precision jig borer, the angle can be indexed within the fitting play d between the reference counterbore part 29 and the angle indexing pin 25. This usually occurs on the order of a few micrometers, but the error e of the index angle is
e = ± tan ⁻¹ (d / r)
In the case of a general fitting backlash amount of 5 μm and a general aspherical mirror disc blank shape r = 20 mm, the error e is ± 0.86 minutes, and for the required tolerance of ± 3 minutes It is well within the acceptable range.

  The stop position (angle) of the rotation main shaft 21 is adjusted by aligning the spot light reflected from the parabolic mirror portion 57 with the cross line intersection of the monitor TV 56 using a precision encoder (not shown) built in the rotation main shaft 21. Set to the stop position (angle). In this state, the position of the spot light reflected from the parabolic mirror 57 is detected, and the cross screw position indicating the reference position set on the monitor TV 56 is set as a target, and the feed screw of the micro feed base 22 is set. 39 is operated to slightly displace fine movement stage 22a, thereby aligning the spot light and the crossing position of the crosshairs. By this alignment, the position of the parabolic mirror part 57 can be always matched with the reference position.

Thereafter, the rotating main shaft 21 is rotated to cut the second aspherical mirror.
The subsequent procedure is repeated as described above, and the plurality of aspherical mirrors 28 are processed while the position of the parabolic mirror portion 57 is always matched with the reference position. As a result, the position is adjusted based on the spot light position by the parabolic mirror 57, and the processing is performed. Therefore, the positions of all the aspherical mirrors in the radial direction are within the adjustment accuracy range, and the position accuracy is improved. . This adjustment accuracy depends on the size of the spot light, the performance of the PSD 54, the set magnification of the magnifying lens 53, the feed accuracy of the minute feed base 22, etc., all of which are 1 micrometer comparable to the size of the spot light. Adjustment can be made at a degree, and by further improving each accuracy, an accuracy of 1 micrometer or less can be obtained.

  The aspherical mirror disk 58 processed in this way is used, for example, as a scan mirror for a video signal of a video projector or the like, and as shown in FIG. 5, the back surface 58a is formed on the reference end surface portion 12a of the rotary shaft 12 on the product side. To prevent the occurrence of tilt and irradiate the parabolic mirror unit 57 with a parallel laser beam from the spot light detection unit 59 having the same configuration as described above, and the spot light obtained by reflection therefrom. By detecting the position and displaying it on the monitor television 61 via the computer 60, it is possible to detect a shift in the radial direction and perform position correction. This position correction may be performed so that the spot light is shifted to the center position of the arc drawn on the monitor television 61 when the rotating shaft 12 is rotated.

  In this way, by detecting the spot light from the parabolic mirror 57 and adjusting so as to eliminate the rotational shake, the rotation axis of the product and the symmetrical central axes of the plurality of aspheric surfaces are made to coincide with each other. An aspherical mirror disk 58 can be attached.

  In the present embodiment, as an actuator for causing the minute feed base 22 to be minutely displaced, a piezoelectric displacement element is provided on the side of the fine movement stage 22a, and a predetermined voltage is applied to the piezoelectric displacement element so as to be minutely displaced. Is also possible.

  Further, as a modified example of the angle indexing mechanism of the aspherical mirror disk blank 26 ′, the reference counterbore portion 29 may be provided on the side surface of the aspherical mirror disk blank 26 ′, and the angle indexing pin 25 is arranged in the radial direction. Alternatively, the reference counterbore portion 29 may be fitted. According to this configuration, since the angle indexing operation can be performed without removing the aspherical mirror disk blank 26 'from the rotation reference shaft 24, workability is improved.

  In addition, as a mechanism for calculating the angle, a coupling unit made of uneven teeth cut into a shape that meshes with each other at a predetermined angle may be used, or an angle using a commercially available general-purpose coupling unit. Can be assured of accuracy within 5 seconds.

