Measuring device

Abstract

To provide a measuring device equipped with a compact and lightweight movable body.SOLUTION: A measuring device 1 comprises: a movable unit 11 having a mirror 113; a movable unit 12 having a light emission point 121, a light incidence point 122, and an optical system; a drive mechanism 13; and a control unit 14. First light and second light emitted from the light emission point 121 is irradiated on the mirror 113 via the optical system, and first reflected light which is reflected light of the first light from the mirror 113 and second reflected light which is reflected light of the second light from the mirror 113, respectively, enter the light incidence point 122 via the optical system. The control unit 14 controls the drive mechanism 13 on the basis of intensity of the first reflected light and the second reflected light having entered the light incidence point 122 so as to adjust a position of the movable unit 12. A first wavelength which is a peak wavelength of the first light is different from a second wavelength which is a peak wavelength of the second light, and the optical power of the optical system in the first wavelength is different from the optical power of the optical system in the second wavelength.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a measuring device.

Background Art

[0002] Contact three-dimensional shape measuring instruments are used to measure the shape of lenses and the like with high precision. Patent Document 1 discloses the configuration of an optical probe used in a contact three-dimensional shape measuring instrument.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present disclosure is to provide a measuring device including a small and lightweight movable body.

Means for Solving the Problems

[0005] A measuring device according to one aspect of the present disclosure includes a first movable body having a reflector, a second movable body having a light emission point, a light incident point, and an optical system, a drive mechanism for adjusting the position of the second movable body, and a control unit for controlling the drive mechanism. The first light and the second light emitted from the light emission point are irradiated onto the reflector via the optical system. The first reflected light, which is the reflected light of the first light from the reflector, and the second reflected light, which is the reflected light of the second light from the reflector, each enter the light incident point via the optical system. The control unit adjusts the position of the second movable body by controlling the drive mechanism based on the intensity of each of the first reflected light and the second reflected light that enters the light incident point. The first wavelength, which is the peak wavelength of the first light, is different from the second wavelength, which is the peak wavelength of the second light, and the optical power of the optical system at the first wavelength is different from the optical power of the optical system at the second wavelength.

Advantages of the Invention

[0006] According to the present disclosure, it is possible to provide a measuring device including a small and lightweight movable body.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0008] (Summary of the Present Disclosure) The inventor has found the following problems with the optical probe used in the three-dimensional shape measuring device disclosed in Patent Document 1. Hereinafter, the problems of the conventional optical probe will be described with reference to the configuration of the optical probe disclosed in Patent Document 1.

[0009] FIG. 6 is a diagram showing a schematic configuration of a conventional three-dimensional shape measuring device. As shown in FIG. 6, the three-dimensional shape measuring device 1x includes an optical probe 10x. The optical probe 10x is composed of two elements, a movable part 11x and a movable part 12x.

[0010] The movable part 11x moves up and down along the shape of the object to be measured (not shown). The three-dimensional shape measuring device 1x irradiates the movable part 11x with light Lx (shown by a broken line in FIG. 6) from the outside of the optical probe 10x, and determines the position of the movable part 11x based on the reflected light. Thereby, the three-dimensional shape measuring device 1x obtains the shape information of the object to be measured.

[0011] The movable part 12x has a function of restricting the movement of the movable part 11x in the vertical direction. Further, the movable part 11x and the movable part 12x are connected by a spring 15x. In order to keep the contact strength between the movable part 12x and the object to be measured within a certain range, it is necessary to make the relative position between the movable part 11x and the movable part 12x within a certain range.

[0012] Also, in the configuration of Patent Document 1, an objective lens 125x is placed on the movable part 12x. The objective lens 125x condenses the light incident from the outside of the optical probe 10x onto a mirror 113x on the movable part 11x. The objective lens 125x emits the reflected light by the mirror 113x to a laser length measuring device (not shown) outside the optical probe 10x. In order for the reflected light to return to the laser length measuring device, the mirror 113x of the movable part 11x needs to be located near the focal position of the objective lens 125x of the movable part 12x. Also in the optical probe 10x, it is necessary to make the relative position between the movable part 11x and the movable part 12x within a certain range in this sense.

[0013] The movable part 12x includes a semiconductor laser 21x, a photodetector 31ax, and a photodetector 31bx as means for measuring the relative position between the movable part 11x and the movable part 12x. The reason why the movable part 12x includes two photodetectors 31ax and 31bx is that the dependencies of the signal intensities of the relative positions between the movable part 11x and the movable part 12x are different. With this configuration, when it deviates from the desired relative position, it is possible to calculate in which direction and by how much the movable part 12x should be moved to achieve the desired relative position.

[0014] As shown in FIG. 6, the contact type three-dimensional shape measuring instrument includes a driving means 13x and a relative position measuring means 14x.

[0015] The relative position measuring means 14x calculates the relative position between the movable part 11x and the movable part 12x based on the outputs of the photodetectors 31ax and 31bx respectively. The driving means 13x adjusts the relative position between the movable part 11x and the movable part 12x by changing the position of the movable part 12x so that the relative position becomes constant.

[0016] The three-dimensional shape measuring instrument changes the lateral relative position between the optical probe 10x and the measurement object in order to measure the three-dimensional shape of the measurement object. In this case, the position of the movable part 11x changes in the vertical direction according to the shape of the measurement object. Each time the lateral relative position is changed, it is necessary to measure the relative position and change the position of the movable part 12x in order to keep the relative position between the movable part 11x and the movable part 12x constant.

[0017] However, if the position change speed of the movable part 12x is slow, it will limit the shape measurement. Also, if the position change cannot catch up, the relative position between the movable part 11x and the movable part 12x will go out of the appropriate range. In this case, problems such as the movable part 11x being excessively pressed against the measurement object, or the movable part 11x being separated from the measurement object and unable to measure normally will occur.

[0018] The weight of the movable part 12x affects the position change speed of the movable part 12x. In order to increase the position change speed, it is required that the movable part 12x be as lightweight as possible. Also, in order to suppress physical interference between the object to be measured and the movable part 12x, it is required that the movable part 12x be as small as possible.

[0019] Therefore, an object of the present disclosure is to provide a measuring device including a small and lightweight movable body.

[0020] The measuring device according to the first aspect of the present disclosure includes a first movable body having a reflector, a second movable body having a light emission point, a light incident point, and an optical system, a drive mechanism for adjusting the position of the second movable body, and a control unit for controlling the drive mechanism. The first light and the second light emitted from the light emission point are irradiated onto the reflector via the optical system. The first reflected light, which is the reflected light of the first light from the reflector, and the second reflected light, which is the reflected light of the second light from the reflector, each enter the light incident point via the optical system. The control unit controls the drive mechanism based on the intensity of each of the first reflected light and the second reflected light incident on the light incident point, thereby adjusting the position of the second movable body. The first wavelength, which is the peak wavelength of the first light, is different from the second wavelength, which is the peak wavelength of the second light, and the optical power of the optical system at the first wavelength is different from the optical power of the optical system at the second wavelength.

[0021] Thereby, by using an optical system having different optical powers at the first wavelength and the second wavelength, the intensities of the first reflected light and the second reflected light incident on the light incident point can be made different. Based on this intensity difference, it becomes possible to calculate and adjust the relative position between the first movable body and the second movable body. Since it is not necessary to provide a light incident point for each wavelength, the elements arranged on the second movable body can be reduced. Therefore, miniaturization and weight reduction of the second movable body can be achieved.

[0022] The measuring device according to the second aspect of the present disclosure is the measuring device according to the first aspect, and includes an optical fiber. Both the light emission point and the light incidence point are the first end of the optical fiber.

[0023] As a result, since the light emission point and the light incidence point are the ends of the optical fiber, it is possible to reduce the size and weight of the second movable body. This is because generally the size of the end of the optical fiber is smaller than that of the semiconductor laser and the photodetector, so it can contribute to the reduction in size and weight of the second movable body. Further, when elements such as a semiconductor laser and a photodetector are provided, a power supply line for supplying power to operate the elements and a signal line for extracting the signal output from the elements are required. On the other hand, by using an optical fiber, it is not necessary to provide a power supply line and a signal line, and the number of cables connected to the second movable body can be reduced. Also in this respect, it is possible to reduce the size and weight of the second movable body.

