JP5103775B2 - Detector, shape measuring device, and shape measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detector for a shape measuring instrument, capable of quickly attaining accurate measurement with a probe that tracks along the surface shape of an object to be measured. <P>SOLUTION: A rod member 3 displaced in &plusmn;Z-directions, along the surface shape of a work W. Contact pressure, i.e. pressing force, of a contact part 35a to a surface of the work W is controlled so as to be constant at a proper value, by regulating control air supplied to a pressure acting chamber 27, when XY-scanning a probe unit 10A. The first air pressure in the pressure acting chamber 27 can be controlled therein with precision of 0.06 kPa or lower, by the existence of ultraprecise regulators R1, R2, and the contact pressure of the contact part 35a is thereby restrained about 2 mg or lower of fluctuations. That is, the fluctuations in the deformation of the work W, resulting from the fluctuation of the contact pressure becomes 1 nm or lower to make the measurement errors caused by the deformation of the work W to become 1 nm or lower. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a detector for a shape measuring device for measuring the surface shape and the like of a lens and other optical elements, and a shape measuring device and method using such a detector.

  Conventionally, various techniques have been proposed as techniques for measuring a three-dimensional shape (three-dimensional shape) of an optical element having a mirror surface or a lens surface. For example, there is a contact-type measurement method in which a stylus is brought into direct contact with the surface of an object to be measured and the amount of displacement is measured (see Patent Document 1). In addition, a non-contact measurement method has been proposed in which a laser beam or the like is incident on the surface of an object to be measured and the surface irregularities are measured by receiving the reflected light (see Patent Document 2).

The former contact-type measurement method does not depend on the surface physical properties of the object to be measured because the stylus is brought into direct contact with the object to be measured. For this reason, the contact-type measurement method can accurately measure various objects to be measured. As such a contact-type measurement method, there is a method in which the stylus is supported by an air bearing type cylinder, and an urging force that cancels the weight of the stylus is applied to the rod in the cylinder block by, for example, controlled air pressure. (See Patent Document 3).
JP-A-5-209741 Japanese Patent No. 3046635 JP 2002-162220 A

  In the example using an air bearing type cylinder as described above, a regulator for biasing force control is provided to give a precise biasing force to the stylus, but a special regulator is not provided for the air bearing. Instead, it is only connected to a pressurized gas source. However, as a result of studies by the present inventor, it has been found that the contact pressure of the stylus against the object to be measured cannot be sufficiently controlled only by providing a regulator for controlling the urging force against the stylus. It has been found that the contact pressure of the stylus is affected by fluctuations in the air pressure supplied to the air bearing, resulting in a decrease in shape measurement accuracy.

  Therefore, an object of the present invention is to provide a detector for a shape measuring apparatus that can realize high-precision measurement by precisely controlling the contact pressure of a stylus.

  Another object of the present invention is to provide a shape measuring device incorporating the detector and a shape measuring method using the detector.

In order to solve the above problems, a detector for a shape measuring apparatus according to the present invention includes a contact body that contacts a body to be detected as a measurement target, and a contact member that has a shaft-like member that supports the contact body at one end. And a cylinder-shaped holding body that holds the shaft-shaped member in a state where the axial direction is a vertical direction and one end is a lower end, and is attached to the holding body and receives the supply of the first air pressure, a biasing means for applying a biasing force in the vertical direction upward along the axial direction with respect to the contacts, provided in association with the carrier, by receiving the supply of the second air pressure, axially contact without contact And a first pressure regulator that controls the first air pressure supplied to the urging means with a first resolution of 0.02 kPa or less and a fluctuation amount of 0.06 kPa or less. A first air supply control unit having a first supply air supply to the air bearing Air pressure controls in the following second resolution 0.02 kPa, and a second air supply control unit having a second pressure regulator controlled by the amount of variation of less 0.06KPa, said biasing means, said The side surface of the shaft-like member inserted through the holding body has a step-like stress generating surface formed so as to face the one end side, and the contact pressure of the contact body with respect to the detected body is 0 It is controlled with a resolution of .7 mg or less and controlled with a fluctuation amount of 2 mg or less.

