WO2022149290A1 - Displacement sensor - Google Patents

Displacement sensor Download PDF

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Publication number
WO2022149290A1
WO2022149290A1 PCT/JP2021/007847 JP2021007847W WO2022149290A1 WO 2022149290 A1 WO2022149290 A1 WO 2022149290A1 JP 2021007847 W JP2021007847 W JP 2021007847W WO 2022149290 A1 WO2022149290 A1 WO 2022149290A1
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Prior art keywords
optical fiber
light
displacement sensor
sensor head
core diameter
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PCT/JP2021/007847
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French (fr)
Japanese (ja)
Inventor
潤 ▲高▼嶋
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オムロン株式会社
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Priority to CN202180082421.1A priority Critical patent/CN116601459A/en
Publication of WO2022149290A1 publication Critical patent/WO2022149290A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C3/00—Measuring distances in line of sight; Optical rangefinders
    • G01C3/02—Details
    • G01C3/06—Use of electric means to obtain final indication

Definitions

  • the present invention relates to a displacement sensor.
  • a confocal measuring device using a confocal optical system has been used as a device for measuring the displacement of a measurement object in a non-contact manner.
  • the confocal measuring device described in Patent Document 1 below has a confocal optical system using a diffractive lens between a light source and an object to be measured.
  • the light emitted from the light source is applied to the object to be measured by the confocal optical system at a focal length corresponding to the wavelength. Then, by detecting the peak of the wavelength of the reflected light, the displacement of the object to be measured can be measured.
  • Patent Document 2 discloses a technique relating to a confocal measuring device having improved detection accuracy of the position of a measurement object, and the confocal measuring device includes a second optical fiber connected to a spectroscope and a second optical fiber connected to the spectroscope.
  • the core diameter of the third optical fiber connected to the sensor head is 5 ⁇ m to 25 ⁇ m. Further, it is described that the core diameter may be different between the second optical fiber and the third optical fiber.
  • the measurement accuracy of the confocal measuring device As an index of the measurement accuracy of the confocal measuring device as described above, there are, for example, linearity, static resolution, moving resolution, etc., but when displacement measurement is performed, these are added to obtain the final measurement error.
  • the measurement error due to the movement resolution is generally the largest among these measurement accuracy indexes, and it is one of the important issues to improve this.
  • an object of the present invention is to provide a displacement sensor capable of achieving appropriate measurement accuracy and measurement speed while suppressing a decrease in moving resolution and light receiving amount.
  • the displacement sensor has a light source that outputs white light, a light guide portion that includes at least one optical fiber, and white light that is incident through the light guide portion along the optical axis direction.
  • a sensor head that accommodates a diffractive lens that causes chromatic aberration and irradiates the measurement object with light that causes chromatic aberration, and a light guide unit that collects the reflected light that is reflected by the measurement object and collected by the sensor head.
  • the optical fiber connected to the sensor head comprising a spectroscope, which is acquired through and measures the spectrum of reflected light, has a larger core diameter than the optical fiber connected to the spectroscope.
  • the displacement sensor according to one aspect of the present invention is configured such that the optical fiber connected to the sensor head has a larger core diameter than the optical fiber connected to the spectroscope, and thus has a moving resolution. It is possible to realize appropriate measurement accuracy and measurement speed while suppressing a decrease in the amount of received light.
  • the optical fiber arranged between the sensor head and the spectroscope may include a tapered portion in which the core diameter continuously changes.
  • the optical fiber connected to the sensor head has a larger core diameter than the optical fiber connected to the spectroscope.
  • the light guide unit includes a first optical fiber connected to a light source, a second optical fiber connected to a sensor head, a third optical fiber connected to a spectroscope, a first optical fiber, and a first optical fiber. It may include an optical coupler to which a second optical fiber and a third optical fiber are connected.
  • the optical fiber connected to the sensor head is more than the optical fiber connected to the spectroscope.
  • the second optical fiber may include a tapered portion in which the core diameter continuously changes.
  • the optical fiber connected to the sensor head can be configured to have a larger core diameter than the optical fiber connected to the spectroscope.
