confocal displacement meter

Abstract

This invention provides a confocal displacement meter capable of reducing measurement errors. A light projection unit (120) emits light having multiple wavelengths. A lens unit (220) causes chromatic aberration along the optical axis in the light emitted by the light projection unit (120). Furthermore, the lens unit (220) converges the chromatic aberration light and uses this light to illuminate a measurement object (S). The wavelengths of light used to illuminate the measurement object (S) via the lens unit (220) that are reflected by the surface of the measurement object (S) while being focused pass through multiple pinholes. An arithmetic processing unit (150) calculates the displacement of the measurement object (S) based on the signal intensity of each wavelength of an average signal corresponding to the average intensity of each wavelength of the multiple wavelengths of light passing through the multiple pinholes.

Description

[0001] This application is a divisional application of the application filed on December 21, 2016, with application number 201680076178.1 (PCT / JP2016 / 088008) and entitled "Confocal Displacement Meter". Technical Field

[0002] This invention relates to a confocal displacement meter that uses light with a wide wavelength band. Background Technology

[0003] Confocal displacement meters are known as devices for measuring the displacement of the surface of a measurement object in a non-contact manner. For example, Japanese Patent Application Publication No. 2013-130581 (Patent Document 1) describes a colorimetric point sensor (CPS) system for measuring the displacement of the surface of a measurement object as the distance from a predetermined reference position to the measurement object. The CPS described in Patent Document 1 includes optical paths of two confocal systems. Light with multiple wavelengths is input into these optical paths. Light passing through any of the optical paths is selectively output to the measurement object.

[0004] The first optical path is configured such that light of different wavelengths is focused at different distances near the surface location of the object being measured along the optical axis. Light passing through the first optical path is reflected on the surface of the object being measured. Of the reflected light, only light focused at the location of an opening arranged as a spatial filter in the first path is guided through the opening to the wavelength detector. The spectral profile of the light detected by the wavelength detector (the first output spectral profile) includes a component representing the measurement distance (a distance-dependent profile component) and a distance-independent profile component.

[0005] The second optical path is configured such that light of different wavelengths is focused at approximately the same distance near the surface location of the object being measured. The light passing through the second optical path is reflected on the surface of the object. Of the reflected light, only light focused at the location of an opening arranged as a spatial filter in the second path is guided through this opening to the wavelength detector. The spectral profile of the light detected by the wavelength detector (the second output spectral profile) does not include distance-dependent profile components but only distance-independent profile components. The second output spectral profile is used to correct the first output spectral profile for potential measurement errors related to the distance-independent profile components.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2013-130581 Summary of the Invention

[0009] The problem the invention aims to solve

[0010] In the CPS system described in Patent Document 1, reliability is improved because correction is performed on the first output spectral profile. Specifically, measurement errors arising from the material component of the measured object as a distance-independent profile component, the spectral profile component of the light source associated with the light source, or the component associated with the wavelength detector are reduced. However, in a confocal displacement meter, measurement errors occur due to the influence of irregular reflections on the surface of the measured object, resulting in measurement errors greater than the surface roughness. This measurement error cannot be reduced in the CPS system described in Patent Document 1.

[0011] The purpose of this invention is to provide a confocal displacement meter that can reduce measurement errors.

[0012] Solution for solving the problem

[0013] (1) The confocal displacement meter according to the present invention is a confocal displacement meter for measuring the displacement of a measurement object using a confocal optical system, the confocal displacement meter comprising: a light projection section configured to emit light having a plurality of wavelengths; an optical member configured to cause the light emitted by the light projection section to produce a chromatic aberration along the optical axis, to converge the light having the chromatic aberration, and to cause the light to irradiate the measurement object; a pinhole member comprising a plurality of pinholes, the plurality of pinholes allowing light having wavelengths that are reflected while being focused on the surface of the measurement object to pass through in the light irradiated by the optical member onto the measurement object; and a displacement measuring section configured to calculate the displacement of the measurement object based on the signal intensity of each wavelength of an average signal, wherein the average signal corresponds to the average value of the intensity of each wavelength associated with the plurality of light passing through the plurality of pinholes.

[0014] In this confocal displacement meter, light with multiple wavelengths is emitted by a light projection unit. Chromatic aberration along the optical axis is generated by the optical component causing the light emitted by the light projection unit. The light with chromatic aberration is converged by the optical component and illuminates the object being measured. Of the light illuminating the object by the optical component, light with wavelengths that are reflected while being focused on the surface of the object passes through multiple pinholes in the pinhole component. The displacement measuring unit calculates the displacement of the object based on the signal intensity of each wavelength of an average signal, wherein the average signal corresponds to the average intensity of each wavelength associated with the multiple wavelengths of light passing through the multiple pinholes.

[0015] Due to irregular reflections on the surface of the object being measured, light focused at a position different from the object's surface may sometimes pass through any one of the pinholes. Even in this case, using the structure described above, the intensity of each wavelength related to the multiple light rays passing through multiple pinholes is averaged in the average signal. Therefore, the light component that causes random measurement errors due to irregular reflections is canceled out. As a result, the error in the displacement of the object measured by the confocal displacement gauge can be reduced.

[0016] (2) The confocal displacement meter may include a first optical fiber. The end of the first optical fiber may be the pinhole. The first optical fiber may be the pinhole component. In this case, it is not necessary to arrange the pinhole and the first optical fiber separately. As a result, the structure of the confocal displacement meter can be made compact. The first optical fiber can be used to guide light passing through multiple pinholes to the displacement measuring unit more efficiently. In addition, the degree of freedom in the structure of the optical path used to guide light passing through the pinholes to the displacement measuring unit is increased.

[0017] (3) The light projection section may include: a second optical fiber, which includes one end and another end; a laser light source; and a phosphor disposed at the one end of the second optical fiber and configured to absorb light emitted by the laser light source and emit light having a wavelength different from that emitted by the laser light source, wherein the second optical fiber receives the light emitted by the phosphor from the one end and guides the received light from the other end to the first optical fiber.

[0018] In this configuration, light with multiple wavelengths can be easily generated using a laser source and a phosphor. The generated light can then be efficiently emitted via a second optical fiber and a first optical fiber.

[0019] (4) Multiple first optical fibers can be provided. The ends of the multiple first optical fibers can be the multiple pinholes. In this case, it is not necessary to arrange the multiple pinholes and the multiple first optical fibers separately. As a result, the structure of the confocal displacement meter can be made compact. Light passing through the multiple pinholes can be efficiently guided to the displacement measuring unit via the multiple first optical fibers respectively. In addition, the degree of freedom in the structure of the optical path used to guide the light passing through the multiple pinholes to the displacement measuring unit is increased.

[0020] (5) The displacement measuring unit may include: a combining unit configured to combine multiple lights passing through the plurality of pinholes to generate a combined light; a beam splitting unit configured to split the combined light obtained by the combining unit; a light receiving unit configured to receive the light after it has been split by the beam splitting unit and output an electrical light receiving signal representing the amount of light received at each wavelength related to the light obtained by the combining unit as an average signal; and a calculation unit configured to calculate the displacement of the measured object based on the average signal output from the light receiving unit.

[0021] In this configuration, multiple beams of light passing through multiple pinholes are combined by a combining unit before being received by the light-receiving unit, thereby generating a single composite light. Therefore, the electrical light-receiving signal output from the light-receiving unit, representing the amount of light received at each wavelength, is an average signal obtained by integrating the intensities of each wavelength related to the multiple beams. Using this structure, arithmetic operations for generating the average signal are unnecessary. As a result, the displacement of the object being measured can be calculated quickly and efficiently.

[0022] (6) The combining unit may include a first fiber coupler, a second fiber coupler, a plurality of first fibers, a second fiber, a third fiber, and a fourth fiber. The second fiber is connected to the first fiber coupler to guide the light emitted by the light projection unit to the first fiber coupler. The fourth fiber is connected to the first fiber coupler and the second fiber coupler to transmit light between the first fiber coupler and the second fiber coupler. Each of the plurality of first fibers is connected to the second fiber coupler to guide the light guided to the second fiber coupler by the second fiber and the fourth fiber to the optical component and to guide the light reflected while focused on the surface of the measurement object to the second fiber coupler. The third fiber is connected to the first fiber coupler to guide the light guided to the first fiber coupler by the fourth fiber and the plurality of first fibers to the beam splitter.

[0023] In this configuration, light emitted from the light projection unit is guided to the optical component via a second optical fiber, a first optical fiber coupler, a fourth optical fiber, a second optical fiber coupler, and multiple first optical fibers. As a result, using a simple structure, the light emitted from the light projection unit can be converged and directed onto the object being measured while simultaneously causing chromatic aberration. The light reflected while focused on the surface of the object passes through multiple pinholes. The multiple beams passing through these pinholes are then guided to the beam splitter via multiple first optical fibers, second optical fiber couplers, a fourth optical fiber, a first optical fiber coupler, and a third optical fiber. Therefore, the multiple beams passing through the pinholes are combined into a single beam during the process of being guided to the beam splitter. Consequently, an average signal can be easily generated.

[0024] (7) The combining unit may include an optical fiber coupler, a plurality of first optical fibers, a second optical fiber and a third optical fiber, wherein the second optical fiber is connected to the optical fiber coupler to guide the light emitted by the light projection unit to the optical fiber coupler, each of the plurality of first optical fibers is connected to the optical fiber coupler to guide the light guided by the second optical fiber to the optical fiber coupler to the optical component and to guide the light reflected while being focused on the surface of the measurement object to the optical fiber coupler, and the third optical fiber is connected to the optical fiber coupler to guide the light guided by the plurality of first optical fibers to the optical fiber coupler to the beam splitter.

[0025] In this configuration, light emitted from the light projection section is guided to the optical component via a second optical fiber, an optical fiber coupler, and multiple first optical fibers. As a result, using a simple structure, the light emitted from the light projection section can be converged and directed onto the object being measured while simultaneously causing chromatic aberration. The light reflected while focused on the surface of the object passes through multiple pinholes. The multiple beams passing through the pinholes are then guided to the beam splitter via multiple first optical fibers, an optical fiber coupler, and a third optical fiber. Therefore, the multiple beams passing through the pinholes are combined into a single beam during the process of being guided to the beam splitter. Consequently, an average signal can be easily generated.

[0026] (8) The displacement measuring unit may include: a beam splitter configured to split multiple lights passing through the plurality of pinholes respectively; a light receiving unit configured to receive the multiple lights after being split by the beam splitter respectively, and output multiple electrical light receiving signals representing the amount of light received at each wavelength related to each of the multiple lights passing through the plurality of pinholes; and a calculation unit configured to average or integrate the multiple light receiving signals output from the light receiving unit for each wavelength, thereby calculating an average signal as the signal intensity at each wavelength, and calculating the displacement of the measured object based on the calculated average signal.

[0027] In this configuration, the light-receiving unit outputs multiple light-receiving signals, each corresponding to a different light beam passing through multiple pinholes. The calculation unit averages or integrates these multiple light-receiving signals for each wavelength, thereby calculating an average signal. Using this structure, the calculation of the average signal can take into account the desired averaging or integration of the intensities of multiple light beams. As a result, the displacement of the object being measured can be calculated more accurately.

[0028] (9) The displacement measuring unit may include: a synthesis unit configured to partially synthesize multiple lights passing through the plurality of pinholes, thereby generating multiple synthesized lights; a beam splitting unit configured to split the multiple synthesized lights synthesized by the synthesis unit; a light receiving unit configured to receive the multiple lights after being split by the beam splitting unit, and output multiple electrical light receiving signals representing the amount of light received at each wavelength related to each of the multiple lights passing through the plurality of pinholes; and a calculation unit configured to average or integrate the multiple light receiving signals output from the light receiving unit for each wavelength, thereby calculating an average signal as the signal intensity at each wavelength, and calculating the displacement of the measured object based on the calculated average signal.

[0029] In this configuration, multiple beams of light passing through multiple pinholes are partially combined by a combining unit before being received by the light-receiving unit, thereby generating multiple composite beams. The light-receiving unit outputs multiple light-receiving signals, each corresponding to one of the composite beams. The multiple light-receiving signals output from the light-receiving unit are averaged or integrated for each wavelength, thereby calculating an average signal. Using this structure, the calculation of the average signal can be performed with a desired average or integration considering the intensity of the multiple composite beams. As a result, the displacement of the object being measured can be calculated more accurately.

[0030] (10) The displacement measuring unit may include: a switching unit configured to switch the illumination and non-illumination of the light converged by the optical component onto the measuring object, such that multiple lights sequentially illuminate the measuring object; a beam splitting unit configured to split the multiple lights separately after the switching unit illuminates the measuring object with the multiple lights that sequentially pass through the multiple pinholes; a light receiving unit configured to receive the multiple lights after they have been split by the beam splitting unit within a single exposure time period, and output an electrical light receiving signal representing the amount of light received at each wavelength related to the received light as an average signal; and a calculation unit configured to calculate the displacement of the measuring object based on the average signal output from the light receiving unit.

[0031] In this configuration, the light-receiving unit receives multiple beams of light sequentially passing through multiple pinholes within a single exposure time period. Therefore, the electrical light-receiving signal output from the light-receiving unit, representing the amount of light received at each wavelength, is an average signal obtained by integrating the intensities of each wavelength related to the multiple beams of light. Using this structure, arithmetic operations for generating the average signal are unnecessary. As a result, the displacement of the object being measured can be calculated efficiently.

[0032] (11) The displacement measuring unit may include: a switching unit configured to switch the illumination and non-illumination of the light converged by the optical component onto the measuring object, such that multiple lights sequentially illuminate the measuring object; a beam splitting unit configured to split the multiple lights after the multiple lights sequentially passing through the multiple pinholes illuminate the measuring object using the switching unit; a light receiving unit configured to receive the multiple lights after they have been split by the beam splitting unit, and output multiple electrical light receiving signals representing the amount of light received at each wavelength related to each of the multiple lights passing through the multiple pinholes; and a calculation unit configured to average or integrate the multiple light receiving signals output from the light receiving unit for each wavelength, thereby calculating an average signal as the signal intensity at each wavelength, and calculating the displacement of the measuring object based on the calculated average signal.