[0024] The measuring device according to the third aspect of the present disclosure is the measuring device according to the first aspect or the second aspect, and in the first light and the second light, wavelength components having a predetermined intensity or more do not overlap with each other.

[0025] As a result, it is only necessary to detect the light intensities of only two wavelengths, the first wavelength and the second wavelength. Since the amount of calculation and the calculation time can be reduced compared with the case of performing spectral measurement by spectroscopy, the relative positions of the first movable body and the second movable body can be calculated and adjusted in a short period of time. Therefore, it is possible to contribute to the speeding up of the measurement of the measurement object.

[0026] The measuring device according to the fourth aspect of the present disclosure is a measuring device according to any one of the first to third aspects, wherein light used for measuring an object is incident on the optical system, and a third wavelength that is the peak wavelength of the light used for measuring the object is different from both the first wavelength and the second wavelength, and the optical power of the optical system at the third wavelength is approximately equal to one of the optical power of the optical system at the first wavelength and the optical power of the optical system at the second wavelength, and is different from the other.

[0027] Thereby, it is possible to easily separate the light used for measuring the measurement object from the light used for measuring the relative positions of the first movable body and the second movable body. It is possible to suppress the adverse effects exerted by the lights on each other, and it is possible to improve the measurement accuracy of each.

[0028] The measuring device according to the fifth aspect of the present disclosure is a measuring device according to the fourth aspect, and includes an interferometer that interferes the light used for measuring the object.

[0029] Thereby, it becomes possible to measure the surface shape of the measurement object based on distance measurement using light interference.

[0030] The measuring device according to the sixth aspect of the present disclosure is a measuring device according to any one of the first to fifth aspects, and includes a light intensity measuring unit that measures the intensity of each of the first reflected light and the second reflected light incident on the light incident point.

[0031] Thereby, since the light intensity measuring unit can be provided separately from the second movable body, it becomes easy to replace the light intensity measuring unit when it deteriorates.

[0032] The measuring device according to the seventh aspect of the present disclosure is the measuring device according to the sixth aspect, wherein the light intensity measuring unit includes a first photodiode that photoelectrically converts the first reflected light and outputs a first signal, a second photodiode that photoelectrically converts the second reflected light and outputs a second signal, a first circuit that performs analog-to-digital conversion on the first signal, and a second circuit that is different from the first circuit and performs analog-to-digital conversion on the second signal.

[0033] Accordingly, it is only necessary to detect the light intensities of only two wavelengths, i.e., the first wavelength and the second wavelength. Since the amount of calculation and the calculation time can be reduced compared to the case where spectroscopy is performed for spectral measurement, the relative positions of the first movable body and the second movable body can be calculated and adjusted in a short period of time. Therefore, it is possible to contribute to speeding up the measurement of the measurement object.

[0034] The measuring device according to the eighth aspect of the present disclosure is the measuring device according to the sixth aspect, wherein the light intensity measuring unit includes a first photodiode that photoelectrically converts the first reflected light and outputs a first signal, a second photodiode that photoelectrically converts the second reflected light and outputs a second signal, and a differential operation circuit that receives each of the inputs of the first signal and the second signal.

[0035] Accordingly, it is only necessary to detect the light intensities of only two wavelengths, i.e., the first wavelength and the second wavelength. Since the amount of calculation and the calculation time can be reduced compared to the case where spectroscopy is performed for spectral measurement, the relative positions of the first movable body and the second movable body can be calculated and adjusted in a short period of time. Therefore, it is possible to contribute to speeding up the measurement of the measurement object.

[0036] The measuring device according to the ninth aspect of the present disclosure is the measuring device according to the second aspect, further including a light source unit, and the light emitted from the light source unit enters from an end portion of the optical fiber opposite to the first end portion, is guided through the fiber, and is emitted as the first light and the second light from the first end portion.

[0037] As a result, since the light source unit can be provided separately from the second movable body, it becomes easier to replace the light source unit when it deteriorates. Further, it is possible to suppress a decrease in the measurement accuracy of the measurement object due to the influence of heat generated when the light source unit emits light.

[0038] The measuring device according to the tenth aspect of the present disclosure is the measuring device according to the ninth aspect, wherein the light source unit includes a first laser light source that emits the first light and a second laser light source that emits the second light, which is different from the first laser light source.

[0039] As a result, individual laser light sources that emit light according to the wavelength can be used.

[0040] The measuring device according to the eleventh aspect of the present disclosure is the measuring device according to the ninth aspect, wherein the light source unit is a laser light source including a first active region that emits the first light and a second active region that emits the second light.

[0041] As a result, the number of laser light sources can be made one, and the configuration of the light source unit can be simplified.

[0042] The measuring device according to the twelfth aspect of the present disclosure is the measuring device according to the ninth aspect, wherein the light source unit is a gas laser light source that emits the first light and the second light.

[0043] As a result, the number of laser light sources can be made one, and the configuration of the light source unit can be simplified. Further, various light sources can be used in the measuring device of the present disclosure regardless of the principle of laser oscillation.

[0044] The measuring device according to the thirteenth aspect of the present disclosure is the measuring device according to any one of the first aspect to the twelfth aspect, wherein the optical system includes an achromatic lens.

[0045] As a result, by means of the achromatic lens, the third wavelength of the light used for measuring the object to be measured can be made substantially equal to one of the first wavelength of the first light and the second wavelength of the second light used for measuring the relative position between the first movable body and the second movable body, and can be made different from the other. For this reason, it is possible to easily separate the light used for measuring the object to be measured from the light used for measuring the relative position between the first movable body and the second movable body. It is possible to suppress the adverse effects exerted by the lights on each other, and it is possible to improve the measurement accuracy of each.

[0046] Hereinafter, embodiments of the present disclosure will be specifically described with reference to the drawings.

[0047] Note that all of the embodiments described below show comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components, steps, order of steps, etc. shown in the following embodiments are merely examples, and are not intended to limit the present disclosure. In addition, among the components in the following embodiments, the components not described in the independent claims are described as optional components.

[0048] Each drawing is merely a schematic diagram for explaining concepts, and does not show the actual size, shape, etc. Therefore, for example, the scales in each drawing do not necessarily match. In each drawing, substantially the same configurations are denoted by the same reference numerals, and redundant descriptions are omitted or simplified.

[0049] In addition, in this specification, the light emission point is the light emission portion of the light into the second movable body and is a portion having a predetermined area. For example, the light emission point is the end portion of an optical fiber, the light emission surface of a light emitting element, or the like. The light incident point is the incident portion of the light propagated inside the second movable body to the photodetector and is a portion having a predetermined area. For example, the light incident point is the end portion of an optical fiber, a pinhole, or the like.

[0050] In addition, in this specification, the "vertical direction" means the direction in which the relative position between the first movable body and the second movable body can change. Specifically, the direction parallel to the axis of the stylus of the first movable body is the vertical direction. The tip direction along the axis of the stylus is the "downward direction", and the opposite direction is the "upward direction". The tip of the stylus contacts the object to be measured.

[0051] In addition, in this specification, ordinal numbers such as "first" and "second" do not mean the number or order of components unless otherwise specified, and are used for the purpose of avoiding confusion and distinguishing between components of the same type.

[0052] (Embodiment 1) First, the measuring device according to Embodiment 1 will be described. The measuring device according to this embodiment has a configuration in which the end of an optical fiber is connected to a movable part instead of a laser light source and a photodetector provided in the movable part.

[0053] Hereinafter, the specific configuration of the measuring device according to this embodiment will be described with reference to FIG. 1. FIG. 1 is a diagram showing a schematic configuration of the measuring device according to this embodiment.

[0054] The measuring device 1 according to this embodiment is a three-dimensional shape measuring instrument. Specifically, the measuring device 1 measures the surface shape of an object to be measured (not shown). As shown in FIG. 1, the measuring device 1 includes a probe 10, a drive mechanism 13, a control unit 14, a spring 15, optical fibers 16, 17, and 18, and a circulator 19. The measuring device 1 also includes a light source unit 20, a light intensity measuring unit 30, an interferometer 40, and an air supply unit 50.

[0055] [Probe] The probe 10 includes a movable part 11 and a movable part 12. The movable part 11 is an example of a first movable body having a reflector. The movable part 12 is an example of a second movable body having a light emission point, a light incidence point, and an optical system.

