Measuring head and confocal displacement sensor

Abstract

Provided are a measuring head and a confocal displacement sensor capable of suppressing a decrease in measurement reliability of the confocal displacement sensor in a high-temperature environment. The measuring head is used for a confocal displacement sensor with a white light source. The measuring head has a configuration in which a plurality of glass lenses are housed in a head metal housing. A metal spring member biases the plurality of glass lenses including the lenses toward a + x direction in a state in which the lenses abut against the annular screws, the metal spring member being provided in the head metal housing. Alternatively, a thermally expandable polyimide member is provided inside the metal case.

Description

Technical Field

[0001] The invention relates to a measuring head for a confocal displacement sensor and the confocal displacement sensor. Background Art

[0002] An example of a device for measuring the displacement of the surface of a measurement object by a non-contact method includes a confocal displacement sensor, which includes a white light source, an optical fiber and a measuring head. In the confocal displacement sensor, light (white light) of a wide wavelength band generated by a white light source is guided to the measuring head through the optical fiber. The measuring head mainly includes a plurality of lenses and a head housing that accommodates them, and the light guided through the optical fiber is emitted to the measurement object through the plurality of lenses. At the same time, chromatic aberration is generated in the light emitted to the measurement object through the plurality of lenses. In addition, the measuring head receives light focused and reflected on the surface of the measurement object. The displacement of the surface of the measurement object is measured based on the light received by the measuring head. According to the confocal displacement sensor, the measurable range of the measurement object is extended by arranging the measuring head at a desired position.

[0003] The displacement measurement accuracy of the confocal displacement sensor decreases due to various factors. Therefore, a configuration for suppressing the decrease in measurement accuracy has been proposed.

[0004] For example, JP2019-002722A proposes a confocal displacement sensor including a diffraction lens and a refractive lens having different spherical aberration polarities in order to suppress a reduction in measurement accuracy caused by the spherical aberration of an optical component (lens of a measuring head).

[0005] Meanwhile, in the case where the measurement object is arranged in a high temperature environment, it is conceivable to arrange the measuring head in the high temperature environment. However, each time the measuring head is arranged in a high temperature environment, the positional relationship of the plurality of lenses is likely to change randomly depending on the temperature of the environment in which the measuring head is arranged, the linear expansion coefficient of each component of the measuring head, and the like. In the case where any one of the plurality of lenses contains a resin material, the resin material is likely to deform in a high temperature environment. In these cases, the measurement reliability of the confocal displacement sensor in a high temperature environment is reduced. Summary of the invention

[0006] An object of the present invention is to provide a measuring head and a confocal displacement sensor capable of suppressing a decrease in the measurement reliability of the confocal displacement sensor in a high-temperature environment.

[0007] According to one embodiment of the present invention, a measuring head is a measuring head for a confocal displacement sensor having a white light source, and includes: a housing made of metal, formed into a tubular shape, and having a first end and a second end; an optical fiber connected to the first end of the housing and guiding light generated from the white light source to the first end of the housing; a plurality of lenses made of glass, including a first lens, housed inside the housing to be aligned in an axial direction of the housing and movable in the axial direction, and converging light guided by the optical fiber to the first end on a measurement object through the second end while generating chromatic aberration along an optical axis; a first movement limiting portion, the first movement limiting portion being provided in a predetermined first portion inside the housing, and limiting movement of the first lens in any one of a first direction from the first end toward the second end in the axial direction and a second direction opposite to the first direction when the first lens abuts against the first movement limiting portion; and a biasing member made of metal and biasing some or all of the plurality of lenses including the first lens in the one direction by elastic force in a state where the first lens abuts against the first movement limiting portion.

[0008] According to another embodiment of the present invention, a measuring head is a measuring head for a confocal displacement sensor having a white light source, and includes: a housing, which is made of metal, formed into a tubular shape, and has a first end and a second end; an optical fiber, which is connected to the first end of the housing and guides light generated from the white light source to the first end of the housing; a plurality of lenses, which are made of glass, including a first lens, which is accommodated inside the housing to be aligned in an axial direction of the housing and can be moved in the axial direction, and which converges the light guided by the optical fiber to the first end on a measurement object through the second end while generating chromatic aberration along the optical axis; a first movement limiting portion, the first lens A movement limiting portion is provided in a predetermined first portion inside the shell, and when the first lens abuts against the first movement limiting portion, the movement of the first lens in any one of a first direction from the first end toward the second end in the axial direction and a second direction opposite to the first direction is limited; and a thermal expansion member, which is made of polyimide and is provided inside the shell at a position separated from the first movement limiting portion in the axial direction, wherein in a state where the first lens abuts against the first movement limiting portion, some or all of the multiple lenses including the first lens are held between the first movement limiting portion and the fixing member.

[0009] According to another embodiment of the present invention, a confocal displacement sensor includes: the above-mentioned measuring head; a white light source, which generates light to be guided to the measuring head; and a displacement measuring unit, which calculates the displacement of the measuring object based on the light emitted from the measuring head to the measuring object and reflected by the measuring object.

[0010] According to the present invention, it is possible to suppress a decrease in the measurement reliability of the confocal displacement sensor in a high-temperature environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic diagram illustrating the configuration of a confocal displacement sensor according to an embodiment of the present invention;

[0012] Figure 2 is an external perspective view illustrating an example of a measuring head according to an embodiment of the present invention;

[0013] Figure 3 Observed in the +Z direction Figure 2 A side view of the measuring head in FIG.

[0014] Figure 4 It is along the Figure 2 and Figure 3 A cross-sectional view of the measuring head taken by a virtual plane indicated by a dotted line in FIG.

[0015] Figure 5 yes Figure 1 An exploded perspective view of the measuring head in FIG.

[0016] FIG. 6A to FIG. 6C is a view for describing details of the configuration and function of a spring member accommodated in a head housing;

[0017] Fig. 7A and Figure 7B is a view illustrating a reference example for describing the function of a spring member;

[0018] Figure 8 is a view for describing a first arrangement condition of the spring member in the head housing;

[0019] Fig. 9 It is along the Figure 2 and Figure 3 A cross-sectional view of the measuring head taken by a virtual plane indicated by a double-dotted line in FIG.

[0020] Fig.10 is an external perspective view of a light bending unit and a plurality of distance adjustment members;

[0021] FIG. 11A to FIG. 11D The diagram is provided by Fig.10A view of changes in the measuring direction and measurable range of the measuring head caused by the light bending unit and the plurality of distance adjustment members; and

[0022] Fig.12 is a cross-sectional view illustrating an example of a measuring head according to another embodiment. DETAILED DESCRIPTION

[0023] Hereinafter, a measuring head and a confocal displacement sensor including the same according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0024] 1. Basic configuration of confocal displacement sensor

[0025] Figure 1 Schematic diagram illustrating the configuration of a confocal displacement sensor according to an embodiment of the present invention; Figure 1 As shown, the confocal displacement sensor 9 includes measuring heads 1A and 1B, measuring units 100A and 100B, light guide units 300A and 300B, a control unit 2, and a personal computer (PC) 3. The light guide unit 300A includes a plurality of optical fibers and optically connects some constituent elements (a light projection unit 120 and a spectroscope unit 130 to be described later) inside the measuring head 1A and the measuring unit 100A.

[0026] The measuring unit 100A includes a unit housing 110, a light projection unit 120, a spectroscope unit 130, a light receiving unit 140, a measurement control unit 150, and a sub-display unit 190. The unit housing 110 accommodates the light projection unit 120, the spectroscope unit 130, the light receiving unit 140, and the measurement control unit 150. The sub-display unit 190 includes a display such as a seven-segment display or a dot matrix display. The light projection unit 120 includes a white light source that generates light having a wide and continuous wavelength band (e.g., 500nm to 700nm), that is, light having a plurality of continuous wavelengths (white light), and is configured to be able to emit light generated from the white light source. The light emitted by the light projection unit 120 is input to the optical fiber 311 of the light guide unit 300A, which will be described later.

[0027] The spectroscope unit 130 includes a diffraction grating 131 and a plurality of (in this example, two) lenses 132 and 133. As will be described later, a portion of the light emitted by the light projection unit 120 and reflected by the surface of the measuring object S is output from the optical fiber 312 of the light guide unit 300A, which will be described later. The light output from the optical fiber 312 passes through the lens 132 to be substantially collimated and is incident on the diffraction grating 131. The diffraction grating 131 is a reflective diffraction grating. The light incident on the diffraction grating 131 is partitioned so as to be reflected at different angles for each wavelength, and passes through the lens 133 to be focused on different positions in one dimension for each wavelength.

[0028] The light receiving unit 140 includes an imaging element (one-dimensional line sensor) in which a plurality of pixels are arranged one-dimensionally. The imaging element may be a multi-partitioned photodiode (PD), a charge coupled device (CCD) camera, or a complementary metal oxide semiconductor (CMOS) image sensor, or may be another element. The light receiving unit 140 is arranged so that a plurality of pixels of the imaging element receive light at a plurality of focus positions, which are different for each wavelength and are formed by the lens 133 of the spectroscope unit 130. An analog electrical signal (hereinafter referred to as a light receiving signal) corresponding to the amount of received light is output from each pixel of the light receiving unit 140. The light receiving signal indicates the intensity of the light received by each pixel.

[0029] The measurement control unit 150 includes a central processing unit (CPU) and a memory or a microcomputer. The measurement control unit 150 stores a control program and stores various types of data such as measurement conditions for displacement measurement. These data are given from the control unit 2 to be described later. The measurement control unit 150 controls the light projection unit 120 and the light receiving unit 140 based on the stored control program and data, and calculates the displacement of the surface of the measurement object S based on the light reception signal output from the light receiving unit 140. The measurement control unit 150 causes the sub-display unit 190 to display the calculation result of the displacement.

[0030] The measurement control unit 150 is connected to the control unit 2, and the control unit 2 is also connected to the PC 3. The measurement control unit 150 provides the control unit 2 with the calculation result of the displacement and the light reception signal output from the light reception unit 140. The configuration and operation of the control unit 2 and the PC 3 will be described later.

[0031] The measurement head 1A includes a head housing 10 , a fiber receptacle 30 , and a plurality of (in this example, four) lenses 221 , 222 , 223 , and 224 . The head housing 10 accommodates the plurality of lenses 221 , 222 , 223 , and 224 .

[0032] The fiber receptacle 30 is attached to the head housing 10. A fiber connector 330 (to be described later) of the light guide unit 300A is connected to the fiber receptacle 30. The fiber connector 330 holds one end of an optical fiber 319 of the light guide unit 300A, which will be described later.