[0033] In this configuration, the light-receiving unit outputs multiple light-receiving signals, each corresponding to a different light beam that sequentially passes through multiple pinholes. The calculation unit averages or integrates these multiple light-receiving signals for each wavelength, thereby calculating an average signal. Using this structure, the calculation of the average signal can take into account the desired averaging or integration of the intensities of multiple light beams. As a result, the displacement of the object being measured can be calculated more accurately.

[0034] (12) The first optical fiber can be configured to guide the light emitted by the light projection section to the optical component. In this case, the light emitted by the light projection section can be guided to the optical component more efficiently using the first optical fiber. This increases the degree of freedom in the structure of the optical path used to guide the light emitted by the light projection section to the optical component.

[0035] (13) The confocal displacement meter may further include: a processing device; and a head, wherein the processing device includes the light projection part, the beam splitter, the light receiving part and the calculation part, and further includes a first housing configured to accommodate the light projection part, the beam splitter, the light receiving part and the calculation part, and the head includes the optical component, and further includes a second housing configured to accommodate the optical component.

[0036] In this configuration, the processing unit, including the light projection section, beam splitting section, light receiving section, and calculation section, is separated from the head, which includes optical components. Therefore, it is easier to use a head that includes optical components that generate appropriate chromatic aberrations based on the shape or arrangement of the object being measured, or that has an appropriate focal length. As a result, the displacement of the object being measured can be measured more easily.

[0037] (14) A pinhole at the end of the first optical fiber can be provided in the head, and the first optical fiber can be arranged to guide light from the head to the processing device. In this case, the processing device can be separated from the head, while only the head can be placed in various environments where the object to be measured is placed.

[0038] (15) The plurality of pinholes can be arranged side by side in a plane that intersects the optical path.

[0039] In this configuration, multiple pinholes allow light reflected from different parts of the object's surface to pass through. Therefore, the component of light that introduces random measurement errors due to irregular reflections on the object's surface is more definitively canceled out in the average signal. Consequently, the error in the displacement of the object measured by the confocal displacement gauge can be further reduced.

[0040] (16) The plurality of pinholes can be arranged such that multiple rays of light, which are reflected while focused on multiple portions of the surface of the object being measured, can pass through. In this case, the components of light that produce random measurement errors due to irregular reflections on the surface of the object being measured are more definitively canceled in the average signal. As a result, the error in the displacement of the object being measured by the confocal displacement meter can be further reduced.

[0041] (17) The light projection unit may include: a light source configured to emit light having a single wavelength; and a phosphor configured to absorb the light emitted by the light source and emit light having a wavelength different from that emitted by the light source. In this case, light having multiple wavelengths can be easily generated.

[0042] (18) The confocal displacement meter according to the present invention is a confocal displacement meter for measuring the displacement of a measurement object within a measurement range using a confocal optical system. The confocal displacement meter includes: a head having a first housing, an optical component, and a plurality of pinholes disposed within the first housing and corresponding to the confocal optical system; the optical component disposed within the first housing having a lens that generates chromatic aberration along the axial direction and focuses light passing through the plurality of pinholes at different positions along the optical axis of the measurement range according to the wavelength of the light; an optical fiber unit having a plurality of optical fibers having an end corresponding to the plurality of pinholes of the head; and a processing unit mechanically and optically coupled to the head via the optical fiber unit, wherein the processing unit has: a second housing; and a light projection unit disposed within the second housing. The device contains a light projection unit that emits light of multiple wavelengths. The light is guided through the optical fiber unit to a plurality of pinholes located on the head, and then irradiates the object to be measured within the measurement range from the pinholes. A beam splitter, disposed within the second housing, receives input light reflected from the object via the pinholes and the optical fiber unit, and splits the light from the optical fiber unit according to each wavelength. A light receiving unit, disposed within the second housing, receives the input light after it has been split by the beam splitter, and outputs the input light as an electrical signal. A calculation unit, disposed within the second housing, receives the input electrical signal and calculates the displacement of the object based on the signal intensity of each wavelength of an average signal, wherein the average signal corresponds to the average intensity of each wavelength associated with the light passing through each optical fiber.

[0043] The effects of the invention

[0044] According to the present invention, the measurement error of the object being measured can be reduced. Attached Figure Description

[0045] Figure 1 This is a schematic diagram showing the structure of a confocal displacement meter according to a first embodiment of the present invention.

[0046] Figure 2 This diagram illustrates the operating principle of a confocal displacement meter.

[0047] Figure 3 This is a cross-sectional view showing the arrangement of the optical fibers in the optical fiber unit.

[0048] Figure 4 It is a graph showing the relationship between the wavelength of the light received by the light-receiving part and the intensity of the light signal.

[0049] Figure 5 These are plan and cross-sectional views showing the structure of the light projection section.

[0050] Figure 6 This is a schematic diagram illustrating an example of light reflected in a part different from the object being measured.

[0051] Figure 7 It is a diagram showing the received light waveform that includes unnecessary components.

[0052] Figure 8 This is a diagram showing the basic waveform of the received light waveform.

[0053] Figure 9 This is a diagram showing the received waveform after the basic waveform has been removed.

[0054] Figure 10 It is a diagram showing the path of light guided to the light-receiving part.

[0055] Figure 11 It shows that you are being guided to Figure 10 The diagram shows the light waveform of the light-receiving part.

[0056] Figure 12 This is a diagram showing an example of a display device for a control device in its initial state.

[0057] Figure 13 It is shown in Figure 12 The first display area shown is a diagram of an example of the measurement results.

[0058] Figure 14 It is shown in Figure 12 A diagram showing an example of the light-receiving waveform displayed in the first display area.

[0059] Figure 15 It is shown in Figure 12 The diagram shows an example of an input screen for settings information displayed in the first display area.

[0060] Figure 16 This demonstrates the confirmation process through light reception. Figure 12 The diagram shows an example of the change information displayed in the first display area.

[0061] Figure 17 This demonstrates the confirmation process through light reception. Figure 12 The diagram shows an example of the change information displayed in the first display area.

[0062] Figure 18 This demonstrates the confirmation process through light reception. Figure 12 The diagram shows an example of the change information displayed in the first display area.

[0063] Figure 19 This demonstrates the confirmation process through light reception. Figure 12The diagram shows an example of the change information displayed in the first display area.

[0064] Figure 20 This demonstrates the confirmation process through light reception. Figure 12 The diagram shows an example of the change information displayed in the first display area.

[0065] Figure 21 This demonstrates the confirmation process through light reception. Figure 12 The diagram shows an example of the change information displayed in the first display area.

[0066] Figure 22 This is a flowchart used to illustrate the displacement measurement process.

[0067] Figure 23 It is used for explanation Figure 22 The flowchart shown is for the light reception confirmation process.

[0068] Figure 24 It is used for explanation Figure 22 The flowchart shown is for the light reception confirmation process.

[0069] Figure 25 This is a diagram showing a first modified example of the light guide section.

[0070] Figure 26 This is a diagram showing a second modified example of the light guide section.

[0071] Figure 27 This is a diagram showing a third modified example of the light guide section.

[0072] Figure 28 The diagram shows the first to fourth modified examples of the lens unit.

[0073] Figure 29 This is a diagram showing a modified example of the light projection section.

[0074] Figure 30 This is a diagram showing a modified example of the beam splitter.

[0075] Figure 31 This is a schematic diagram illustrating the structure of a confocal displacement meter according to a second embodiment of the present invention.

[0076] Figure 32 It is shown Figure 31 The diagram shows the structure of the beam splitter.

[0077] Figure 33 It is shown Figure 32 The diagram shows the light-receiving part and the light-receiving waveform.

[0078] Figure 34 This is a schematic diagram showing the structure of a confocal displacement meter according to a first modified example of the second embodiment.

[0079] Figure 35 This is a schematic diagram showing the structure of a confocal displacement meter according to a second variation of the second embodiment.

[0080] Figure 36 This is a schematic diagram showing the structure of a confocal displacement meter according to a third embodiment of the present invention.

[0081] Figure 37 This is a diagram showing the received light waveform obtained by the processing unit.

[0082] Figure 38 This is a schematic diagram illustrating the structure of a confocal displacement meter according to other embodiments.

[0083] Figure 39 It is shown in Figure 12 The diagram shows another example of a settings information input screen displayed in the first display area.

[0084] Figure 40 This demonstrates the confirmation process via light reception when the user has set a threshold ratio. Figure 12 The diagram shows an example of the change information displayed in the first display area.

[0085] Explanation of reference numerals in the attached figures

[0086] 100 processing device

[0087] 110,210 Housing

[0088] 120 Light Projection Unit

[0089] 121 Light Source

[0090] 122 fluorescent cells

[0091] 123 Ring Toss

[0092] Lenses 124, 128, 132, 133

[0093] 125 retainer

[0094] 126 Filter Components

[0095] 127 Component Retainer

[0096] 127A Light Source Fixing Part

[0097] 127B Ring Fixing Part

[0098] 127C Lens Mounting Part

[0099] 129 Reflecting component

[0100] 130,130A~130D spectrometer

[0101] 131 Diffraction Grating

[0102] Light-receiving section 140, 140A~140D

[0103] Areas receiving light: 141–144

[0104] 150 Computing and Processing Unit

[0105] 151 Storage Department

[0106] 152 Control Department

[0107] 160 Display Section

[0108] 200 measuring heads

[0109] 220 lens unit

[0110] 221 Refractive Lens

[0111] 222 Diffraction Lens

[0112] 223 Objective Lens

[0113] 224 Flat Panel Lens

[0114] 300 Light Guide Section

[0115] 301 Fiber Optic Unit

[0116] 302 Retaining Component

[0117] 310a core

[0118] 310b cladding

[0119] Fiber optic cables 311~318, 311A~311D, 312A~312D

[0120] 320, 330, 340, 350 fiber optic couplers

[0121] Ports 321-324, 331-336, 341-343, 351-355, 361-366

[0122] 325, 337, 344, 356, 367 Main body

[0123] 360° light switch

[0124] 371 Semi-transparent and semi-reflective mirror

[0125] 372,373 Spatial Filters

[0126] 372a, 373a pinhole

[0127] 400 control device

[0128] 401 Display Device

[0129] 402 Operations Department

[0130] 403 CPU (Central Processing Unit)

[0131] 404 memory

[0132] 410 First display area

[0133] 450 Second display area

[0134] 451 Light Receiving Confirmation Button

[0135] 452 Confirm Settings Button

[0136] 453 Confirm End Button

[0137] 454 Measurement Start Button

[0138] Input fields 461, 462

[0139] 463,464 Display format buttons

[0140] 491 Toggle Button

[0141] 500 confocal displacement meter

[0142] BL basic waveform

[0143] L1 diameter

[0144] L2 distance

[0145] MR measurement range

[0146] P0,Px~Pz peaks

[0147] P1, P2 focus positions

[0148] RP reference position

[0149] S Measurement object

[0150] W0~W4 received light waveform

[0151] Peak wavelengths λ0~λ4, λx, λy Detailed Implementation

[0152] [1] First embodiment

[0153] (1) Basic structure of confocal displacement gauge

[0154] The confocal displacement meter according to the first embodiment of the present invention will be described below with reference to the accompanying drawings. Figure 1 This is a schematic diagram illustrating the structure of a confocal displacement meter according to a first embodiment of the present invention. Figure 1 As shown, the confocal displacement meter 500 includes a processing unit 100, a measuring head 200, a light guide 300, and a control unit 400. The light guide 300 includes a plurality of optical fibers and optically connects the processing unit 100 and the measuring head 200.

[0155] The processing device 100 includes a housing 110, a light projection section 120, a beam splitter 130, a light receiver 140, a processing unit 150, and a display unit 160. The housing 110 houses the light projection section 120, the beam splitter 130, the light receiver 140, and the processing unit 150. The light projection section 120 is configured to emit light with a wide wavelength band (e.g., 500 nm to 700 nm), i.e., light with multiple wavelengths. The detailed structure of the light projection section 120 is described below. The light emitted by the light projection section 120 is input to the optical fiber 311 of the light guide section 300, as described below.

[0156] The beam splitter 130 includes a diffraction grating 131 and a plurality of lenses (two in this example) 132 and 133. As described below, a portion of the light emitted by the light projection section 120 and reflected on the surface of the measurement object S is output from the optical fiber 312 of the light guide section 300. The light output from the optical fiber 312 passes through the lens 132, thereby being substantially collimated and incident on the diffraction grating 131. In this embodiment, the diffraction grating 131 is a reflective diffraction grating. The light incident on the diffraction grating 131 is split to be reflected at different angles for each wavelength and passes through the lens 133, thereby being focused at a position in one dimension that is different for each wavelength.

[0157] The light-receiving unit 140 includes a plurality of pixels arranged in a one-dimensional image sensor (one-dimensional line sensor). The image sensor can be a multi-segment PD (photodiode), CCD (charge-coupled device) camera, or CMOS (complementary metal-oxide-semiconductor) image sensor, or other components. The light-receiving unit 140 is arranged such that the plurality of pixels of the image sensor receive light at multiple focusing positions different for each wavelength, formed by the lens 133 of the beam splitter 130. An analog electrical signal (hereinafter referred to as a light-receiving signal) corresponding to the amount of light received is output from the pixels of the light-receiving unit 140.

[0158] The processing unit 150 includes a storage unit 151 and a control unit 152. The storage unit 151 includes, for example, a ROM (Read-Only Memory), RAM (Random Access Memory), or a hard disk. The storage unit 151 stores the displacement measurement program and various data used for displacement measurement. The control unit 152 includes, for example, a CPU (Central Processing Unit). The control unit 152 acquires the light signal output by the light receiving unit 140 and performs displacement measurement processing for the measurement object S based on the displacement measurement program and data stored in the storage unit 151.

[0159] The measuring head 200 includes a housing 210 having a generally axisymmetric shape (e.g., cylindrical shape) and a lens unit 220. The housing 210 houses the lens unit 220. The lens unit 220 includes a refractive lens 221, a diffractive lens 222, and an objective lens 223. Light from the processing device 100, output from the light guide 300, passes sequentially through the refractive lens 221 and the diffractive lens 222. As a result, chromatic aberration is produced along the optical axis. The objective lens 223 is arranged such that the light producing chromatic aberration can be focused onto a position near the surface of the object being measured, S.