[0056] The movable part 11 includes a stylus 111, a slide part 112, and a mirror 113. The stylus 111 is fixed to the slide part 112. When measuring a measurement object, the tip of the stylus 111 contacts the measurement object. When the stylus 111 contacts the measurement object, the movable part 11 changes its vertical position according to the shape of the measurement object. The slide part 112 restricts the movement of the movable part 11 in the vertical direction. The mirror 113 is an example of a reflector included in the first movable body. The relative positional relationships among the stylus 111, the slide part 112, and the mirror 113 are fixed.

[0057] The movable part 12 includes a guide mechanism 120a and a probe housing 120b. The relative positional relationship between the guide mechanism 120a and the probe housing 120b is fixed. In the present embodiment, the movable part 12 has a light emission point 121 and a light incident point 122. The light emission point 121 is the same as the light incident point 122 and is the end 161 of the optical fiber 16. The movable part 12 also has an optical system fixed to the probe housing 120b.

[0058] The optical system includes a collimator lens 123, a condenser lens 125, and an optical element 129.

[0059] The collimator lens 123 converts the light emitted from the light emission point 121 into light that is nearly parallel (hereinafter referred to as parallel light). The nearly parallel light means light with a smaller divergence angle than the light before it enters the collimator lens 123, that is, the light emitted from the end 161 of the optical fiber 16 in the present embodiment. Further, the collimator lens 123 condenses the light traveling from the opposite direction, specifically, the reflected light by the mirror 113, near the end 161 of the optical fiber 16 which is the light incident point 122.

[0060] The condensing lens 125 condenses the incident light near the mirror 113. For example, the condensing lens 125 condenses the parallel light that has been converted by the collimator lens 123 and reflected by the optical element 129 near the mirror 113. Also, the condensing lens 125 converts the reflected light by the mirror 113 into parallel light and makes it incident on the collimator lens 123 via the optical element 129. Further, in the present embodiment, the condensing lens 125 condenses the light L used for measuring the measurement object near the mirror 113. Also, the condensing lens 125 converts the reflected light of the light L by the mirror 113 into parallel light and makes it incident on the interferometer 40 via the optical element 129.

[0061] The optical element 129 is an optical element for superposing the optical path of the measurement light L used by the interferometer 40 and the light for measuring the relative position between the movable part 11 and the movable part 12 and making it incident on the mirror 113. Also, the optical element 129 separates the reflected light that has been reflected from the mirror 113 and passed through the condensing lens 125 into the reflected light for making it incident on the interferometer 40 and the reflected light for measuring the relative position between the movable part 11 and the movable part 12. The optical element 129 is, for example, a dichroic mirror, but it may also be a half mirror, a beam splitter cube, a polarization beam splitter cube, etc.

[0062] For example, if the wavelength of the light L used by the interferometer 40 and the wavelength of the light for measuring the relative position between the movable part 11 and the movable part 12 are made different, the optical paths of both lights can be combined and almost completely separated by an optical element having wavelength dependence such as a dichroic mirror. In the configuration of FIG. 1, as the optical element 129, a dichroic mirror that transmits the light L used by the interferometer 40 and reflects the light for measuring the relative position between the movable part 11 and the movable part 12 is used.

[0063] Alternatively, if the polarization of the light L used by the interferometer 40 is different from the polarization of the light for measuring the relative positions of the movable part 11 and the movable part 12, the optical paths of both lights can be combined and almost completely separated by an optical element having polarization dependence such as a polarization beam splitter cube. Further, when a configuration is adopted in which the optical path of the light used by the interferometer 40 and the optical path of the light for measuring the relative positions of the movable part 11 and the movable part 12 are overlapped using an unpolarized beam splitter, an optical element that transmits one light and blocks the other light on the optical path where the two lights are to be separated, for example, a notch filter, a band-pass filter, a long-pass filter, or a short-pass filter, may be arranged.

[0064] In the present embodiment, the optical system included in the movable part 12 may include an optical element having optical power in addition to the collimator lens 123 and the condenser lens 125. Further, in the present embodiment, an optical element for adjusting the optical path so that the light that has passed through the collimator lens 123 is incident on the condenser lens 125 may be provided.

[0065] In the present embodiment, the light emitted from the light emission point 121 includes first light and second light. The first light and the second light are irradiated onto the mirror 113 through the optical system included in the movable part 12. Specifically, the first light and the second light are converted into parallel light by the collimator lens 123, then reflected by the optical element 129, and condensed near the mirror 113 by the condenser lens 125. The first wavelength λ1, which is the peak wavelength of the first light, is different from the second wavelength λ2, which is the peak wavelength of the second light.

[0066] The reflected light from the mirror 113 includes first reflected light and second reflected light. The first reflected light is the reflected light of the first light from the mirror 113. The second reflected light is the reflected light of the second light from the mirror 113. In the present embodiment, the peak wavelength of the first reflected light is the same as the peak wavelength of the first light and is the first wavelength λ1. The peak wavelength of the second reflected light is the same as the peak wavelength of the second light and is the second wavelength λ2.

[0067] The optical power of the optical system included in the movable part 12 at the first wavelength λ1 is different from the optical power at the second wavelength λ2 of the optical system. Specifically, among the optical elements on the optical path through which the first light and the second light pass in the optical system included in the movable part 12, at least one of the optical elements has a different optical power with respect to the first wavelength λ1 and the optical power with respect to the second wavelength λ2.

[0068] Note that the optical power is proportional to the reciprocal of the focal length. In this specification, that two optical powers are different means that the two optical powers are not in a substantially equal state. That two optical powers are substantially equal means the case where the ratio of the difference between the two optical powers to the larger of the two optical powers is less than 10%. Therefore, that two optical powers are different means the case where the ratio of the difference between the two optical powers to the larger of the two optical powers is 10% or more.

[0069] The element in which the optical power with respect to the first wavelength λ1 is different from the optical power with respect to the second wavelength λ2 is the collimator lens 123 or the condenser lens 125, but it may be an optical element other than these lenses. For example, an element whose optical power strongly depends on the wavelength, such as a diffractive optical element, may be arranged on the optical path through which both the first light and the second light pass.

[0070] Alternatively, the optical power of the collimator lens 123 may be made substantially the same for the first light and the second light, and the difference in the optical power between the first light and the second light may be increased in other optical elements. When this configuration is adopted, when the first light and the second light emitted from the end portion 161 of the optical fiber 16 are incident on the collimator lens 123, both of them are converted into parallel light (collimated light). In that case, the calculation of the ratio at which the first light and the second light return to the end portion 161 of the optical fiber 16 due to the change in the relative position between the movable part 11 and the movable part 12 becomes easy, and there is an advantage that the device design and adjustment become easy.

[0071] The movable part 12 has a variable relative position with respect to the movable part 11. The guide mechanism 120a of the movable part 12 restricts the movement of the movable part 11 in the vertical direction. An air supply unit 50 is connected to the movable part 11. The movement of the movable part 11 can be smoothly performed by the air supplied from the air supply unit 50.

[0072] In the present embodiment, the movable part 11 and the movable part 12 are connected by a spring 15. The spring 15 is an example of an elastic body provided in the measuring device 1. The spring 15 applies a force in the direction of pressing the movable part 11 against the object to be measured (specifically, downward) to the movable part 11. Thereby, the contact between the stylus 111 and the object to be measured is easily ensured, and the reliability of the measurement can be enhanced.

[0073] The measuring device 1 may include rubber, which is another example of an elastic body, instead of the spring 15. Further, the measuring device 1 may not include an elastic body. For example, the movable part 11 and the movable part 12 may be connected by a mechanism using a magnet or the like.

[0074] [Drive mechanism] The drive mechanism 13 adjusts the position of the movable part 12. Specifically, the drive mechanism 13 receives a control signal from the control unit 14 and changes the position of the movable part 12. The drive mechanism 13 is, for example, a linear motor or the like, but is not particularly limited as long as it can adjust the position of the movable part 12.

[0075] [Control unit] The control unit 14 controls the drive mechanism 13. The control unit 14 is a control signal generation unit that generates a control signal to be output to the drive mechanism 13.

