JP2006023367A - Shape variable mirror - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shape variable mirror with which damage of a mirror or driving devices can be prevented by releasing stress to be generated at the joint parts among the mirror and the driving devices. <P>SOLUTION: The shape variable mirror is driven so as to correct the wavefront of incident light. In the shape variable mirror, a bar-shaped member (103) is provided between a mirror part (101) and the driving device (102) of a pertinent mirror part and the mirror is equipped with a block part (107) whose length in the longitudinal direction is 0.2 to 0.6 times as long as the length of the bar-shape member and whose cross-sectional area is 9 to 64 times as large as the cross-sectional area of the member in a plane vertical to the longitudinal direction at a position including the center of the longitudinal direction of the member. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a deformable mirror that is driven so as to correct a wavefront of incident light.

  Lasers are widely used in laser communications, laser ranging devices, laser processing devices, laser light sources, and the like. In order to improve the quality and condensing performance of the laser beam, the wavefront of the laser beam is measured and the wavefront is corrected by a deformable mirror based on the result.

  In addition, in order to increase the resolution of the observation image of the large astronomical telescope and the received image of the remote sensing, the wavefront of the received light is measured, and the wavefront is corrected by the deformable mirror based on the result.

  FIG. 1 shows an example of an optical system for correcting the wavefront of light using a deformable mirror. Light incident on the variable shape mirror 1 from the laser oscillator 5 is reflected and incident on the half mirror 2. Part of the light incident on the half mirror 2 is reflected and reaches the light wavefront detector 3. The optical wavefront detector 3 detects the amount of distortion of the optical wavefront and sends the result to the control device 4 for the deformable mirror. The control device 4 for the deformable mirror operates the drive device for the deformable mirror 1 so as to minimize the detected distortion amount of the light wavefront, and corrects the optical path difference of the incident light.

  Next, a drive device for the deformable mirror will be described. FIG. 2 is a diagram showing a variable shape mirror driving device and a mirror. A plurality of driving devices are provided on the rear surface of the mirror so that they can be individually operated. As the length of the driving device changes, the shape of the mirror of the portion of the driving device changes. The drive device is formed from a piezoelectric element, a linear motor, an electromagnetic coil, or the like. Alternatively, a hydraulic drive device may be used.

  The structure of the deformable mirror is disclosed in, for example, Patent Document 1 (FIG. 1 and others), Patent Document 2 (FIG. 1 and others), Patent Document 3 (FIG. 1 and others), Patent Document 4 (FIG. 2 and others), and the like. Yes.

JP-A-5-333274 Japanese Patent Laid-Open No. 7-66463 JP 9-138304 A Japanese Patent Laid-Open No. 2002-13389

  In a conventional deformable mirror, when the drive device is operated to deform the mirror, a large stress is generated at the joint between the mirror and the drive device, and the mirror or the drive device is damaged when used repeatedly. There is. The stress includes a direction perpendicular to the mirror surface, that is, a stress in the substantially longitudinal direction of the driving device, and a stress substantially perpendicular to the direction of the mirror surface, that is, the longitudinal direction of the driving device. Both the mirror and the driving device have a sufficiently strong structure against the former stress. Multiplying the breakage of the mirror and the drive device is the latter stress, the stress in the direction of the mirror surface, that is, the stress substantially perpendicular to the longitudinal direction of the drive device. If the stress generated at the joint between the mirror and the driving device can be released, the mirror or the driving device can be prevented from being damaged.

Therefore, there is a problem of how to release stress in a direction substantially perpendicular to the direction of the mirror surface, that is, the longitudinal direction of the driving device.

  The deformable mirror according to the present invention is driven to correct the wavefront of incident light. In the variable shape mirror according to the present invention, a rod-shaped member is provided between the mirror portion and the driving device of the mirror portion, and the length in the longitudinal direction is the length of the rod-shaped member at a position including the center in the longitudinal direction of the rod-shaped member. A block portion having a cross-sectional area of 9 to 64 times the cross-sectional area of the rod-shaped member is provided on the surface perpendicular to the longitudinal direction of the rod-shaped member.

  Therefore, the stress acting between the mirror and the driving device is released by the rod-shaped member. Further, the length in the longitudinal direction is 0.2 to 0.6 times the length of the rod-shaped member, and the cross-sectional area in the plane perpendicular to the longitudinal direction of the rod-shaped member is 9 to 64 times the sectional area of the rod-shaped member. By providing the double block portion, the rod-shaped member does not buckle.