[0160] The light guide section 300 includes multiple (eight in this example) optical fibers 311-318 and multiple (two in this example) optical fiber couplers 320 and 330. Figure 1 In the example shown, fiber optic coupler 320 is disposed in housing 110 of processing device 100, and fiber optic coupler 330 is disposed in housing 210 of measuring head 200. The invention is not limited thereto. Fiber optic coupler 320 may be disposed in a portion other than housing 110 of processing device 100. Fiber optic coupler 330 may be disposed in a portion other than housing 210 of measuring head 200.

[0161] The fiber optic coupler 320 has a so-called 2×2 type structure. The fiber optic coupler 320 includes four ports 321-324 and a main body 325. Ports 321 and 322, and ports 323 and 324, are connected to the main body 325 in a manner opposite to each other across the main body 325. Light input to at least one of ports 321 and 322 is output from each of ports 323 and 324. Light input to at least one of ports 323 and 324 is output from each of ports 321 and 322.

[0162] The fiber optic coupler 330 has a so-called 2×4 type structure. The fiber optic coupler 330 includes six ports 331-336 and a main body 337. Ports 331 and 332, and ports 333-336, are connected to the main body 337 in a manner opposite to each other across the main body 337. Light input to at least one of ports 331 and 332 is output from each of the ports 333-336. Light input to at least one of ports 333-336 is output from each of the ports 331 and 332.

[0163] Fiber optic cables 311 and 312 are connected to ports 321 and 322 of fiber optic coupler 320, respectively. Fiber optic cables 313 to 316 are connected to ports 333 to 336 of fiber optic coupler 330, respectively. Port 323 of fiber optic coupler 320 and port 331 of fiber optic coupler 330 are connected via fiber optic cable 317. Port 324 of fiber optic coupler 320 and port 332 of fiber optic coupler 330 are connected via fiber optic cable 318.

[0164] Using this structure, the light emitted by the light projection unit 120 of the processing device 100 is input to port 321 of the fiber optic coupler 320 via optical fiber 311. The light input to port 321 is output from ports 323 and 324, and is input to ports 331 and 332 of the fiber optic coupler 330 via optical fibers 317 and 318. The light input to ports 331 and 332 is output from ports 333 to 336, and is irradiated onto the measurement object S via optical fibers 313 to 316 and lens unit 220.

[0165] A portion of the light reflected from the surface of the object being measured, S, is input to ports 333-336 of the fiber optic coupler 330 via lens unit 220 and optical fibers 313-316. The light input to ports 333-336 is output from ports 331 and 332, and is input to ports 323 and 324 of the fiber optic coupler 320 via optical fibers 317 and 318. The light input to ports 323 and 324 is output from ports 321 and 322. The light output from port 322 is guided to the beam splitter 130 via optical fiber 312. As a result, displacement measurement processing is performed.

[0166] The display unit 160 includes an indicator such as a seven-segment indicator or a dot matrix indicator. The display unit 160 is disposed in the housing 110 of the processing device 100 and connected to the arithmetic processing unit 150. Values ​​such as the measured distance calculated by the displacement measurement processing of the arithmetic processing unit 150 are displayed on the display unit 160.

[0167] The control device 400 is configured as, for example, a personal computer and is connected to the arithmetic processing unit 150 of the processing device 100. The control device 400 includes a display device 401, an operation unit 402, a CPU (central processing unit) 403, and a memory 404. The display device 401 includes, for example, a liquid crystal display panel or an organic EL (electroluminescent) panel. In addition to displaying numerical values ​​such as the measurement distance calculated by the displacement measurement processing of the arithmetic processing unit 150, the display device 401 can also display values ​​used in the following description. Figure 4 The solid line shown represents the waveform of the light-receiving signal (light-receiving waveform W0). The operation unit 402 includes indicating devices such as a mouse and a keyboard.

[0168] CPU 403 is configured to operate in the measurement mode and verification mode described below. A reference range for determining pass / fail status of the measurement distance for the measured object S can be set in CPU 403. In this case, if the measurement distance is within the reference range, a judgment result indicating that the measured object S is a non-defective product (e.g., "OK") is displayed on display device 401. On the other hand, if the measurement distance is outside the reference range, a judgment result indicating that the measured object S is a defective product (e.g., "NG") is displayed on display device 401. The displacement measurement program and various data used for displacement measurement are stored in memory 404.

[0169] (2) Operating principle of confocal displacement gauge

[0170] Figure 2 This diagram illustrates the operating principle of the confocal displacement meter 500. In the following description, to facilitate understanding of the operating principle of the confocal displacement meter 500 according to this embodiment, the operating principle of a general confocal displacement meter will first be explained using light output from an optical fiber (optical fiber 313 in this example) to the measuring head 200.

[0171] Light output from fiber optic 313 passes through refractive lens 221 and diffractive lens 222. This results in chromatic aberration. The chromatic aberration-affected light passes through objective lens 223, whereby it is focused at different positions for each wavelength. For example, light with shorter wavelengths is focused closer to objective lens 223, while light with longer wavelengths is focused further away. The range between the closest focusing position P1 to objective lens 223 and the farthest focusing position P2 is the measurement range MR. In this example, refractive lens 221 has a convex shape, while diffractive lens 222 has a concave shape. In this case, the chromatic aberration is increased. Consequently, the measurement range MR can be increased.

[0172] When the surface of the object being measured, S, is present within the measurement range MR, light passing through objective lens 223 illuminates the surface of the object being measured, and is then reflected by that surface into a wide range. As described below, optical fiber 313 includes a core 310a and a cladding 310b (refer to the description below). Figure 3 In this embodiment, the end portion of the optical fiber 313 functions as a spatial filter including a very small pinhole. Therefore, most of the light reflected from the surface of the object being measured S is not input to the optical fiber 313.

[0173] On the other hand, light of a specific wavelength, focused on the surface of the object being measured S, is reflected from the surface and passes through the lens unit 220, thus being input to the end portion of the core 310a of the optical fiber 313. The wavelength of the light input to the optical fiber 313 represents the measurement distance. The measurement distance is the distance from a predetermined reference position RP to the position on the surface of the object being measured S. Note that in this example, the reference position RP is the position of the end portion of the housing 210 closest to the object being measured S.

[0174] The light input to fiber optic 313 is guided to Figure 1 The processing device 100 shown has its light split by a diffraction grating 131 and focused by a lens 133 at different positions for each wavelength. Multiple pixels of the light-receiving unit 140 are respectively arranged at the focusing positions of multiple lights, each with a different wavelength. Therefore, the pixels of the light-receiving unit 140 receive light having wavelengths associated with those pixels and output a light-receiving signal.

[0175] Using this structure, the wavelength of the received light can be specified by specifying the position of the pixel in the light-receiving section 140 that outputs the light-receiving signal. The measurement distance can be specified by specifying the wavelength of the received light. The operating principle of a typical confocal displacement meter is as described above. However, due to the irregular reflection of light on the surface of the object being measured S, light focused at a position different from the position on the surface of the object being measured S is sometimes input to the optical fiber 313. In this case, a measurement error occurs at the measurement distance specified by the processing device 100 that is greater than the surface roughness of the object being measured S.

[0176] Therefore, in the confocal displacement meter 500 according to this embodiment, the light input from the processing device 100 is output from each of the four optical fibers 313 to 316. The four optical fibers 313 to 316 are integrally configured as an optical fiber unit. Figure 3 This is a cross-sectional view showing the arrangement of optical fibers 313 to 316 in this optical fiber unit. For example... Figure 3 As shown, in the fiber unit 301, four optical fibers 313 to 316 are integrally held by the holding member 302.

[0177] Optical fibers 313-316 include a core 310a and a cladding 310b. The core 310a is covered by the cladding 310b. Light input to one end of the core 310a in optical fibers 313-316 is output from the other ends of the core 310a. Note that optical fibers 311, 312, 317, and 318 have the same structure as optical fibers 313-316.

[0178] At the center of fiber optic unit 301 and Figure 2 With the centers of the lens units 220 shown approximately aligned, the optical fibers of the fiber unit 301 are ideally arranged symmetrically with respect to the optical axis of the lens units 220. Figure 3 In the example shown, the center of the fiber optic unit 301 is arranged on the optical axis of the optical system 220. The cores 310a (optical axes) of the fibers 313-316 are arranged symmetrically with respect to the optical axis of the lens unit 220. In this case, the cores 310a (optical axes) of the fibers 313-316 are separated from the center of the fiber optic unit 301 (i.e., the optical axis of the lens unit 220) by approximately the same distance.

[0179] Thus, the core 310a of optical fibers 313-316 is arranged at a position approximately equidistant from the optical axis of lens unit 220. Therefore, the optical design of lens unit 220 for inducing aberrations along the optical axis can be readily performed. The optical axis not only means that the optical axes of refractive lens 221, diffractive lens 222, and objective lens 223 are approximately aligned with each other, but it can also mean the optical axis of any one or more of the refractive lens 221, diffractive lens 222, and objective lens 223.

[0180] The light output from optical fibers 314-316 exhibits the same behavior as the light output from optical fiber 313 described above. Therefore, this light is projected from the measuring head 200 onto four portions of the surface of the object being measured, S. Figure 3 In the example shown, optical fibers 313-316 are arranged at the four corners of a square. The diameter L1 of core 310a is preferably 200 μm or less, and more preferably 50 μm or less. In this case, since the four optical fibers 313-316 are arranged close to each other, it appears to the user as if light is shining on a portion of the surface of the object being measured, S.

[0181] Of the light reflected from the four portions of the surface of the object being measured, the light focused on a specific portion of the surface is input to the optical fibers 313-316 corresponding to that portion and received by the light-receiving unit 140. The distance L2 between the centers of adjacent cores 310a is ideally more than three times the diameter L1. In this case, with a distance L2 more than three times the diameter L1, the light reflected while focused on a specific portion of the surface of the object being measured passes through the pinholes of the optical fibers 313-316 corresponding to that portion. This light passes almost unaffected by interference from the pinholes of the other optical fibers 313-316 not corresponding to that portion.

[0182] The distance L2 between the centers of adjacent cores 310a is preferably more than five times but less than ten times the diameter L1. In this case, with a distance L2 that is more than five times but less than ten times the diameter L1, it further prevents light reflected while focused on a portion of the surface of the object being measured S from passing through other pinholes that do not correspond to that portion as interfering light. Since the multiple beams do not significantly separate, they can pass through the vicinity of the center of the lens unit 220. Therefore, aberrations that reduce measurement accuracy, such as cometary aberrations, are almost non-existent. In this example, the diameter L1 is, for example, 50 μm, and the distance L2 is, for example, 250 μm.

[0183] Figure 4 It is a graph showing the relationship between the wavelength of the light received by the light receiving unit 140 and the intensity of the light signal. Figure 4 The horizontal axis represents the wavelength of the received light, and the vertical axis represents the intensity of the received light signal. This also applies to the following description. Figures 7-9 . Figure 4 and the following Figures 7-9 The horizontal axis is equivalent to the position of the pixel in the light-receiving part 140.

[0184] exist Figure 4 In the hypothetical separation state, dotted lines, dashed lines, double-dotted lines, and dashed lines are used to represent the waveforms (hereinafter referred to as received waveforms) W1 to W4 of the light received signals input to optical fibers 313 to 316, respectively. The peak wavelengths (hereinafter referred to as peak wavelengths) of the received waveforms W1 to W4 are λ1 to λ4, respectively. The peak wavelengths λ1 to λ4 of the multiple received waveforms W1 to W4 are different from each other due to the irregular reflections on the surface of the measurement object S.

[0185] However, in reality, the light input to optical fibers 313-316 is mixed until it is output from optical fiber 312. As a result, the light output from optical fiber 312 undergoes intensity averaging. This averaging process refers to the process used to generate an average signal that corresponds to the average intensity of each wavelength associated with multiple wavelengths of light passing through multiple pinholes. In this example, the averaging process is an integration process.

[0186] In this example, the optical signals passing through the pinhole are mixed as they pass through fiber couplers 330, 317 and 318, fiber coupler 320, and 312. The mixed optical signals are then converted into electrical signals by the light-receiving unit 140 via the beam splitter 130. That is, in this example, averaging is performed on the optical signals. Figure 4 In the diagram, a solid line represents the received light waveform W0 corresponding to the slightly delayed light received by the light-receiving unit 140. The peak wavelength of the received light waveform W0 is λ0.

[0187] This optical averaging of the received waveform W0 eliminates light components that cause random measurement errors due to irregular reflections. Therefore, the peak wavelength λ0 is closer to the peak wavelength corresponding to the actual measurement distance than peak wavelengths λ1 to λ4. The actual measurement distance is the distance that should be specified when there are no irregular reflections of light. Therefore, the measurement distance can be specified more accurately by specifying the peak wavelength λ0 of the received waveform W0.

[0188] (3) Light projection section

[0189] Figure 5 (a) and (b) are a plan view and a cross-sectional view, respectively, showing the structure of the light projection section 120. Figure 5 As shown, the light projection unit 120 includes a light source 121, a phosphor 122, a collar 123, a lens 124, a holder 125, a filter element 126, and an element holder 127. The element holder 127 includes a light source fixing part 127A, a collar fixing part 127B, and a lens fixing part 127C. The light source 121, the collar 123, and the lens 124 are respectively fixed to the light source fixing part 127A, the collar fixing part 127B, and the lens fixing part 127C of the element holder 127.

[0190] Light source 121 is a laser light source that emits light with a single wavelength. In this embodiment, light source 121 emits light in the blue or ultraviolet region with a wavelength below 450 nm. Phosphor 122 absorbs the excitation light in the blue or ultraviolet region and emits fluorescence in a wavelength region different from that of the excitation light. Phosphor 122 may emit fluorescence in the yellow region, the green region, or the red region. Phosphor 122 may be configured from multiple fluorescent components.

[0191] Ring 123 Keep Figure 1 The light guide 300 shown is located at the end of the optical fiber 311. A lens 124 is arranged between the light source 121 and the ferrule 123. One end face of a ring-shaped retainer 125 is attached to the end of the ferrule 123 (optical fiber 311). A phosphor 122 is housed in the inner periphery of the retainer 125. A filter element 126 is attached to the other end face of the retainer 125 to cover the phosphor 122 in the retainer 125. The filter element 126 is a reflective filter. The filter element 126 reflects light from the yellow, green, or red regions and allows light from the blue or ultraviolet regions to pass through.