[0076] Specifically, the control unit 14 adjusts the position of the movable part 12 by controlling the drive mechanism 13 based on the intensity of each of the first reflected light and the second reflected light incident on the light incident point 122. More specifically, the control unit 14 calculates the relative position between the movable part 11 and the movable part 12 based on the output signal from the light intensity measurement unit 30. The control unit 14 calculates the distance and direction by which the movable part 12 should be moved in order to keep the calculated relative position within a specified range. Then, the control unit 14 transmits a control signal for moving the movable part 12 by the calculated distance in the calculated direction to the drive mechanism 13. The method for calculating the relative position between the movable part 11 and the movable part 12 will be described later.

[0077] [Optical fiber] The optical fiber 16 has an end portion 161 and an end portion 162.

[0078] The end portion 161 is an example of a first end portion and is the light emission point 121 of the movable part 12. Further, the end portion 161 is also the light incident point 122 of the movable part 12. The end portion 161 is fixed to the probe housing 120b, which is a component of the probe 10, either directly or via other components.

[0079] The end portion 162 is the end portion of the optical fiber 16 on the side opposite to the end portion 161. The end portion 162 is not fixed to the probe housing 120b. The end portion 162 is connected to the circulator 19. One end of the optical fiber 17 and one end of the optical fiber 18 are respectively connected to the circulator 19.

[0080] The circulator 19 is an example of a directional coupler that allows the light emitted from the light source unit 20 and guided by the optical fiber 17 to enter the optical fiber 16, but not the optical fiber 18. Further, the circulator 19 allows the reflected light that enters from the light incident point 122 and is guided by the optical fiber 16 to enter the optical fiber 18, but not the optical fiber 17. In this way, the circulator 19 can separate the light input / output paths. By using the circulator 19, the utilization efficiency of the light emitted from the light source unit 20, the utilization efficiency of the reflected light to be measured, and the signal-to-noise ratio can be increased.

[0081] Note that the use of the circulator 19 is not essential, and a configuration using a non-directional coupler such as a splitter may also be used. Further, for example, instead of the optical fibers 16, 17, and 18 and the circulator 19, a bifurcated optical fiber may be used, and one of the two ends may be fixed to the probe housing 120b.

[0082] The other end of the optical fiber 17 is connected to the light source unit 20, and the light from the light source unit 20 is incident thereon. The light emitted from the light source unit 20 is guided by the optical fiber 17, passes through the circulator 19, enters from the end 162 of the optical fiber 16, is guided by the optical fiber 16, and is emitted from the end 161.

[0083] The other end of the optical fiber 18 is connected to the light intensity measurement unit 30, and emits the first reflected light and the second reflected light guided by the optical fiber 18 to the light intensity measurement unit 30.

[0084] Note that the optical fiber 17 may be a fiber laser in which the optical fiber itself emits light. Alternatively, the optical fiber 17 may have a wavelength conversion function, such as a fluorescent optical fiber or a non-linear optical fiber. In this case, the optical fiber 17 may emit only the light after wavelength conversion, or both the light before wavelength conversion and the light after wavelength conversion. In this way, the optical fiber 17 and the light source unit 20 may be integrated.

[0085] The optical fibers 16, 17, and 18 may be single-mode fibers or multimode fibers. For example, when the optical fiber 16 is a single-mode fiber, the light emission point 121 and the light incident point 122 can be made smaller. By making the light emission point 121 and the light incident point 122 smaller, an optical path with less divergence can be created by the optical system of the movable part 12. As a result, it becomes easier to configure a system in which the change in the amount of light of the photodetectors 31a and 31b is sensitive to the change in the relative position between the movable part 11 and the movable part 12. When the optical fiber 16 is a multimode fiber, there is an advantage that the light emitted from the light source unit 20 is easily incident on the end portion 162 of the optical fiber 16. Therefore, it is advantageous from the viewpoint of the signal-to-noise ratio.

[0086] Also, the optical fibers 16, 17, and 18 may use polarization-maintaining fibers. By using a polarization-maintaining fiber, it becomes easy to separate the light used by the interferometer 40 and the light for measuring the relative position between the movable part 11 and the movable part 12 using a polarization optical element.

[0087] [Light source unit] The light source unit 20 emits light that can be detected by the light intensity measurement unit 30. There is no particular limitation on the wavelength of the light emitted by the light source unit 20. For example, if the wavelength is different from the light used by the interferometer 40, separation of the two can be easily achieved by an optical element 129 such as a dichroic mirror.

[0088] In this embodiment, the light source unit 20 emits first light and second light. Both the spectrum of the first light and the spectrum of the second light are light with a narrow distribution width. The distribution width can be represented by a wavelength width having a predetermined intensity or more. For example, the full width at half maximum is an example of the distribution width. The narrower the distribution widths of both the spectrum of the first light and the spectrum of the second light are, the more sensitive the change in the amount of light incident on the optical fiber 16 due to the change in the relative position between the movable part 11 and the movable part 12 can be made. For example, both the full width at half maximum of the spectrum of the first light and the full width at half maximum of the spectrum of the second light are 50 nm or less. Alternatively, both the full width at half maximum of the spectrum of the first light and the full width at half maximum of the spectrum of the second light may be 10 nm or less. For example, the first light and the second light do not have wavelength components having a predetermined intensity or more overlapping with each other. The predetermined intensity or more is, for example, half of the peak intensity of each light.

[0089] In this way, by setting the spectrum of the first light and the spectrum of the second light to have different narrow distribution widths from each other, the separation between the first light and the second light is facilitated, and with respect to the relative position between the movable part 11 and the movable part 12, the curve indicated by the intensity of the first light and the curve indicated by the intensity of the second light can be made sufficiently different. As a result, the accuracy of detecting the relative position from the difference between the intensity of the first light and the intensity of the second light can be improved.

[0090] Examples of light sources with a narrow distribution width include, for example, laser light sources. Since the emission point of a laser light source is small, it can be efficiently incident on an optical fiber. As the laser light source, for example, a semiconductor laser can be used. The semiconductor laser has the advantages of being small in size and having a low driving voltage. Also, as the laser light source, a gas laser light source or a DPSS (Diode Pumped Solid State) laser may be used. These laser light sources have the advantages of having a narrow wavelength linewidth and being easy to stabilize the peak wavelength. Further, a fiber laser may be used as the laser light source. The fiber laser has the advantage of being easily coupled with an optical fiber. In particular, a single-mode fiber may be difficult to connect to a light source that emits light into free space, but it is easy with a fiber laser. Since the present disclosure does not depend on the oscillation principle of a laser, an implementer of the present disclosure can freely select a laser light source.

[0091] As other light sources with a narrow spectral width, a discharge tube having a line spectrum derived from atomic transitions, such as a high-pressure mercury lamp, may be used. However, the implementation of the present disclosure does not necessarily require a laser light source or a discharge tube, and a light-emitting diode or the like may be used.

[0092] In the present embodiment, as shown in FIG. 1, the light source unit 20 includes laser elements 21a and 21b, optical systems 22a and 22b, and a light combining element 23. The laser element 21a is an example of a first laser light source that emits first light, and is, for example, a semiconductor laser. The laser element 21b is an example of a second laser light source that emits second light, and is, for example, a semiconductor laser.

[0093] The optical system 22a is an optical element for causing the light emitted from the laser element 21a to enter the light combining element 23. The optical system 22b is an optical element for causing the light emitted from the laser element 21b to enter the light combining element 23. The light combining element 23 is, for example, a wavelength combiner or a dichroic optical element or the like. Thereby, the optical paths of the first light and the second light can be made the same and enter the optical fiber 17. Note that the overlapping of the optical paths may be performed in free space or with an optical fiber element. Note that the light source unit 20 may not include the optical systems 22a and 22b and the light combining element 23.

[0094] [Light intensity measurement unit] The light intensity measurement unit 30 measures the intensity of each of the first reflected light and the second reflected light incident on the light incident point 122. Specifically, the light intensity measurement unit 30 independently measures the intensity of the light of the first wavelength λ1 and the intensity of the light of the second wavelength λ2. Alternatively, the light intensity measurement unit 30 may measure the intensity ratio between the intensity of the light of the first wavelength λ1 and the intensity of the light of the second wavelength λ2, or the intensity difference between the intensity of the light of the first wavelength λ1 and the intensity of the light of the second wavelength λ2.