  Further, the shape of the paraboloid mirror portion 57 is not limited to a paraboloid, and may be an axisymmetric aspherical surface or a spherical shape, for example. In the case of such a shape, it is necessary to provide a correction lens in the optical system of the spot light detection units 48 and 59 so that the reflected light ties the spot light at a predetermined focal position.

  As described above, according to this embodiment, the reflecting optical element in which the positional accuracy in the radial direction of the aspherical mirror 28 with respect to the central axis of the aspherical mirror disk 58 is processed to an accuracy of 1 micrometer or less, and the processing It is possible to provide a method and a workpiece positioning apparatus, and it is also possible to provide a reflective optical element that can be attached to the product rotation shaft 12 without eccentricity.

The present embodiment will be described with reference to FIGS.
The present embodiment is different from the first embodiment in that the parabolic mirror in the first embodiment is a diffractive optical mirror.

  In the cross-sectional view of the aspherical mirror disk 58 shown in FIG. 6, the diffraction mirror 62 is cut in advance at the center of the aspherical mirror disk 58. The cross-sectional shape of the diffraction mirror 62 is a concentric blazed (sawtooth) shape symmetrical to the central axis A as shown in FIG. 7 which is a partially enlarged view of FIG. It is comprised so that it may incline. The blaze depth h is preferably set to λ / 2, where λ is the wavelength of the irradiated laser beam, in order to increase diffraction efficiency. Further, the pitch width Pi of the blaze is set to a value calculated from a general diffractive optical theory so that incident reflected light forms spot light of about 1 micrometer at a desired focal length.

  As shown in FIG. 7, blaze cutting is performed by turning by NC control of the angle and position of the cutting edge 63a of the Fresnel bite 63 having a sharp cutting edge, and is processed into a mirror surface.

  When laser light is incident on the diffractive mirror 62 formed in this manner, the reflected light forms spot light at a desired focal length, so that the same function as the parabolic mirror in the first embodiment can be provided. . Therefore, it is possible to process an aspherical mirror disk having the same operation as in the first embodiment and to precisely adjust the mounting position.

  As described above, the position accuracy in the radial direction of the aspherical mirror 28 with respect to the central axis of the aspherical mirror disk 58 is detected by the position detection of the reflected spot light of the diffraction mirror 62 according to the present embodiment. In addition, it is possible to provide a reflective optical element that has been machined, a machining method and a workpiece positioning apparatus, and a reflective optical element that can be attached to the rotary shaft 12 of the product without decentering.

  The present embodiment will be described with reference to FIGS. In addition, a present Example shows the example which processes the shaping | molding die instead of the aspherical mirror disk 58 which was the object of the process in Example 1. FIG.

  FIG. 8 shows the structure of the aspherical mirror disk mold that is the object of processing in this example. The aspherical mirror disk molding die 64 is different from the aspherical mirror disk 58 () shown in FIG. 5 in that the aspherical mirror part 28 has a convex shape corresponding to the shape of the aspherical mirror part 28. It is a point to be. It is desirable that the aspherical mirror disk molding die 64 be preliminarily machined into a convex shape in a blank state so that only the aspherical molding part 65 needs to be cut.

Note that the nesting structure necessary for the aspherical mirror disk molding die 64 in order to precisely transfer the molding surface 64a to the plastic surface by injection molding is omitted here.
By using such an aspherical mirror disk molding die 64 and accurately transferring the aspherical molding part 65 and the parabolic mirror part 57 formed on the molding surface 64a by injection molding, the non-spherical mirror part 65 as shown in FIG. A plastic molded product of the aspherical mirror disk 66 having the spherical mirror 67 and the convex parabolic mirror 68 can be obtained.

  In order to precisely adjust the positional deviation in the radial direction and attach the aspherical mirror disk 66 to the rotary shaft 12 of the product, a spot light detection unit 69 is used instead of the spot light detection unit 59 described above.