[0033] Light is guided to the optical fiber 319 from the measuring unit 100A. The light guided to the optical fiber 319 is output from the optical fiber 319 in the head housing 10 of the measuring head 1A, and passes through a plurality of lenses 221, 222, 223, and 224 in sequence. In the present embodiment, each of the plurality of lenses 221, 222, 223, and 224 has a circular shape when viewed in the optical axis direction of the lens, and is configured using a single member made of glass. In addition, the lens 221 is a magnifying lens that magnifies the light guided from the optical fiber 319. The lenses 222 and 223 are curved lenses that converge the light magnified by the lens 221 while adding a predetermined function. In addition, the lens 224 is a chromatic aberration lens that generates chromatic aberration in the light guided from the lens 223. The light that generates chromatic aberration when passing through the plurality of lenses 221, 222, 223, and 224 is focused at a position near the surface of the measuring object S.

[0034] The light guide unit 300A includes optical fibers 311, 312, and 319, an optical fiber coupler 320, and an optical fiber connector 330. Figure 1 In the example of FIG. 1 , the fiber coupler 320 is provided in the unit housing 110 of the measuring unit 100A. The fiber connector 330 is connected to the measuring head 1A as described above.

[0035] The optical fiber coupler 320 has a so-called 2×2 type configuration, and includes four ports 321 to 323 and a body 324. Figure 1 , illustration of one of the four ports is omitted. Ports 321 and 322 and port 323 are connected to the body 324 so as to face each other, wherein the body 324 is interposed between the ports 321 and 322 and the port 323. Light input to at least one of the ports 321 and 322 is output from the port 323. Light input to the port 323 is output from each of the ports 321 and 322.

[0036] The optical fibers 311 and 312 are connected to ports 321 and 322 of the optical fiber coupler 320, respectively. The other end of the optical fiber 319 is connected to a port 323 of the optical fiber coupler 320.

[0037] According to this configuration, light emitted by the light projection unit 120 of the measuring unit 100A is input to the port 321 of the fiber coupler 320 through the optical fiber 311. The light input to the port 321 is output from the port 323 and is guided to the measuring head 1A through the optical fiber 319. The light guided to the measuring head 1A is emitted to the measuring object S through the plurality of lenses 221, 222, 223, and 224.

[0038] A portion of the light reflected by the surface of the measuring object S is input to one end of the optical fiber 319 through the plurality of lenses 224, 223, 222, and 221. The light input to one end of the optical fiber 319 is input to the port 323 of the fiber coupler 320. The light input to the port 323 is output from the ports 321 and 322. The light output from the ports 321 and 322 is guided to the spectroscope unit 130 through the optical fiber 312. Thus, the displacement of the measuring object S is calculated based on the light emitted from the measuring unit 100A to the measuring object S.

[0039] The measuring unit 100A and the measuring unit 100B have the same configuration, the measuring head 1A and the measuring head 1B have the same configuration, and the light guide unit 300A and the light guide unit 300B have the same configuration. Some constituent elements inside the measuring head 1B and the measuring unit 100B are optically connected through the light guide unit 300B, similar to the example of connection between the measuring head 1A and the measuring unit 100A described above. In addition, the measurement control unit 150 (not shown) of the measuring unit 100B is connected to the control unit 2.

[0040] The measuring object S is irradiated with light emitted from the light projection unit 120 (not shown) of the measuring unit 100B through the measuring head 1B. A part of the light reflected by the surface of the measuring object S returns to the measuring unit 100B through the measuring head 1B. Therefore, the displacement of the measuring object S is calculated based on the light emitted from the measuring head 1B to the measuring object S. In this case, the measurement control unit 150 (not shown) provided in the measuring unit 100B gives the calculation result of the displacement and the light reception signal output from the light receiving unit 140 to the control unit 2.

[0041] The control unit 2 includes a CPU and a memory or a microcomputer. For example, the displacement measurement conditions in the measuring units 100A and 100B are input to the control unit 2 from the PC 3. The measurement conditions include, for example, the light emission amount in the light projection unit 120, the light emission timing in the light projection unit 120, the exposure amount in the light receiving unit 140, etc. The control unit 2 gives the input measurement conditions to the measurement control unit 150 of each of the measuring units 100A and 100B. The measurement operation based on the given measurement conditions is performed in each of the measuring units 100A and 100B.

[0042] The PC 3 includes a CPU 3a and a memory 3b. The memory 3b stores various programs related to the thickness measurement of the measuring object S and various types of data used for the thickness measurement, and the CPU 3a executes the programs stored in the memory 3b. The calculation result of the displacement and the light reception signal given from each of the measuring units 100A and 100B to the control unit 2 are given from the control unit 2 to the PC 3.

[0043] A main display unit 4a and an operation unit 4b are connected to the PC 3. The main display unit 4a includes, for example, a display device such as an organic electroluminescent (EL) panel or a liquid crystal display panel. The operation unit 4b includes a keyboard and a pointing device. The pointing device includes a mouse, a joystick, etc. The user can give various instructions related to thickness measurement to the PC 3 by operating the operation unit 4b.

[0044] In the above-mentioned confocal displacement sensor 9, each of the measuring heads 1A and 1B can be arranged in a space where one or more measuring objects S are arranged, and therefore, the degree of freedom of displacement measurement of the one or more measuring objects S is high. For example, in the case where the measuring object S is a substrate (wafer) on which a circuit is formed, etc., the measuring object S is likely to be arranged in a high temperature environment and a vacuum environment. Even in this case, by arranging each of the measuring heads 1A and 1B together with the measuring object S in a high temperature environment, the displacement of the surface of the measuring object S (the height of the substrate surface) can be measured in the high temperature environment. In addition, by arranging each of the measuring heads 1A and 1B together with the measuring object S in a vacuum environment, the displacement of the surface of the measuring object S (the height of the substrate surface) can be measured in the vacuum environment. Here, in the present embodiment, the high temperature environment refers to a temperature environment of, for example, about 100°C-300°C. In addition, the vacuum environment refers to an environment with a vacuum degree of, for example, about 10^(-7)Pa to 10^(-5)Pa.

[0045] Note that according to the measuring heads 1A and 1B, the thickness of the measuring object S having the first surface and the second surface facing in opposite directions can be measured. For example, the measuring heads 1A and 1B are arranged so as to face each other with the measuring object S interposed between the measuring heads 1A and 1B. In addition, the displacement of the first surface and the second surface of the measuring object S is measured by the measuring heads 1A and 1B. In this case, the thickness of the measuring object S can be measured based on the measurement result of the displacement of the first surface and the second surface of the measuring object S and the distance (head-to-head distance) between the measuring heads 1A and 1B.

[0046] 2. Measuring heads 1A and 1B

[0047] Hereinafter, the configuration of the measuring head 1A will be described in detail as Figure 1 Representative of the measuring heads 1A and 1B.

[0048] <1> External shape of the head housing 10 of the measuring head 1A

[0049] Figure 2 1A is an external perspective view illustrating an example of a measuring head 1A according to an embodiment of the present invention. Figure 2In predetermined views to be described later, arrows indicating the x direction, the y direction, and the z direction orthogonal to each other are attached so that the positional relationship between the respective units of the measuring head 1A and the plurality of constituent elements accommodated in the measuring head 1A can be easily understood.

[0050] In the following description, in the x direction, the direction in which the arrow x is oriented in the drawings is appropriately referred to as the +x direction, and the opposite direction thereof is appropriately referred to as the -x direction. In addition, in the y direction, the direction in which the arrow y is oriented in the drawings is appropriately referred to as the +y direction, and the opposite direction thereof is appropriately referred to as the -y direction. The direction in which the arrow z is oriented in the drawings is appropriately referred to as the +z direction, and the opposite direction thereof is appropriately referred to as the -z direction.

[0051] The head housing 10 of the measuring head 1A is configured using a single member made of metal and has a Figure 2 The head shell 10 is a generally rectangular tube shape extending in the x direction as shown. In the following description, the end of the head shell 10 on the side facing the +x direction is referred to as the front end FE of the head shell 10, and the end of the head shell 10 on the other side facing the -x direction is referred to as the rear end RE of the head shell 10. The center axis of the head shell 10 extending in the longitudinal direction of the head shell 10 is referred to as the head axis 10a. The metal forming the head shell 10 is, for example, stainless steel. In the present embodiment, SUS 304, SUS 316, SUS 316L or SUS 303 defined by the Japanese Industrial Standard (JIS) is used as the stainless steel of the head shell 10.

[0052] The head housing 10 includes a first housing section 11 and a second housing section 12 aligned in the x direction. The first housing section 11 has a rear end RE of the head housing 10, and includes an outer surface 11a facing in the -z direction, an outer surface 11b facing in the +z direction, an outer surface 11c facing in the -y direction, and an outer surface 11d facing in the +y direction. The second housing section 12 has a front end FE of the head housing 10, and includes an outer surface 12a facing in the -z direction, an outer surface 12b facing in the +z direction, an outer surface 12c facing in the -y direction, and an outer surface 12d facing in the +y direction. At a boundary portion between the first housing section 11 and the second housing section 12, two outer surfaces (the outer surface of the first housing section 11 and the outer surface of the second housing section 12) facing in a common direction and adjacent to each other in the x direction are flush with each other.

[0053] With such a configuration, the measuring head 1A can easily attach a part of the outer surface of the head case 10 to a flat mounting surface. In addition, according to the above configuration, in the case where two measuring heads 1A are arranged adjacent to each other, the head case 10 of one of the two measuring heads 1A and the head case 10 of the other measuring head 1A can be in surface contact with each other. Therefore, compared with the case where the head case 10 has a cylindrical outer circumferential surface, a plurality of measuring heads 1A can be stably mounted on a predetermined mounting surface.

[0054] Here, two recesses 11x and 11y are formed in the first housing section 11. The two recesses 11x and 11y are aligned in the circumferential direction relative to the head axis 10a. Specifically, one recess 11x is formed so as to recess a portion of the outer surfaces 11b and 11c, and the other recess 11y is formed so as to recess a portion of each of the outer surfaces 11b and 11d. No recess is formed in the outer surface 11a. Therefore, as will be described later Figure 3 As shown in the third balloon-shaped dialog box from the left in FIG. 1 , a cross section orthogonal to the x direction of a portion of the first housing section 11 where two recesses 11x and 11y are formed has a T-shape ( Figure 3 inverted T-shape).