[0095] For example, as shown in FIG. 1, the light intensity measurement unit 30 includes photodetectors 31a and 31b, a light separation element 32, and AD conversion circuits 33a and 33b.

[0096] The light separation element 32 separates the first reflected light and the second reflected light that are incident on the light incident point 122 and guided through the optical fibers 16 and 18. The light separation element 32 is, for example, an optical fiber wavelength splitter. In the present embodiment, the first wavelength λ1 and the second wavelength λ2 are separated from each other and can be easily separated. Alternatively, the light separation element 32 may be a dichroic mirror or a dichroic cube. Further, the light separation element 32 may be a diffraction grating or a prism or the like.

[0097] Alternatively, the optical separation element 32 may include a fiber splitter, a half mirror, or the like that splits light at a specific intensity ratio regardless of wavelength. Thereby, after splitting the optical path of the light guided through the optical fiber 18 into two, optical filters that allow only the first wavelength λ1 or the second wavelength λ2 to pass through may be arranged in the two optical paths, respectively.

[0098] The photodetector 31a is an example of a first photodiode, and photoelectrically converts the first reflected light to output a first signal. The AD conversion circuit 33a is an example of a first circuit, and performs analog-digital conversion on the first signal output from the photodetector 31a. The AD conversion circuit 33a outputs the first signal converted into a digital signal to the control unit 14.

[0099] The photodetector 31b is an example of a second photodiode, and photoelectrically converts the second reflected light to output a second signal. The AD conversion circuit 33b is an example of a second circuit, and performs analog-digital conversion on the second signal output from the photodetector 31b. The AD conversion circuit 33b outputs the second signal converted into a digital signal to the control unit 14.

[0100] Note that the AD conversion function performed by the AD conversion circuits 33a and 33b may be possessed by the control unit 14. The configuration of the light intensity measurement unit 30 is not limited to the example shown in FIG. 1.

[0101] As described above, in the present embodiment, the light intensity measurement unit 30 can be realized with a simple configuration of two photodetectors (for example, two photodiodes) 31a and 31b and two AD conversion circuits 33a and 33b. If white light is split by a diffraction grating, a prism, or the like and spectrum measurement is performed with an array detector, it is difficult to provide an AD converter for each photodiode of the array detector. For this reason, since it is necessary to switch and use a limited number of AD converters, it is difficult to calculate the relative position in a short cycle.

[0102] In this embodiment, it is only necessary to measure the intensities of only two wavelengths, the first wavelength λ1 and the second wavelength λ2. For this reason, the relative positions of the movable part 11 and the movable part 12 can be calculated at short intervals, and the relative positions can be controlled.

[0103] In the example shown in FIG. 1, although the AD conversion circuits 33a and 33b are connected to the respective two photodetectors 31a and 31b, the present invention is not limited to this. As in the light intensity measurement unit 30A of the measuring device 1A shown in FIG. 2, a differential operation circuit 34 may be connected to the two photodetectors 31a and 31b. Here, FIG. 2 is a diagram showing a schematic configuration of a measuring device according to a modification of the present embodiment.

[0104] The differential operation circuit 34 receives an input of a first signal output from the photodetector 31a and a second signal output from the photodetector 31b. The differential operation circuit 34 calculates the difference between the first signal and the second signal, and transmits a signal representing the calculated difference to the control unit 14. The differential operation circuit 34 is realized by a differential amplifier circuit such as an operational amplifier, for example.

[0105] [Interferometer] The interferometer 40 measures the position of the mirror 113 of the movable part 11 of the probe 10 using the light L. The position of the mirror 113 is fixed relative to the stylus 111. Since the position of the stylus 111 that contacts the measurement object changes along the shape of the measurement object, the shape of the measurement object can be measured by measuring the position of the mirror 113.

[0106] The interferometer 40 uses, for example, a wavelength-stabilized He-Ne laser or a frequency-stabilized semiconductor laser as a light source for the light L for measurement. Note that the probe 10 may separately include a mirror that reflects the light L for the interferometer 40 and a mirror that reflects light for measuring the relative position between the movable part 11 and the movable part 12.

[0107] [Method for Controlling Relative Positions of Movable Part 11 and Movable Part 12] Next, a method for controlling the relative positions of the movable part 11 and the movable part 12 will be described.

[0108] The first light and the second light emitted from the light source unit 20 are guided through the optical fiber 17, the circulator 19, and the optical fiber 16, and are emitted from the end portion 161 which is the light emission point 121. The first light and the second light emitted from the end portion 161 of the optical fiber 16 are converted into parallel light by the collimator lens 123 and propagate inside the probe housing 120b. Specifically, the parallel light from the collimator lens 123 is reflected by the optical element 129 and enters the condenser lens 125.

[0109] The first light and the second light which are parallel light are converted by the condenser lens 125 into light converged in the vicinity of the mirror 113 and are reflected by the mirror 113. The reflected light (i.e., the first reflected light and the second reflected light) reflected by the mirror 113 passes through the condenser lens 125 again, becomes parallel light, propagates inside the probe housing 120b, enters the collimator lens 123 again, and then is converged in a region close to the end portion 161 of the optical fiber 16.

[0110] The paths of the first light and the second light differ depending on the relative positions of the condenser lens 125 included in the movable part 12 and the mirror 113 included in the movable part 11. That is, the paths of the first light and the second light depend on the relative positions of the movable part 11 and the movable part 12.

[0111] The closer the light is converged by the collimator lens 123 in a region close to the end portion 161 of the optical fiber 16, the larger the amount of light entering the inside of the optical fiber 16 becomes. Therefore, the light intensity measured by the light intensity measurement unit 30 becomes higher. The position where the light is converged by the collimator lens 123 depends on the relative positions of the condenser lens 125 and the mirror 113.

[0112] Therefore, for example, if the movable part 12 is controlled so that the intensity of the first light measured by the light intensity measurement unit 30 is always maximum, the relative positions of the movable part 11 and the movable part 12 can be made constant.

[0113] At this time, when only the intensity of the first light is used, it is impossible to determine in which direction the movable part 12 should be driven when the intensity is not at its maximum. Therefore, in the measuring device 1 according to the present embodiment, not only the first light but also the second light having a different peak wavelength is used.

[0114] Here, an optical system on the path where the first light and the second light exit from the end portion 161 of the optical fiber 16 and are condensed again at the end portion 161 of the optical fiber 16 as the first reflected light and the second reflected light includes at least one having different optical powers for the first wavelength λ1 and the second wavelength λ2. With this configuration, the relative position between the movable part 11 and the movable part 12 when the intensity of the first wavelength λ1 detected by the light intensity measurement unit 30 is maximized, and the relative position between the movable part 11 and the movable part 12 when the intensity of the second wavelength λ2 detected by the light intensity measurement unit 30 is maximized can be changed.

[0115] FIG. 3 is a diagram showing the relationship between the relative position of the two movable parts and the intensity of light. Specifically, FIG. 3 shows a schematic diagram of the relationship between the relative position between the mirror 113 of the movable part 11 and the condenser lens 125 of the movable part 12, and the intensities of the first light and the second light. The light intensity of each of the first light and the second light is maximized at a relative position where the end portion 161, which is the light emission point 121, and the end portion 161, which becomes the light incident point via the optical system, are optically conjugate. As shown in FIG. 3, since the optical power of at least one optical element constituting the optical system is different for the first wavelength λ1 and the second wavelength λ2, the relative position when the intensity of the first wavelength λ1 is maximized and the relative position when the intensity of the second wavelength λ2 is maximized are different.

[0116] Note that FIG. 3 shows a case where the optical power of the first wavelength λ1 is greater than the optical power of the second wavelength λ2 of the condenser lens 125. That is, the focal length of the condenser lens 125 at the second wavelength λ2 is shorter than the focal length of the condenser lens 125 at the first wavelength λ1, and the second wavelength λ2 is conjugated at a relative position shorter than the relative position conjugated at the first wavelength λ1.