  The spot light detection unit 69 irradiates the convex paraboloidal mirror 68 with the laser light emitted from the beam splitter 52 in the direction of the reflection mirror through the focus lens 70 and the condenser lens 71, and reflects one of the reflected light therefrom. This is different from the spot light detection unit 59 in that the light is focused on the PSD 54 by the focus lens 70 and the magnifying lens 53 after being condensed by the condenser lens 71. .

  By using the aspherical mirror disk molding die 64 having the above-described configuration as an injection molding die, the aspherical mirror disc molding die 64 is formed with a precision of 1 micrometer or less in the radial direction with respect to the position of the convex parabolic mirror 68 as a reference. The aspherical mirror disk 66 having a plurality of aspherical mirrors 67 can be mass-produced.

  Further, when the aspherical mirror disk 66 is attached to the rotating shaft 12 of the product, a laser beam is irradiated from the spot light detection unit 69 to the convex paraboloid mirror portion 68 formed by transfer, and the reflected light is spotted. By detecting the position as light, the radial displacement can be positioned with an accuracy of 1 micrometer or less.

  As described above, according to the present embodiment, the reflective optical element forming die 64 that can be processed with the radial positional accuracy of the aspherical mirror 67 with respect to the central axis of the aspherical mirror disc 66 being 1 micrometer or less. In addition, it is possible to provide a processing method and a workpiece positioning apparatus, and it is also possible to provide a molded product of a reflective optical element that can be attached to the rotation shaft 12 of the product without eccentricity.

The present invention is not limited to the above-described embodiments, and various improvements and changes can be made without departing from the scope of the present invention.
For example, each of the embodiments described above was for the production of an aspherical mirror disk in which a plurality of aspherical mirrors are arranged, but the same applies to a mirror disk in which a plurality of spherical mirrors are arranged on a plane in a rotational axis symmetry. It is also possible to make it.

It is a figure explaining the processing method of the aspherical mirror disk concerning Example 1. FIG. It is a top view of a minute feed stand. It is a fragmentary sectional view (the 1) of a minute feed stand. It is a fragmentary sectional view (the 2) of a minute feed stand. It is a figure which shows the mode of the attachment to the product of the aspherical mirror disk produced by Example 1. FIG. 6 is a cross-sectional view of an aspherical mirror disk manufactured according to Example 2. FIG. It is a figure which shows the mode of the turning process of the diffractive optical mirror part in FIG. 6 by a Fresnel bite. FIG. 6 is a cross-sectional view of an aspherical mirror disk molding die produced according to Example 3. It is a figure which shows the mode of the attachment to the product of the aspherical mirror disk molded article produced by Example 3. FIG. It is a figure which shows the example of the shape of an aspherical mirror disk. It is a figure explaining the prior art example of the processing method of the aspherical mirror disk shown in FIG. It is a figure which shows the mode of the attachment to the product of the aspherical mirror disk shown in FIG.

Explanation of symbols

1, 58, 66 Aspherical mirror disc 1 ', 26' Aspherical mirror disc blank 1'a, 26'a Aspherical mirror disc blank processed surface 2, 28, 67 Aspherical mirror 3, 27 Mounting reference hole 4 Fixing hole 5, 20 Ultra-precision lathe 6, 21 Rotating spindle 6a, 21a Rotating spindle end face 7 Workpiece mounting plate 8, 24 Rotation reference axis 9, 25 Angle indexing pin 10, 29 Reference counterbore 11, 31 Diamond tool 12 Product side rotation Axis 12a Reference end face part 12b Reference side face 13 Aspherical mirror disk back face 14, 30 Balance weight 22 Fine feed base 22a Fine movement stage 22b Fixed base 22c Fine movement stage side part 23 Mounting base 32 Tool holder 34 Machine base 35, 36 NC feed stage 37 Elastic pin 37a Elastic pin end Part 37b Notch 38 Microfeed mechanism 39 Feed screw 40, 41 Support member 42, 43 Bearing 44 Pressing member 44a Pressing member end surface 45 Spring 46 Abutting member 46a Abutting member end surface 47, 59, 69 Spot light detection unit 48 Detection unit box 48a Detection unit box opening 49 Detection unit box support member 50 Laser oscillator 51 Collimator lens 52 Beam splitter 53 Magnifying lens 54 PSD
55, 60 Computer 56, 61 Monitor TV 57 Parabolic Mirror 58a Aspherical Mirror Disc Back 62 Diffraction Mirror 63 Fresnel Bite 63 Cutting Edge 64 Aspherical Mirror Disc Mold 64a Molding Surface 65 Aspherical Molding Part 68 Convex Parabolic Surface Mirror 70 Focus lens 71 Condenser lens