In the detector, the first pressure regulator controls the first air pressure with a first resolution of 0.02 kPa or less and a fluctuation amount of 0.06 kPa or less, and the second pressure regulator controls the second air pressure to 0. Since the control is performed with the second resolution of 02 kPa or less and with the fluctuation amount of 0.06 kPa or less, the air bearing prevents the biasing means from interfering with the setting accuracy of the contact pressure with respect to the object to be measured. Thus, the urging means can be operated in its original state, and the contact pressure of the contact body can be precisely controlled, so that highly accurate shape measurement can be realized. At this time, the contact pressure of the contact body with respect to the object to be detected is controlled with a resolution of 0.7 mg or less and controlled with a fluctuation amount of 2 mg or less. The variation of the deformation of the measurement object is 1 nm or less, and the measurement error due to the deformation can be 1 nm or less.

  In a specific aspect or aspect of the present invention, in the detector, the first air supply control unit cancels a part of the weight of the contactor and the weight part remaining without being canceled is measured by the contact body. Contact pressure. In this case, the contact pressure can be set by simple weighting that partially cancels the dead weight of the contact.

  According to a specific aspect of the present invention, in the detector described above, the urging means faces the one end side on the side surface of the shaft-like member that is inserted into the insertion hole of the outer frame body that constitutes the holding body. Has a step-like stress generating surface. In this case, the urging force applied to the contact can be adjusted with high accuracy by the stress generating surface that can be easily formed on the side surface of the shaft-shaped member.

  According to another aspect of the present invention, a light detection surface that is provided on the shaft-like member and reflects the inspection light, and a displacement sensor that irradiates the light detection surface with the inspection light and detects the reflected light are further provided. In this case, the displacement amount of the contact can be measured with high accuracy while being non-contact, and the undulation of the surface of the detected object can be measured with high accuracy based on the measurement result.

The shape measuring apparatus of the present invention includes the above-described detector, a moving unit that relatively moves the object to be measured in a direction perpendicular to the axial direction with respect to the contact, and a relative movement of the object to be measured by the moving unit. Computation means for calculating the amount of axial displacement of the contact caused by the contact between the surface and the contact based on the output of the displacement sensor and measuring the shape of the object to be measured.

  In the above shape measuring apparatus, the displacement of the contact is calculated from the output of the displacement sensor by the computing means while moving the measured object relative to the contact by the moving means. It can be efficiently measured as a process.

The shape measuring method of the present invention measures the axial position of a contact by contacting the contact that contacts the surface of the object to be measured while making contact with the surface of the object to be measured, thereby measuring the surface of the object to be measured. A shape measuring method for measuring a shape , wherein the first air pressure is supplied by an urging means attached to a cylindrical holding body for holding a shaft-shaped member and axially applied to a contact. An upward biasing force is applied along the holding body, and the air bearing provided in association with the holding body receives the supply of the second air pressure to support the contactor in a non-contacting manner so as to be displaceable in the axial direction. Has a step-like stress generating surface formed so as to face one end side on the side surface of the shaft- shaped member inserted through the holder hole, and is vertically upward along the axial direction with respect to the contact Alternatively, the first air pressure supplied to the urging means for applying the downward urging force is the first air pressure. The air pressure is controlled with a first resolution of 0.02 kPa or less and controlled with a fluctuation amount of 0.06 kPa or less, and the second air pressure supplied to the air bearing that supports the contactor so as to be displaceable in the axial direction without contact is 0.00. By controlling with a second resolution of 02 kPa or less and with a fluctuation amount of 0.06 kPa or less, the contact pressure of the contact body to the detected object is controlled with a resolution of 0.7 mg or less and a fluctuation amount of 2 mg or less. It is controlled by.

In the above-described shape measuring method, it is possible to prevent the air bearing from interfering with the urging means to reduce the setting accuracy of the contact pressure of the contact body with respect to the object to be measured. Thereby, the urging means can be operated in its original state, and the contact pressure of the contact body can be precisely controlled, so that highly accurate shape measurement can be realized. At this time , the contact pressure of the contact body with respect to the object to be detected is controlled with a resolution of 0.7 mg or less and controlled with a fluctuation amount of 2 mg or less. The variation of the deformation of the measurement object is 1 nm or less, and the measurement error due to the deformation can be 1 nm or less.

  Hereinafter, a detector for a shape measuring apparatus according to an embodiment of the present invention will be specifically described with reference to the drawings.