[0117] For example, when controlling the relative position so that the intensity of the light with the first wavelength λ1 is maximized, if the intensities of the light with the first wavelength λ1 and the light with the second wavelength λ2 both decrease, the control unit 14 controls the drive mechanism 13 to bring the relative positions of the movable unit 11 (specifically, the mirror 113) and the movable unit 12 (specifically, the condenser lens 125) closer to each other. Further, when the intensity of the light with the first wavelength λ1 decreases while the intensity of the light with the second wavelength λ2 increases, the control unit 14 controls the drive mechanism 13 to move the relative positions of the movable unit 11 and the movable unit 12 farther apart. Thereby, the relative positions of the movable unit 11 and the movable unit 12 can be kept within a certain range.

[0118] Alternatively, the control unit 14 may control the drive mechanism 13 based on the difference between the intensity of the light with the first wavelength λ1 and the intensity of the light with the second wavelength λ2. For example, the control unit 14 controls the drive mechanism 13 to keep the relative position at a position where the intensity difference is 0. In this case, when the intensity difference is positive, the control unit 14 controls the drive mechanism 13 to bring the relative positions of the movable unit 11 and the movable unit 12 closer to each other. When the intensity difference is negative, the control unit 14 controls the drive mechanism 13 to move the relative positions of the movable unit 11 and the movable unit 12 farther apart. Thereby, the relative positions of the movable unit 11 and the movable unit 12 can be kept within a certain range. Such control is an example, and other control may be performed.

[0119] Note that it is desirable to control the relative positions of the movable unit 11 and the movable unit 12 so that the interferometer 40 can measure most favorably. In the case where the light L used by the interferometer 40 is condensed by the condenser lens 125 and reflected by the mirror 113, control is performed such that the mirror 113 is disposed at the focal position of the condenser lens 125 at the wavelength of the light L used by the interferometer 40.

[0120] This can be achieved by assuming that the focal length of the condenser lens 125 at either one of the first wavelength λ1 and the second wavelength λ2 is approximately equal to the focal length of the condenser lens 125 at the wavelength (third wavelength) λ3 of the light L used by the interferometer 40, and controlling the relative position so that the detected intensity of the light L having such an approximately equal wavelength is maximized.

[0121] To make the focal length of the condenser lens 125 at the wavelength λ3 of the light L used by the interferometer 40 substantially equal to the focal length of the condenser lens 125 at one of the first wavelength λ1 and the second wavelength λ2, there are the following two methods.

[0122] The first method is to bring the wavelengths closer to each other.

[0123] One of the first wavelength λ1 and the second wavelength λ2 is made close to the wavelength λ3 of the light used by the interferometer 40. In that case, the focal length of the condenser lens 125 in the probe 10 with respect to the wavelength λ3 of the light L used by the interferometer 40 and the focal length with respect to one of the first wavelength λ1 or the second wavelength λ2 become close. For example, when the difference between the wavelength λ3 and one of the first wavelength λ1 or the second wavelength λ2 is less than 5 nm when the wavelength λ3 is less than 500 nm, and less than 10 nm when the wavelength λ3 is 500 nm or more. The wavelength λ3 may be equal to one of the first wavelength λ1 or the second wavelength λ2.

[0124] When the first light or the second light is incident on the interferometer 40, there is a possibility of adversely affecting the measurement of the measurement object. Also, when the light L used by the interferometer 40 is incident on the light intensity measurement unit 30, there is a possibility of adversely affecting the measurement of the relative position between the movable part 11 and the movable part 12.

[0125] Therefore, in order to avoid the incidence of undesirable light, the movable part 12 may be provided with a mechanism that does not allow undesirable light to be incident. The mechanism may be provided in the condenser lens 125 or the optical element 129, or may be provided as an optical element different from the condenser lens 125 or the optical element 129. For example, when the polarization states of the first light and the second light are different from the polarization state of the light L used by the interferometer 40, one light can be transmitted while the other is blocked using a polarization optical element.

[0126] Alternatively, it is not necessary for the wavelength λ3 of the light used by the interferometer 40 to exactly match the first wavelength λ1 or the second wavelength λ2, and it may be slightly offset. For example, by selecting the optical material of the lens and designing its shape, a lens with a wavelength difference of about 10 nm and almost the same focal length, more specifically, a difference in focal length within 5% can be designed.

[0127] Also, in a filter using a dielectric multilayer film, it is easy to form a band-pass filter with a transmission width of 10 nm or less, or a notch filter with a rejection width of 10 nanometers or less. For example, a band-pass filter that transmits the wavelength λ3 of the light L used by the interferometer 40 and blocks the first wavelength λ1 and the second wavelength λ2 may be arranged in the optical path leading to the interferometer 40, and a notch filter that blocks the wavelength λ3 of the light used by the interferometer 40 and transmits the first wavelength λ1 and the second wavelength λ2 may be arranged in the optical path leading to the light intensity measurement unit 30. Thereby, it is possible to avoid the mixing of light that is not preferable for each of the interferometer 40 and the light intensity measurement unit 30.

[0128] The second method is a method using a lens having the same focal length at a plurality of wavelengths.

[0129] A lens formed by combining a plurality of optical materials having different refractive index dispersions can have the same focal length at a plurality of wavelengths. As an example, the wavelength dependence of the focal length of an achromatic lens formed by combining two optical materials is shown in FIG. 4. FIG. 4 is a diagram showing the relationship between the wavelength of incident light and the focal length of the achromatic lens. For example, an achromatic lens having the characteristics shown in FIG. 4 is used as the condenser lens 125.

[0130] The focal length of an achromatic lens exhibits a characteristic of having basically one pole with respect to wavelength. Therefore, except at the pole, there are two wavelengths having the same focal length. At this time, one wavelength is taken as the wavelength λ3 of the light L used by the interferometer 40, and the other wavelength is taken as the wavelength of the first light or the second light. Thereby, while making the focal length of the condenser lens 125 substantially coincide at one of the wavelength λ3 and the first wavelength λ1 or the second wavelength λ2, the wavelengths of each other can be made greatly different.

[0131] In the example shown in FIG. 4, an example is shown in which the first wavelength λ1 is a wavelength having the same focal length as the wavelength λ3 of the light L used by the interferometer 40, and the focal length at the second wavelength λ2 is shorter than those. Of course, other combinations may be used. For example, the focal length at the second wavelength λ2 may be longer than the focal length at the wavelength λ3 of the light L used by the interferometer 40.

[0132] When using an achromatic lens, since the wavelengths can be made greatly different, separation of light by a dichroic mirror or a dielectric multilayer filter becomes easy. For example, if both the first wavelength λ1 and the second wavelength λ2 are selected to be shorter or longer than the wavelength λ3 of the light used by the interferometer 40, it becomes easy to separate the light L used by the interferometer 40 from the first light and the second light by a dichroic mirror.

[0133] Note that the focal length at the wavelength λ3 of the light L used by the interferometer 40 does not have to exactly match the focal length at the first wavelength λ1 or the focal length at the second wavelength λ2. If the difference in focal length is sufficiently small, the effect can be obtained. Specifically, the optical power of the optical element at the wavelength λ3 may be substantially equal to the optical power of the optical element at the wavelength λ1 or λ2.

[0134] [Regarding the effect] Subsequently, the effect of the measuring device 1 according to the present embodiment will be described while comparing with the conventional optical probe 10x shown in FIG. 6.

[0135] Specifically, in the conventional example, in order to measure the relative position between the movable part 11x and the movable part 12x, the movable part 12x is provided with a semiconductor laser 21x, two photodetectors 31ax and 31bx, a beam splitter and two pinholes. On the other hand, in the measuring device 1, instead of having these components, the end 161 of the optical fiber 16 is connected to the movable part 12. The advantages of such a configuration will be described.

[0136] The first advantage is the miniaturization and weight reduction of the movable part 12.

[0137] The semiconductor laser 21x is generally housed in a package having a metal housing and a glass window with a size of about several millimeters in order to suppress deterioration due to the atmosphere or the like. On the other hand, a metal housing and a glass window are not required at the end 162 of the optical fiber 16 which is the light emission point 121. Therefore, by omitting these, the weight of the movable part 12 can be reduced.

[0138] Also, in terms of size, for the optical fiber 16, the diameter of the end 161 can be set to 1 mm or less. Therefore, by using the end 162 of the optical fiber 16 as the light emission point 121 instead of the semiconductor laser 21x, the size of the movable part 12 can be reduced.

