JP2007069283A - Processing apparatus and manufacturing method using the processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a machining device capable of measuring and machining a machining surface without removing an optical element, and a manufacturing method using the machining device. <P>SOLUTION: This machining device 1 is capable of machining the optical element 20 by a small tool 13 for correcting a part in a holding state of the optical element 20 in a holder 12. Machining and shape accuracy (wavefront aberration) can be measured in the holding state of the optical element 20 in the holder 12 by providing a measuring optical system 2 and a lighting optical system 3 by a Shack-Hartman principle. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a processing apparatus capable of measuring accuracy and polishing of an optical element and a manufacturing method using the processing apparatus.

  For manufacturing an optical element, there is a method of removing a surplus portion of the surface by polishing, and various types of processing apparatuses are used. When the processing surface is a flat surface or a spherical surface, and the required accuracy can be confirmed with the Newton prototype, measurement can be performed with the optical element attached to the processing apparatus. However, if the machined surface is aspherical or if the required accuracy is further increased, measurement with the machine attached to the machining device is not possible, and measurement must be performed on an interferometer or an ultra-high accuracy CMM. Don't be. Processing equipment that feeds back the results of measurements using an interferometer or ultra-high-precision 3D measuring machine and enables correction processing is put to practical use, but processing and measurement are performed separately. (For example, refer to Patent Document 1).

JP 2000-97666 A

  In this way, if the machined surface is aspherical or if the accuracy is beyond the use limit of Newton's prototype even on a spherical surface, an interferometer or an ultra-high-precision CMM must be used. There is a problem that the working efficiency is deteriorated because the optical element must be attached and detached between the processing device and the measuring device. There is also a problem that it is difficult to improve processing accuracy because errors due to the attachment / detachment of optical elements and positioning errors for each measurement occur. Although it is possible to mount an interferometer or ultra-high-precision 3D measuring machine on the processing equipment, each measurement method has a movable part and a contact part (if the interferometer is a fringe scan) and is polished. Not suitable for processing environment.

  The present invention has been made in view of such problems, and an object thereof is to provide a processing apparatus capable of measuring and processing a processed surface without removing an optical element.

  In order to solve the above-described problems, a processing apparatus according to the present invention is held by a holding unit (for example, the holder 12 in the embodiment) that holds a workpiece (for example, the optical element 20 in the embodiment) and the holding unit. A processing unit for processing the processed member (for example, the small tool 13 for partial correction in the embodiment) and a measuring unit for measuring the shape accuracy of the processed member (for example, the measurement optical system 2 and the illumination optical system 3 in the embodiment) ).

  In such a processing apparatus according to the present invention, the member to be processed is formed of a material that transmits light, and the measurement unit includes a point light source (for example, the white light source 4 and the slit plate 5 in the embodiment) and the point light source. A first conversion unit (for example, the collimator lens 6 in the embodiment) that converts a light beam emitted from the parallel beam into a parallel light beam, and irradiates the workpiece with the parallel light beam converted by the first conversion unit. A second conversion unit (for example, the spherical mirror 10 in the embodiment) that converts a transmitted light beam into a parallel light beam and a plurality of microlenses arranged two-dimensionally are converted by the second conversion unit. A wave based on the Shack-Hartmann principle, which is composed of a microlens array that forms an image of parallel light beams with each microlens and an image sensor that detects an image formed with the microlens array. Is preferably measured is the optical system. Further, at this time, the point light source is preferably configured to emit visible light.

  Moreover, it is preferable that the processing apparatus which concerns on this invention can process the to-be-processed member by a process part, and can measure the shape accuracy of the to-be-processed member by a measurement part in the state which hold | maintained the to-be-processed member with the holding member.

  Moreover, the processing device according to the present invention includes a control unit (for example, the analysis device 14 in the embodiment) that controls the processing unit based on the shape accuracy of the processing member measured by the measurement unit and processes the processing member. It is preferable to have.

  Furthermore, the processing apparatus according to the present invention preferably includes a positioning unit (for example, the positioning mechanism 15 in the embodiment) in which the holding unit is configured to be rotatable and performs positioning in the rotation direction of the holding unit.