  • the third optical fiber may include a tapered portion in which the core diameter continuously changes.
  • the optical fiber connected to the sensor head can be configured to have a larger core diameter than the optical fiber connected to the spectroscope.
  • the second optical fiber may have a core diameter larger than that of the third optical fiber.
  • the second optical fiber and the third optical fiber can be used so that the optical fiber connected to the sensor head has a larger core diameter than the optical fiber connected to the spectroscope. ..
  • the optical fiber connected to the sensor head may have the same numerical aperture as the diffractive lens.
  • the displacement sensor according to one aspect of the present invention can improve the measurement speed while suppressing the deterioration of the measurement accuracy.
  • the optical fiber connected to the sensor head may have a numerical aperture larger than that of the diffractive lens.
  • the displacement sensor according to one aspect of the present invention can improve the measurement accuracy while suppressing the decrease in the measurement speed.
  • a displacement sensor capable of achieving appropriate measurement accuracy and measurement speed while suppressing a decrease in moving resolution and light receiving amount.
  • FIG. 10 It is a block diagram which shows an example of the schematic structure of the displacement sensor 10 which concerns on each embodiment of this invention. It is a figure which shows typically the structure of the displacement sensor 11 which concerns on 1st Embodiment of this invention. It is a figure which shows a specific example of the optical fiber which has a taper part. It is a figure which shows the internal structure of the optical fiber which includes the taper part. It is a figure which shows the evaluation of the displacement sensor 11 shown in FIG. It is a figure which shows the relationship between a sensor head waveform and a spectroscope waveform, and a light-receiving waveform.
  • FIG. 1 is a configuration diagram showing an example of a schematic configuration of a displacement sensor 10 according to each embodiment of the present invention.
  • the displacement sensor 10 includes a controller 100, a light guide unit 200, and a sensor head 300, and measures a distance to a measurement object TA by using a cofocal optical system.
  • the controller 100 includes a light source 110, a spectroscope 120, and a processing unit 130, and the spectroscope 120 further includes a collimator lens 121, a diffraction grating 122, an adjustment lens 123, and a light receiving element 124.
  • the light guide unit 200 is arranged between the controller 100 and the sensor head 300, and has, for example, a first optical fiber 210, a second optical fiber 220, a third optical fiber 230, and an optical coupler 240. Propagate light. A part of the light guide unit 200 may be housed in the controller 100.
  • the sensor head 300 is configured to be detachably attached to the controller 100 via the light guide unit 200, and has, for example, a diffractive lens 310 and an objective lens 320.
  • the light source 110 outputs, for example, white light to the first optical fiber 210.
  • the light source 110 may adjust the amount of white light based on the command of the processing unit 130.
  • the light emitted by the light source 110 is not limited to white light as long as it is light containing a plurality of wavelength components and includes a wavelength range that covers the measurement distance range required for the displacement sensor 10. do not have.
  • One end of the first optical fiber 210 is optically connected to the light source 110, one end of the second optical fiber 220 is optically connected to the sensor head 300, and the third optical fiber 230 is. , One end thereof is optically connected to the spectroscope 120.
  • the other end of the first optical fiber 210, the other end of the third optical fiber 230, and the other end of the second optical fiber 220 are optically coupled via an optical coupler 240.
  • the optical coupler 240 transmits the light (irradiation light) incident from the first optical fiber 210 to the second optical fiber 220, and divides the light (reflected light) incident from the second optical fiber 220 into the first. It is transmitted to the optical fiber 210 and the third optical fiber 230, respectively. The light transmitted from the second optical fiber 220 to the first optical fiber 210 by the optical coupler 240 is terminated by the light source 110.
  • White light output from the light source 110 is incident on the sensor head 300 via the first optical fiber 210, the optical coupler 240, and the second optical fiber 220.
  • the sensor head 300 is a diffractive lens 310 that causes chromatic aberration along the optical axis direction of white light emitted from the end face of the second optical fiber 220, and an objective lens that collects the light that causes chromatic aberration on the measurement object TA. It accommodates 320 and irradiates the measurement object TA with the light that causes the chromatic aberration.