[0055] Two through holes h1 extending in the z direction (see later described) Figure 3 ) is formed in a portion of the first housing segment 11 located between a space where the notch 11x is formed and a space in the -z direction relative to the first housing segment 11. In addition, two through holes h1 extending in the z direction are also formed in a portion of the first housing segment 11 located between a space where the notch 11y is formed and a space in the -z direction relative to the first housing segment 11. These multiple through holes h1 are used, for example, to attach the measuring head 1A to a desired member. In this case, a screw member, a coupling member, or the like is inserted into any one of the multiple through holes h1.

[0056] A circular opening portion through which light emitted from the measuring head 1A toward the measuring object S and reflected by the measuring object S passes is formed in the front end portion FE of the head housing 10 . Figure 2 The example illustrates a state in which a portion of the lens 224 accommodated in the head housing 10 is exposed from the opening portion of the front end portion FE. In addition, four threaded holes h2 are respectively formed at the four corners of the front end portion FE of the head housing 10 so as to surround the opening portion at intervals of 90° when viewed in the x direction. The four threaded holes h2 of the front end portion FE are used to attach the light bending unit 50 (described later) as needed when the measuring head 1A is used. Fig.10 ) or distance adjustment member 60 ( Fig.10 ).

[0057] A plurality of (in this example, four) threaded holes h3 extending in the x direction are formed in the rear end portion RE of the head housing 10. In this example, the four threaded holes h3 are respectively formed at the four corners of the rear end portion RE of the head housing 10. The four threaded holes h3 of the rear end portion RE are used to connect the optical fiber receptacle 30 to the head housing 10 using four screws SC1. In this example, the optical fiber receptacle 30 and the optical fiber connector 330 connected to the head housing 10 are formed using the same material as that of the head housing 10.

[0058] A plurality of through holes h4 through which the internal space of the head case 10 communicates with the external space are formed in a portion of the plurality of outer surfaces ( 11 a to 11 d and 12 a to 12 d ) of the head case 10 . Figure 2 The diagram shows a state in which a plurality of through holes h4 are formed in one outer surface 12d of the second housing section 12. For example, when the measuring head 1A is arranged in a vacuum environment, these through holes h4 suppress generation of a large pressure difference between the inner space and the outer space of the head housing 10.

[0059] <2> Internal shape of the head housing 10

[0060] Figure 3 When observing in the +z direction Figure 2 A side view of the measuring head 1A in FIG. The head housing 10 has an internal space extending from the rear end RE to the front end FE along the head axis 10a. Figure 3 In FIG. 1 , the shape of the internal space of the head housing 10 is indicated by a single-dot chain line. Figure 3 , schematic cross-sectional views (end views) of the head housing 10 taken along lines A1 - A1 , A2 - A2 , and A3 - A3 aligned at intervals in the x direction are illustrated in three balloon-shaped dialog boxes, respectively.

[0061] exist Figure 3 , lines A1-A1 and A2-A2 are lines overlapping two portions of the first shell segment 11, and line A3-A3 is a line overlapping a portion of the second shell segment 12. Each of the first shell segment 11 and the second shell segment 12 of the head shell 10 has an inner circumferential surface having a circular cross-section orthogonal to the head axis 10a.

[0062] like Figure 3 As shown, the first housing section 11 includes a first inner circumferential surface 11i and a second inner circumferential surface 11j. The first inner circumferential surface 11i has a cylindrical shape with a constant diameter and extends from the rear end portion RE of the head housing 10 to a position close to the boundary portion between the first housing section 11 and the second housing section 12. The axis of the first inner circumferential surface 11i coincides with the head axis 10a. In addition, the first inner circumferential surface 11i has an inner diameter similar to the outer diameter of the optical fiber 319, for example.

[0063] The second inner circumferential surface 11j has a cylindrical shape with a constant diameter and extends from the end of the first inner circumferential surface 11i in the +x direction to the boundary portion between the first shell section 11 and the second shell section 12. The axis of the second inner circumferential surface 11j coincides with the head axis 10a. In addition, the second inner circumferential surface 11j has an inner diameter larger than that of the first inner circumferential surface 11i. Therefore, a step portion having an annular shape when viewed in the -x direction is formed inside the first shell section 11 (described later). Figure 4 The first step portion st1 in the figure).

[0064] The second shell section 12 includes a third inner circumferential surface 12i. The third inner circumferential surface 12i has a cylindrical shape having a substantially constant upper diameter and extending from a boundary portion between the first shell section 11 and the second shell section 12 to the front end portion FE of the head shell 10. The axis of the third inner circumferential surface 12i coincides with the head axis 10a. In addition, the third inner circumferential surface 12i has an inner diameter that is larger than the inner diameters of the first inner circumferential surface 11i and the second inner circumferential surface 11j of the first shell section 11. Therefore, a step portion having an annular shape when viewed in the -x direction is formed at the boundary portion between the first shell section 11 and the second shell section 12 inside the head shell 10 (described later). Figure 4 The second step portion st2 in the figure).

[0065] <3> Configuration of optical fiber 319

[0066] exist Figure 3 , a balloon-shaped dialog box leading out from the optical fiber 319 further illustrates the configuration of the optical fiber 319 held by the optical fiber connector 330. The optical fiber 319 includes a core 319a coated with a cladding 319b. The optical fiber receptacle 30 is connected to the optical fiber connector 330, whereby the core 319a at the distal end of one end of the optical fiber 319 is held so as to be located between the plurality of lenses 221 to 224 ( Figure 1 Note that in the present embodiment, the head axis 10a of the head housing 10 is aligned with the plurality of lenses 221 to 224 ( Figure 1 ) coincides with the optical axis of the optical fiber 319. In addition, in the present embodiment, the distal end of one end of the optical fiber 319 is used as a spatial filter having a tiny pinhole.

[0067] In a part of the optical fiber 319 located between the measuring head 1A and the measuring unit 100A, a coating 319c made of a resin using polyimide is provided so as to coat the cladding 319b. In addition, a spiral tube 319d made of stainless steel is provided so as to cover the coating 319c. The core 319a and the cladding 319b are made of quartz and have high heat resistance. In addition, the coating 319c made of polyimide and the spiral tube 319d made of stainless steel have relatively high heat resistance compared with resins other than polyimide. In this way, in the optical fiber 319 according to the present embodiment, each of the core 319a, the cladding 319b, the coating 319c and the spiral tube 319d has relatively high heat resistance. Therefore, even when used in a high temperature environment, high reliability of optical transmission is provided.

[0068] Note that the optical fiber 319 according to the present embodiment has a configuration including only one core 319a as described above. The optical fiber 319 may have a configuration including a plurality of cores 319a without being limited to this example. In this case, for example, a plurality of bundled cores 319a are coated with a cladding 319b, and a coating 319c and a spiral tube 319d are also provided so as to coat the cladding 319b. Alternatively, a plurality of cores 319a coated with a cladding 319b and a coating 319c are bundled. The spiral tube 319d is provided to protect such a component.

[0069] <4> Various components provided inside the head housing 10

[0070] Figure 4 It is along the Figure 2 and Figure 3 2 is a cross-sectional view of the measuring head 1A taken along a virtual plane VS1 indicated by a dotted line. Figure 5 yes Figure 1 Exploded perspective view of the measuring head 1A in FIG.

[0071] As described above, an annular step portion is formed inside the first shell section 11. In addition, a step portion is also formed at a boundary portion between the first shell section 11 and the second shell section 12 inside the head shell 10. In the following description, the step portion formed inside the first shell section 11 is referred to as a first step portion st1. In addition, the step portion formed at a boundary portion between the first shell section 11 and the second shell section 12 inside the head shell 10 is referred to as a second step portion st2. Figure 4 , the first step portion st1 and the second step portion st2 are indicated by white arrows, respectively.

[0072] like Figure 4As shown, the lens 221, the spacers 41 and 42, the spring member 43, the lens 222, the spacer 44, the lens 223, the spacer 45, the lens 224, and the annular screw 46 are housed in the head housing 10 so as to be sequentially aligned in the +x direction between the first step portion st1 and the front end portion FE. The spacers 41, 42, 44 and 45, the spring member 43, and the annular screw 46 are formed using the same material as that of the head housing 10.

[0073] The outer diameter of the lens 221 is larger than the inner diameter of the first inner circumferential surface 11i of the first shell section 11, and is slightly smaller than the inner diameter of the second inner circumferential surface 11j of the first shell section 11. Therefore, the lens 221 is fitted into the second inner circumferential surface 11j of the first shell section 11. In this state, a portion (peripheral edge) of the end surface of the lens 221 in the -x direction abuts against the first step portion st1. Therefore, the lens 221 is restricted from moving in the -x direction relative to the first step portion st1.

[0074] In addition, the thickness of the lens 221 (the dimension of the lens 221 in the optical axis direction) is greater than the distance between the first step portion st1 and the second step portion st2 in the x direction. Therefore, a portion of the lens 221 (including the end surface in the +x direction) protrudes into the second housing section 12.

[0075] The spacer 41 is a generally disk-shaped member having a diameter slightly smaller than the inner diameter of the third inner circumferential surface 12i. Figure 5 As shown, a circular opening portion 41a having an inner diameter smaller than an outer diameter of the lens 221 is formed in the central portion of the spacer 41. In addition, two through holes 41b are formed in the spacer 41 so as to sandwich the opening portion 41a.

[0076] like Figure 4 As shown, the spacer 41 is provided in the second housing section 12 so as to abut against a portion (peripheral edge) of the end surface of the lens 221 in the +x direction. The spacer 42 is an annular member having the same outer diameter as that of the spacer 41, and is provided in the second housing section 12 so as to abut against the spacer 41. The inner diameter of the spacer 42 is determined so as not to block the two through holes 41b ( Figure 5 In this case, the two through holes 41b ( Figure 5 ) is used as a gas flow path for preventing the formation of a sealed space between the spacer 41 and the second step portion st2.

[0077] Since no sealed space is formed between the spacer 41 and the second step portion st2, when the measuring head 1A is arranged in a vacuum environment, the pressure distribution in the head case 10 does not change greatly. This prevents the measuring head 1A from being unintentionally deformed due to a large change in pressure distribution.

[0078] The spacers 41 and 42 are used to position the spring member 43 at a predetermined position in the x direction inside the head housing 10. For example, when assembling the measuring head 1A, a plurality of spacers 41 and 42 having a plurality of thicknesses are prepared in advance. Then, an appropriate spacer 41 or 42 is selected and used according to the predetermined position of the spring member 43 in the x direction, the size of each unit in the head housing 10, and the size of the lens 221.