  The variable shape mirror according to an embodiment of the present invention includes a mirror joint portion between the rod-shaped member and the mirror portion, and a drive device joint portion between the rod-shaped member and the drive device.

  Therefore, the rod-shaped member and the mirror portion and the rod-shaped member and the driving device are securely connected.

  In the variable shape mirror according to one embodiment of the present invention, the rod-shaped member is made of metal.

  In the variable shape mirror according to an embodiment of the present invention, the rod-shaped member is made of molybdenum, tantalum, or carbon steel.

  Therefore, the rod-shaped member has high rigidity and is convenient for releasing stress.

  In the variable shape mirror according to one embodiment of the present invention, the block portion is cylindrical, and the position of the cylindrical rotational symmetry axis and the position of the rod-shaped member overlap.

  Therefore, the block portion is axisymmetric with respect to the rod-shaped member as an axis, which is convenient for releasing stress.

  In the variable shape mirror according to one embodiment of the present invention, the rod-shaped member has a circular cross section, and the ratio of the diameter of the circle to the length of the rod-shaped member is 1/30 to 1/5.

  Therefore, the shape of the rod-shaped member is convenient for releasing the stress.

  In the deformable mirror according to an embodiment of the present invention, the length of the rod-shaped member is 50 to 200 times the maximum displacement amount of the drive device.

  Therefore, the rod-shaped member can sufficiently cope with the displacement of the drive device.

  FIG. 3 is a view showing a deformable mirror according to an embodiment of the present invention. In the variable shape mirror of FIG. 3, a rod-like member 103 is provided between the back surface of the mirror 101 and the driving device 102.

  When one of the driving devices is displaced as shown in FIG. 3 or when one of the driving devices is displaced more than the adjacent one as shown in FIG. In this case, stress in a direction substantially perpendicular to the direction of the mirror surface, that is, the longitudinal direction of the driving device is generated. In the present embodiment, the stress is released by the deformation of the rod-shaped member 103.

  Details of the structure of the rod-shaped member are shown in FIGS. You may provide the junction part 105 of a rod-shaped member and the mirror 101, and the junction part 106 of a rod-shaped member and a drive device in the both ends of a rod-shaped member. The joint 105 and the mirror, and the joint 106 and the driving device are connected by bonding or the like. In order to ensure the connection, it is preferable that the cross-sectional area of the joint is larger than the cross-sectional area of the bar-shaped member in the plane perpendicular to the longitudinal direction of the bar-shaped member. However, the cross-sectional area of the joint 105 with the mirror is set to a size that does not hinder the deformation of the mirror. In this embodiment, the diameter of the cross section of the joint portion 105 with the mirror is ½ of the diameter of the cross section of the joint portion 106 with the driving device. The material of the rod-shaped portion of the rod-shaped member is preferably molybdenum, tantalum, carbon steel or the like. The material of the joining parts 105 and 106 is preferably molybdenum, tantalum, carbon steel or the like. The joint and the rod-shaped part are connected by caulking or welding. Moreover, you may make it form integrally.

  The dimension of the rod-shaped member of FIG. 5 is shown below.

11mm length including joints at both ends
Each joint length 2.0mm
Length of rod-shaped part 7.0mm
Section diameter 1.0mm at the junction with the mirror
Sectional diameter of the joint with the drive device 2.0mm
Cross section diameter of rod-shaped part 0.3mm

  As shown in FIG. 6, for example, a cylindrical block 107 may be provided at a position including the center in the longitudinal direction of the rod-shaped member. As described above, the stress is released by the deformation of the rod-shaped member 103. However, in the structure shown in FIG. 5, it is considered that excessive stress is generated in the rod-shaped portion and buckling occurs. In the structure shown in FIG. 6, the provision of the block 107 prevents the occurrence of buckling in the rod-shaped portion. The material of the block 107 is preferably molybdenum, tantalum, carbon steel or the like. Connect the block and the rod-shaped part by caulking. Moreover, you may make it form integrally.

  The dimension of the rod-shaped member of FIG. 6 is shown below.

11mm length including joints at both ends
Each joint length 2.0mm
Length of block part 3.0mm
The length of the bar-like part excluding the block part (two places above and below the block part)
2.0mm
Section diameter 1.0mm at the junction with the mirror
Sectional diameter of the joint with the drive device 2.0mm
Cross section diameter of block part 2.0mm
Cross section diameter of rod-shaped part 0.3mm

  FIG. 7 is a simulation result when one of the drive devices is driven in a structure that does not include a block portion, and shows displacements that occur in the rod-like member of the drive device and the surrounding rod-like members. FIG. 8 is a simulation result when one of the drive devices is driven in a structure including a block portion, and shows displacements generated in the rod-like member of the drive device and the surrounding rod-like members. 7 and 8, the larger the displacement, the darker the color is displayed.