[0192] Using this structure, light emitted from light source 121 passes through lens 124, thereby focusing as excitation light onto phosphor 122. Phosphor 122 absorbs the excitation light and emits fluorescence. The excitation light that passes through phosphor 122 but is not absorbed by phosphor 122 mixes with the fluorescence emitted from phosphor 122, thereby generating broadband light. In this example, to generate the light obtained by mixing excitation light and fluorescence in a desired ratio, the thickness of phosphor 122 in the optical path direction is set to, for example, 10 μm to 200 μm. The concentration of phosphor 122 in holder 125 is set to, for example, 30% to 60%.

[0193] The light generated in the light projection section 120 passes through the ferrule 123 and is thus input into the optical fiber 311. The fluorescence emitted by the phosphor 122 in the opposite direction to the optical fiber 311 is reflected by the filter element 126 back into the direction of the optical fiber 311. As a result, fluorescence can be efficiently input into the optical fiber 311.

[0194] In this example, phosphor 122 is housed in retainer 125. However, the invention is not limited thereto. Phosphor 122 can be coated onto the end face of collar 123. In this case, light projection section 120 does not include retainer 125. Light projection section 120 has filter element 126. However, the invention is not limited thereto. If sufficient fluorescence is input to optical fiber 311, light projection section 120 may not include filter element 126.

[0195] (4) Computation and processing unit

[0196] exist Figure 1 The storage unit 151 of the processing unit 150 shows that the positions of the pixels of the light-receiving unit 140, the peak wavelength λ0 of the output light-receiving waveform W0, and the conversion formula for the measurement distance are pre-stored. The control unit 152 of the processing unit 150 specifies the position of the pixel outputting the light-receiving signal, and sequentially calculates the peak wavelength λ0 of the light-receiving waveform W0 and the measurement distance based on the specified pixel position and the conversion formula stored in the storage unit 151. As a result, the thickness, distance, or displacement of the object to be measured S can be measured. The control unit 152 performs basic waveform removal and temperature characteristic correction of the light-receiving unit 140 to calculate the measurement distance more accurately.

[0197] (a) Removal of the basic waveform

[0198] Light reflected from a part that is different from the object being measured, S, is sometimes received by the light-receiving part 140. Figure 6 This is a schematic diagram illustrating an example of light reflected from a portion different from the measured object S. Figure 6 In the example shown, light directly reflected by the refracting lens 221 of the lens unit 220 (the light indicated by the arrow) is input into optical fibers 313-316. Such light does not contain a component representing the measured distance, but contains unnecessary components.

[0199] Figure 7 This is a diagram showing the received light waveform W0, which includes unwanted components. (See diagram for example.) Figure 7 As shown, the received light waveform W0 includes three peaks: P0, Px, and Py. Peak P0 is generated by light reflected from the surface of the object being measured, S. Peak P0 has a steep shape and a wavelength of λ0. Peak Px is generated by light reflected from a portion of the object being measured, different from the object S. Peak Px has a smooth shape and a wavelength of λx.

[0200] Peak Py is a light source with an oscillating wavelength λy reflected from a portion different from the measured object S. Figure 5 The light emitted by (b) is produced. Peak Py has a steep shape. The peak wavelength is λy. Note that in this example, the intensity of the excitation light emitted by light source 121, which is the laser source, is high. Therefore, light with the same wavelength component as the excitation light is not used as the measurement light.

[0201] The peak wavelength λx is relatively close to the peak wavelength λ0. Peak Px is wide. Therefore, peak P0 is buried within peak Px. In this case, it is difficult to accurately specify the peak wavelength λ0. Therefore, a correction is performed to remove the portion (hereinafter referred to as the fundamental waveform BL) caused by peak Px from the received waveform W0.

[0202] Figure 8This is a diagram showing the basic waveform BL of the received waveform W0. In this embodiment, the control unit 152 applies low-pass filtering processing for identifying peaks Px and P0 to the received waveform W0, thereby obtaining... Figure 8 The basic waveform BL is shown. The methods for obtaining the basic waveform BL are not limited to those described above. Data representing the basic waveform BL can be pre-stored... Figure 1 In the storage unit 151 shown. In this case, the control unit 152 is based on the acquired... Figure 8 The basic waveform BL shown is used to correct the received waveform W0, so as to transform the basic waveform BL from... Figure 7 Removed from the light-receiving waveform W0 shown.

[0203] Figure 9 This is a diagram showing the received waveform W0 after removing the basic waveform BL. Figure 9 In the example shown, the peak wavelength λ0 and Figure 7 The peak wavelength λ0 shown is slightly shifted towards the shorter wavelength side. Thus, by removing the base waveform BL from the received waveform W0, the peak wavelength λ0 can be specified more accurately. Consequently, the measurement distance can be calculated more accurately. Note that the portion resulting from the peak Py of the received waveform W0 does not affect the correct specification of the peak wavelength λ0. Therefore, this portion is not removed from the received waveform W0. The invention is not limited thereto. Processing for removing the portion resulting from the peak Py from the received waveform W0 can be performed.

[0204] (b) Correction of the temperature characteristics of the light-receiving part

[0205] As described above, light with a specific wavelength is received by a pixel of the light-receiving section 140 associated with that wavelength. However, due to changes in the position or tilt of the light-receiving surface of the light-receiving section 140 caused by ambient temperature variations, light with a specific wavelength may sometimes be received by a pixel different from the pixel associated with that wavelength. In this case, the measurement distance cannot be accurately calculated. Therefore, temperature characteristics correction of the light-receiving section 140 is performed as described below.

[0206] Figure 10 This is a diagram showing the path of light guided to the light-receiving part 140. (As shown) Figure 10 As shown, in addition to the first-order light obtained by the diffraction grating 131, the zero-order light, which is orthogonally reflected by the diffraction grating 131, is also guided to the light-receiving part 140. Figure 10 In the diagram, solid lines represent first-order light, and dashed lines represent zero-order light. Zero-order light is not used for distance calculations.

[0207] Figure 11 It shows that you are being guided to Figure 10 The diagram shows the light-receiving waveform W0 of the light-receiving part 140. Figure 11The horizontal axis represents the position of the pixels in the light-receiving section 140, and the vertical axis represents the intensity of the light signal. For example... Figure 11 As shown, the received waveform W0 includes a portion corresponding to the first-order light and a portion corresponding to the zero-order light. Figure 7 The received waveform W0 shown is the same. The portion of the received waveform W0 corresponding to the first-order light includes three peaks P0, Px, and Py. The portion of the received waveform W0 corresponding to the zero-order light includes one peak Pz.

[0208] exist Figure 1 In the storage unit 151 shown, the position of the pixel where the center of at least one of peaks Px, Py, and Pz should appear is pre-stored as a reference position. The control unit 152 specifies the positions of peaks Px to Pz corresponding to the reference positions stored in the storage unit 151. The control unit 152 compares the specified positions of peaks Px to Pz with the reference positions, thereby calculating the deviation of the pixel positions, and corrects the position of the received waveform W0 based on the calculated pixel position deviation. Figure 11 In the diagram, the received light waveform W0 after position correction is represented by dots and lines.

[0209] In the storage unit 151, the interval between pixels where the center of at least two of the peaks Px, Py, and Pz should appear is pre-stored as a reference interval. The control unit 152 specifies the interval between the peaks Px to Pz corresponding to the reference interval stored in the storage unit 151. The control unit 152 compares the specified interval between the peaks Px to Pz with the reference interval to calculate the deviation of the pixel interval, and corrects the shape of the light-receiving waveform W0 based on the calculated deviation of the pixel interval.

[0210] As a correction to the temperature characteristics of the light-receiving section 140, only one of the following corrections can be performed: correction of the position of the light-receiving waveform W0 based on pixel position deviation and correction of the shape of the light-receiving waveform W0 based on pixel spacing deviation; or both corrections can be performed. The correction to the temperature characteristics of the light-receiving section 140 is performed prior to the removal of the base waveform BL. The measurement distance can be calculated more accurately by specifying the peak P0 of the corrected light-receiving waveform W0.

[0211] (5) Basic usage examples of confocal displacement gauges

[0212] This section describes a basic usage example of the confocal displacement meter 500. In the following example, it is assumed that the power supply to the confocal displacement meter 500 is initially turned on. Figure 1 The CPU 403 of the control device 400 shown is in measurement mode.

[0213] First, the user fixes the object to be measured, S, on the displacement measurement platform. Then, the user roughly positions the measuring head 200 relative to the object to be measured, so that light emitted from the measuring head 200 illuminates the object to be measured. The measuring head 200 is then fixed to the user's desired position in a desired posture using clamping members or the like.

[0214] Figure 12 This is a diagram showing an example of the display of the display device 401 of the control device 400 in its initial state. (See diagram for example.) Figure 12 As shown, for example, a first display area 410 and a second display area 450 are provided in the display device 401. In the initial state, nothing is displayed in the first display area 410. On the other hand, a light reception confirmation button 451, a confirmation setting button 452, a confirmation end button 453, and a measurement start button 454 are displayed in the second display area 450.

[0215] Unless the relative position and orientation of the measuring head 200 relative to the object S are appropriate, it is difficult to accurately measure the displacement of the object S. Therefore, in order to adjust the position and orientation of the measuring head 200 more appropriately, the user uses... Figure 1 The operation unit 402 is used to operate the light-receiving confirmation button 451. In this case, the CPU 403 switches from measurement mode to confirmation mode. In confirmation mode, the CPU 403 generates change information at fixed intervals. The generated change information is displayed in the first display area 410. The specific content of the change information and a display example are described below.

[0216] In this state, the user can fine-tune the position and orientation of the measuring head 200 while confirming the changes, thus achieving a more appropriate positioning of the measuring head 200. Once the measuring head 200 is positioned, the user uses... Figure 1 The operation unit 402 is used to operate the confirmation end button 453. As a result, the operation mode of the CPU 403 switches from confirmation mode to measurement mode. Afterwards, the user can operate the measurement start button 454 to measure the displacement of the measurement object S.

[0217] When the CPU 403 is in measurement mode and measuring the displacement of the object S, the numerical value representing the measurement result or the light waveform acquired at the current time point will be displayed. Figure 12 In the first display area 410 shown. Figure 13 It is shown in Figure 12 A diagram showing an example of measurement results displayed in the first display area 410. Figure 14 It is shown in Figure 12 A diagram showing an example of the light-receiving waveform displayed in the first display area 410.

[0218] exist Figure 13 In the example shown, the numerical value representing the displacement measurement result is displayed in the first display area 410, and a toggle button 491 is also displayed. Figure 14 In the example shown, the light waveform acquired at the current time point is displayed in the first display area 410, along with a toggle button 491. The user can then use... Figure 1 Operation of the shown operation unit 402 Figure 13 The switch button 491 shown switches the display state of the first display area 410 to [the desired state]. Figure 14 The display status shows the received light waveform. Users can... Figure 1 Operation of the shown operation unit 402 Figure 14 The switch button 491 shown switches the display state of the first display area 410 to [the desired state]. Figure 13 The display status shows the measurement results using numerical values.

[0219] When the CPU 403 is in the confirmation mode, during the light reception confirmation process, the CPU 403 can determine the appropriateness of the position and posture of the measuring head 200 based on whether the peak value of the light signal is higher than a specific threshold (hereinafter referred to as appropriateness judgment), and cause the display device 401 to display the judgment result along with the change information. The CPU 403 can use only peaks within a specific wavelength range to perform this appropriateness judgment. In addition, the CPU 403 can display the change information on the display device 401 in various forms.

[0220] The information, including the appropriateness judgment threshold used in the light reception confirmation process, the wavelength range for appropriateness judgment, and the display format, is stored as setting information. Figure 1 The memory 404 shown is used by the user. Figure 1 Operation of the shown operation unit 402 Figure 12 The confirmation setting button 452 is shown, and these types of information are entered to cause the memory 404 to store the desired setting information.

[0221] Figure 15 It is shown in Figure 12 This is an example diagram of an input screen for setting information displayed in the first display area 410. Figure 15 In the example shown, two input fields 461 and 462 and two display format buttons 463 and 464 are displayed within the first display area 410. The user uses input field 461 to specify the threshold for suitability assessment. The user uses input field 462 to specify the wavelength range for suitability assessment. The user uses display format buttons 463 and 464 to select whether to display, for example, a scatter plot or waveform graph showing the change in peak light intensity from a point before the current time to the current time as change information.

[0222] Note that for multiple wavelength ranges, the appropriateness judgment thresholds can be set to different values. In this case, for example, multiple input fields can be displayed on the settings screen for inputting multiple thresholds corresponding to the multiple wavelength ranges respectively. The appropriateness judgment thresholds can be pre-stored in memory 404 by the manufacturer of the confocal displacement meter 500.

[0223] Figures 16-21 This demonstrates the confirmation process through light reception. Figure 12 A diagram illustrating an example of the change information displayed in the first display area 410. Figure 16 In the example shown, the change information displayed in the first display area includes: the peak value of the light-receiving signal acquired at the current time point (hereinafter referred to as the current peak value), the maximum value of the peak value of the light-receiving signal acquired from the start of the light-receiving confirmation process to the current time point (hereinafter referred to as the past maximum peak value), and a scatter plot showing the changes in the peak value of the light-receiving signal from the start of the light-receiving confirmation process to the current time point. Additionally, the suitability judgment results of the position and orientation of the measuring head 200 are displayed.

[0224] exist Figure 16 In the scatter plot, the horizontal axis represents time, and the vertical axis represents the intensity of the received light signal. In this scatter plot, the peak values ​​of the received light signal acquired by the control unit 152 at fixed intervals from the start of the light reception confirmation process are displayed as dots, and a pre-set appropriateness judgment threshold is represented by a dotted line. Note that the user can set the display period of the peak values ​​and the scale of the horizontal axis.

[0225] In addition, Figure 16 In the example shown, the past maximum peak value and the point corresponding to that peak value are highlighted, as indicated by shading. As a result, the user can easily identify the change in the peak value of the received light signal over time by visually recognizing the display device 401. Therefore, the position and orientation of the measuring head 200 can be adjusted to obtain even higher peak values.