[0079] like Figure 5 As shown, the spring member 43 has a flat and generally cylindrical shape. Figure 4 As shown, the spring member 43 is provided in the second housing section 12 so as to abut against the spacer 42 with the axis of the spring member 43 along the head axis 10a. In addition, the spring member 43 also has an outer diameter that is the same as or substantially the same as that of the spacers 41 and 42. In addition, the spring member 43 is configured to be expandable and contractible in the axial direction of the spring member 43 by elastic force. The details of the spring member 43 will be described later.

[0080] The lens 222 is provided in the second housing section 12 so as to abut against the spring member 43. In addition, the lens 223 is provided in the +x direction of the lens 222 with the spacer 44 interposed between the lens 223 and the lens 222. In addition, the lens 224 is provided in the +x direction of the lens 223 with the spacer interposed between the lens 224 and the lens 223.

[0081] Each of the three lenses 222, 223, and 224 has an outer diameter that is the same as or substantially the same as that of the spacers 41 and 42 and the spring member 43. Each of the spacers 44 and 45 is an annular member having a constant thickness and has an outer diameter that is the same as or substantially the same as that of the spacers 41 and 42 and the spring member 43.

[0082] Thread processing is performed on a range having a constant width in the -x direction from the front end portion FE of the third inner circumferential surface 12i of the second housing section 12. That is, a portion of the third inner circumferential surface 12i forms an internal thread portion 12j in the second housing section 12. The internal thread portion 12j is formed so as to be located near the lens 224 in a state where a plurality of constituent elements (41 to 45 and 221 to 224) are accommodated in the head housing 10 so as to contact each other.

[0083] The annular screw 46 is an external thread corresponding to the internal thread portion 12j of the second housing section 12. The annular screw 46 is attached to the internal thread portion 12j of the second housing section 12 in a state where a plurality of constituent elements (41 to 45 and 221 to 224) are accommodated in the head housing 10 so as to be in contact with each other. The inner diameter of the annular screw 46 is smaller than the outer diameter of the lens 224. Therefore, when the annular screw 46 is attached to the internal thread portion 12j, a portion of the annular screw 46 abuts against a portion (peripheral edge) of the end surface of the lens 224 facing the +x direction. In addition, the annular screw 46 is screwed so that a predetermined amount of load in the x direction acts on the spring member 43 in a state of contact with the lens 224.

[0084] Here, the configuration and function of the spring member 43 will be described in detail. FIG. 6A to FIG. 6C 1 is a view for describing the details of the configuration and function of the spring member 43 accommodated in the head case 10. As described above, the spring member 43 has a flat and substantially cylindrical shape. Fig. 6A There is shown an external perspective view of the spring member 43. The spring member 43 includes a base portion 43a, a small diameter portion 43b, and a flange portion 43c aligned in the direction of the axis ca.

[0085] The base portion 43a and the flange portion 43c have a common outer diameter slightly smaller than the outer diameter of the third inner circumferential surface 12i of the second housing segment 12. Meanwhile, the small diameter portion 43b has an outer diameter smaller than the outer diameters of the base portion 43a and the flange portion 43c (about 2 / 3 of the outer diameter). In addition, the base portion 43a, the small diameter portion 43b and the flange portion 43c have a substantially constant inner diameter. Furthermore, the peripheral edge of the flange portion 43c is formed so as to protrude in a direction opposite to the base portion 43a.

[0086] With this configuration, when a load in the direction of the axis ca acts between the flange portion 43c and the base portion 43a, the small diameter portion 43b and the flange portion 43c are elastically deformed, and the length of the spring member 43 in the direction of the axis ca changes. In the following description, the state of the spring member 43 when the load in the direction of the axis ca does not act or does not substantially act on the spring member 43 is referred to as a reference state.

[0087] When the measuring head 1A is arranged in a high temperature environment, when thermal expansion occurs in the head housing 10, the plurality of lenses 221 to 224 accommodated in the head housing 10 are likely to be greatly displaced to unexpected positions in an unexpected posture. Therefore, in the present embodiment, the annular screw 46 is screwed so that a predetermined amount of load in the x direction acts on the spring member 43 in a state where the measuring head 1A is at room temperature (e.g., 25° C.). That is, the spring member 43 is provided so as to bias the plurality of lenses 221 to 224 in the x direction by the elastic force of the spring member 43 in a room temperature environment.

[0088] Figure 6B and Figure 6C FIG. 4 is a diagram showing a configuration example for describing the function of the spring member 43. Figure 6B As shown, for example, it is assumed that the first annular member r1 and the second annular member r2 are fixed to the first portion p1 and the second portion p2 different from each other in the x direction in the third inner circumferential surface 12i of the head housing 10 in a room temperature environment. In addition, it is assumed that the spring member 43 and the lens 222 are arranged to be aligned in sequence in the +x direction between the first annular member r1 and the second annular member r2.

[0089] Here, the distance D11 between the first portion p1 and the second portion p2 in the x direction is set so that a predetermined amount of load in the x direction acts on the spring member 43. In other words, the distance D11 is set so that the spring member 43 biases the lens 222 between the first portion p1 and the second portion p2 toward the second ring member r2. Figure 6B The spring member 43 is shown to be contracted in the x direction relative to the reference state due to deformation of the small diameter portion 43 b and the flange portion 43 c.

[0090] Assumptions include Figure 6B The configuration of the head housing 10 is arranged in a room temperature environment to a high temperature environment. In this case, as Figure 6C As shown, due to the thermal expansion of the head housing 10, the distance D12 between the first part p1 and the second part p2 is greater than the distance D11 corresponding to the room temperature environment. At this time, the spring member 43 in a state of contraction from the reference state in the room temperature environment continuously biases the lens 222 toward the second annular member r2 and presses the lens 222 against the second annular member r2. This prevents the lens 222 provided in the head housing 10 from shifting to an unexpected position in an unexpected posture.

[0091] Fig. 7A and Figure 7B 4 is a view illustrating a reference example for describing the function of the spring member 43. Fig. 7AAs shown, it is assumed that the lens 222 is fixed in a room temperature environment in a state of being sandwiched between the first ring member r1 and the second ring member r2 without using the spring member 43 in the head housing 10 .

[0092] When such a configuration is arranged in a high temperature environment starting from a room temperature environment, the distance between the first annular member r1 and the second annular member r2 increases due to thermal expansion of the head case 10, as shown in FIG. Figure 7B Therefore, when the linear expansion coefficient of the lens 222 is smaller than the linear expansion coefficient of the head housing 10, a gap is generated between the lens 222 and at least one of the first annular member r1 and the second annular member r2. Therefore, the lens 222 is likely to shift to an unexpected position in an unexpected posture.

[0093] In view of the above point, the spring member 43 is held in the head housing 10 in a state contracted in the x direction from the reference state in the room temperature environment, depending on the screwing amount of the ring screw 46. In this case, the spring member 43 biases the lenses 222 to 224 toward the ring screw 46 in the +x direction. In addition, the spring member 43 biases the lens 221 toward the first step portion st1 in the -x direction. In this way, the spring member 43 serves as a member that prevents the plurality of lenses 221 to 224 from being in a floating state in the head housing 10 as the temperature environment in which the measuring head 1A is arranged changes.

[0094] <5> Preferred arrangement of the spring member 43 in the head housing 10

[0095] (a) First Arrangement Condition will be described as a preferred arrangement condition of the spring member 43 in the head housing 10 . Figure 8 4 is a view for describing a first arrangement condition of the spring member 43 in the head housing 10. Figure 8 , the outer edge of the path of the light passing through the head housing 10 corresponds to Figure 4 Cross-sectional view of measuring head 1A Figure 1 From is indicated by a dotted line. Figure 8 It can be seen that the spring member 43 is provided so that the light guided from the optical fiber 319 into the head housing 10 passes through the inner side of the spring member 43 .

[0096] In the above-mentioned measuring head 1A, the plurality of lenses 221 to 224 accommodated in the head housing 10 can be regarded as a combined optical system (hereinafter, referred to as a combined optical system). Figure 8 As shown, the first arrangement condition of the spring member 43 is that when light travels in the +x direction in the head housing 10 , the spring member 43 is arranged at a position closer to the rear end portion RE than a principal point pp defined in the combined optical system.

[0097] In the region closer to the rear end portion RE than the principal point pp in the internal space of the head case 10, the cross-sectional area of ​​the light traveling in the head case 10 gradually expands in the +x direction from the size of the core 319a of the optical fiber 319. Therefore, in the case where the spring member 43 is provided according to the first arrangement condition, even when the size of the head case 10 is restricted, it is easy to arrange the spring member 43 so as not to interfere with the optical path inside the head case 10. In addition, the spring member 43 can be made close to the rear end portion RE, and therefore, the size increase of the head case 10 in the x direction is reduced.

[0098] (b) The second arrangement condition will be described as a preferred arrangement condition of the spring member 43 in the head housing 10. Some of the plurality of lenses 221 to 224 provided in the measuring head 1A have an effective diameter larger than the inner diameter of the spring member 43. Specifically, among the plurality of lenses 221 to 224, the lenses 222 to 224 have an effective diameter larger than the inner diameter of the spring member 43. On the other hand, the lens 221 has an effective diameter smaller than the inner diameter of the spring member 43.

[0099] In such a configuration, the second arrangement condition of the spring member 43 is that the spring member 43 is arranged at a position closer to the rear end portion RE than the lenses 222 to 224 having an effective diameter larger than the inner diameter of the spring member 43. In the case where the spring member 43 is provided according to the second arrangement condition, even when the size of the head case 10 is restricted, it is easy to arrange the spring member 43 so as not to interfere with the optical path inside the head case 10. In addition, the spring member 43 can be made close to the rear end portion RE, and therefore, the size increase of the head case 10 in the x direction is reduced.

[0100] (c) The third arrangement condition is described as a preferred arrangement condition of the spring member 43 in the head housing 10. Among the plurality of lenses 221 to 224 provided in the measuring head 1A, the lens 221 is a magnifying lens, and causes the light guided from the optical fiber 319 to travel in the +x direction while expanding the cross-sectional area of ​​the light. In this way, the region in which the cross-sectional area of ​​the light propagating in the +x direction is gradually expanded by at least one of the plurality of lenses 221 to 224 in the head housing 10 is referred to as a light expansion region. In this case, the third arrangement condition of the spring member 43 is that the spring member 43 is arranged in the light expansion region.