[0139] In addition, the optical fiber 16 has high symmetry and emits light from a circular cross-section with a small diameter. In particular, for a single-mode fiber, its cross-section is extremely small. Therefore, the optical fiber 16 can emit light with a uniform spatial mode. Therefore, the light emitted from the optical fiber 16 can suppress divergence even when it is converted into collimated light with a small diameter using a small and lightweight lens with a short focal length as the collimator lens 123.

[0140] If the optical path can be shortened, components such as lenses, prisms, and mirrors included in the optical system fixed to the movable part 12 can be made smaller respectively. Therefore, the entire optical system can be miniaturized and lightened, contributing to the miniaturization of the movable part 12.

[0141] In addition, the optical system of the movable part 12 may include a GRIN (Graded-Index) lens fixed to the end 161 of the optical fiber 16. By using a GRIN lens, it is also possible to omit the collimator lens 123, enabling further miniaturization and weight reduction of the movable part 12.

[0142] Light with uniform spatial modes can be focused in a smaller range. This means that a pinhole with a smaller hole diameter can be used as a pinhole for detecting the relative position between the movable part 11 and the movable part 12. Alternatively, it means that the focal length of the lens that focuses light toward the pinhole can be shortened. Therefore, these also contribute to the miniaturization and weight reduction of the movable part 12.

[0143] On the other hand, the conventional semiconductor laser 21x as a light source emits light that spreads spatially and is asymmetric in the vertical and horizontal directions. Therefore, divergence easily occurs in collimated light with a small diameter, making it difficult to miniaturize the optical system such as a lens.

[0144] Also, similar to the case of the semiconductor laser 21x, the photodetectors 31ax and 31bx also need to be about several millimeters in diameter for encapsulation. In contrast, in this embodiment, the photodetectors 31a and 31b are arranged separately from the movable part 12, and the end 161 of the optical fiber 16 is connected to the movable part 12. Also in this regard, the movable part 12 can be miniaturized and lightened. In addition, in this embodiment, a light-shielding member having a pinhole can be omitted. Therefore, further miniaturization and weight reduction are possible.

[0145] The second advantage is the reduction of wiring.

[0146] To operate the semiconductor laser 21x, it is necessary to connect it to a power source using separate electric wires for the anode and the cathode respectively. That is, at least two electric wires need to be connected to the semiconductor laser 21x fixed to the movable part 12. If an output monitor installed inside a general semiconductor laser 21x is also used, one more electric wire is required. Similarly, for the photodetectors 31ax and 31bx, power lines and signal lines are needed. The more electric wires are connected to the movable part 12, the more difficult it is to miniaturize the movable part 12.

[0147] In contrast, in the present embodiment, the light source unit 20 and the light intensity measurement unit 30 are provided separately from the movable part 12. Only one optical fiber 16 needs to be connected to the movable part 12 for light emission. Therefore, the movable part 12 can be miniaturized.

[0148] The third advantage is the reduction of heat generation.

[0149] In the semiconductor laser 21x, usually less than half of the consumed power is converted into light. The rest of the power is released as heat. The waste heat from the semiconductor laser 21x fixed to the movable part 12 causes a temperature rise inside the movable part 12. The temperature rise inside the movable part 12 varies the refractive index of the internal air and generates so-called fluctuations. Since the light L of the distance measurement mechanism for measuring the shape of the measurement object also passes through the movable part 12, this fluctuation has an adverse effect on the accuracy of measuring the shape of the measurement object.

[0150] In contrast, in the present embodiment, the light source unit 20, which is the main heat source, is not provided in the movable part 12. In the optical fiber 16 connected to the movable part 12, the heat generation of the part fixed to the movable part 12 can be almost ignored. Therefore, the influence of heat can be greatly reduced, and a decrease in the accuracy of measuring the measurement object can be suppressed.

[0151] The fourth advantage is the ease of replacement.

[0152] The semiconductor laser 21x generally has a lifespan of about 10,000 hours, which corresponds to about one year when continuously lit. When the semiconductor laser 21x deteriorates, it becomes difficult to measure the relative position between the movable part 11 and the movable part 12, so the semiconductor laser 21x needs to be replaced.

[0153] When the semiconductor laser 21x is fixed to the movable part 12, each time it is replaced, adjustment work on the optical system fixed to the movable part 12 is required. Since the optical system of the movable part 12 is also partially shared by the interferometer 40 for shape measurement of the object to be measured, careful attention is required for its adjustment.

[0154] On the other hand, in this embodiment, the laser element 21 is arranged separately from the movable part 12. In this case, even if the laser element 21 is replaced, only the adjustment of the coupling optical system with the optical fiber 16 needs to be performed. Therefore, the replacement adjustment work can be made easier.

[0155] (Embodiment 2) Subsequently, Embodiment 2 will be described. In the measuring device according to this embodiment, as the light source unit, a light source capable of simultaneously generating the first light and the second light is used.

[0156] FIG. 5 is a diagram showing a schematic configuration of the measuring device according to this embodiment. As shown in FIG. 5, compared with the measuring device 1 according to Embodiment 1, the measuring device 2 includes a light source unit 20A instead of the light source unit 20. Other configurations are the same as those in Embodiment 1. Hereinafter, the description will be centered on the differences from Embodiment 1, and the description of the common points will be omitted.

[0157] The light source unit 20A includes a laser element 21 and an optical system 22. The laser element 21 is an example of a light source that simultaneously generates a first light and a second light. Specifically, the laser element 21 is an example of a laser light source that includes a first active region that emits the first light and a second active region that emits the second light. The optical system 22 is an element that causes the first light and the second light emitted from the laser element 21 to enter the optical fiber 17. For example, the optical system 22 is a condenser lens. The optical system 22 may be a filter that transmits only a desired wavelength.

[0158] For example, the laser element 21 is a semiconductor laser capable of simultaneously oscillating multiple wavelengths. As the laser element 21, for example, a CD-DVD dual-wavelength laser can be used. The CD-DVD dual-wavelength laser has a first active region that oscillates at about 650 nm and a second active region that oscillates at about 780 nm formed in one chip. Although the positions of the active regions that emit light of each wavelength are spatially separated, it is relatively easy to cause the light of both to enter the same core by one optical system for a multimode fiber.

[0159] Note that the light source capable of simultaneously generating the first light and the second light is not limited to a semiconductor laser.

[0160] Instead of the laser element 21, a gas laser light source may be used. For example, a gas laser such as an Ar laser has a plurality of discrete oscillation wavelengths. Therefore, by devising the design of the resonator or the like, it is possible to simultaneously oscillate multiple wavelengths. For example, a multi-wavelength Ar laser capable of simultaneously oscillating light of 457 nm, 488 nm, and 514 nm is known. Of these wavelengths, two desired wavelengths may be selected and used. Of course, two desired wavelengths of a multi-wavelength gas laser having other oscillation wavelengths may be selected.

[0161] In addition, instead of the laser element 21, there is a light-emitting tube using gas. The light-emitting tube using gas has a plurality of discrete emission lines. For example, a high-pressure mercury lamp has strong emission lines at 405 nm and 436 nm respectively. It is possible to extract light of a specific wavelength by using an optical filter, a prism, a diffraction grating, or the like.

[0162] [Modification Example] In Embodiment 2, an example in which one light source simultaneously oscillates the first light and the second light was shown. However, as a method of generating light having another wavelength spectrum from one light source, there is a method using fluorescence.

[0163] Fluorescence is a phenomenon in which a phosphor is excited by a certain wavelength and emits light with a longer wavelength. Examples of phosphors include organic molecules such as aromatics, direct-transition type semiconductors and quantum dots containing them, glasses or crystals containing rare earths, etc. Among these, phosphors using quantum dots and phosphors containing rare earths are useful for the measuring device of the present disclosure because of their narrow fluorescence spectrum width. However, even for light with a wide spectrum width, the measuring device of the present disclosure can be implemented. It is also possible to narrow the spectrum width by using a band-pass filter or the like.

[0164] Fluorescence generation by the phosphor may be performed in free space. Alternatively, it may be performed in an optical fiber containing a phosphor in the core or the cladding layer. In the case of a configuration in which wavelength conversion is performed in the optical fiber, it is not necessary to separately incident two lights on one core, and the device configuration and adjustment become simple.