[0226] exist Figure 16 The example shown displays the position / posture suitability assessment result. The result is displayed as "OK" when the peak value of the received light signal exceeds a threshold, and as "NG" when the peak value does not exceed the threshold. When the position / posture suitability assessment result is displayed as "OK," the user is prompted to end the adjustment. The threshold used to display "OK" or "NG" for the position / posture suitability assessment result is related to the threshold value. Figure 15 The appropriateness thresholds set for the images shown may be the same or different.

[0227] For example, if the position / posture appropriateness at the current time point is better than in the past, the position / posture appropriateness judgment result can be displayed as "OK". The position / posture appropriateness judgment result can also be displayed as "OK" when the position / posture appropriateness at the current time point is better than in the past and exceeds the minimum limiting range of the object S that the confocal displacement meter 500 can measure.

[0228] When the position and posture suitability assessment result is within the range where further adjustments to the position and posture will not significantly affect the measurement accuracy, notify the user that the adjustment is complete, so as to prompt the user to proceed to the displacement measurement step.

[0229] In addition to the points mentioned below, Figure 17 The example shown is the same as Figure 16 The example shown is the same. Figure 17 In the example shown, instead of a scatter plot, a waveform graph is used to display the change in the peak value of the received light signal from the start of the light reception confirmation process up to the current time point.

[0230] exist Figure 18 In the example shown, the current peak value and the past maximum peak value are displayed as change information. A waveform diagram including the received light waveform at the current time point and the received light waveform when the past maximum peak value was obtained is displayed as change information. In addition, the appropriateness judgment results of the position and posture of the measuring head 200 are displayed.

[0231] exist Figure 18 In the waveform diagram, the horizontal axis represents the wavelength of the light received by the light-receiving unit 140, and the vertical axis represents the intensity of the light signal. The waveform diagram uses dashed lines to represent the light-receiving waveform at the point of greatest past peak value, and solid lines to represent the light-receiving waveform at the current time point. As a result, the user can visually identify the display device 401 while adjusting the position and orientation of the measuring head 200 so that the peak of the light-receiving waveform at the current time point exceeds the peak of the past light-receiving waveform represented by the dashed lines.

[0232] Figure 18 The horizontal axis of the waveform diagram shows the wavelength, which corresponds to the distance between the measured object S and the measuring head 200 along the optical axis of the measuring head 200. Therefore, the user can visually identify the positional relationship between the measured object S and the measuring head 200 along the optical axis of the measuring head 200 by recognizing the received light waveform at the current time point. Consequently, the user can easily adjust the position of the measuring head 200 so that the peak wavelength of the received light signal is aligned with the optical axis of the measuring head 200. Figure 2 The measurement range shown is within the wavelength range corresponding to MR.

[0233] In addition to the points mentioned below, Figure 19 The example shown is the same as Figure 18The example shown is the same. Figure 19 In the example shown, instead of Figure 18 The waveform diagram shown includes the following light-receiving waveforms: the light-receiving waveform at the current time point, and multiple light-receiving waveforms acquired by the control unit 152 at fixed intervals from the start of the light-receiving confirmation process.

[0234] exist Figure 19 In the waveform diagram shown, the horizontal axis represents the wavelength of the light received by the light-receiving unit 140, and the vertical axis represents the intensity of the light signal. In this waveform diagram, dotted lines represent multiple previously acquired light-receiving waveforms, and solid lines represent the light-receiving waveform at the current time point. As a result, the user can visually identify the display device 401 while adjusting the position and orientation of the measuring head 200 so that the peak of the light signal at the current time point exceeds the peaks of the multiple past light-receiving waveforms represented by the dotted lines.

[0235] In addition to the points mentioned below, Figure 20 The example shown is the same as Figure 18 The example shown is the same. Figure 20 In the example shown, instead of Figure 18 The waveform diagram shown includes the light-receiving waveform at the current time point and the following envelope, wherein the envelope is used to connect the peaks of multiple light-receiving waveforms acquired by the control unit 152 from the start of the light-receiving confirmation process.

[0236] exist Figure 20 In the waveform diagram shown, the horizontal axis represents the wavelength of the light received by the light-receiving unit 140, and the vertical axis represents the intensity of the light signal. In this waveform diagram, a dotted line represents the envelope connecting the peaks of multiple previously acquired light-receiving waveforms, and a solid line represents the light-receiving waveform at the current time point. As a result, the user can visually identify the display device 401 while adjusting the position and orientation of the measuring head 200 so that the height of the peak of the light signal at the current time point is close to or exceeds the highest point of the envelope represented by the dotted line.

[0237] In addition to the points mentioned below, Figure 21 The example shown is the same as Figure 16 The example shown is the same. Figure 21 In the example shown, Figure 18 The waveform diagram along with Figure 16 Scattered points Figure 1 This is displayed. In this case, the user can easily identify the changes in the peak of the received light signal over time and the changes in the received light waveform over time. Note that in Figure 21 In the example shown, instead of the scatter plot displayed on the left side of the first display area 410, a display can be shown Figure 17 The waveform diagram can be displayed. Figure 19 The waveform of 20 is displayed as the waveform on the right side of the first display area 410.

[0238] (6) Displacement measurement processing

[0239] Figure 22 This is a flowchart illustrating the displacement measurement process. When the power to the confocal displacement meter 500 is switched on... Figure 1 The CPU 403 shown executes the displacement measurement process described below at fixed intervals. Initially, the CPU 403 is in measurement mode. It is assumed that the display on the display device 401... Figure 12 The image shown.

[0240] First, CPU 403 operates, for example... Figure 12 The light reception confirmation button 451 shown is used to determine whether a switch to the confirmation mode has been indicated (step S1). If a switch to the confirmation mode has been indicated, the CPU 403 performs light reception confirmation processing in step S20 as described below, and then ends the displacement measurement processing.

[0241] On the other hand, without indication of switching to confirmation mode, CPU 403, for example, operates... Figure 12 The confirmation setting button 452 is used to determine whether the confirmation mode setting has been indicated (step S2). If the confirmation mode setting has been indicated, the control unit 152 receives setting information in response to the user's operation on the operation unit 402 (step S11), stores the received setting information in the memory 404 (step S12), and ends the displacement measurement process.

[0242] If no confirmation mode is specified in step S2, the CPU 403 will, for example, operate... Figure 12 The measurement start button 454 is used to determine whether the measurement has started (step S3). If the measurement has not started, the CPU 403 performs the processing of step S1.

[0243] On the other hand, when the start of the measurement is indicated, the CPU 403 acquires the light-receiving signal given by the control unit 152 (step S4). The control unit 152 performs basic waveform removal and temperature characteristic correction on the light-receiving signal given by the control unit 152.

[0244] Similar to the storage unit 151, the memory 404 stores in advance the position of the pixels of the light-receiving unit 140, the peak wavelength of the output light-receiving waveform, and a conversion formula for the measurement distance. The CPU 403 calculates the displacement of the measured object S based on the corrected light-receiving signal and the conversion formula stored in the memory 404 (step S5). Furthermore, the CPU 403 displays the calculated displacement on the display device 401 (step S6). Afterwards, the CPU 403 determines whether the displacement has been determined by, for example, user operation. Figure 1 The operation unit 402 indicated whether the measurement had ended (step S7). If the measurement had ended, the CPU 403 terminated the displacement measurement process. If the measurement had not ended, the CPU 403 executed the process in step S4.

[0245] Figure 23 and Figure 24 It is used for explanation Figure 22 The flowchart shown illustrates the light reception confirmation process. As described above, in Figure 22 If step S1 indicates a switch to confirmation mode, then execute... Figure 23 and 24 The light reception confirmation process is shown.

[0246] First, the CPU 403 resets the timer (not shown) built into the control device 400 and starts counting (step S21). The CPU 403 sets the value of the variable i, which represents the number of times the light signal is acquired, to 1 (step S22).

[0247] Subsequently, the CPU 403 acquires the light-receiving signal from the control unit 152 (step S23). The control unit 152 performs basic waveform removal and temperature characteristic correction on the light-receiving signal from the control unit 152. Then, the CPU 403 stores the acquired light-receiving waveform as the first light-receiving waveform in the memory 404, extracts the peak of the acquired light-receiving signal, and stores the value of that peak as the first peak value in the memory 404 (step S24). The CPU 403 displays the first peak value stored in the memory 404 as the current peak value on the display device 401 (step S25).

[0248] Subsequently, CPU 403 determines whether a predetermined fixed time period has elapsed since the processing in step S21 based on the timer count (step S26). If the fixed time has not elapsed, CPU 403 executes the processing in step S33 as described below. On the other hand, if the fixed time has elapsed, CPU 403 resets the timer and starts counting again (step S27). CPU 403 increments the value of variable i by 1 (step S28).

[0249] Subsequently, the CPU 403 acquires the light-receiving signal output from the light-receiving unit 140 (step S29). The CPU removes the basic waveform and corrects the temperature characteristics of the light-receiving unit 140 from the light-receiving signal given by the control unit 152. Then, the CPU 403 stores the acquired light-receiving waveform of the light-receiving signal as the i-th light-receiving waveform in the memory 404, extracts the peak of the acquired light-receiving signal, and stores the value of that peak as the i-th peak value in the memory 404 (step S30). The CPU 403 generates change information based on the i-th peak value and the i-th light-receiving waveform stored in the memory 404, as well as the first peak value to the (i-1)-th peak value and the first light-receiving waveform to the (i-1)-th light-receiving waveform, and displays the generated change information on the display device 401 (step S31). Note that the change information includes at least one of the first peak value to the (i-1)-th peak value and the i-th peak value (current peak value).

[0250] Then, the CPU 403 determines the appropriateness of the position and posture of the measuring head 200 based on a threshold that is stored in the memory 404 as setting information in advance, and displays the determination result on the display device 401 (step S32). Note that if the threshold is not stored in the memory 404, the processing of step S32 can be omitted.

[0251] Subsequently, CPU 403 operates, for example... Figure 12 The confirmation button 453 indicates whether the light reception confirmation process has ended (step S33). If the light reception confirmation process has not ended, the CPU 403 executes the processing in step S26. Conversely, if the light reception confirmation process has ended, the CPU 403 terminates the light reception confirmation process. The change information includes a graph showing the change in the peak value of the light-receiving signal over time (see...). Figure 16 and 17 In the case of ( ), the CPU 403 can store a graph of the end time of the light confirmation process in the storage unit 151.

[0252] (7) Effect

[0253] In the confocal displacement meter 500 according to this embodiment, light having multiple wavelengths is emitted by the light projection unit 120. A lens unit 220 causes chromatic aberration in the light emitted by the light projection unit 120. The light with chromatic aberration is converged by the lens unit 220 and irradiates the object being measured, S. Of the light irradiated on the object being measured via the lens unit 220, light having wavelengths that are focused on the surface of the object being measured and reflected passes through multiple optical fibers 313-316.

[0254] Multiple beams passing through optical fibers 313-316 are guided to the beam splitter 130 via fiber coupler 330, optical fibers 317 and 318, fiber coupler 320, and optical fiber 312. Therefore, the multiple beams passing through optical fibers 313-316 are combined into a single beam during the process of being guided to the beam splitter 130. As a result, the multiple beams can be easily averaged. The control unit 152 calculates the displacement of the measurement object S based on the intensity of the averaged light.

[0255] Due to irregular reflections on the surface of the object being measured, S, light focused at a position different from the surface of the object may sometimes pass through any of the optical fibers 313-316. Even in this case, using the structure described above, the intensity of each wavelength related to the multiple light rays passing through the multiple optical fibers 313-316 is averaged during the averaging process. As a result, the light component that causes random measurement errors due to irregular reflections is canceled out. Consequently, the error in the measured displacement of the object being measured, S, can be reduced. In this structure, arithmetic operations for averaging are unnecessary. As a result, the displacement of the object being measured, S, can be calculated quickly and efficiently.

[0256] In this embodiment, the end portions of optical fibers 313-316 are used as pinholes. In this case, it is not necessary to arrange multiple pinholes separately. As a result, the structure of the confocal displacement meter 500 can be made compact.

[0257] In this way, it is desirable to form the cladding 310b of the optical fibers 313-316 as a light-shielding part (pinhole member) and the core 310a as a pinhole. As a result, a confocal optical system can be realized with a simple structure. On the other hand, where light loss is permissible, a light-shielding member obtained by setting multiple pinholes in a light-shielding plate can be arranged at the end of the optical fibers 313-316 on the measuring head 200 side.

[0258] Furthermore, in this embodiment, the processing device 100 and the measuring head 200 are separately provided and optically connected via the light guide 300. Therefore, it is easy to perform measurements using a measuring head 200 that includes a lens unit 220 that generates appropriate chromatic aberration based on the shape or arrangement of the object being measured S, or a lens unit 220 with an appropriate focal length. As a result, the displacement of the object being measured S can be measured more easily.

[0259] Since the light guide 300 includes an optical fiber, the processing device 100 and the measuring head 200 can be arranged separately from each other. No mechanically driven components are provided in the measuring head 200. There is no heat source in the measuring head 200. Therefore, the measuring head 200 can be arranged in various environments. As described below, if the exposed portion of the measuring head 200 is formed of glass, the measuring head 200 can be arranged in even more different environments.

[0260] When using a laser light source as the light source 121, the light guide 300 preferably includes an optical fiber. For example, in the case of... Figure 5 As shown in (b), when the phosphor 122 is excited by a laser emitted from the light source 121 to generate light with multiple wavelengths, the light generated by using an optical fiber can be extracted efficiently. Using an optical fiber, the extracted light can be efficiently provided to the measuring head 200.

[0261] exist Figure 1 In this design, the fiber optic coupler 330 is disposed within the housing 210 of the measuring head 200. However, the fiber optic coupler 330 can also be disposed within the connector portion between the measuring head 200 and the optical fibers 313-316. By arranging the fiber optic coupler 330 within a robust housing (connector portion) of metal or the like, the size of the measuring head 200 can be prevented from increasing while securing and protecting the fiber optic coupler 300. The fiber optic coupler 330 can be disposed near the connector portion.

[0262] like Figure 1 As shown, fiber optic coupler 320 is arranged on the processing device 100 side, and fiber optic coupler 330 is arranged on the measuring head 200 side. Fiber optic couplers 320 and 330 are connected by optical fibers 317 and 318, each comprising two cores 310a. This structure allows for greater design freedom in the arrangement of fiber optic couplers 320 and 330 while reducing the loss of optical signals reflected from the measured object S.