[0101] According to the above configuration, even when the size of the head housing 10 is limited, it is easy to arrange the spring member 43 so as not to interfere with the optical path inside the head housing 10. In addition, by making the light expansion area inside the head housing 10 close to the rear end portion RE, the increase in the size of the head housing 10 in the x direction is reduced.

[0102] <6> Adhesives

[0103] like Figure 5 As shown, when assembling the measuring head 1A, basically, the annular screw 46 is attached from the front end FE in a state where the plurality of constituent elements (41 to 45 and 221 to 224) are accommodated in the head housing 10. The fiber receptacle 30 is connected to the rear end RE of the head housing 10 using a plurality of screws SC1.

[0104] Here, an adhesive made of an inorganic material is used to further strengthen the fixed state of the fastening portion of the screw in the measuring head 1A according to the present embodiment. The inorganic material of the adhesive is, for example, ceramic powder.

[0105] Specifically, in the present embodiment, when the annular screw 46 is attached to the internal threaded portion 12j of the second housing section 12, an adhesive made of an inorganic material is applied between the annular screw 46 and the internal threaded portion 12j, such as by Figure 4 In this case, since the adhesive does not contain organic materials, even when the measuring head 1A is arranged in a vacuum environment, the generation of exhaust gas from the adhesive is suppressed. Therefore, the reduction in the vacuum level caused by the adhesive is suppressed.

[0106] Fig. 9 It is along the Figure 2 and Figure 3 2 is a cross-sectional view of the measuring head 1A taken along a virtual plane VS2 indicated by a double-dashed line. Fig. 9 The cross-sectional view of illustrates a state where the fiber receptacle 30 is attached to the rear end portion RE of the head housing 10 using a plurality of screws SC1.

[0107] In this embodiment, when the optical fiber receptacle 30 is screwed to the head housing 10, an adhesive made of an inorganic material is applied between the screw SC1 and the threaded hole h3, such as by Fig. 9 In this case, since the adhesive does not contain organic materials, even when the measuring head 1A is arranged in a vacuum environment, the generation of exhaust gas from the adhesive is suppressed. Therefore, the reduction in the vacuum level caused by the adhesive is suppressed.

[0108] When the measuring head 1A is assembled using an adhesive made of an inorganic material as described above, it is preferable to apply the adhesive so as not to be exposed. Therefore, powder of an inorganic material such as ceramic is suppressed from scattering around the measuring head 1A.

[0109] 3. Light bending unit and distance adjustment member

[0110] Each of the measuring heads 1A and 1B may further include a light bending unit that is detachably attached to the head housing 10 and changes the traveling direction of light emitted from the head housing 10 at a predetermined angle (90° in this example). In addition, each of the measuring heads 1A and 1B may further include a plurality of distance adjustment members that adjust the measurable range of displacement of each of the measuring heads 1A and 1B when the light bending unit is attached.

[0111] Fig.10 is an external perspective view of a light bending unit and a plurality of distance adjustment members. Fig.10 An exploded perspective view of the light bending unit 50 and an external perspective view of a plurality of (in this example, two) distance adjustment members 60 are illustrated, and Figure 2 The external perspective view of the measuring head 1A in FIG. Fig.10 , a schematic longitudinal cross-sectional view and a schematic end view of the light bending unit 50 are illustrated in balloon-shaped dialog boxes.

[0112] like Fig.10 As shown, the light bending unit 50 includes a body MB, a reflector 54, a leaf spring 55, and a fixing plate 56. The reflector 54 is connected to the leaf spring 55. Therefore, the reflector 54 and the leaf spring 55 can be integrally operated when the light bending unit 50 is assembled. Note that Fig.10 The external perspective view illustrates a state where the reflector 54 and the leaf spring 55 are separated from each other, so as to facilitate understanding of the shapes and positional relationship of the reflector 54 and the leaf spring 55. The main body MB has a rear end surface 51, a front end inclined surface 52, and an emitting surface 53. The rear end surface 51 is formed to be able to contact with the front end portion FE of the head housing 10. The front end inclined surface 52 faces the rear end surface 51 at a position of the rear end surface 51 in the +x direction, and is inclined at 45° relative to the rear end surface 51. The emitting surface 53 is orthogonal to the rear end surface 51.

[0113] In the light bending unit 50, a substantially triangular longitudinal section is formed by the rear end surface 51, the front end inclined surface 52 and the emitting surface 53, as shown in FIG. Fig.10 Opening portions 51a, 52a and 53a are formed in the rear end surface 51, the front end inclined surface 52 and the emission surface 53, respectively.

[0114] The reflector 54 is provided on the front end inclined surface 52 so as to cover the opening portion 52a. The fixing plate 56 is a plate-shaped member made of metal, and two protrusions 56a are formed on one surface thereof. The fixing plate 56 is attached to the front end inclined surface 52 using screws (not shown) so that the leaf spring 55 is located in the +x direction relative to the reflector 54, and the two protrusions 56a face the -x direction. Here, the leaf spring 55 is formed with two pressed portions extending in the -z direction and the +z direction, respectively. In addition, the two protrusions 56a of the fixing plate 56 are formed so as to correspond to the two pressed portions of the leaf spring 55. Therefore, in a state where the fixing plate 56 is attached to the front end inclined surface 52, the two pressed portions of the leaf spring 55 are pressed by the two protrusions 56a of the fixing plate 56 so as to approach the reflector 54. Therefore, the reflector 54 is maintained in a state biased toward the front end inclined surface 52 by the leaf spring 55.

[0115] In the main body MB of the light bending unit 50, four screw holes h2 ( Figure 2 ) corresponding to four through holes 57. Therefore, the light bending unit 50 can be easily attached to the head housing 10 by inserting four screws SC2 through the four through holes 57 of the body MB into the four threaded holes h2 of the head housing 10 and screwing the corresponding screws SC2.

[0116] Note that two or three screws SC2 may be used to attach the light bending unit 50 to the head housing 10. For example, two screws SC2 are inserted through two through holes 57 of the light bending unit 50 into two threaded holes h2 of the head housing 10, which are arranged diagonally across the head axis 10a. Thus, the light bending unit 50 can be attached to the head housing 10.

[0117] In a state where the light bending unit 50 is attached to the head housing 10, light emitted from the inside of the head housing 10 through the opening portion of the front end portion FE is incident on the reflective mirror 54 through the opening portions 51a and 52a of the main body MB. Therefore, the light incident on the reflective mirror 54 is reflected by the reflective mirror 54 to be bent by 90°, and travels toward the side of the measuring head 1A (in a direction orthogonal to the head axis 10a) through the opening portion 53a of the main body MB. Therefore, according to Fig.10 With the light bending unit 50 in FIG. 1 , the measurement direction of the posture of the measurement object S relative to the head housing 10 can be changed by 90°.

[0118] The range in which the displacement of the measuring object S can be measured from the front end portion FE of the head housing 10 in the measuring head 1A (hereinafter, referred to as the measuring range) is determined by the lenses 221 to 224 accommodated in the head housing 10. Therefore, the measuring range from the emission surface 53 of the light bending unit 50 when the light bending unit 50 is attached to the head housing 10 can be appropriately changed by adjusting the distance between the head housing 10 and the light bending unit 50. Therefore, a plurality of distance adjusting members 60 are used.

[0119] Each of the plurality of distance adjustment members 60 has a rear end surface and a front end surface. The rear end surface and the front end surface have a substantially rectangular shape (in this example, a substantially square shape) corresponding to the front end portion FE of the head housing 10. The rear end surface of the distance adjustment member 60 is formed to be able to contact the front end portion FE of the head housing 10. The front end surface of the distance adjustment member 60 is formed to be able to contact the rear end surface 51 of the light bending unit 50.

[0120] An opening through which light emitted from the head housing 10 passes is formed in the central portion from the front end surface to the rear end surface of the distance adjustment member 60. In addition, two through holes 61 and two threaded holes 62 are formed at four corners of the front end surface of the distance adjustment member 60 when viewed in the x direction so as to surround the opening in the central portion. The two through holes 61 are located at diagonal positions across the opening in the central portion on one side, and the two threaded holes 62 are located at diagonal positions across the opening in the central portion on the other side.

[0121] The two through holes 61 of one distance adjusting member 60 are used to insert the two screws SC3 into the two threaded holes h2 of the head housing 10 through the two through holes 61, and screw the one distance adjusting member 60 to the head housing 10. Alternatively, the two through holes 61 of one distance adjusting member 60 are used to insert the two screws SC3 into the two threaded holes 62 of the other distance adjusting member 60 through the two through holes 61, and screw the one distance adjusting member 60 to the other distance adjusting member 60.

[0122] The two threaded holes 62 of one distance adjusting member 60 are used to screw the other distance adjusting member 60 onto the front end surface of one distance adjusting member 60 using the two screws SC3 as described above. Alternatively, the two threaded holes 62 of one distance adjusting member 60 are used to screw the light bending unit 50 to one distance adjusting member 60 by inserting the two screws SC2 through the two through holes 57 of the light bending unit 50.

[0123] As described above, when the light bending unit 50 is attached to the head housing 10 , the distance adjusting member 60 may be inserted between the head housing 10 and the light bending unit 50 .

[0124] FIG. 11A to FIG. 11D The diagram is provided by Fig.10 FIG. 1 is a diagram showing changes in the measuring direction and measurable range of the measuring head 1A caused by the light bending unit 50 and the plurality of distance adjustment members 60. Fig.11A , a path of light having one wavelength (hereinafter, referred to as specific wavelength light) emitted from the head housing 10 in a state where the light bending unit 50 and the plurality of distance adjustment members 60 are not attached is indicated by a dotted line. Fig.11A In the example of FIG. 1 , the light of a specific wavelength emitted from the head housing 10 travels along the head axis 10 a. Therefore, the displacement measurement direction coincides with the direction of the head axis 10 a.

[0125] exist Fig. 11B , the path of the specific wavelength light emitted from the head housing 10 in a state where the light bending unit 50 is attached is indicated by a dotted line. Fig. 11B In the example of FIG. 1 , the light of a specific wavelength emitted from the head housing 10 travels in a direction bent 90° from the head axis 10a by the light bending unit 50. Therefore, the displacement measurement direction is orthogonal to the head axis 10a. Fig. 11B In the example of FIG. 5 , light of a specific wavelength emitted from the emission surface 53 of the light bending unit 50 is focused at positions separated by a distance D1.

[0126] exist Fig. 11C , the path of the specific wavelength light emitted from the head housing 10 in a state where the light bending unit 50 and one distance adjusting member 60 are attached is indicated by a dotted line. Fig. 11C For example, the light of a specific wavelength emitted from the emission surface 53 of the light bending unit 50 is focused at a ratio of Fig. 11B The distance D1 is shorter than the distance D2 that separates them.