  • the light 410 of the first wavelength, the light 420 of the second wavelength, and the light 430 of the third wavelength are used in the order of relatively short focal lengths.
  • the light 420 of the second wavelength is focused on the surface of the object TA to be measured (second focal position), while the light 410 of the first wavelength is focused on the front side of the object TA to be measured (first focal position).
  • the light 430 of the third wavelength is in focus behind the measurement object TA (third focal position).
  • the light reflected on the surface of the measurement object TA is collected by the objective lens 320, collected through the diffractive lens 310, and returned to the core of the second optical fiber 220.
  • Most of the reflected light of the second wavelength light 420 is incident on the second optical fiber 220 because the light 420 of the second wavelength is focused on the end face of the second optical fiber 220, but the light of other wavelengths is the second optical fiber 220.
  • the end face of the light is out of focus, and most of it does not enter the second optical fiber 220.
  • the reflected light incident on the second optical fiber 220 is transmitted to the third optical fiber 230 via the optical coupler 240 and input to the spectroscope 120.
  • the reflected light incident on the second optical fiber 220 is also transmitted to the first optical fiber 210 via the optical coupler 240, but is terminated by the light source 110.
  • the spectroscope 120 acquires the reflected light reflected by the measurement object TA and collected by the sensor head 300 via the second optical fiber 220, the optical coupler 240, and the third optical fiber 230, and the spectrum of the reflected light is obtained. To measure.
  • the spectroscope 120 includes a collimeter lens 121 that collects the reflected light emitted from the third optical fiber 230, a diffraction grid 122 that disperses the reflected light, an adjustment lens 123 that collects the dispersed reflected light, and the dispersed reflected light. Includes a light receiving element 124 that receives light.
  • the processing unit 130 detects the position of the measurement target TA based on the light receiving amount distribution signal indicating the wavelength and the light amount of the light received by the light receiving element 124. Specifically, the position of the measurement target TA can be measured by detecting the peak of the wavelength in the received light waveform with the spectroscope 120, but in the case of this example, among the light reflected by the measurement target TA.
  • the light 420 of the second wavelength which is focused on the optical fiber, appears as a peak in the spectroscope 120, and the position of the measurement target TA can be detected.
  • the amount of light received that affects the measurement speed of the displacement sensor 10 is affected by the coupling efficiency of the sensor head 300, it is considered that it can be improved by setting a large numerical aperture (NA) of the diffractive lens 310. This is contrary to the measures for improving the movement resolution.
  • the waveform of the light focused by the sensor head 300 (hereinafter, may be referred to as “sensor head waveform” or the like) is combined with the device characteristic waveform (hereinafter, “spectrometer waveform”) caused by a device such as the spectroscope 120.
  • the light receiving waveform light receiving amount distribution signal
  • the light receiving amount may decrease.
  • the inventors of the present invention have found that the second optical fiber 220 connected to the sensor head 300 has a larger core diameter than the third optical fiber 230 connected to the spectroscope 120.
  • FIG. 2 is a diagram schematically showing the configuration of the displacement sensor 11 according to the first embodiment of the present invention.
  • the displacement sensor 11 includes a light source 110, a spectroscope 120, and a sensor head 300, and light is propagated through the light guide unit 201, respectively.
  • the light guide unit 201 includes a first optical fiber 211, a second optical fiber 221 and a third optical fiber 231 and an optical coupler 241.
  • Each optical fiber has the following core diameter and numerical aperture (NA). Has.
  • a tapered portion whose core diameter changes continuously is provided.
  • FIG. 3A is a diagram showing a specific example of an optical fiber provided with a tapered portion
  • FIG. 3B is a diagram showing an internal structure of the optical fiber provided with the tapered portion.
  • the tapered portion is formed by continuously and gradually changing the diameter of the optical fiber over a range of 1 m out of the 3 m optical fiber.
  • a tapered portion is formed at the end portion of the optical fiber, but the present invention is not limited to this. May have a cylindrical shape of 50 ⁇ m and 100 ⁇ m, respectively.