[0263] (8) Variations

[0264] (a) Example of a modified light guide

[0265] In this embodiment, the light guide 300 includes two fiber optic couplers 320 and 330. However, the invention is not limited thereto. The light guide 300 may not include one or both of the fiber optic couplers 320 and 330. Figure 25 This is a diagram showing a first modified example of the light guide section 300. Figure 25 In the example shown, the light guide 300 does not include Figure 1 The optical fibers 317 and 318 and the optical fiber coupler 320 are shown. Optical fibers 311 to 316 are connected to ports 331 to 336 of the optical fiber coupler 330, respectively.

[0266] exist Figure 25 In the example shown, the fiber optic coupler 330 is disposed outside the housing 110 of the processing device 100. However, the fiber optic coupler 330 may be disposed inside the housing 110 of the processing device 100. Figure 25 In the example shown, the fiber optic coupler 330 is disposed on the side of the light guide section 300 near the processing device 100. However, the fiber optic coupler 330 may be disposed near the measuring head 200 or inside the connector section.

[0267] exist Figure 25 In the example shown, only one fiber optic coupler is used. No fiber optic coupler is arranged in the measurement head 200. Therefore, the measurement head 200 is easy to assemble. By arranging the fiber optic coupler 330 on the side of the processing device 100, which has a larger accommodating space compared to the measurement head 200, both ease of assembly and reduction of optical loss can be achieved.

[0268] Figure 26 This is a diagram showing a second modified example of the light guide section 300. Figure 26 In the example shown, instead of Figure 1 The fiber optic coupler 330 shown includes a light guide section 300 comprising two fiber optic couplers 340. Each fiber optic coupler 340 has a so-called 1×2 type structure and includes three ports 341 to 343 and a main body 344. Ports 341 and 342, and port 343, are connected to the main body 344 in a manner opposite to each other across the main body 344. Light input to at least one of ports 341 and 342 is output from port 343. Light input to port 343 is output from each of ports 341 and 342.

[0269] Optical fibers 313 and 314 are connected to ports 341 and 342 of a fiber optic coupler 340, respectively. Optical fibers 315 and 316 are connected to ports 341 and 342 of another fiber optic coupler 340, respectively. Port 323 of fiber optic coupler 320 and port 343 of fiber optic coupler 340 are connected via optical fiber 317. Port 324 of fiber optic coupler 320 and port 343 of another fiber optic coupler 340 are connected via optical fiber 318.

[0270] exist Figure 26 In the example shown, the fiber optic coupler 320 is disposed outside the housing 110 of the processing device 100. However, the fiber optic coupler 320 may be disposed inside the housing 110 of the processing device 100. The fiber optic coupler 340 is disposed outside the measuring head 200. However, the fiber optic coupler 340 may be accommodated inside the connector portion of the measuring head 200.

[0271] exist Figure 26In the example shown, two fiber optic couplers 340 are positioned on the side of the measuring head 200. In this configuration, the layout for placing the fiber optic couplers 340 within the measuring head 200 can be easily implemented. This reduces light loss reflected from the measured object S.

[0272] Figure 27 This is a diagram showing a third modified example of the light guide section 300. Figure 27 In the example shown, instead of Figure 1 The fiber optic couplers 320 and 330 shown, and the light guide section 300 includes two fiber optic couplers 340 and 350. Figure 27 The light guide portion 300 shown does not include Figure 1 The optical fiber shown is 318. Figure 27 The fiber optic coupler 340 shown has a connection with Figure 26 The fiber optic coupler 340 shown has the same structure.

[0273] The fiber optic coupler 350 has a so-called 1×4 type structure and includes five ports 351-355 and a main body 356. Ports 351-354 and port 355 are connected to the main body 356 in a manner opposite to each other across the main body 356. Light input to at least one of ports 351-354 is output from port 355. Light input to port 355 is output from each of the ports 351-354.

[0274] Fiber optic cables 311 and 312 are connected to ports 341 and 342 of fiber optic coupler 340, respectively. Fiber optic cables 313 to 316 are connected to ports 351 to 354 of fiber optic coupler 350, respectively. Port 343 of fiber optic coupler 340 and port 355 of fiber optic coupler 350 are connected via fiber optic cable 317.

[0275] In this embodiment, fiber optic couplers 320, 330, 340, and 350 are used for optical coupling and splitting. However, the invention is not limited thereto. Without using fiber optic couplers 320, 330, 340, and 350, multiple optical fibers 311-318, each with multiple cores 310a fused into one, can be used for optical coupling and splitting.

[0276] exist Figure 27 In the example shown, the fiber optic coupler 340 is disposed outside the housing 110 of the processing device 100. However, the fiber optic coupler 340 may be disposed inside the housing 110 of the processing device 100. The fiber optic coupler 350 is disposed outside the measuring head 200. However, the fiber optic coupler 350 may be housed within the connector portion of the measuring head 200. Instead of the fiber optic coupler 340, an optical circulator can be used. As a result, light loss can be further reduced compared to the case where the fiber optic coupler 340 is used.

[0277] (b) Modified example of lens unit

[0278] In this embodiment, the lens unit 220 includes a refractive lens 221 and a diffractive lens 222. However, the invention is not limited thereto. The lens unit 220 may not include one or both of the refractive lens 221 and the diffractive lens 222. Figure 28 Figures (a) to (d) show the first to fourth variations of the lens unit 220.

[0279] like Figure 28 As shown in (a), the lens unit 220 of the first modified example includes a diffraction lens 222 and an objective lens 223, but does not include... Figure 1 The refractive lens 221 is shown. (As shown) Figure 28 As shown in (b), similar to the first variant, the lens unit 220 of the second variant includes a diffraction lens 222 and an objective lens 223, but does not include... Figure 1 The refractive lens 221 is shown. In the second variation, the diffractive lens 222 and the objective lens 223 are arranged in positions opposite to those in the first variation.

[0280] like Figure 28 As shown in (c), instead of the diffractive lens 222 of the first modification, the lens unit 220 of the third modification includes a flat plate lens 224. Figure 28 As shown in (d), instead of the diffractive lens 222 of the second variation, the lens unit 220 of the fourth variation includes a flat lens 224.

[0281] Thus, the lens unit 220 may include, for example, a diffractive lens, a flat lens, a GRIN (gradient refractive index) lens, or a prism, or a combination of these lenses. Utilizing these structures of the lens unit 220, chromatic aberration can be generated along the optical axis of the light emitted from the light projection section 120. The light with chromatic aberration can be converged and irradiated onto the measurement object S.

[0282] The lens can be a glass lens, a resin lens, or a lens made of resin-processed glass. Glass lenses have high heat resistance. Resin lenses can be manufactured inexpensively. Lenses made of resin-processed glass can be manufactured relatively inexpensively and have relatively high heat resistance.

[0283] The lens in lens unit 220 closest to the object being measured, S, is preferably made of glass. The measuring head 200 is placed in an environment containing water or oil, such as a manufacturing production line in a factory. When the optical system, such as the lens, which is exposed to the outside of the measuring head 200, is made of glass, the oil resistance, water resistance, and contamination resistance of the measuring head 200 can be improved.

[0284] Similarly, the portion of the optical system of lens unit 220 exposed to external air is preferably formed of glass. Alternatively, the refractive lens 221, diffractive lens 222, objective lens 223, or flat lens 224 may be formed of resin instead of glass. The portion of lens unit 220 exposed to external air may be formed of glass. For example, in Figure 28 In the example shown in (b), a protective glass can be provided on the lower side of the diffraction lens 222 (the side of the measurement object S).

[0285] (c) Example of a modified light projection section

[0286] In this embodiment, the optical axis of the light emitted from the light source 121 and the central axis of the collar 123 are arranged in a straight line. However, the present invention is not limited thereto. Figure 29 This is a diagram showing a modified example of the light projection section 120. (See diagram for example.) Figure 29 As shown, the light projection section 120 of this modified example includes a light source 121, a phosphor 122, a collar 123, lenses 124 and 128, and a reflective member 129. Lens 124 is disposed between the light source 121 and the reflective member 129. Lens 128 is disposed between the reflective member 129 and the collar 123. The phosphor 122 is coated onto the reflective surface of the reflective member 129.

[0287] Light emitted from light source 121 passes through lens 124, thereby converging as excitation light onto phosphor 122 coated on reflective member 129. Phosphor 122 absorbs the excitation light and emits fluorescence. The excitation light that passes through phosphor 122 but is not absorbed by phosphor 122 mixes with the fluorescence emitted from phosphor 122, thereby generating broadband light. The generated light is reflected on the reflective surface of reflective member 129, and is thus guided to collar 123 via lens 128. As a result, the light is input to optical fiber 311. In this structure, the degree of freedom in arranging optical elements is increased. Therefore, it is easier to miniaturize the light projection section 120.

[0288] To increase the intensity of the light generated by the light projection section 120, it is desirable to increase the amount of light emitted by the light source 121. On the other hand, as the amount of light emitted from the light source 121 increases, the heat generated by the phosphor 122 increases. As a result, the reflection efficiency of the reflective member 129 decreases, and the emission of fluorescence from the phosphor 122 is easily saturated. Therefore, the reflective member 129 can be configured to be rotatable or movable. As a result, the phosphor 122 is cooled and heat generation is reduced. Consequently, the intensity of the light generated by the light projection section 120 can be further increased.

[0289] (d) Example of a modified beam splitter

[0290] In this embodiment, the diffraction grating 131 of the beam splitter 130 is reflective. However, the present invention is not limited thereto. Figure 30 This is a diagram showing a modified example of the beam splitter 130. (See diagram below.) Figure 30 As shown, in a modified example of the beam-splitting section 130, the diffraction grating 131 is a transmission type. Light incident on the diffraction grating 131 is split and transmitted at different angles for each wavelength. The light split by the diffraction grating 131 passes through the lens 133 and is thus focused at the pixel position of the light-receiving section 140, which is different for each wavelength.

[0291] [2] Second embodiment

[0292] (1) Basic structure of confocal displacement gauge

[0293] Regarding the confocal displacement meter according to the second embodiment of the present invention, the differences from the confocal displacement meter 500 according to the first embodiment will be explained. Figure 31 This is a schematic diagram illustrating the structure of a confocal displacement meter according to a second embodiment of the present invention. Figure 31 As shown, the light guide section 300 of the confocal displacement meter 500 includes multiple (four in this example) fiber optic couplers 340 and multiple (twelve in this example) optical fibers 311A-311D, 312A-312D and 313-316. Figure 31 The fiber optic coupler 340 shown has a connection with Figure 26 The fiber optic coupler 340 shown has the same structure.

[0294] Optical fibers 311A ​​to 311D are connected to ports 341 of the four optical fiber couplers 340, respectively. Optical fibers 312A to 312D are connected to ports 342 of the four optical fiber couplers 340, respectively. Optical fibers 313 to 316 are connected to ports 343 of the four optical fiber couplers 340, respectively. Light emitted from the light projection unit 120 is input into optical fibers 311A ​​to 311D. Light output from optical fibers 312A to 312D is guided to the beam splitter 130.

[0295] Using this structure, light emitted from the light projection unit 120 is input to port 341 of the fiber optic coupler 340 via optical fibers 311A-311D. The light input to port 341 is output from port 343 corresponding to port 341, and is irradiated onto the measurement object S via optical fibers 313-316 corresponding to port 341 and the measuring head 200. A portion of the light reflected from the surface of the measurement object S is input to port 343 via the measuring head 200 and optical fibers 313-316. The light input to port 343 is output from ports 341 and 342 corresponding to port 343. The light output from port 342 is guided to the beam splitter 130 via optical fibers 312A-312D.

[0296] Figure 32 It is shown Figure 31A diagram showing the structure of the beam splitter 130. (See diagram for reference.) Figure 32 As shown, the light output from optical fibers 312A to 312D passes through lens 132, thereby being approximately collimated and incident on diffraction grating 131. The light incident on diffraction grating 131 is split and reflected at different angles for each wavelength.

[0297] Figure 33 It is shown Figure 32 The diagram shows the light-receiving part 140 and the light-receiving waveform. (See diagram for reference.) Figure 33 As shown in (a), the light-receiving unit 140 includes a plurality of pixels arranged in a two-dimensional manner as an imaging element (two-dimensional line sensor). The imaging element may be a multi-segment PD, CCD camera, or CMOS image sensor, or other elements. The light-receiving unit 140 includes four rectangular light-receiving areas 141 to 144. The light-receiving areas 141 to 144 are arranged side by side in the width direction (the direction perpendicular to the long side direction). The light-receiving areas 141 to 144 serve as a one-dimensional line sensor.

[0298] from Figure 32 The light output from optical fibers 312A-312D and split by diffraction grating 131 passes through lens 133, thereby being focused onto different one-dimensional positions on light-receiving regions 141-144 for each wavelength. A light-receiving signal corresponding to the amount of light received is output from each pixel in light-receiving regions 141-144 to the processing unit 150. Figure 33 In (a), white circles are used to represent pixels in the light-receiving areas 141-144 that output the light-receiving signal with the maximum intensity.

[0299] Figure 33 In (b), the horizontal axis represents the wavelength of the received light, and the vertical axis represents the intensity of the received light signal. Figure 32 The arithmetic processing unit 150 shown acquires, for example, Figure 33 (b) shows the light-receiving waveforms W1 to W4 corresponding to the light-receiving areas 141 to 144. The arithmetic processing unit 150 performs averaging processing on the acquired light-receiving waveforms W1 to W4, thereby generating a signal corresponding to the light-receiving areas 141 to 144. Figure 4 The received light waveform W0 shown is the same as the received light waveform W0.

[0300] Averaging can be performed by calculating an average value, an integral value, a weighted average, or other calculated values. In averaging, a desired averaging or integration can be performed considering the intensities of multiple lights passing through multiple optical fibers 313-316. This averaging is then performed electrically on the received light waveform W0. As a result, components of light that cause random measurement errors due to irregular reflections are canceled out. The measurement distance can be specified more accurately by specifying the peak wavelength λ0 of the received light waveform W0.