  FIG. 1 is a front view of a detector 10 according to the embodiment, and FIG. 2 is an enlarged side sectional view for explaining a main part of the detector 10 shown in FIG.

  The detector 10 includes a probe device 10A on the main body side and a laser interferometer 10B that detects displacement of a movable portion of the probe device 10A. Here, the probe apparatus 10 </ b> A includes a cylinder block 2 that is a holding body, a rod member 3 that is a shaft-like member, and a support member 4.

  In the probe apparatus 10A, the cylinder block 2 is fixed to the support member 4 and supported in a stable state. The cylinder block 2 is a portion as an outer frame body that holds the rod member 3 so that the axial direction of the rod member 3 extends in the vertical direction, that is, the Z direction, and has a rod insertion hole 21 at the center as shown in FIG. . The rod insertion hole 21 has a substantially rectangular cross section and extends along the Z direction in which the cylinder block 2 should extend. The rod insertion hole 21 penetrates in the Z direction and opens at the center of the upper and lower end faces of the cylinder block 2.

  The rod member 3 is a portion that moves up and down in the ± Z direction following the surface shape of the workpiece W that is the object to be measured or the detected object, that is, a contact, and is inserted into a rod insertion hole 21 provided in the cylinder block 2. It is possible to displace in the Z direction which is the axial direction. The lower end portion 31 which is one end portion of the rod member 3 protrudes downward from the opening on the lower end surface side of the rod insertion hole 21, and the upper end portion 33 of the rod member 3 is the opening on the upper end surface side of the rod insertion hole 21. Protrudes upward from the top. In addition, the rod member 3 is provided with a probe main body 35 and a mirror member 36, which will be described later, at both end portions 31 and 33 in the vertical direction of the quadrangular columnar shaft member BD. The shaft-shaped member BD is integrally formed of, for example, a low-expansion coefficient and a lightweight ceramic material.

  A spherical contact portion 35 a made of ruby, diamond, steel, or the like is fixed to the tip of the probe main body 35 protruding from the lower end portion 31 of the rod member 3. The contact portion 35a is a contact body for making contact with the workpiece W, which is an object to be measured, and can be displaced in the Z direction together with the shaft-shaped member BD. By providing such a contact portion 35a, the possibility that the surface of the workpiece W is damaged by the probe main body 35 can be reduced, and the probe main body 35 can be stably brought into contact with the surface of the workpiece W. The contact portion 35a can be exchanged together with the probe main body 35. That is, for example, a male screw 35 c is formed on the upper portion of the probe main body 35, and a female screw 35 d is formed on the lower portion of the lower end portion 31. For example, a plurality of types of probe main bodies 35 are attached to and detached from the lower end portion 31. Can be attached as possible. That is, a plurality of types of probe main bodies 35 can be used properly according to the forming material and surface shape of the workpiece W, and the material and shape of the contact portion 35a can be appropriately changed.

  The upper surface of the Z mirror member 36 which is a measurement target fixed to the upper end portion 33 of the rod member 3 is a mirror surface extending in the XY plane, that is, a light detection surface for detecting the displacement of the rod member 3 in the Z direction. A Z mirror 36a is provided. Since the Z mirror 36a reflects the detection light ML from the displacement sensor provided above, that is, the laser interferometer 10B (see FIG. 1) as the light irradiation means, the laser interferometer 10B uses the rod based on the reflected light RL. The displacement amount of the member 3 can be calculated.

  A stepped portion 39 is formed on the side surface 3a of the rod member 3 as a portion for applying a levitation force in the + Z direction vertically above. This stepped portion 39 has a stress generating surface 39a formed so as to face the probe main body 35 side, that is, downward in the vertical direction. As will be described in detail later, the stress generating surface 39a serves as an urging means for providing the rod member 3 with a thrust or urging force (levitation force) upward in the vertical direction that at least partially eliminates the weight of the rod member 3. Fulfill. Due to the thrust or urging force vertically applied to the rod member 3 by the step portion 39, the rod member 3 can be in a suspended state in which the weight of the rod member 3 is partially offset, and the rod member 3 is moved downward in the vertical direction. You can adjust the power to descend. Thereby, the contact part 35a of the rod member 3 lower end can be made to contact with the workpiece | work W surface with arbitrary forces.