Claims (9)

An optical element in which a plurality of mirror surfaces made of an aspherical surface or a spherical surface are arranged on the surface in a rotational axis symmetry,
When a laser beam is incident in parallel to the rotation axis in the rotational axis symmetry, a reflection mirror portion that forms a spot light on the rotation axis when the reflected light of the laser beam is incident on the surface on which the mirror surface is formed An optical element formed.   The optical element according to claim 1, wherein the reflection mirror unit is a parabolic mirror.   The optical element according to claim 1, wherein the reflection mirror unit is a diffraction grating mirror. A method for producing an optical element in which a plurality of mirror surfaces made of an aspherical surface or a spherical surface are arranged on the surface in a rotational axis symmetry,
Detecting the position of the spot light formed by condensing the reflected light when the laser light is incident on the reflection mirror part formed in advance on the surface forming the mirror surface,
A perpendicular line hanging from the position of the spot light to the surface is a rotation axis in the rotation axis symmetry,
Positioning each of the mirror surfaces based on the rotation axis;
A method for producing an optical element. A molding die for an optical element in which a plurality of mirror surfaces made of an aspherical surface or a spherical surface are arranged on the surface in a rotational axis symmetry,
When a laser beam is incident in parallel to the rotation axis in the rotational axis symmetry, a reflection mirror portion that forms a spot light on the rotation axis when the reflected light of the laser beam is incident on the surface on which the mirror surface is formed A mold characterized by being formed.   The mold according to claim 5, wherein the reflection mirror portion is a parabolic mirror.   The mold according to claim 5, wherein the reflection mirror part is a diffraction grating mirror. A method of producing a molding die for an optical element in which a plurality of mirror surfaces made of an aspherical surface or a spherical surface are arranged on the surface in a rotational axis symmetry,
Detecting the position of the spot light formed by condensing the reflected light when the laser light is incident on the reflection mirror part formed in advance on the surface forming the mirror surface,
A perpendicular line hanging from the position of the spot light to the surface is a rotation axis in the rotation axis symmetry,
Positioning each of the mirror surfaces based on the rotation axis;
A method for producing a mold characterized by the above. A workpiece positioning device used for production of an optical element or a molding die thereof in which a plurality of mirror surfaces made of an aspherical surface or a spherical surface are arranged on the surface in a rotational axis symmetry,
A detection unit that is adjusted and positioned at an arbitrary position in the radial direction of the rotation spindle from the workpiece rotation spindle of the ultra-precision machining machine, and a laser beam oscillation unit that excites laser light applied to the workpiece attached to the rotation spindle, And the said detection unit provided with the detection part which detects the position of the spot light formed with the reflected light from the workpiece | work of the said irradiated laser beam,
A microfeed unit that is attached to the workpiece rotation spindle end of the ultra-precision machine and configured to allow microfeeding of the workpiece in the radial direction of the workpiece rotation spindle;
A rotational positioning unit that is attached to a predetermined position from the center of the work rotation spindle on the microfeed mechanism and that can position the work at an arbitrary rotation angle having a rotation axis parallel to the work rotation spindle;
A workpiece positioning apparatus characterized by comprising:

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