[0127] exist Fig.11D , the path of the specific wavelength light emitted from the head housing 10 in a state where the light bending unit 50 and the two distance adjustment members 60 are attached is indicated by a dotted line. Fig.11D For example, the light of a specific wavelength emitted from the emitting surface 53 of the light bending unit 50 is focused at a ratio of Fig. 11C The distance D2 is shorter than the distance D3 separating them.

[0128] In this manner, according to the light bending unit 50 and the plurality of distance adjusting members 60 , the degree of freedom of the position and attitude of the measuring head 1A when measuring the displacement of the measuring object S increases.

[0129] Note that in the above-mentioned light bending unit 50, a reflector in which aluminum is vapor-deposited on one surface of glass is used as the reflector 54. Therefore, all the constituent elements of the light bending unit 50 are formed using metal or glass. In addition, the distance adjustment member 60 is configured using a single member made of metal, which is the same as the head housing 10. In these cases, the light bending unit 50 and the plurality of distance adjustment members 60 do not contain any organic substances. Therefore, even in the case where the measuring head 1A is arranged in a vacuum environment in a state where any one of the light bending unit 50 and the plurality of distance adjustment members 60 is attached to the head housing 10, exhaust gas is prevented from being generated from the measuring head 1A. In addition, a decrease in the degree of vacuum caused by the light bending unit 50 and the plurality of distance adjustment members 60 is suppressed.

[0130] 4. Effect

[0131] (a) The plurality of lenses 221, 222, 223, and 224 are accommodated in the head housing 10 of each of the measuring heads 1A and 1B so as to be aligned between the first step portion st1 and the annular screw 46. The spring member 43 is provided between the two lenses 221 and 222.

[0132] The movement of the lens 224 in the +x direction is restricted by abutting against the annular screw 46. In this state, the lenses 222, 223, and 224 are biased in the +x direction by the spring member 43. On the other hand, the movement of the lens 221 in the -x direction is restricted by abutting against the first step portion st1. In this state, the lens 221 is biased in the -x direction by the spring member 43.

[0133] According to this configuration, even when the sizes of the respective constituent elements of the measuring heads 1A and 1B change due to thermal expansion because the measuring heads 1A and 1B are arranged in a high temperature environment, each of the plurality of lenses 221 to 224 is biased toward a direction in which movement is restricted. Therefore, each of the lenses 221 to 224 is fixed to a predetermined portion inside the head housing 10 and is not in a floating state. Therefore, each lens is prevented from being greatly displaced to an unexpected position in an unexpected posture whenever the measuring heads 1A and 1B are arranged in a high temperature environment.

[0134] In addition, the head housing 10, the spacers 41, 42, 44 and 45, the spring member 43, the annular screw 46 and the optical fiber receptacle 30 are made of the same metal material as in the above-mentioned measuring heads 1A and 1B. In addition, the plurality of lenses 221 to 224 are formed using glass. Therefore, compared with the case where any one of the head housing 10, the spacers 41, 42, 44 and 45, the spring member 43, the annular screw 46, the optical fiber receptacle 30 and the plurality of lenses 221 to 224 is formed using an organic material such as resin, the heat resistance of the measuring heads 1A and 1B is improved. In addition, compared with the member using resin, the degree of deformation of the parts formed using metal and glass due to temperature change is easier to grasp. Therefore, it is easy to correct the measured value in consideration of the temperature change.

[0135] Therefore, it is possible to suppress a decrease in the measurement reliability of the confocal displacement sensor 9 of the measuring heads 1A and 1B according to the present embodiment in a high-temperature environment.

[0136] (b) In addition, in the present embodiment as described above, one spring member 43 is used as a common member for biasing the four lenses 221 to 224. Therefore, compared with the case where four biasing members are provided separately to bias the four lenses 221 to 224, respectively, an increase in the number of parts and an increase in size of the measuring heads 1A and 1B are suppressed.

[0137] (c) In addition, according to the above configuration, the materials of the corresponding constituent elements of the measuring heads 1A and 1B do not substantially contain any organic material. Therefore, even when the measuring heads 1A and 1B are arranged in a vacuum environment, it is unlikely that exhaust gas will be generated from the measuring heads 1A and 1B. Therefore, when the measuring heads 1A and 1B are arranged in a vacuum environment, a decrease in the vacuum level in the vacuum environment caused by the exhaust gas from the measuring heads 1A and 1B is suppressed. Therefore, a decrease in the measurement reliability of the confocal displacement sensor 9 in a vacuum environment is also suppressed.

[0138] (d) In the head case 10 , the notches 11 x and 11 y are formed in the first case section 11 , and a plurality of through holes h1 for attaching the measuring heads 1A and 1B to desired portions are formed.

[0139] In the measuring heads 1A and 1B, the cross section of light traveling inside the first housing section 11 is smaller than the cross section of light traveling inside the second housing section 12. Therefore, compared with a case where a structure for attaching the measuring heads 1A and 1B to a desired portion is provided in the second housing section 12, an increase in the size of the measuring heads 1A and 1B is suppressed.

[0140] (e) In the measuring heads 1A and 1B, the head housing 10, the spacers 41, 42, 44 and 45, the spring member 43, the annular screw 46 and the optical fiber receptacle 30 are made of stainless steel (SUS 304, SUS 316, SUS 316L or SUS 303). Stainless steel is extremely unlikely to generate exhaust gas in a vacuum environment. Therefore, even when the measuring heads 1A and 1B are arranged in a vacuum environment, exhaust gas is unlikely to be generated from the measuring heads 1A and 1B. Therefore, when the measuring heads 1A and 1B are arranged in a vacuum environment, a decrease in the degree of vacuum caused by the constituent members of the measuring heads 1A and 1B is suppressed.

[0141] 5. Other embodiments

[0142] (A) In each of the measuring heads 1A and 1B according to the above-described embodiments, the spring member 43 is accommodated in the head housing 10 so as to bias each of the plurality of lenses 221 to 224 in the x direction, but the present invention is not limited thereto.

[0143] Fig.12 is a cross-sectional view illustrating an example of a measuring head 1A according to another embodiment. Fig.12 The cross-sectional view corresponds to the above embodiment. Figure 4 In the following, the cross-sectional view of Fig.12 The measuring head 1A in FIG. 1 is different from the measuring head 1A according to the above-described embodiment.

[0144] exist Fig.12 In the measuring head 1A in FIG. 1 , according to the above-described embodiment, the thermal expansion member 49 having a substantially cylindrical shape is provided in the head case 10 instead of the spring member 43. The thermal expansion member 49 is made of a polyimide resin having relatively high heat resistance.

[0145] The thermal expansion member 49 is provided so that the axis of the thermal expansion member 49 extends in the x direction. In a room temperature environment, both ends of the thermal expansion member 49 in the x direction are in contact with a portion of the spacer 42 and a portion of the lens 222, respectively.

[0146] The linear expansion coefficient of polyimide is greater than that of metal. Therefore, in the above-mentioned measuring head 1A, when the size of the corresponding component of the measuring head 1A changes due to thermal expansion, the thermal expansion member 49 expands more than the multiple lenses 221 to 224 and the head housing 10. Therefore, when the measuring head 1A is arranged in a high temperature environment, each of the multiple lenses 221 to 224 is biased in the direction in which the movement is limited by the expanded thermal expansion member 49. Therefore, each of the lenses 221 to 224 is fixed to a predetermined portion inside the head housing 10, and is not in a floating state as in the example of the above-mentioned embodiment. Therefore, whenever the measuring head 1A is arranged in a high temperature environment, each lens is prevented from being greatly displaced to an unexpected position with an unexpected posture.

[0147] Therefore, by using polyimide having high heat resistance as the polyimide used for the thermal expansion member, it is possible to suppress a decrease in the measurement reliability of the confocal displacement sensor 9 in a high temperature environment.

[0148] (b) Although four lenses 221 to 224 are provided in the head housing 10 according to the above embodiment, the present invention is not limited thereto. As long as the displacement of the measuring object S can be measured, only two lenses, only three lenses, or five or more lenses may be provided in the head housing 10.

[0149] (c) Although according to the above-described embodiment, one spring member 43 is used as a member for biasing the plurality of lenses 221 to 224 in the x-direction in the measuring heads 1A and 1B, the present invention is not limited thereto. A plurality of spring members may be provided in the head housing 10 so as to correspond to the plurality of lenses 221 to 224, respectively, and each lens may be biased in the x-direction by the corresponding spring member.

[0150] (d) Although in the measuring heads 1A and 1B according to the above-described embodiments, the first step portion st1 in the head housing 10 limits the movement of the lens 221 in the -x direction, the present invention is not limited thereto. As a configuration for limiting the movement of the lens 221 in the -x direction, a configuration using an annular screw may be adopted. In this case, the first step portion st1 and the second step portion st2 are not necessarily formed inside the head housing 10. In addition, it is sufficient that the lens 221 is formed so as to abut against the annular screw and not pass through the inside of the annular screw. Therefore, it is sufficient that the lens 221 has an outer shape larger than the inner diameter of the annular screw and can have an outer diameter that is the same as the outer diameters of the other lenses 222, 223, and 224.

[0151] (e) Although in the measuring heads 1A and 1B according to the above-described embodiments, each of the spacers 41, 42, 44, and 45 is provided between two lenses among the plurality of lenses 221 to 224 accommodated in the head housing 10, the present invention is not limited thereto. The spacer is not necessarily provided between any two lenses among the plurality of lenses 221 to 224.

[0152] (f) In the measuring heads 1A and 1B according to the above-described embodiments, the spring member 43 may be provided at a position in the +x direction relative to the plurality of lenses (221 to 224) in the head housing 10, or may be provided at a position in the -x direction relative to the plurality of lenses (221 to 224).

[0153] 6. Correspondence between each component of the claims and each unit of the embodiments

[0154] Hereinafter, an example of the correspondence relationship between each constituent element of the claims and each unit of the embodiment will be described, but the present invention is not limited to the following examples. Various other elements having the configuration or function described in the claims may be used as the corresponding constituent elements of the claims.

[0155] In the above-mentioned embodiment, the white light source included in the light projection unit 120 is an example of a white light source, the confocal displacement sensor 9 is an example of a confocal displacement sensor, the measuring heads 1A and 1B are examples of measuring heads, the rear end portion RE of the head housing 10 is an example of a first end portion, the front end portion FE of the head housing 10 is an example of a second end portion, the head housing 10 is an example of a housing, and the optical fiber 319 of the light guiding units 300A and 300B is an example of an optical fiber.