  An upper bearing member 23 made of a porous body is provided along the inner wall surface 21 a at the upper portion of the inner wall surface 21 a of the rod insertion hole 21 formed in the cylinder block 2. The upper bearing member 23 includes a plurality of sets of porous plates facing the outer peripheral surface SS of the rod member 3. Also, a lower bearing member 24 made of a porous body is provided along the inner wall surface 21 a at the lower portion of the inner wall surface 21 a of the rod insertion hole 21. The lower bearing member 24 also includes a plurality of sets of porous plates that face the outer peripheral surface SS of the rod member 3. The upper bearing member 23 and the lower bearing member 24 described above function as an air bearing that supports the rod member 3 in a non-contact manner so as to be displaceable in the Z direction together with the outer peripheral surface SS of the rod member 3 described below.

  An air supply port 26 is formed on the outer surface of the cylinder block 2. The air supply port 26 communicates with the inner wall surface 21a of the rod insertion hole 21 via the upper bearing member 23 and the lower bearing member 24 which are bearings, and the pressurized air from the air supply source P is super It is supplied to the upper bearing member 23 and the lower bearing member 24 through a precision regulator (pressure tight regulator) R2 and a pipe L2. The supply pressure of the control air to the air supply port 26 is monitored by, for example, a pressure sensor PS provided on the path of the pipe L2, and the detection result of the pressure sensor PS is sent to an ultra-precision regulator R2 having a built-in pressure control valve. Provide feedback. That is, the air pressure supplied to the back surfaces of the bearing members 23 and 24 can be adjusted with high precision by the super-precision regulator R2, which is the second air supply control unit, and is remotely controlled by a control device (not shown). . The pressurized air from the ultraprecision regulator R2 passes through the upper bearing member 23 and the lower bearing member 24, reaches the outer surface, and is jetted toward the side surface 3a of the rod member 3. The rod member 3 is supported so as to be displaceable in the vertical direction with respect to the rod insertion hole 21 of the cylinder block 2 in a non-contact manner by the static pressure of the pressurized air ejected from both the bearing members 23 and 24.

  A pressure acting chamber 27 is formed between the upper bearing member 23 and the lower bearing member 24 and below the step portion 39 of the rod member 3. When the rod member 3 is inserted into the rod insertion hole 21, the pressure acting chamber 27 is a semi-airtight structure sandwiched between the inner wall surface 21 a of the rod insertion hole 21 and the side surface 3 a of the rod member 3 or the stress generation surface 39 a. It becomes a space of state. Here, the pressure resolution of the ultraprecision regulator R1 is set to about 0.02 kPa or less, as will be described later.

  A thrust port 28 is formed in the middle of the outer surface of the cylinder block 2. The thrust port 28 communicates with the pressure acting chamber 27 on the inner wall side of the rod insertion hole 21. Pressurized air from the air supply source P is pressured via the ultraprecision regulator (pressure tight regulator) R1 and the pipe L1. It is supplied to the working chamber 27. The supply pressure of control air to the thrust port 28 is monitored by, for example, a pressure sensor PS provided on the path of the pipe L1, and the detection result of the pressure sensor PS is fed back to the ultraprecision regulator R1 having a built-in pressure control valve. Is done. That is, the atmospheric pressure in the pressure working chamber 27 can be adjusted with high accuracy by the ultraprecision regulator R1 that is the first air supply control unit, and is remotely controlled by a control device (not shown). The pressure action chamber 27 and the thrust port 28 described above, together with the stepped portion 39 provided on the side surface 3 a of the rod member 3, are the portions in which the levitation force is applied in the + Z direction vertically above, that is, the rod member 3 in the vertical direction. It functions as an urging means for applying an urging force upward. Here, the pressure resolution of the ultraprecision regulator R1 is set to about 0.02 kPa or less, as will be described later.

  When the control air is supplied to the thrust port 28 by the ultraprecision regulator R2 as described above, the control air acts on the stress generation surface 39a of the step portion 39. That is, the thrust that pushes in the + Z direction on the root side, that is, the floating force, is applied to the rod member 3 by the control air from the thrust port 28. Here, the area of the stress generating surface 39a, which is the step area of the stepped portion 39, can generate the necessary levitation force corresponding to the pressure of the pressurized air, so that the super-precision regulator R1. By controlling the pressure of the pressurized air supplied from above, it is possible to apply an upward biasing force, that is, a lifting force, to the rod member 3 so as to eliminate the weight of the rod member 3. Further, by adjusting the pressure value of the pressurized air supplied from the ultra-precision regulator R1, the levitation force applied to the rod member 3 by the step portion 39 changes, so that the contact portion 35a at the lower end of the rod member 3 is moved to the workpiece W. The surface can be brought into contact with any pressing force.