  The manufacturing method according to the present invention is a manufacturing method for processing a workpiece using a processing device having a holding portion, a processing portion, and a measuring portion, and the step of holding the workpiece in the holding portion; The step includes processing the workpiece held by the holding portion with the machining portion, and measuring the shape accuracy of the workpiece with the measurement portion. At this time, the member to be processed is formed of a material that transmits light, and the measurement unit includes a point light source, a first conversion unit that converts a light beam emitted from the point light source into a parallel light beam, and a first conversion unit. A second conversion unit that irradiates the workpiece with the parallel luminous flux converted by the step, converts the light beam transmitted through the workpiece into a parallel luminous flux, and a plurality of two-dimensionally arranged microlenses, The wavefront according to Shack-Hartmann's principle composed of a microlens array that forms images of parallel light beams converted by the two conversion units on each microlens and an image sensor that detects an image formed on the microlens array A measurement optical system is preferable.

  In order to explain the present invention in an easy-to-understand manner, the constituent elements of the embodiment have been described, but it goes without saying that the present invention is not limited thereto.

  When the machining apparatus according to the present invention is configured as described above, a machining apparatus capable of machining a workpiece and measuring the shape accuracy can be provided.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. First, the structure of the processing apparatus 1 which concerns on this invention is demonstrated using FIG. This processing apparatus 1 measures the wavefront aberration of a transmitted wavefront that passes through an optical element 20 in a finishing process stage (a state in which light is transmitted), and performs a finishing process (partial correction) according to the measurement result. . First, the optical system of the processing apparatus 1 will be described. The optical system 20 includes a measuring optical system 2 arranged in the vertical direction with the optical element 20 interposed therebetween, and an illumination optical system 3 arranged on the side thereof.

  The illumination optical system 3 is arranged side by side in the left-right direction, and a white light source 4, a slit plate 5, a collimator lens 6, and a half mirror 7 are sequentially arranged on the optical axis. A pinhole penetrating in the thickness direction is formed at a substantially central portion of the slit plate 5, and this pinhole is located on the optical axis of the illumination optical system 3. White light emitted from the white light source 4 is applied to the slit plate 5 through the optical fiber 4a. The white light beam that has passed through the pinhole of the slit plate 5 is converted into a parallel light beam by the collimator lens 6 and enters the half mirror 7. The half mirror 7 is disposed at a point where the optical axes of the illumination optical system 3 and the measurement optical system 2 intersect with each other, and reflects a part of white light and transmits the rest. As will be described later, the half mirror 7 is also used in the measurement optical system 2, and a part of the parallel light beam incident on the half mirror 7 is reflected upward by the half mirror 7 and enters the measurement optical system 2.

  In the measurement optical system 2, a spherical mirror 10, an optical element 20, a half mirror 7, a microlens array 8, and an imaging element 9 are arranged in order from the top on the optical axis. The parallel light beam reflected by the half mirror 7 enters the optical element 20 and is condensed, and once formed, the light is reflected by the spherical mirror 10. The light beam reflected by the spherical mirror 10 is again transmitted through the optical element 20 to become a parallel light beam and enters the half mirror 7, and a part of the light beam is transmitted and enters the microlens array 8. The microlens array 8 is a lens assembly in which a plurality of minute lenses (microlenses) are two-dimensionally arrayed, and light beams that have passed through each microlens are image pickup devices arranged on the focal plane of each microlens. 9 is imaged as each point image. The image signal output from the image sensor 9 is analyzed by the analysis device 14.

  Here, a method for measuring the wavefront aberration of the optical element 20 in the processing apparatus 1 according to the present embodiment will be briefly described. The measurement optical system 2 and the illumination optical system 3 are examples of a transmission wavefront measurement optical system based on the Shack-Hartmann principle. Light from a point light source emitted from a pinhole of the slit plate 4 is converted into a parallel light beam by a collimator lens 5. An apparatus for analyzing the amount of wavefront aberration of the optical element 20 and its distribution according to the position of each point image converted and transmitted through the optical element 20 and further imaged on the imaging element 9 at the focal plane of the microlens by the microlens array 8 14 can be calculated. Here, the position of the point image refers to the point image formed by the microlens array 8 when the above measurement is performed by replacing the spherical mirror 12 with a plane mirror in a state where the optical element 20 is not attached to the holder 12. The deviation from the position.