[0156] In addition, lens 224 is an example of a first lens, the head axis 10a is an example of the axis of the shell, lenses 221 to 224 are examples of multiple lenses, the internal threaded portion 12j of the third inner circumferential surface 12i is an example of a first portion, the +x direction is an example of a first direction, the -x direction is an example of a second direction, the annular screw 46 is an example of a first movement limiting portion and a limiting member, and the spring member 43 is an example of a biasing member.

[0157] In addition, spacers 41, 42, 44 and 45 are examples of one or more spacers, lens 221 is an example of a second lens, the first step portion st1 in the head housing 10 is an example of the second portion and the second movement limiting portion, the third inner circumferential surface 12i of the second housing section 12 is an example of an inner circumferential surface of the housing, the principal point pp of the combined optical system is an example of a principal point, and the outer surfaces 11a, 11b, 11c, 11d, 12a, 12b, 12c and 12d are examples of outer surfaces.

[0158] In addition, the first shell segment 11 is an example of a first shell segment, the second shell segment 12 is an example of a second shell segment, the first inner circumferential surface 11i, the second inner circumferential surface 11j and the third inner circumferential surface 12i are examples of inner circumferential surfaces of the shell, the portion in which a plurality of through holes h1 are formed in the first shell segment 11 is an example of an attachment portion, the light bending unit 50 is an example of a light bending unit, and the distance adjustment member 60 is an example of a distance adjustment member.

[0159] In addition, the fiber receptacle 30 is an example of a fiber connecting member, the screw SC1 is an example of a screw, the thermal expansion member 49 is an example of a thermal expansion member, and the measuring units 100A and 100B are examples of a displacement measuring unit.

[0160] 7. Overview of Embodiments

[0161] (Item 1) The measuring head according to Item 1 is a measuring head for a confocal displacement sensor having a white light source, and includes:

[0162] a housing made of metal, formed into a tubular shape, and having a first end and a second end;

[0163] an optical fiber connected to the first end of the housing and directing light generated from the white light source to the first end of the housing;

[0164] a plurality of lenses made of glass, including a first lens housed inside the housing to be aligned in an axial direction of the housing and movable in the axial direction, and converging light guided by the optical fiber to the first end portion on a measurement object through the second end portion while generating chromatic aberration along an optical axis;

[0165] a first movement limiting portion which is provided in a predetermined first portion inside the housing and which limits movement of the first lens in any one of a first direction from the first end toward the second end in the axial direction and a second direction opposite to the first direction when the first lens abuts against the first movement limiting portion; and

[0166] A biasing member is made of metal and biases some or all of the plurality of lenses including the first lens in the one direction by elastic force in a state where the first lens abuts on the first movement restricting portion.

[0167] In the measuring head, a plurality of lenses including a first lens are accommodated in a tubular housing for alignment. The first lens is restricted from moving in any one of a first direction and a second direction by abutting against a first movement restricting portion. In a state where the first lens abuts against the first movement restricting portion, some or all of the plurality of lenses including the first lens are biased in one direction by a biasing member.

[0168] In this case, even when the measuring head is arranged in a high temperature environment, when the size of the corresponding component elements of the measuring head changes due to thermal expansion, some or all of the multiple lenses including the first lens are restricted from moving in one direction. That is, each lens biased by the biasing member is fixed to a predetermined portion inside the housing and is not in a floating state. Therefore, each lens is prevented from being greatly displaced to an unexpected position in an unexpected posture whenever the measuring head is arranged in a high temperature environment.

[0169] In addition, in the measuring head, the housing and the biasing member are made of metal, and the plurality of lenses are made of glass. Therefore, the heat resistance of the measuring head is improved compared to the case where any one of the housing, the biasing member, and the plurality of lenses is formed using an organic material. In addition, the degree of deformation of the components formed using metal and glass due to temperature changes is easier to grasp than the case where resin is used. Therefore, it is easy to correct the measured value in consideration of the temperature change.

[0170] Therefore, it is possible to suppress a decrease in the measurement reliability of the confocal displacement sensor in a high-temperature environment.

[0171] Furthermore, according to the above configuration, since the housing and the biasing member are formed using metal, and the plurality of lenses are formed using glass, even when the measuring head is arranged in a vacuum environment, it is unlikely that exhaust gas will be generated from the housing, the biasing member, and the lens. Therefore, when the measuring head is arranged in a vacuum environment, a decrease in the vacuum level in the vacuum environment due to the housing, the biasing member, and the lens is suppressed. It is also possible to suppress a decrease in the measurement reliability of the confocal displacement sensor in a vacuum environment.

[0172] (Item 2) In the measuring head according to Item 1,

[0173] The measuring head may also include

[0174] one or more spacers, the one or more spacers being made of metal and accommodated inside the housing so as to be movable in the axial direction of the housing, and

[0175] Each of the one or more spacers may be provided between two lenses adjacent in the axial direction among the plurality of lenses.

[0176] In this case, the heat resistance of the measuring head is improved compared to the case where the spacer is formed using an organic material. In addition, even when the measuring head is arranged in a vacuum environment, the generation of exhaust gas from the spacer is prevented, and the reduction in the vacuum level caused by the spacer is suppressed.

[0177] (Item 3) In the measuring head according to Item 1 or 2,

[0178] The first movement limiting portion may abut against the first lens to limit the movement of the first lens in the first direction.

[0179] The plurality of lenses may include a second lens disposed in the housing between the first lens and the second end,

[0180] The measuring head may further include a second movement limiting portion, which is provided in the second portion, the second portion is located between the first portion and the second end portion inside the housing, and the second movement limiting portion abuts against the second lens among the plurality of lenses to limit the second lens from moving in the second direction, and

[0181] The biasing member may

[0182] is provided in the housing between the first lens and the second lens, and

[0183] In a state where the first lens abuts against the first movement limiting portion and the second lens abuts against the second movement limiting portion, some of the multiple lenses including the first lens are biased in the first direction by elastic force, and the remaining lenses of the multiple lenses including the second lens are biased in the second direction by elastic force.

[0184] In this case, even when the measuring head is arranged in a high temperature environment, when the size of the corresponding component elements of the measuring head changes due to thermal expansion, some lenses including the first lens are restricted from moving in the first direction. In addition, the remaining lenses including the second lens among the plurality of lenses are restricted from moving in the second direction. Therefore, all the plurality of lenses are fixed to a predetermined portion inside the housing and are not in a floating state. Therefore, whenever the measuring head is arranged in a high temperature environment, each of all the lenses is prevented from being greatly displaced to an unexpected position in an unexpected posture.

[0185] In addition, since the biasing member is arranged between some lenses including the first lens and the remaining lenses including the second lens in the above configuration, it is not necessary to separately prepare a plurality of biasing members for biasing the plurality of lenses. Therefore, an increase in the number of components and an increase in size of the measuring head are suppressed.

[0186] (Item 4) In the measuring head according to any one of Items 1 to 3,

[0187] The housing may have a cylindrical inner circumferential surface extending in the axial direction,

[0188] The biasing member may be formed into a tubular shape extending a certain distance in the axial direction of the housing, and when light travels in the first direction in the housing, the biasing member is arranged at a position closer to the first end than a principal point defined in an optical system combining the plurality of lenses, and

[0189] Light traveling in the housing may pass through an inner side of the biasing member.

[0190] In at least a portion of the region inside the housing that is closer to the first end than the main point, the cross-sectional area of ​​the light traveling inside the housing from the first end gradually expands in the first direction from the size of the optical fiber. Therefore, according to the above configuration, even when the size of the housing is limited, it is easy to arrange the biasing member so as not to interfere with the path of the light inside the housing. In addition, since the biasing member can be brought close to the first end, the increase in the size of the housing in the axial direction is reduced.

[0191] (Item 5) In the measuring head according to any one of Items 1 to 4,

[0192] The housing may have a cylindrical inner circumferential surface extending in the axial direction,

[0193] The biasing member may be formed in a tubular shape extending a certain distance in the axial direction of the housing,

[0194] Some of the plurality of lenses may have an effective diameter greater than an inner diameter of the biasing member,

[0195] The biasing member may be disposed within the housing at a position closer to the first end than some of the plurality of lenses, and

[0196] Light traveling in the housing may pass through an inner side of the biasing member.

[0197] According to the above configuration, even when the size of the housing is limited, it is easy to arrange the biasing member so as not to interfere with the path of light inside the housing. In addition, since the biasing member can be close to the first end, the increase in the size of the housing in the axial direction is reduced.

[0198] (Item 6) In the measuring head according to Item 3,

[0199] The housing may have a cylindrical inner circumferential surface extending in the axial direction,

[0200] The plurality of lenses may be arranged to allow the light guided to the first end to travel in the first direction while expanding a cross-sectional area of ​​the light in a partial region inside the housing.

[0201] The biasing member may be formed into a tubular shape extending a certain distance in the axial direction of the housing and arranged in the partial region in the housing, and

[0202] Light traveling in the housing may pass through an inner side of the biasing member.

[0203] According to the above configuration, even when the size of the shell is limited, it is easy to arrange the biasing member so as not to interfere with the path of light inside the shell. In addition, since a partial area inside the shell can be made close to the first end, the increase in the size of the shell in the axial direction is reduced.

[0204] (Item 7) In the measuring head according to any one of Items 1 to 6, at least a portion of the housing may have a rectangular tubular outer surface extending in the axial direction and having a rectangular cross section.

[0205] In this case, the measuring head is easily mounted on a predetermined mounting surface, compared with the case where the housing has a cylindrical outer circumferential surface.

[0206] (Item 8) In the measuring head according to any one of Items 1 to 3,

[0207] The housing may

[0208] comprising a first shell section and a second shell section, the first shell section and the second shell section being sequentially aligned in the first direction, and

[0209] having an inner circumferential surface having a cylindrical shape and extending in an axial direction from the first housing section to the second housing section,

[0210] The inner diameter of the inner circumferential surface in the first shell section may be smaller than the inner diameter of the inner circumferential surface in the second shell section.

[0211] The plurality of lenses may be housed in the second housing section, and

[0212] An attachment portion configured to attach the measuring head to another member may be formed on an outer surface of the first housing section.

[0213] In this case, compared with the case where the attachment portion is provided in the second housing section, an increase in the size of the measuring head can be suppressed.