  • the range in which the tapered portion is formed is not limited to about 1/3 or 1 m of the length of the optical fiber, and may be appropriately set according to the core diameters at both ends and the like.
  • the half-price width of the sensor head 300 is affected by the core diameter of the optical fiber on the sensor head 300 side and the NA of the diffractive lens 310, and the moving resolution is affected by the half-price width and spot diameter of the sensor head 300.
  • the NA of the diffractive lens 310 is the same as that of the comparative example.
  • the displacement sensor 11 has a core diameter of 100 ⁇ m of the optical fiber on the sensor head 300 side, which is twice that of the comparative example, but the spot diameter is also doubled accordingly. As a result, the displacement sensor 11 is able to suppress a decrease in movement resolution as compared with the comparative example.
  • the half-value width of the light receiving waveform (light receiving amount distribution signal), the waveform of the light focused by the sensor head 300 (sensor head waveform), and the device characteristic waveform (spectrometer waveform) caused by a device such as the spectroscope 120.
  • the half-value width of the light receiving waveform (light receiving amount distribution signal)
  • the waveform of the light focused by the sensor head 300 (sensor head waveform)
  • the device characteristic waveform (spectrometer waveform) caused by a device such as the spectroscope 120.
  • FIG. 5 is a diagram showing the relationship between the sensor head waveform and the spectroscope waveform and the received light waveform.
  • each waveform shows the amount of light on the vertical axis and the wavelength on the horizontal axis.
  • the received light waveform is obtained by a convolution operation in which the spectroscope waveform is synthesized with the sensor head waveform, and the half width of the received light waveform is approximately the half width of the sensor head waveform and the spectroscope waveform. Calculated based on the full width at half maximum.
  • the full width at half maximum is the length (width) of the intersection of the light receiving amount line of 50% of the light receiving amount peak (maximum value) and the light receiving amount distribution signal, and is an index showing the degree of spread of the Gaussian distribution. be. Since the received light waveform appears as a peak at the wavelength of the light focused on the measurement target TA, the position of the measurement target TA can be appropriately measured by the peak appearing more clearly. .. That is, if the full width at half maximum is small, it can be said that the measurement accuracy is high.
  • the amount of light received may decrease in the relationship between the half-value width of the sensor head waveform and the half-value width of the spectroscope waveform.
  • FIG. 6 is a diagram showing the relationship between the half-value width of the sensor head waveform, the half-value width of the spectroscope waveform, and the amount of received light.
  • the amount of received light decreases as the half-value width of the sensor head waveform / half-value width of the spectroscope waveform decreases.
  • FIG. 5B when the half width of the sensor head waveform is reduced, the half width of the received light waveform is reduced and the half width of the sensor head waveform / half width of the spectroscope waveform is also reduced. As a result, the amount of light received is significantly reduced.
  • the displacement sensor 11 since the light guide portion 201 includes the second optical fiber 221 provided with the tapered portion, the optical fiber connected to the sensor head 300 is It has a larger core diameter than the optical fiber connected to the spectroscope 120. As a result, the amount of light received can be significantly increased while suppressing the decrease in moving resolution. As a result, the displacement sensor 11 can improve the measurement speed while suppressing the deterioration of the measurement accuracy.
  • the optical fiber used in the present embodiment may be a single core having a single core or a multi-core having a plurality of cores, but the above may be applied even when the single core is applied. Since the effect is obtained, it also leads to the reduction of the cost burden due to the application of multi-core.
  • FIG. 7 is a diagram schematically showing the configuration of the displacement sensor 12 according to the second embodiment of the present invention.
  • the displacement sensor 12 has a different NA of the diffractive lens 310 in the sensor head 300 as compared with the displacement sensor 11 according to the first embodiment.
  • the NA of the diffractive lens 310 is 0.05.
  • the NA of the diffractive lens 310 with respect to the NA of the optical fiber on the sensor head 300 side is 1/2, which is the same as the comparative example. Therefore, the displacement sensor 12 and the comparative example have the same coupling efficiency (ratio) of the sensor head, and suppress the decrease in the amount of received light.