  Here, the roles of the ultraprecision regulator R2 for the bearing members 23 and 24 and the ultraprecision regulator R1 for the pressure acting chamber 27 will be specifically described.

  By controlling the urging force, that is, the levitation force applied to the rod member 3, control of the contact pressure of the contact portion 35a against the surface of the workpiece W is achieved. When the workpiece W is a molded product such as a resin, for example, the surface is deformed by the contact pressure of the contact portion 35a. Therefore, the measurement error of the surface shape is also reduced by suppressing such variation of the contact pressure. In order to suppress the measurement error due to deformation of the workpiece W, which is a molded product such as resin, to 1 nm or less, for example, it is premised on that error generation due to surface deformation is reduced, and the contact pressure of the contact portion 35a varies by about 2 mg or less. It is necessary to limit the amount. If it demonstrates with a specific example, when measuring the workpiece | work W which is a resin molded product with the contact part 35a made from a ruby, it turns out that the fluctuation | variation of 10 mg of contact pressure will cause the increase / decrease in surface deformation of 3.6 nm. Such an increase or decrease in surface deformation directly becomes a measurement error.

In order to suppress the contact pressure of the contact portion 35a to a fluctuation amount of about 2 mg or less as described above, the first air pressure generated by the ultraprecision regulator R1 provided for the pressure action chamber 27 is a fluctuation amount of 0.06 kPa or less. It is necessary to control with. This is based on the premise that the area of the stress generating surface 39a provided on the rod member 3 is about 0.7 mm ² or less. In other words, if the super-precision regulator R1 can control the first air pressure with an accuracy of 0.06 kPa or less, the contact pressure of the contact portion 35a can be kept within a fluctuation of about 2 mg. It is expected that the measurement error can be reduced to about 1 nm or less. At this time, in order to control the first air pressure generated by the ultraprecision regulator R1 with an accuracy of 0.06 kPa or less, it is generally necessary to set the first resolution, which is the performance of the ultraprecision regulator R1, to about 0.02 kPa or less. is there.

On the other hand, even if only the first air pressure generated by the superprecision regulator R1 is precisely controlled, the contact pressure of the contact portion 35a cannot be suppressed to a fluctuation amount of about 2 mg or less in the actual detector 10. This is presumably because the contact pressure of the contact portion 35a is affected by the fluctuation of the second air pressure supplied to the bearing members 23, 24, and as a result, the shape measurement accuracy is lowered. That is, since the pressure acting chamber 27 and the bearing members 23 and 24 are not completely cut off and communicate with each other, the first air pressure given to the pressure acting chamber 27 and the bearing members 23 and 24 are given. The present inventor has found that the second air pressure interferes with each other and affects the measurement accuracy. That is, the second air pressure supplied to the bearing members 23 and 24 inherently affects the stability and smoothness of the shaft support, as in the case of the first air pressure supplied to the pressure working chamber 27. Pressure fluctuations do not directly affect shape measurement accuracy. However, as described above, there is a possibility that a certain amount of air flows between the bearing members 23 and 24 and the pressure action chamber 27, so that the fluctuation of the second air pressure disturbs the air pressure in the pressure action chamber 27. The present inventor has confirmed that there is a possibility that this may occur, and this may not be negligible. For this reason, not only the first air pressure is controlled to the fluctuation amount of 0.06 kPa or less by the super-precision regulator R1, but also the fluctuation of 0.06 kPa or less, which is equal to or less than the first air pressure, by the super-precision regulator R2. Control the amount. Thereby, the contact pressure of the contact part 35a can be reliably held to about 2 mg or less, and it is expected that the measurement error due to deformation of the workpiece W is reliably held to about 1 nm or less. In the above, in order to control the second air pressure generated by the ultraprecision regulator R2 with an accuracy of 0.06 kPa or less, generally, the second resolution that is the performance of the ultraprecision regulator R2 is 0.02 kPa equivalent to the first resolution. Must be less than or equal to Note that the second resolution of the super-precision regulator R2 does not need to be exactly the same as the first resolution of the super-precision regulator R1, and may be less than or equal to the equivalent. Here, that the first resolution and the second resolution are substantially equivalent means that the difference between the two resolutions is 0 to 0.01 kPa or less. That is, in the present embodiment, the second resolution of the ultraprecision regulator R2 is 0.02 kPa ± 0.01 kPa or less.