[0301] use Figure 31 The structure shown allows for easy elimination of outliers and calculation of displacement in the optical signals of fibers 312A to 312D, even when such outliers exist. For example, it can be conceivable that only the corresponding... Figure 33 The intensity of the light signal in the light-receiving area 143 shown in (a) is either greater or less than the intensity of the light signals corresponding to the other light-receiving areas 141, 142, and 144. In this case, it is conceivable that there is dirt in the measuring head 200 or that an abnormal value is detected due to the influence of stray light, etc. Therefore, the light signal corresponding to the light-receiving area 143 can be excluded, and the displacement can be calculated using the light signals corresponding to the other light-receiving areas 141, 142, and 144.

[0302] Since the four optical signals are received independently, any arithmetic operation, such as weighted integration, can be performed as an averaging process when calculating displacement. Furthermore, since the light-receiving regions 141-144 of the light-receiving section 140 are connected, the arrangement space of the light-receiving section 140 can be reduced. Instead of the fiber optic coupler 340, an optical circulator can be used. As a result, light loss can be reduced compared to the case where the fiber optic coupler 340 is used.

[0303] (2) Variation

[0304] (a) First variation of the second embodiment

[0305] In this embodiment, the light-receiving part 140 is implemented by a two-dimensional line sensor. However, the present invention is not limited thereto. Figure 34 This is a schematic diagram showing the structure of the confocal displacement meter 500 according to a first modified example of the second embodiment. Figure 34 As shown, instead Figure 31 The beam splitter 130 and light receiver 140 shown, according to the first modified example of the confocal displacement meter 500, include a plurality of beam splitters 130A to 130D and a plurality of light receivers 140A to 140D (four in this example).

[0306] The beam splitters 130A to 130D have the same characteristics as in the first embodiment. Figure 1 The beam splitter 130 shown has the same structure. The light receiving parts 140A to 140D have the same structure as in the first embodiment. Figure 1 The structure of the light-receiving unit 140 shown is the same. Therefore, the light-receiving units 140A to 140D are implemented by a one-dimensional line sensor. The light-receiving units 140A to 140D are arranged to receive the light after it has been split by the beam-splitting units 130A to 130D.

[0307] The light output from optical fibers 312A to 312D is guided to beam splitters 130A to 130D, respectively. The light output from optical fibers 312A to 312D passes through beam splitters 130A to 130D corresponding to optical fibers 312A to 312D. Figure 32 The lens 132 shown is thus substantially collimated and incident on the diffraction grating 131. The light incident on the diffraction grating 131 is split and reflected at different angles for each wavelength. The light split by the diffraction grating 131 passes through the lens 133 and is thus focused on the pixel positions of the light-receiving portions 140A to 140D, which are different for each wavelength.

[0308] A light-receiving signal corresponding to the amount of light received is output from each pixel of the light-receiving units 140A to 140D to the arithmetic processing unit 150. The arithmetic processing unit 150 electrically averages the light-receiving waveform acquired from the light-receiving units 140A to 140D, thereby generating a signal corresponding to the amount of light received. Figure 4 The received light waveform W0 shown is the same as the received light waveform W0. As a result, the measurement distance is calculated.

[0309] In the first variation of the second embodiment, the diffraction grating 131 and lenses 132 and 133 in the plurality of beam splitters 130A to 130D can be implemented by common diffraction grating 131 and lenses 132 and 133, respectively. That is, Figure 33 The light-receiving areas 141 to 144 of the light-receiving part 140 shown in (a) can each be implemented by a separate one-dimensional line sensor.

[0310] use Figure 34 In the structure shown, since the multiple light-receiving units 140A to 140D are arranged independently, independent signal processing can be performed on the light received by the light-receiving units 140A to 140D. As a result, the displacement by which noise is removed can be calculated.

[0311] (b) Second variation of the second embodiment

[0312] Figure 35 This is a schematic diagram showing the structure of the confocal displacement gauge 500 in the second modified example of the second embodiment. (See attached diagram.) Figure 35 As shown, instead Figure 31 The beam splitter 130, light receiver 140, and fiber coupler 340 shown, according to the second modification, the confocal displacement meter 500 includes a plurality of (two in this example) beam splitters 130A and 130B, a plurality of (two in this example) light receivers 140A and 140B, and a plurality of (two in this example) fiber couplers 320. The confocal displacement meter 500 according to the second modification does not include... Figure 31 The optical fibers shown are 311C, 311D, 312C, and 312D.

[0313] Fiber optic coupler 320 has with Figure 1 The fiber optic couplers 320 shown have the same structure. Fiber optic cables 311A ​​and 311B are connected to ports 321 of the two fiber optic couplers 320, respectively. Fiber optic cables 312A and 312B are connected to ports 322 of the two fiber optic couplers 320, respectively. Fiber optic cables 313 and 314 are connected to ports 323 and 324 of one fiber optic coupler 320, respectively. Fiber optic cables 315 and 316 are connected to ports 323 and 324 of another fiber optic coupler 320, respectively.

[0314] The beam splitters 130A and 130B have the same Figure 34 The beam splitters 130A to 130D shown have the same structure. The light receiving sections 140A and 140B have the same structure as... Figure 34 The light-receiving units 140A to 140D shown have the same structure. Therefore, light-receiving units 140A and 140B are implemented using one-dimensional line sensors. The light emitted by the light projection unit 120 is input to optical fibers 311A ​​and 311B. The light output from optical fibers 312A and 312B is guided to beam splitters 130A and 130B, respectively. The light split by beam splitters 130A and 130B is received by light-receiving units 140A and 140B, respectively.

[0315] Using this structure, light emitted from the light projection unit 120 is input to port 321 of the fiber optic coupler 320 via optical fibers 311A ​​and 311B. The light input to port 321 is output from ports 323 and 324 corresponding to port 321, and is irradiated onto the measurement object S via optical fibers 313-316 corresponding to port 321 and the measuring head 200. A portion of the light reflected from the surface of the measurement object S is input to ports 323 and 324 via the measuring head 200 and optical fibers 313-316. The light input to ports 323 and 324 is output from ports 321 and 322 corresponding to ports 323 and 324. The light output from port 322 is guided to beam splitters 130A and 130B corresponding to port 322 via optical fibers 312A and 312B corresponding to port 322.

[0316] The light input to fibers 313 and 314 is mixed until it exits from fiber 312A. The light input to fibers 315 and 316 is mixed until it exits from fiber 312B. As a result, the light output from fiber 312A and the light output from fiber 312B undergo intensity averaging (integration in this example).

[0317] The light output from optical fibers 312A and 312B passes through lens 132 in beam-splitting sections 130A and 130B corresponding to optical fibers 312A and 312B, thereby achieving approximate collimation, and then incident on diffraction grating 131. The light incident on diffraction grating 131 is split and reflected at different angles for each wavelength. The light split by diffraction grating 131 passes through lens 133, thereby focusing on the pixel positions of light-receiving sections 140A and 140B, which are different for each wavelength.

[0318] The light-receiving signal corresponding to the amount of light received is output from each pixel of the light-receiving units 140A and 140B to the arithmetic processing unit 150. The arithmetic processing unit 150 further averages the light-receiving waveforms obtained from the light-receiving units 140A and 140B, thereby generating a signal corresponding to the light received amount. Figure 4 The received light waveform W0 shown is the same as the received light waveform W0. Therefore, in this example, averaging of the received light waveform W0 is performed both optically and electrically. Thus, the measurement distance is calculated.

[0319] use Figure 35 The structure shown allows for the arbitrary selection of two light groups for intensity integration. By analyzing the data from... Figure 3 By integrating the intensities of the two light rays output from the two optical fibers whose centers are opposite each other in the cross-fiber unit 301 shown, the light component that causes random measurement errors due to irregular reflections can be removed more efficiently.

[0320] Therefore, optical fibers 313 and 316, whose centers are opposite each other across optical fiber unit 301, are intended to be connected to ports 323 and 324 of an optical fiber coupler 320, respectively. Similarly, optical fibers 314 and 315, whose centers are opposite each other across optical fiber unit 301, are intended to be connected to ports 323 and 324 of another optical fiber coupler 320, respectively.

[0321] [3] Third embodiment

[0322] Regarding the confocal displacement meter according to the third embodiment of the present invention, the differences from the confocal displacement meter 500 according to the first embodiment will be explained. Figure 36 This is a schematic diagram illustrating the structure of a confocal displacement meter according to a third embodiment of the present invention. Figure 36 As shown, instead Figure 1 The two fiber optic couplers 320 and 330 shown, and the light guide section 300 of the confocal displacement meter 500 include an optical switch 360. The light guide section 300 does not include... Figure 1 The optical fibers shown are 317 and 318.

[0323] The optical switch 360 has a so-called 2×4 type structure and includes six ports 361 to 366 and a main body 367. Ports 361 and 362, as well as ports 363 to 366, are connected to the main body 367 in a manner opposite to each other across the main body 367. Optical fibers 311 to 316 are respectively connected to ports 361 to 366 of the optical switch 360.

[0324] Light input to any of ports 361 and 362 can be output from any of ports 363 to 366. The control unit 152 of the processing unit 150 switches the connection state between ports 361 and 362 and ports 363 to 366 for each of four equal time periods t1 to t4.

[0325] During time period t1, light input to port 361 is output from port 363, and light input to port 363 is output from port 362. During time period t2 following t1, light input to port 361 is output from port 364, and light input to port 364 is output from port 362. During time period t3 following t2, light input to port 361 is output from port 365, and light input to port 365 is output from port 362. During time period t4 following t3, light input to port 361 is output from port 366, and light input to port 366 is output from port 362.

[0326] Therefore, during time period t1, the light emitted by the light projection unit 120 of the processing device 100 is input to port 361 of the optical switch 360 via optical fiber 311. The light input to port 361 is output from port 363 and illuminates the measurement object S via optical fiber 313 and lens unit 220. A portion of the light reflected from the surface of the measurement object S is input to port 363 via lens unit 220 and optical fiber 313. The light input to port 363 is output from port 362 and guided to beam splitter 130 via optical fiber 312.

[0327] Similarly, during time period t2, the light emitted by the light projection unit 120 of the processing device 100 is input to port 361 of the optical switch 360 via optical fiber 311. The light input to port 361 is output from port 364 and illuminates the measurement object S via optical fiber 314 and lens unit 220. A portion of the light reflected from the surface of the measurement object S is input to port 364 via lens unit 220 and optical fiber 314. The light input to port 364 is output from port 362 and guided to beam splitter 130 via optical fiber 312.

[0328] During time period t3, the light emitted by the light projection unit 120 of the processing device 100 is input to port 361 of the optical switch 360 via optical fiber 311. The light input to port 361 is output from port 365 and illuminates the measurement object S via optical fiber 315 and lens unit 220. A portion of the light reflected from the surface of the measurement object S is input to port 365 via lens unit 220 and optical fiber 315. The light input to port 365 is output from port 362 and guided to beam splitter 130 via optical fiber 312.

[0329] During time period t4, the light emitted by the light projection unit 120 of the processing device 100 is input to port 361 of the optical switch 360 via optical fiber 311. The light input to port 361 is output from port 366 and illuminates the measurement object S via optical fiber 316 and lens unit 220. A portion of the light reflected from the surface of the measurement object S is input to port 366 via lens unit 220 and optical fiber 316. The light input to port 366 is output from port 362 and guided to beam splitter 130 via optical fiber 312.

[0330] The light-receiving signal is output from each pixel of the light-receiving unit 140 to the arithmetic processing unit 150. Figure 37 This is a diagram showing the light-receiving waveform acquired by the arithmetic processing unit 150. Figure 37 The horizontal axis represents the wavelength of the received light, and the vertical axis represents the intensity of the received light signal. For example... Figure 37 As shown, the arithmetic processing unit 150 acquires the light-receiving waveforms W1 to W4 during the time periods t1 to t4, respectively.

[0331] The arithmetic processing unit 150 averages the acquired light-receiving waveforms W1 to W4, thereby generating a signal with... Figure 4 The received waveform W0 shown is the same as the received waveform W0. Similar to the second embodiment, the averaging process can be the calculation of an average value, the calculation of an integral value, or the calculation of a weighted average or other calculated value. In the averaging process, a desired averaging or integration can be performed taking into account the intensity of multiple lights passing through the multiple optical fibers 313-316. Thus, the averaging process for the received waveform W0 is performed electrically. As a result, the light components that cause random measurement errors due to irregular reflections are canceled out. The measurement distance can be specified more accurately by specifying the peak wavelength λ0 of the received waveform W0.

[0332] Optionally, the light-receiving unit 140 can perform exposure within a time period t1 to t4. The light-receiving signal, after integration during the exposure time period, can be output from each pixel of the light-receiving unit 140 to the arithmetic processing unit 150. In this case, the arithmetic processing unit 150 acquires the light-receiving waveform W0 corresponding to the light that has undergone intensity averaging (integration processing in this example). In this case, it is not necessary to perform arithmetic operations for averaging. As a result, the displacement of the measured object S can be calculated quickly and efficiently.

[0333] Thus, in the first to third embodiments, since the light guide 300 includes an optical fiber, it can be easily configured as a confocal displacement meter 500. Using this structure, light splitting and combining can be easily performed using various optical components. By connecting multiple optical fibers, light mixing is easily achieved. Furthermore, optical signals can be easily propagated between the processing device 100 and the measuring head 200. In the light projection section 120, the phosphor 122 is excited using a laser emitted from the light source 121. Light with multiple wavelengths is generated. Therefore, the generated light can be efficiently emitted using optical fibers.

[0334] [4] Other embodiments

[0335] (1) In the above embodiment, the light guide 300 includes an optical fiber. The optical fiber is used to transmit light between the processing device 100 and the measuring head 200. However, the present invention is not limited thereto. The light guide 300 may not include an optical fiber. Optical elements such as mirrors and semi-transparent mirrors can be used to transmit light between the processing device 100 and the measuring head 200.

[0336] Figure 38 This is a schematic diagram illustrating the structure of a confocal displacement meter according to other embodiments. Figure 38 In the diagram, for ease of understanding, the path of light is shown only on a portion of the object being measured, S. Figure 38 In this example, the paths of the light illuminating the other three parts of the measured object S are omitted. However, in Figure 38 The confocal displacement meter 500 shown is provided with four light sources 121, and four spatial filters 372 and four spatial filters 373 corresponding to the four light sources 121 respectively.