[0165] In addition, wavelength conversion means other than the phosphor may be used. For example, a non-linear optical crystal may be used to generate light of a different wavelength from light of a certain wavelength by using a phenomenon such as SHG (second harmonic generation). Alternatively, light of a different wavelength set may be generated from a combination of lights of two or more wavelengths by using SFG (sum frequency generation). Alternatively, by using OPO (optical parametric oscillation) to split light of one wavelength into two, light of two wavelengths may be obtained. The non-linear optical crystal can be easily placed on the optical fiber path, for example, if it is a waveguide type PPLN (periodically poled lithium niobate).

[0166] (Other embodiments) As described above, the measuring device according to one or more aspects has been described based on the embodiments, but the present disclosure is not limited to these embodiments. As long as the gist of the present disclosure is not deviated from, various modifications conceived by those skilled in the art applied to these embodiments, and forms constructed by combining components in different embodiments are also included in the scope of the present disclosure.

[0167] For example, in the measuring device according to each embodiment, the movable part 11 and the movable part 12 may not be connected at all. By utilizing the self-weight of the movable part 11, the relative position in the vertical direction between the movable part 11 and the movable part 12 may be variable. In this case, by adjusting the posture of the measuring device so that the vertical direction coincides with the plumb direction, the self-weight of the movable part 11 can be effectively utilized. Note that a restricting part such as a protrusion for restricting the position of the movable part 11 may be provided so that the movable part 11 does not separate from the movable part 12.

[0168] In addition, although an example in which the light incident point and the light exit point are the same and are the end portions of one optical fiber has been shown, the present disclosure is not limited thereto. The light incident point and the light exit point may be different. For example, the end portion of the first optical fiber that is the light incident point and the end portion of the second optical fiber that is the light exit point may be connected to the movable part 12, respectively.

[0169] Further, the present disclosure may be implemented as a control system or a control method for a movable body included in a measuring device. The control system is realized by, for example, one or more computer devices. Specifically, the control system includes a control unit that controls a drive mechanism for adjusting the positions of a light emission point, a light incidence point, and a second movable body having an optical system. The first light and the second light emitted from the light emission point are irradiated onto a reflector of the first movable body via the optical system. The first reflected light and the second reflected light reflected from the reflector are incident on the light incidence point via the optical system, respectively. The control unit adjusts the position of the second movable body by controlling the drive mechanism based on the intensity of each of the first reflected light and the second reflected light incident on the light incidence point. The first wavelength, which is the peak wavelength of the first light, is different from the second wavelength, which is the peak wavelength of the second light. The optical power of the optical system at the first wavelength is different from the optical power of the optical system at the second wavelength.

[0170] Further, the present disclosure may be implemented as a non-contact measuring device. Specifically, when measuring a measurement object, the first movable body of the measuring device does not have to contact the measurement object. For example, the interferometer may be configured to irradiate light onto the surface of the measurement object and receive the reflected light of the light from the measurement object.

[0171] Note that the one or more computer devices include, for example, a non-volatile memory storing a program, a volatile memory that is a temporary storage area for executing the program, an input / output port, a processor for executing the program, and the like. Further, the control system may be a programmable FPGA (Field Programmable Gate Array) or a reconfigurable processor in which the connection and setting of circuit cells in an LSI can be reconfigured. The functions executed by the control system may be realized by software or by hardware.

[0172] In addition, a method for controlling a movable body included in a measuring device includes a step of controlling a drive mechanism that adjusts the positions of a light emission point, a light incidence point, and a second movable body having an optical system. The first light and the second light emitted from the light emission point are irradiated onto a reflector included in the first movable body via the optical system. The first reflected light and the second reflected light reflected from the reflector are incident on the light incidence point via the optical system, respectively. In the controlling step, the position of the second movable body is adjusted by controlling the drive mechanism based on the intensity of each of the first reflected light and the second reflected light incident on the light incidence point. A first wavelength, which is the peak wavelength of the first light, is different from a second wavelength, which is the peak wavelength of the second light. The optical power of the optical system at the first wavelength is different from the optical power of the optical system at the second wavelength.

[0173] In addition, the present disclosure may be implemented as a program that causes a computer to execute a method for controlling a movable body included in a measuring device. Further, the present disclosure may be implemented as a non-transitory recording medium that stores the program.

[0174] In addition, various changes, replacements, additions, omissions, etc. can be made to each of the above embodiments within the scope of the claims or the equivalent scope thereof.

Industrial Applicability

[0175] The present disclosure can be used in various measuring devices such as inspections of industrial products that require highly accurate distance measurement.

Description of Reference Numerals

[0176] 1, 1A, 2 Measuring device 10 Probe 11, 12 Movable part 13 Drive mechanism 14 Control unit 15 Spring 16, 17, 18 Optical fiber 19 Circulator 20, 20A Light source unit 21, 21a, 21b Laser element 22, 22a, 22b Optical systems 23 Photosynthetic element 30, 30A Light intensity measurement unit 31a, 31b Photodetectors 32 Optical separator 33a, 33b AD conversion circuits 34 Differential operation circuit 40 Interferometer 50 Air supply unit 111 Stylus 112 Slide part 113 Mirror 120a Guide mechanism 120b Probe housing 121 Light emission point 122 Light incident point 123 Collimator lens 125 Condensing lens 129 Optical element 161, 162 Ends

Claims

1. a first movable body having a reflector; a second movable body having a light emission point, a light incident point, and an optical system; a drive mechanism for adjusting the position of the second movable body; a control unit for controlling the drive mechanism, comprising: the first light and the second light emitted from the light emission point are irradiated onto the reflector through the optical system; a first reflected light that is the reflected light of the first light from the reflector and a second reflected light that is the reflected light of the second light from the reflector each enter the light incident point through the optical system; the control unit adjusts the position of the second movable body by controlling the drive mechanism based on the intensity of each of the first reflected light and the second reflected light incident on the light incident point; a first wavelength that is the peak wavelength of the first light is different from a second wavelength that is the peak wavelength of the second light; the optical power of the optical system at the first wavelength is different from the optical power of the optical system at the second wavelength; a measuring device.

2. comprising an optical fiber, wherein both the light emission point and the light incident point are the first end portion of the optical fiber; the measuring device according to claim 1.

3. the first light and the second light have no overlapping wavelength components with a predetermined intensity or more; the measuring device according to claim 1.

4. light for measuring an object enters the optical system, a third wavelength that is the peak wavelength of the light used for measuring the object is different from both the first wavelength and the second wavelength, the optical power of the optical system at the third wavelength is approximately equal to one of the optical power of the optical system at the first wavelength and the optical power of the optical system at the second wavelength, and is different from the other; the measuring device according to any one of claims 1 to 3.

5. comprising an interferometer for interfering the light used for measuring the object; the measuring device according to claim 4.

6. comprising a light intensity measuring unit for measuring the intensity of each of the first reflected light and the second reflected light incident on the light incident point; the measuring device according to any one of claims 1 to 3.

7. the light intensity measuring unit: a first photodiode that photoelectrically converts the first reflected light and outputs a first signal; a second photodiode that photoelectrically converts the second reflected light and outputs a second signal; a first circuit for analog-digital converting the first signal; A second circuit that is different from the first circuit and that performs analog-to-digital conversion on the second signal. The measuring device according to claim 6.

8. The light intensity measurement unit A first photodiode that photoelectrically converts the first reflected light and outputs a first signal; A second photodiode that photoelectrically converts the second reflected light and outputs a second signal; A differential operation circuit that receives inputs of each of the first signal and the second signal. The measuring device according to claim 6.

9. Comprising a light source unit, The light emitted from the light source unit is incident from an end portion of the optical fiber opposite to the first end portion, guided through the optical fiber, and emitted as the first light and the second light from the first end portion. The measuring device according to claim 2.

10. The light source unit A first laser light source that emits the first light; A second laser light source that is different from the first laser light source and that emits the second light. The measuring device according to claim 9.

11. The light source unit is a laser light source including a first active region that emits the first light and a second active region that emits the second light. The measuring device according to claim 9.

12. The light source unit is a gas laser light source that emits the first light and the second light. The measuring device according to claim 9.

13. The optical system includes an achromatic lens. The measuring device according to any one of claims 1 to 3.

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