[0214] (Item 9) In the measuring head according to any one of Items 1 to 8,

[0215] The measurement head may further include a light bending unit configured to be detachably attached to the second end portion and to bend light emitted from the second end portion in a predetermined direction intersecting the axial direction.

[0216] In this case, the degree of freedom of the position and attitude of the measuring head when measuring the displacement of the measurement object increases.

[0217] (Item 10) In the measuring head according to Item 9, the measuring head may further include one or more distance adjustment members, which are configured to be detachably attached between the second end and the light bending unit and adjust the distance between the measuring head and the light bending unit.

[0218] In this case, the degree of freedom of the position and attitude of the measuring head when measuring the displacement of the measurement object increases.

[0219] (Item 11) In the measuring head according to any one of Items 1 to 10, the metal forming the housing and the biasing member may be stainless steel.

[0220] In this case, even when the measuring head is arranged in a vacuum environment, it is unlikely that exhaust gas will be generated from the housing and the biasing member. Therefore, a decrease in the vacuum level caused by the housing and the biasing member is suppressed.

[0221] (Item 12) In the measuring head according to any one of Items 1 to 11,

[0222] The first movement restricting portion may be configured by connecting a restricting member separate from the housing to the first portion inside the housing, and

[0223] An adhesive made of an inorganic material may be used for the connection portion between the housing and the restricting member.

[0224] In this case, even when the measuring head is arranged in a vacuum environment, a decrease in the vacuum level due to the adhesive is suppressed.

[0225] (Item 13) In the measuring head according to any one of Items 1 to 12,

[0226] The measuring head may further include an optical fiber connecting member configured to connect the optical fiber to the first end portion of the housing.

[0227] The fiber optic connection member may be connected to the first end of the housing using one or more screws, and

[0228] An adhesive made of an inorganic material may be used for the fastening portion of each of the one or more screws.

[0229] In this case, even when the measuring head is arranged in a vacuum environment, a decrease in the vacuum level due to the adhesive is suppressed.

[0230] (Item 14) The measuring head according to Item 14 is a measuring head for a confocal displacement sensor having a white light source, and includes:

[0231] a housing made of metal, formed into a tubular shape, and having a first end and a second end;

[0232] an optical fiber connected to the first end of the housing and directing light generated from the white light source to the first end of the housing;

[0233] a plurality of lenses made of glass, including a first lens housed inside the housing to be aligned in an axial direction of the housing and movable in the axial direction, and converging light guided by the optical fiber to the first end portion on a measurement object through the second end portion while generating chromatic aberration along an optical axis;

[0234] a first movement limiting portion which is provided in a predetermined first portion inside the housing and which limits movement of the first lens in any one of a first direction from the first end toward the second end in the axial direction and a second direction opposite to the first direction when the first lens abuts against the first movement limiting portion; and

[0235] a thermal expansion member made of polyimide and provided inside the housing at a position separated from the first movement restricting portion in the axial direction,

[0236] In a state in which the first lens abuts on the first movement restricting portion, some or all of the plurality of lenses including the first lens are held between the first movement restricting portion and the thermal expansion member.

[0237] The linear expansion coefficient of polyimide is greater than that of metal. Therefore, in the measuring head, when the size of the corresponding component of the measuring head changes due to thermal expansion, the thermal expansion member expands more than the plurality of lenses and the housing. Therefore, some or all of the plurality of lenses including the first lens are biased in one direction by the thermal expansion member and are restricted from moving in one direction. Therefore, whenever the measuring head is arranged in a high temperature environment, each lens is prevented from being greatly displaced to an unexpected position in an unexpected posture.

[0238] In addition, in the measuring head, the housing is made of metal, and the plurality of lenses are made of glass. Therefore, the heat resistance of the measuring head is improved by using polyimide having high heat resistance as the polyimide used for the thermal expansion member.

[0239] Therefore, it is possible to suppress a decrease in the measurement reliability of the confocal displacement sensor in a high-temperature environment.

[0240] (Item 15) The confocal displacement sensor according to Item 15, comprising:

[0241] A measuring head according to any one of claims 1 to 14;

[0242] a white light source that generates light to be directed to the measurement head; and

[0243] A displacement measuring unit calculates a displacement of a measurement object based on light emitted from the measuring head to the measurement object and reflected by the measurement object.

[0244] The confocal displacement sensor includes the above-described measuring head. Therefore, a decrease in measurement reliability in a high-temperature environment is suppressed.

Claims

1. A measuring head for a confocal displacement sensor having a white light source, the measuring head comprising: a housing made of metal, formed into a tubular shape, and having a first end and a second end; an optical fiber connected to the first end of the housing and guiding light generated from the white light source to the first end of the housing; a plurality of lenses made of glass, including a first lens, housed inside the housing so as to be aligned in an axial direction of the housing and movable in the axial direction, and to converge light guided by the optical fiber to the first end portion on a measurement object through the second end portion while generating chromatic aberration along an optical axis; a first movement limiting portion which is provided in a predetermined first portion inside the housing and, when the first lens abuts against the first movement limiting portion, limits movement of the first lens in any one of the following directions: a first direction from the first end toward the second end in the axial direction, and a second direction opposite to the first direction; as well as A biasing member is made of metal and biases some or all of the multiple lenses in the one direction by elastic force when the first lens abuts against the first movement limiting portion, some or all of the multiple lenses including the first lens.

2. The measuring head according to claim 1, further comprising one or more spacers, the one or more spacers being made of metal and being accommodated inside the housing so as to be movable in the axial direction of the housing, Each of the one or more spacers is provided between two lenses adjacent to each other in the axial direction among the plurality of lenses.

3. The measuring head according to claim 1 or 2, wherein The first movement limiting portion abuts against the first lens to limit the movement of the first lens in the first direction, and The plurality of lenses includes a second lens disposed between the first lens and the second end portion in the housing, The measuring head further includes a second movement limiting portion, which is provided in a second portion, the second portion is located between the first portion and the second end portion inside the housing, and the second movement limiting portion abuts against the second lens among the plurality of lenses to limit the second lens from moving in the second direction. offset member, The biasing member is provided between the first lens and the second lens in the housing, and The biasing member biases some of the multiple lenses including the first lens in the first direction by elastic force, and biases the remaining lenses including the second lens in the second direction by elastic force, when the first lens abuts against the first movement limiting portion and the second lens abuts against the second movement limiting portion.

4. The measuring head according to claim 1 or 2, wherein The housing has a cylindrical inner circumferential surface extending in the axial direction, The biasing member is formed into a tubular shape extending a certain distance in the axial direction of the housing, and when light travels in the first direction in the housing, the biasing member is arranged at a position closer to the first end than a principal point defined in an optical system combining the plurality of lenses, and Light traveling in the housing passes through the inner side of the biasing member.

5. The measuring head according to claim 1 or 2, wherein The housing has: a cylindrical inner circumferential surface extending in the axial direction, The biasing member is formed into a tubular shape extending a certain distance in the axial direction of the housing, Some of the plurality of lenses have an effective diameter that is greater than an inner diameter of the biasing member, The biasing member is disposed at a position closer to the first end than some of the plurality of lenses inside the housing, and Light traveling in the housing passes through the inner side of the biasing member.

6. The measuring head according to claim 3, wherein The housing has: a cylindrical inner circumferential surface extending in the axial direction, The plurality of lenses are arranged to allow the light guided to the first end to travel in the first direction while expanding the cross-sectional area of ​​the light in a partial region inside the housing, The biasing member is formed into a tubular shape extending a certain distance in the axial direction of the housing and is arranged in the partial region in the housing, and Light traveling in the housing passes through the inner side of the biasing member. 7 . The measuring head according to claim 1 , wherein at least a portion of the housing has a rectangular tubular outer surface extending in the axial direction and having a rectangular cross section.

8. The measuring head according to claim 1 or 2, wherein The housing includes a first housing section and a second housing section, the first housing section and the second housing section are sequentially aligned in the first direction, and The housing has an inner circumferential surface having a cylindrical shape and extending in an axial direction from the first housing section to the second housing section, The inner diameter of the inner circumferential surface in the first shell section is smaller than the inner diameter of the inner circumferential surface in the second shell section, The plurality of lenses are housed in the second housing section, and An attachment portion is formed on an outer surface of the first housing segment, the attachment portion being configured to attach the measuring head to another member. 9 . The measuring head according to claim 1 , further comprising a light bending unit configured to be detachably attached to the second end portion and to bend light emitted from the second end portion in a predetermined direction intersecting the axial direction.

10. The measuring head according to claim 9, further comprising one or more distance adjustment members, which are configured to be detachably attached between the second end and the light bending unit and adjust the distance between the measuring head and the light bending unit.

11. A measurement head according to claim 1 or 2, wherein the metal forming the housing and the biasing member is stainless steel.

12. The measuring head according to claim 1 or 2, wherein The first movement restricting portion is configured by connecting a restricting member separate from the housing to the first portion inside the housing, and An adhesive made of an inorganic material is used for a connection portion between the housing and the restricting member.

13. The measuring head according to claim 1 or 2, further comprising an optical fiber connecting member, wherein the optical fiber connecting member is configured to: connect the optical fiber to the first end portion of the housing, wherein the optical fiber connecting member is connected to the first end of the housing using one or more screws, and An adhesive made of an inorganic material is used for the fastening portion of each of the one or more screws.

14. A measuring head for a confocal displacement sensor having a white light source, the measuring head comprising: a housing made of metal, formed into a tubular shape, and having a first end and a second end; an optical fiber connected to the first end of the housing and guiding light generated from the white light source to the first end of the housing; a plurality of lenses made of glass, including a first lens, housed inside the housing so as to be aligned in an axial direction of the housing and movable in the axial direction, and to converge light guided by the optical fiber to the first end portion on a measurement object through the second end portion while generating chromatic aberration along an optical axis; a first movement limiting portion which is provided in a predetermined first portion inside the housing and, when the first lens abuts against the first movement limiting portion, limits movement of the first lens in any one of the following directions: a first direction from the first end toward the second end in the axial direction, and a second direction opposite to the first direction; as well as a heat expansion member made of polyimide and provided at a position separated from the first movement restricting portion in the axial direction inside the housing, In a state where the first lens abuts on the first movement restricting portion, some or all of the plurality of lenses including the first lens are held between the first movement restricting portion and the thermal expansion member.

15. A confocal displacement sensor, comprising: A measuring head according to any one of claims 1, 2 or 14; a white light source that generates light to be directed to the measurement head; as well as A displacement measuring unit calculates a displacement of the measurement object based on light emitted from the measuring head to the measurement object and reflected by the measurement object.

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