  Returning to FIG. 1, the laser interferometer 10 </ b> B disposed above the probe device 10 </ b> A has a known structure including a laser light source, an interference optical system, a sensor, and the like, although not shown. Laser light, that is, detection light ML from the laser interferometer 10B is irradiated toward the Z mirror 36a of the Z mirror member 36 provided at the upper end of the rod member 3, and returns from the Z mirror 36a. The reflected light RL, which is light, is reflected in the direction of the laser interferometer 10B and is detected by the laser interferometer 10B. In the laser interferometer 10B, the displacement amount in the Z direction of the rod member 3 can be calculated based on the phase change of the reflected light RL.

  In the detector 10, the rod member 3 is supported by the pressurized air supplied from the air supply source P in a non-contact manner with respect to the bearing members 23 and 24 in the rod insertion hole 21. Further, by the control air supplied from the air supply source P to the pressure acting chamber 27 via the thrust port 28, an arbitrary levitation force (thrust) is applied to the rod member 3 in the vertical direction, that is, in the + Z direction. As a result, the rod member 3 is slightly biased in the −Z direction while almost floating in the cylinder block 2. In this state, the contact member 35a provided at the lower end of the rod member 3 is brought into contact with the surface of the workpiece W, and the probe device 10A is scanned relative to the workpiece W in the XY plane. It is displaced in the ± Z direction along the surface shape of the workpiece W. When the probe apparatus 10A performs XY scanning, the control air supplied to the pressure working chamber 27 is adjusted so that the contact pressure of the contact portion 35a with respect to the surface of the workpiece W, that is, the pressing force is constant at an appropriate value. At this time, the first air pressure in the pressure working chamber 27 can be controlled with an accuracy of 0.06 kPa or less due to the presence of the ultra-precision regulators R1 and R2, and the contact pressure of the contact portion 35a is about 2 mg or less. Can be suppressed. That is, the deformation variation of the workpiece W due to the variation of the contact pressure can be suppressed to 1 nm or less, and the measurement error due to the deformation of the workpiece W can be suppressed to 1 nm or less. The laser beam from the laser interferometer 10B is irradiated toward the Z mirror 36a in parallel with the XY scanning of the probe device 10A in a state where the contact pressure of the contact portion 35a with the surface of the workpiece W is maintained, and the rod member 3 in the Z direction is calculated. Based on this Z displacement amount, the three-dimensional shape of the workpiece W is measured.

  A differential sensor (not shown) is provided at the upper end of the cylinder block 2, for example. This differential sensor is for detecting the direction in which the rod member 3 is displaced from the reference position in the cylinder block 2. As a result, when the rod member 3 rises in the cylinder block 2, for example, an H signal is output, and the entire cylinder block 2 can be gently raised by a mechanism (not shown) accordingly, It becomes possible to return to the position. On the contrary, when the rod member 3 is lowered in the cylinder block 2, for example, an L signal is output, and the cylinder block 2 is gently raised by a mechanism (not shown) in accordance with this to return the rod member 3 to the reference position. Is possible. That is, the probe apparatus 10A can be moved up and down in the ± Z direction as a whole while keeping the position of the rod member 3 with respect to the cylinder block 2 substantially constant.

  FIGS. 3A and 3B are a front view and a side view for explaining the structure of the shape measuring apparatus 100 in which the detector 10 shown in FIG. 1 is incorporated as both displacement detecting means. This shape measuring apparatus 100 has a structure in which an XY stage device 82 and a Z driving device 84 are fixed on a surface plate 81. The operations of the XY stage device 82, the Z drive device 84, and the like are controlled by a control device 99 as a calculation means.