  Except for the spherical mirror 10, members constituting the measurement optical system 2 and the illumination optical system 3 are fixedly held by the housing 11. As shown in FIG. 1, the inside of the housing 11 communicates with a first measurement space portion 11a that extends vertically and has an upper end opened, and a substantially intermediate portion in the vertical direction of the first measurement space portion 11a. The second measurement space 11b is formed in the first measurement space 11a, the half mirror 7, the microlens array 8, and the image sensor 9 are disposed in the first measurement space 11a, and the second measurement space 11b is white. The other end of the optical fiber 4 a having one end connected to the light emitting portion of the light source 4, the slit plate 5, and the collimator lens 6 are disposed.

  The optical element 20 is held by a holder 12 attached to the upper end of the housing 11. The holder 12 is formed with a through hole 12 a penetrating vertically. The optical element 20 is fixedly held at the upper end portion of the through hole 12 a, and the lower end portion is the upper end of the first measurement space portion 11 a of the housing 11. It communicates with the opening. Further, the holder 12 is configured to be rotatable relative to the housing 11 on the same axis as the optical axis of the measurement optical system 2 and is not shown when polishing is performed by the small tool 13 for partial correction. The optical element 20 rotated and held by the unit is rotated. The position in the rotation direction of the holder 12, that is, the position in the rotation direction of the optical element 20 is configured to be positioned by the positioning mechanism 15. The positioning mechanism 15 is configured such that the position of the holder 12 in the rotational direction is accurately measured and positioned by an encoder, for example.

  Now, a procedure for finishing the optical element 20 by the processing apparatus 1 configured as described above will be described. The optical element 20 in the finishing process stage is fixedly held on the holder 12, and the measurement of the transmitted wavefront is started by the above-described method in a state where the position of the holder 12 in the rotational direction is fixed. The analysis device 14 calculates the amount and distribution of the wavefront aberration of the optical element 20 from the position of each point image of the image sensor 9, and determines the amount and location to be removed by polishing. Then, the partial correction small tool 13 disposed above the processing apparatus 1 is controlled by the analysis apparatus 14 to polish the optical element 20. At this time, since the above-described spherical mirror 12 interferes with the partial correction small tool 13, the spherical mirror 12 is moved upward and retracted by a drive mechanism (not shown). When the measurement of the optical element 20 is performed again after the polishing process, the small tool 13 for partial correction is retracted from above the optical element 20, and the measurement is performed by moving the spherical mirror 12 downward. The wavefront aberration of the optical element 20 is measured after the processed surface of the optical element 20 is cleaned.

  In the above embodiment, the case where the light beam transmitted through the optical element 20 is reflected by the spherical mirror 12 has been described. However, as shown in FIG. The wavefront aberration can also be measured by the processing apparatus 1 ′ in which the second collimator lens 17 is arranged and the spherical mirror 12 is replaced with the plane mirror 16. In this case, the parallel light beam reflected by the half mirror 7 and incident on the measurement optical system 2 ′ is once imaged at the focal point of the optical element 20 by the second collimator lens 17 and transmitted through the optical element 20. Is converted to a parallel light beam and reflected by the plane mirror 16. In FIG. 2, the same components as those of the processing apparatus 1 shown in FIG. In such a processing apparatus 1 ′, the light beam that has passed through the optical element 20 becomes a parallel light beam, so that the position of the plane mirror 16 is not limited, and a partial correction is made between the optical element 20 and the plane mirror 16. It is not necessary to configure so that the plane mirror 16 can be retracted upward when the optical element 20 is processed because a sufficient processing space for the small tool 13 can be secured.

  Further, as in the processing apparatus 1 ″ shown in FIG. 3, it is possible to irradiate a parallel light beam from below the optical element 20 and measure the light beam transmitted through the optical element 20 upward. In this case, the illumination optical system 3 ″ and the measurement optical system 2 ″ are arranged above and below the optical element 20 on the optical axis, and the collimated light beam emitted from the collimator lens 6 is temporarily imaged by the optical element 20 to be imaged. The collimator lens 18 forms a parallel light beam, the parallel light beam is imaged by the microlens array 8, and each point image is detected by the image sensor 9. Note that this processing apparatus 1 ″ also has a processing function. Since it is necessary to secure the processing space of the partial correction small tool 13 at the time of processing in the same manner as the apparatus 1 above the optical element 20, as shown in FIG. 3, the second collimator lens 18, the micro lens array 8, Oh Beauty, and stores and holds the image pickup device 9 to detect casing 19, at the time of processing, configured to retract upward by a driving mechanism (not shown) the detection housing 19. Also in FIG. 3, the same constituent elements as those of the processing apparatus 1 shown in FIG.