[0337] like Figure 38 As shown, instead Figure 1 The optical fibers 311-318 and optical fiber couplers 320 and 330 are shown. The light guide section 300 includes a semi-transparent mirror 371 and spatial filters 372 and 373. Pinholes 372a and 373a are formed in the spatial filters 372 and 373, respectively.

[0338] Light emitted from the light projection unit 120 passes through the pinhole 372a of the spatial filter 372, and then through the semi-transparent mirror 371. The light passing through the semi-transparent mirror 371 illuminates the measurement object S via the lens unit 220. A portion of the light reflected from the surface of the measurement object S passes through the lens unit 220 and is reflected by the semi-transparent mirror 371. The light reflected by the semi-transparent mirror 371 passes through the pinhole 373a of the spatial filter 373 and is guided to the beam splitter 130. The light receiving unit 140 receives the light split by the beam splitter 130 and outputs a light receiving signal.

[0339] The processing unit 150 acquires the light-receiving waveform W0, which has been optically or electrically averaged as described in the above embodiment, based on the light-receiving signal output by the light-receiving unit 140. Thus, averaging processing of the light-receiving waveform W0 is performed optically or electrically. As a result, components of light that cause random measurement errors due to irregular reflections are canceled out. The measurement distance can be specified more accurately by specifying the peak wavelength λ0 of the light-receiving waveform W0.

[0340] (2) In the above embodiments, Figure 5 or Figure 29 The light projection section 120 shown mixes the excitation light emitted from the light source 121 and the fluorescence emitted from the phosphor 122, thereby emitting light with a wider wavelength band. However, the invention is not limited thereto. Instead of the light source 121 and the phosphor 122, the light projection section 120 may include a light source that emits light with a wide wavelength band. For example, the light projection section 120 may include an LED (light-emitting diode) or a halogen lamp that emits white light as a light source.

[0341] (3) In the above embodiment, the light projection unit 120 emits light with a continuous wavelength of 500 nm to 700 nm. However, the present invention is not limited thereto. The light projection unit 120 may emit light with other wavelength bands having a continuous wavelength. For example, the light projection unit 120 may emit light with a continuous wavelength in the infrared region, or it may emit light with a continuous wavelength in the ultraviolet region.

[0342] (4) In the above embodiments, the processing device 100 and the measuring head 200 are configured separately. However, the present invention is not limited thereto. The processing device 100 and the measuring head 200 may be configured as a single unit.

[0343] (5) In the above embodiments, the confocal displacement meter 500 is configured to illuminate four portions of the surface of the object being measured S. However, the invention is not limited thereto. The confocal displacement meter 500 may be configured to illuminate two, three, or more portions of the surface of the object being measured S.

[0344] Therefore, the number of optical fibers contained in the optical fiber unit 301 is preferably equal to or greater than two, and more preferably equal to or greater than four. With the increase in the number of optical fibers in the optical fiber unit 301, measurement accuracy can be further improved through averaging. On the other hand, the outer diameter of the optical fiber unit 301 is increased. Therefore, the number of optical fibers can be determined based on the required measurement accuracy and the outer diameter of the optical fiber unit 301.

[0345] (6) In the above embodiments, the fiber optic unit 301 is arranged such that its center is substantially aligned with the optical axis of the lens unit 220. However, the present invention is not limited thereto. The fiber optic unit 301 may be arranged such that its center is separate from the optical axis of the lens unit 220.

[0346] (7) In the above embodiments, the plurality of optical fibers 313-316 are arranged so as not to overlap with the center of the optical fiber unit 301. However, the present invention is not limited thereto. For example, one optical fiber may be arranged to overlap with the center of the optical fiber unit 301. The other plurality of optical fibers may be arranged around the optical fiber.

[0347] Fiber optic cables 313 and 315 can be arranged from Figure 3 The positions of optical fibers 313 and 315 shown are shifted by half a distance L2 in the direction in which they are arranged. In this case, optical fibers 313 to 316 can be arranged such that optical fiber 313 contacts optical fibers 314 and 316 and optical fiber 316 contacts optical fibers 313 and 315.

[0348] (8) In the above embodiments, during the light reception confirmation process, the CPU 403 determines the appropriateness of the position and posture of the measuring head 200 based on whether the peak value of the light received signal is higher than a specific threshold. However, the present invention is not limited thereto. The CPU 403 may determine the appropriateness of the position and posture of the measuring head 200 based on whether the current peak value is higher than a predetermined proportion of the past maximum peak value (hereinafter referred to as the threshold proportion). In this case, the user can set the threshold proportion.

[0349] Figure 39 It is shown in Figure 12 The diagram shows another example of a settings information input screen displayed in the first display area 410. Figure 39 In the example shown, the user uses the topmost input field 461 to specify the threshold ratio. The user enters the desired ratio into input field 461, and the entered ratio is set as the threshold ratio.

[0350] Figure 40 This demonstrates the confirmation processing via light reception when the user sets a threshold ratio. Figure 12 A diagram illustrating an example of the change information displayed in the first display area 410. Figure 40In the example shown, with Figure 16 The example shown is the same, displaying the current peak value, the past maximum peak value, and a scatter plot showing the changes in the peak value of the received signal from the start of the light reception confirmation process to the current time point. The appropriateness judgment results for the position and orientation of the measuring head 200 are also displayed.

[0351] Furthermore, in this example, the threshold ratio set by the user is displayed as a percentage. The value showing the threshold ratio at the current time point relative to the historical maximum peak is used as the value of the intensity of the received light signal. Figure 40 In the scatter plot shown, the dotted lines represent the threshold for appropriateness judgment that changes each time the past maximum peak is updated.

[0352] (9) In the above embodiments, such as Figures 16-21 and Figure 40 As shown, during the light reception confirmation process, a threshold or threshold ratio for the intensity of the received light signal is displayed on the display device 401. However, the threshold may not be displayed. The user can switch the display of the threshold on or off using input from the operation unit 402.

[0353] (10) In Figure 16 , 17 In the examples shown in 21 and 40, when the time involved in the adjustment, the plot or waveform fitting within the frame is lower than the past maximum peak and that past maximum peak exists outside the frame, an indicator representing the presence of the past maximum peak can be shown in the intensity of the received light signal equivalent to the past maximum peak. The intensity of the received light signal on the vertical axis can be normalized based on the current peak or the past maximum peak up to the current time point. For example, if the past maximum peak is 80, the vertical axis can be configured so that 80 is near the upper limit of the vertical axis of received light intensity. If, based on the adjustment and the elapsed time, the past maximum peak increases to 350, the vertical axis of the trend graph can be normalized so that 350 is near the upper limit of the vertical axis of received light intensity.

[0354] [5] The correspondence between the constituent elements of the claims and the parts of the embodiments

[0355] The following examples illustrate the correspondence between the constituent elements of the claims and the parts of the embodiments. However, the present invention is not limited to the examples described below.

[0356] In the above embodiments, the measurement object S is an example of a measurement object. The confocal displacement meter 500 is an example of a confocal displacement meter. The light projection unit 120 is an example of a light projection unit. The lens unit 220 is an example of an optical component. The end portion of the optical fibers 313-316 or the pinhole 373a is an example of a pinhole. The optical fibers 313-316 or the spatial filter 373 is an example of a pinhole component. The processing device 100 and the light guide unit 300 are examples of a displacement measuring unit.

[0357] Beam splitters 130 and 130A-130D are examples of beam splitters. Light receiving units 140 and 140A-140D are examples of light receiving units. The arithmetic processing unit 150 is an example of a computing unit. Optical fibers 313-316 are examples of first optical fibers. The optical switch 360 is an example of a switching unit. Core 310a is an example of a core. The processing device 100 is an example of a processing device. The measuring head 200 is an example of a head. Housings 110 and 210 are examples of a first housing and a second housing, respectively. The light source 121 is an example of a light source. The phosphor 122 is an example of a phosphor.

[0358] exist Figure 1 In the structure shown, fiber optic couplers 320 and 330, and fibers 312-318 are examples of a combining section. Fiber optic couplers 320 and 330 are examples of a first fiber optic coupler and a second fiber optic coupler, respectively. Fiber optic fibers 311 and 312 are examples of a second fiber optic fiber and a third fiber optic fiber, respectively. Fiber optic fibers 317 and 318 are examples of a fourth fiber optic fiber. Figure 25 In the structure shown, fiber coupler 330 and fibers 312-316 are examples of a combining section. Fiber coupler 330 is an example of a fiber coupler. Fibers 311 and 312 are examples of a second fiber and a third fiber, respectively.

[0359] exist Figure 26 In the structure shown, fiber optic couplers 320 and 340, and fibers 312-318, are examples of a combining section. Fiber optic couplers 320 and 340 are examples of a first fiber optic coupler and a second fiber optic coupler, respectively. Fiber optic fibers 311 and 312 are examples of a second fiber optic fiber and a third fiber optic fiber, respectively. Fiber optic fibers 317 and 318 are examples of a fourth fiber optic fiber. Figure 27 In the structure shown, fiber optic couplers 340 and 350, and fibers 312-317 are examples of a combining section. Fiber optic couplers 340 and 350 are examples of a first fiber optic coupler and a second fiber optic coupler, respectively. Fiber optic fibers 311, 312, and 317 are examples of a second to a fourth fiber optic fiber, respectively. Figure 35 In the structure shown, the fiber coupler 320 and the optical fibers 311A, 311B, 312A, 312B and 313 to 316 are examples of the combining section.

[0360] As constituent elements of the claims, various other elements having the structure and function described in the claims may also be used.

[0361] Industrial availability

[0362] This invention can be effectively used in various confocal displacement gauges.

Claims

1. A confocal displacement meter for measuring displacement of a measurement object located in a measurement range using a confocal optical system, the confocal displacement meter comprising: a head having a first housing, optical members, and a plurality of pinholes provided in the first housing and corresponding to the confocal optical system, the optical members provided in the first housing having a lens that generates chromatic aberration along an axial direction and focusing each light passing through the plurality of pinholes to different positions along an optical axis of the measurement range according to a wavelength of the light; an optical fiber unit having a plurality of optical fibers having one end corresponding to the plurality of pinholes of the head; a processing section mechanically and optically coupled with the head via the optical fiber unit, wherein the processing section has: a second housing; a light projecting section provided in the second housing and emitting light having a plurality of wavelengths, the light projecting section emitting the light in such a manner that the light is guided to the plurality of pinholes of the head through the optical fiber unit and irradiated to the measurement object located in the measurement range from the plurality of pinholes; a light splitting section provided in the second housing, receiving input of light reflected from the measurement object via the plurality of pinholes and the optical fiber unit, and splitting the light from the optical fiber unit by each wavelength; a light receiving section provided in the second housing, receiving input of the light split by the light splitting section, and outputting input of the light as an electrical signal; a calculation section provided in the second housing, receiving input of the electrical signal, and calculating displacement of the measurement object based on signal intensity of each wavelength of an average signal corresponding to an average value obtained by averaging intensity of each wavelength related to light passing through each optical fiber with respect to the corresponding wavelength, wherein the average signal is a signal obtained by the averaging process with respect to a plurality of wavelength signals of the light split by the light splitting section after the mixed light output from the plurality of optical fibers. the light projecting section includes:

2. The confocal displacement meter of claim 1, wherein, a laser light source; and a fluorescent body that absorbs light emitted by the laser light source and releases light having a wavelength different from that of the light emitted by the laser light source, wherein the light released by the fluorescent body is guided to the plurality of optical fibers.

3. The confocal displacement meter according to claim 1, wherein: the processing section has an optical coupler in the second housing that couples a plurality of lights passing through the plurality of optical fibers to generate the mixed light, the light splitting section splits the mixed light after being coupled by the optical coupler, the light receiving section receives the light split by the light splitting section and outputs a plurality of electrical light receiving signals representing light receiving amount of each wavelength related to the plurality of wavelength signals split by the light splitting section, the calculation section calculates displacement of the measurement object based on an average signal obtained by the averaging process with respect to the plurality of electrical light receiving signals output by the light receiving section.

4. The confocal displacement meter according to claim 1, wherein: ​ The light-splitting section splits the mixed light output from the plurality of optical fibers, The light-receiving section receives each light after the light-splitting by the light-splitting section, and outputs an electrical light-receiving signal indicating the light-receiving amount of each wavelength related to the plurality of wavelength signals after the light-splitting by the light-splitting section, The calculation section calculates the displacement of the measurement target based on the average signal obtained by the averaging process on the plurality of electrical light-receiving signals output from the light-receiving section.

5. The confocal displacement meter according to claim 1, wherein The processing section further has a combining section that partially combines the plurality of lights passing through the plurality of pinholes, thereby generating a plurality of combined lights, The light-splitting section splits each of the plurality of combined lights combined by the combining section, The light-receiving section receives each light of the plurality of lights after the light-splitting by the light-splitting section, and outputs a plurality of electrical light-receiving signals indicating the light-receiving amount of each wavelength related to each of the plurality of lights passing through the plurality of pinholes, The calculation section averages or integrates the plurality of light-receiving signals output from the light-receiving section for each wavelength, thereby calculating an average signal as a signal intensity of each wavelength, and calculates the displacement of the measurement target based on the calculated average signal.

6. The confocal displacement meter according to any one of claims 1 to 5, wherein Further provided is a display device connected to the processing section, and displaying a waveform in a screen based on the average signal obtained by the calculation section.

7. The confocal displacement meter according to claim 6, wherein The light-receiving section receives light including unnecessary components, The processing section calculates the displacement of the measurement target based on the signal intensity of each wavelength of the average signal from which the unnecessary components are removed, The display device displays a waveform obtained based on the signal intensity of each wavelength of the average signal from which the unnecessary components are removed.

8. The confocal displacement meter according to any one of claims 1 to 5, wherein The lens in the optical member that generates chromatic aberration along the axial direction is a diffractive lens.

9. The confocal displacement meter according to claim 8, wherein The optical member further has an objective lens.

10. The confocal displacement meter according to any one of claims 1 to 2, 4 to 5, wherein The confocal displacement meter has an optical coupler in the second housing, the optical coupler being optically connected to the plurality of optical fibers, the light-projecting section, and the light-splitting section.

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