  The XY stage device 82 is a moving unit, and is operated by being driven by a drive control unit (not shown) under the control of the control device 99. The XY stage device 82 smoothly moves the measurement jig HD, which is detachably fixed on the mounting table 82a provided on the XY stage device 82, two-dimensionally to an arbitrary position in the XY plane. be able to. The position of the measurement jig HD is detected using the X mirror member 83a and the Y mirror member 83b provided on the mounting table 82a. That is, the position of the mounting table 82a in the X-axis direction can be determined using the laser interferometer 83d attached on the surface plate 81 so as to face the X mirror member 83a. Further, the position of the mounting table 82a in the Y-axis direction can be determined by using a laser interferometer 83e mounted on the surface plate 81 so as to face the Y mirror member 83b.

  The Z drive device 84 has a lifting mechanism 86 fixed on a frame 85. The lifting mechanism 86 is fixed to the upper part of the frame 85 and extends in the Z direction, and is supported by the support shaft 86a to be in the Z axis direction. And an elevating member 86b that moves up and down, an elevating drive device 86c that elevates and lowers the elevating member 86b, and a probe device 10A supported by the elevating member 86b.

  In the elevating mechanism 86, the elevating member 86b is supported in a non-contact manner by the support shaft 86a and smoothly moves up and down. The elevating member 86b holds the probe device 10A described in FIG. 1 at the front lower portion, and smoothly elevates as the probe main body 35 provided in the probe device 10A moves up and down. As described with reference to FIG. 2, the probe device 10 </ b> A is supplied with control air from the air supply source P to the air supply port 26, and can move on the Z axis while supporting the rod member 3 in a non-contact manner. Keep in good condition. Further, the probe device 10A is supplied with control air from the air supply source P to the thrust port 28, and can adjust the lifting and lowering force by the ultraprecision regulator R1 or the like. As described above, the contact portion 35a provided at the tip of the rod member 3 can be pressed against the surface of the workpiece W with a constant force. That is, even if the optical element fixed to the measurement jig HD, that is, the surface of the workpiece W is moved up and down, the tip of the probe body 35 can be maintained in contact with the surface of the workpiece W with a low load. Further, the lift drive device 86c moves the probe device 10A up and down together with the lift member 86b while applying feedback based on the detection result of the differential sensor built in the probe device 10A. Thereby, the rod member 3 can be moved up and down over a wide range in a state where a constant low load is applied to the tip of the rod member 3. Therefore, the workpiece W placed on the measuring jig HD is moved in the XY plane by appropriately operating the XY stage device 82 while raising and lowering the rod member 3, that is, the probe main body 35 with a constant load as described above. The tip of the probe body 35 can be moved two-dimensionally along the optical surface of the workpiece W placed on the measurement jig HD. That is, the control device 99 associates the XY coordinates of the mounting table 82a obtained using the laser interferometers 83d and 83e with the Z coordinate of the probe main body 35 obtained using the laser interferometer 10B. By appropriately performing arithmetic processing, the three-dimensional surface shape of the optical surface of the workpiece W can be measured.

  The displacement of the tip position of the probe body 35 (change in the Z coordinate) is detected using a Z mirror member 36 provided at the upper end of the rod member 3 that moves up and down together with the probe body 35. That is, the lower end of the probe main body 35 is detected by using the laser interferometer 10B mounted on the frame 85 so as to face the Z mirror member 36 and detecting the reflected light RL while irradiating the Z mirror member 36 with the detection light ML. That is, the position in the Z-axis direction on the surface of the workpiece W is indirectly known.

  Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments. For example, the number and shape of the stepped portion 39 and the stress generating surface 39a formed on the rod member 3 can be changed as appropriate.

  Further, the arrangement and number of the upper bearing member 23 and the lower bearing member 24 can be appropriately changed according to the measurement object, measurement conditions, and the like.

  The workpiece W is fixed to the surface plate 81 side, and the shape of the surface of the workpiece W is changed by displacing the rod member 3 while moving the detector 10 three-dimensionally by the XY stage device 82 and the Z driving device 84. It can also be measured.

It is a side view of the displacement amount detector which concerns on one Embodiment of this invention. FIG. 2 is a side sectional view of a probe device incorporated in the displacement detector of FIG. 1. (A) And (b) is the front view and side view explaining the structure of the shape measuring apparatus incorporating the probe apparatus shown in FIG. 1, respectively.