  The effects achieved by incorporating the transmission wavefront measuring optical system 2 based on the Shack-Hartmann principle into the processing apparatus 1 for processing (polishing) the optical element 20 in the finishing stage as described above can be summarized as follows. become that way. First, since the transmission wavefront measuring optical system 2 based on the Shack-Hartmann principle has no movable part, the wavefront aberration of the processing surface can be measured with the optical element 20 attached to the processing apparatus 1. Therefore, there is no error due to the attachment / detachment of the optical element 20 with respect to the holder 12, and the positioning accuracy at the time of measurement can be improved, and the processing accuracy of the optical element 20 based on the measurement result can be improved.

  Secondly, in the measurement in the processing apparatus 1 according to the present embodiment, a special light source such as ultraviolet light is not necessary, and measurement can be performed using visible light (white light). It is possible to provide an apparatus for processing such an aspherical or spherical optical element 20. Incidentally, according to the configuration of the processing apparatus 1 ″ as shown in FIG. 3, the half mirror 7 and the spherical mirror 12 (plane mirror 16) are not required, and the measurement optical system 2 ″ and the illumination optical system 3 ″ are simplified, The processing apparatus 1 ″ can be provided at a lower cost.

It is a block diagram which shows the processing apparatus which concerns on this invention. It is a block diagram which shows the processing measure which has sufficient processing space of the optical element. It is a block diagram which shows the processing apparatus which has arrange | positioned the illumination optical system under the optical element, and has arrange | positioned the measurement optical system above the optical element.

Explanation of symbols

1 Processing device 2 Measurement optical system (measurement unit)
3 Illumination optical system (measurement unit)
4 White light source (point light source)
5 Slit plate (point light source)
6 Collimator lens (first converter)
8 Microlens array 9 Image sensor 10 Spherical mirror (second conversion unit)
12 Holder (holding part)
13 Small tool for partial correction (machining part)
14 Analysis device (control unit)
15 Positioning mechanism (positioning part)
20 Optical members (members to be processed)

Claims (8)

A holding part for holding a workpiece,
A processing unit for processing the workpiece to be held by the holding unit;
A processing apparatus having a measuring unit that measures the shape accuracy of the workpiece. The workpiece is formed of a material that transmits light,
The measurement unit irradiates the workpiece with a point light source, a first conversion unit that converts a light beam emitted from the point light source into a parallel light beam, and the parallel light beam converted by the first conversion unit, A second conversion unit that converts a light beam that has passed through the workpiece into a parallel light beam; and a plurality of microlenses that are two-dimensionally arranged, and each of the parallel light beams converted by the second conversion unit. The wavefront measuring optical system according to Shack-Hartmann's principle, comprising a microlens array formed by the microlens and an image sensor for detecting an image formed by the microlens array. The processing apparatus according to 1.   The processing apparatus according to claim 2, wherein the point light source is configured to emit visible light.   2. The shape of the processed member can be measured by the processing unit and the shape accuracy of the processed member can be measured by the measuring unit in a state where the processed member is held by the holding member. The processing apparatus in any one of -3.   5. The apparatus according to claim 1, further comprising a control unit that controls the processing unit based on the shape accuracy of the processing member measured by the measuring unit to process the processing member. Processing equipment. The holding part is configured to be rotatable,
The processing apparatus according to claim 1, further comprising a positioning unit that positions the holding unit in a rotation direction. A manufacturing method for processing a workpiece using a processing device having a holding unit, a processing unit, and a measurement unit,
Holding the workpiece with the holding portion;
Processing the workpiece to be processed held by the holding unit with the processing unit;
Measuring the shape accuracy of the workpiece by the measuring unit. The workpiece is formed of a material that transmits light,
The measurement unit irradiates the workpiece with a point light source, a first conversion unit that converts a light beam emitted from the point light source into a parallel light beam, and the parallel light beam converted by the first conversion unit, A second conversion unit that converts a light beam that has passed through the workpiece into a parallel light beam; and a plurality of microlenses that are two-dimensionally arranged, and each of the parallel light beams converted by the second conversion unit. The wavefront measuring optical system according to Shack-Hartmann's principle, comprising a microlens array formed by the microlens and an image sensor for detecting an image formed by the microlens array. 8. The production method according to 7.

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