  The data used for the simulation of FIG. 7 is as follows.

Drive amount of the drive unit Joint between the drive unit and the rod-shaped part Length 2.0 mm
Diameter 2.0mm
Rod-shaped part length 7.0mm
Diameter 0.3mm
Joining length of rod-shaped part and mirror 2.0mm
Diameter 1.0mm

  The data used for the simulation of FIG. 8 is as follows.

Drive amount of the drive unit Joint between the drive unit and the rod-shaped part Length 2.0 mm
Diameter 2.0mm
Bar-shaped part under the block Length 2.0mm
Diameter 0.3mm
Block length 3.0mm
Diameter 2.0mm
Bar-shaped part on the block Length 2.0mm
Diameter 0.3mm
Joining length of rod-shaped part and mirror 2.0mm
Diameter 1.0mm

  In FIGS. 7 and 8, attention is paid to the displacement of the rod-like portion of the drive device that has been driven to cause the displacement and the joint portion with the mirror. The displacement of the joint portion between the rod-shaped portion of the driving device and the mirror that has been driven and the mirror is larger in the structure including the block of FIG. 8 than in the structure not including the block of FIG. Actually, the displacement amount of the mirror is larger in the structure including the block of FIG. This means that the structure including the block of FIG. 8 allows the driving force to be transmitted more efficiently by the mirror. In the case of a structure that does not include the block of FIG. 7, a force that is not transmitted to the mirror is transmitted to the surrounding rod-like member, and a greater stress is generated.

  The length of the upper and lower bar-like portions of the block in FIG. 8 is about 1/3 of the length of the bar-like portion not including the block in FIG. Since the buckling stress of the rod-shaped body is inversely proportional to the square of the length, the possibility of buckling in the rod-shaped portion of the structure including the block of FIG. 8 is extremely low.

  Thus, the structure including the block of FIG. 8 releases the stress generated at the joint with the mirror. Furthermore, the force of the driving device can be efficiently transmitted by the mirror, and the possibility of causing buckling is extremely low.

It is a figure which shows an example of the optical system for correct | amending the wave front of light using a deformable mirror. It is a figure which shows the drive device and mirror of a shape variable mirror. It is a figure which shows the variable shape mirror by one Embodiment of this invention. It is a figure which shows the variable shape mirror by one Embodiment of this invention. It is a figure which shows the detail of the structure of the rod-shaped member which does not contain a block part. It is a figure which shows the detail of the structure of the rod-shaped member containing a block part. In the structure which does not include a block part, it is a figure which shows the displacement of the rod-shaped member of the said drive device, and the surrounding rod-shaped member when one of the drive devices is driven. In the structure including a block portion, when one of the drive devices is driven, it is a diagram showing the displacement of the rod-shaped member of the drive device and the surrounding rod-shaped members.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 101 Shape variable mirror 102 Drive apparatus 103 Rod-shaped member 105 Joining part 106 with a mirror Joining part 107 with a driving apparatus Block

Claims (7)

  A variable shape mirror that is driven so as to correct the wavefront of incident light, and is provided with a rod-shaped member between the mirror portion and the driving device of the mirror portion, and at a position that includes the longitudinal center of the rod-shaped member, The length in the longitudinal direction is 0.2 to 0.6 times the length of the rod-shaped member, and the cross-sectional area in the plane perpendicular to the longitudinal direction of the rod-shaped member is 9 to 64 times the sectional area of the rod-shaped member. A deformable mirror with a block part.   The variable shape mirror according to claim 1, further comprising a mirror joint portion between the rod-shaped member and the mirror portion, and a drive device joint portion between the rod-shaped member and the drive device.   The variable shape mirror according to claim 1, wherein the rod-shaped member is made of metal. The variable shape mirror according to claim 3, wherein the rod-shaped member is made of molybdenum, tantalum, or carbon steel.   The variable shape mirror according to any one of claims 1 to 4, wherein the block portion has a cylindrical shape, and the position of the cylindrical rotational symmetry axis and the position of the rod-shaped member overlap each other.   The variable shape mirror according to any one of claims 1 to 5, wherein a cross-section of the rod-shaped member is circular, and a ratio of the diameter of the circle to the length of the rod-shaped member is 1/30 to 1/5.   The variable shape mirror according to any one of claims 1 to 6, wherein the length of the rod-shaped member is 50 to 200 times the maximum displacement of the driving device.

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