Explanation of symbols

    DESCRIPTION OF SYMBOLS 2 ... Cylinder block, 3 ... Rod member, 3a ... Side surface, 4 ... Supporting member, 10 ... Detector, 10A ... Probe apparatus, 10B ... Laser interferometer, 21 ... Rod insertion hole, 23, 24 ... Bearing member, 26 ... Air supply port, 27 ... Pressure working chamber, 28 ... Thrust port, 31 ... Lower end, 35 ... Probe body, 36 ... Mirror member, 36a ... Mirror, 39 ... Stepped portion, 39a ... Stress generating surface, 82 ... XY stage device 82a ... mounting table, 83a and 83b ... mirror member, 83d and 83e ... laser interferometer, 84 ... Z drive device, 86 ... elevating mechanism, 99 ... control device, BD ... shaft-like member, HD ... measuring jig, L1 ... Piping, L2 ... Piping, ML ... Detection light, RL ... Reflection light, P ... Air supply source, PS ... Pressure sensor, R1, R2 ... Ultra precision regulator

Claims (7)

A contact having a contact body that is in contact with a body to be detected that is a measurement target, and a shaft-like member that supports the contact body at one end;
A cylindrical holding body that holds the shaft-shaped member in a state where the axial direction is a vertical direction and the one end is the lower end;
An urging means provided along with the holding body, receiving a supply of first air pressure, and applying an urging force vertically upward along the axial direction to the contact;
An air bearing that is provided in association with the holding body, receives the supply of second air pressure, and supports the contactor so as to be displaceable in the axial direction without contact;
A first air supply control unit having a first pressure regulator for controlling the first air pressure supplied to the urging means with a first resolution of 0.02 kPa or less and a variation amount of 0.06 kPa or less. When,
A second air supply control unit having a second pressure regulator for controlling the second air pressure supplied to the air bearing with a second resolution of 0.02 kPa or less and controlling with a fluctuation amount of 0.06 kPa or less; ,
With
The biasing means has a step-like stress generation surface formed to face the one end side on the side surface of the shaft-like member inserted through the holding body,
The contact pressure of the contact body with respect to the detected body is controlled with a resolution of 0.7 mg or less, and is a detector for a shape measuring apparatus controlled with a fluctuation amount of 2 mg or less.   2. The detector according to claim 1, wherein the first air supply control unit cancels a part of the weight of the contactor and uses the remaining weight part without being canceled as a contact pressure with respect to a measurement target of the contact body.   The detector according to any one of claims 1 and 2, wherein a measurement error due to deformation of the detected object is 1 nm or less. According claim 1, further comprising a light detection surface for reflecting the inspection light is provided on the shaft-like member, and a displacement sensor for detecting the reflected light irradiates the inspection light on the optical detection surface Item 4. The detector according to any one of Items 3 to 3 . A detector according to claim 4 ;
Moving means for moving the object to be measured relative to the contact in a direction perpendicular to the axial direction;
The amount of displacement of the contact in the axial direction caused by the contact between the surface of the object to be measured and the contact during relative movement of the object to be measured by the moving means is calculated based on the output of the displacement sensor. A shape measuring device comprising a computing means for measuring the shape of an object. A shape measuring method for measuring the surface shape of the object to be measured by measuring the position in the axial direction of the contact by causing the contactor contacting the surface of the object to be measured to be relatively scanned while contacting the surface of the object to be measured. Because
The biasing means provided along with the cylindrical holder that holds the shaft-shaped member receives a first air pressure and biases the contactor in the vertical direction along the axial direction. The air bearing provided along with the holding body receives the supply of the second air pressure and supports the contactor so as to be displaceable in the axial direction without contact.
The biasing means has a step-like stress generating surface formed to face the one end side on the side surface of the shaft-like member inserted through the holding body hole,
The first air pressure supplied to the urging means for applying an urging force vertically upward or downward along the axial direction to the contact is controlled with a first resolution of 0.02 kPa or less and a fluctuation of 0.06 kPa or less. The second air pressure supplied to the air bearing that supports the contactor so as to be displaceable in the axial direction without contact is controlled with a second resolution of 0.02 kPa or less and a fluctuation amount of 0.06 kPa or less. By controlling, the contact pressure of the contact body with respect to the object to be detected is controlled with a resolution of 0.7 mg or less and controlled with a fluctuation amount of 2 mg or less. The shape measuring method according to claim 6 , wherein a measurement error due to deformation of the detected object is 1 nm or less.

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