  • the core diameter of the optical fiber on the sensor head 300 side is 100 ⁇ m, which is twice that of the comparative example, and the NA of the diffractive lens 310 is 0.05, which is 1/2 that of the comparative example. Therefore, the half price width of the sensor head 300 is the same as that of the comparative example. Further, since the core diameter of the optical fiber on the sensor head 300 side is doubled and the spot diameter is doubled as compared with the comparative example, the moving resolution is greatly improved by averaging within the spot.
  • the diffractive lens of the sensor head 300 has the same configuration as the light guide unit 201 in the displacement sensor 11 according to the first embodiment.
  • the NA is set smaller than the NA of the optical fiber on the sensor head 300 side. This makes it possible to significantly improve the moving resolution while suppressing a decrease in the amount of received light. As a result, the displacement sensor 12 can improve the measurement accuracy while suppressing the decrease in the measurement speed.
  • FIG. 9 is a diagram schematically showing the configuration of the displacement sensor 13 according to the third embodiment of the present invention.
  • the displacement sensor 13 includes a light source 110, a spectroscope 120, and a sensor head 300, and light is propagated through the light guide unit 203, respectively.
  • the light guide unit 203 includes a first optical fiber 213, a second optical fiber 223, a third optical fiber 233, and an optical coupler 243, and each optical fiber has the following core diameter and numerical aperture (NA).
  • NA numerical aperture
  • the optical fiber provided with the tapered portion is the third optical fiber 233, that is, the first embodiment shown in FIG. It is different from the displacement sensor 11 (the second optical fiber 221 is provided with a tapered portion).
  • the first optical fiber 213 has a core diameter twice as large as that of the first optical fiber 211 in the displacement sensor 11 according to the first embodiment shown in FIG. 2, so that the cross-sectional area is quadrupled.
  • NA is 1/2.
  • the amount of light output from the light source 110 and propagated by the first optical fiber 213 is the same as that of the displacement sensor 11 according to the first embodiment.
  • the optical coupler 243 is a coupler that connects two optical fibers having a core diameter of 100 ⁇ m.
  • the third optical fiber 233 is configured to have a tapered portion so that the optical fiber connected to the sensor head 300 has a larger core diameter than the optical fiber connected to the spectroscope 120. ..
  • the displacement sensor 13 can significantly increase the amount of light received (5.5 times) while suppressing the decrease in moving resolution. As a result, the displacement sensor 13 can improve the measurement speed while suppressing the deterioration of the measurement accuracy.
  • the displacement is dislocated.
  • the sensor 13 has the same effect as the displacement sensor 12 according to the second embodiment.
  • the displacement sensor 13 can significantly improve the moving resolution (twice) while suppressing a decrease in the amount of received light. As a result, it is possible to improve the measurement accuracy while suppressing the decrease in the measurement speed.
  • FIG. 10 is a diagram schematically showing the configuration of the displacement sensor 14 according to the fourth embodiment of the present invention.
  • the displacement sensor 14 includes a light source 110, a spectroscope 120, and a sensor head 300, and light is propagated through the light guide unit 204, respectively.
  • the light guide portion 204 has a first optical fiber 214, a second optical fiber 223, a third optical fiber 233, and an optical coupler 244, and each optical fiber has the following core diameter and numerical aperture (NA).
  • NA numerical aperture
  • the optical fiber provided with the tapered portion is the third optical fiber 233, that is, the first embodiment shown in FIG. It is different from the displacement sensor 11 (the second optical fiber 221 is provided with a tapered portion).
  • the displacement sensor 14 according to the fourth embodiment is the same as the displacement sensor 13 according to the third embodiment.
  • the first optical fiber 214 is different from the first optical fiber 213 of the displacement sensor 13 according to the third embodiment shown in FIG. 9, in the displacement sensor 11 according to the first embodiment shown in FIG. It is the same as the first optical fiber 211.
  • the optical coupler 244 is a coupler that couples an optical fiber having a core diameter of 50 ⁇ m and an optical fiber having a core diameter of 100 ⁇ m.
  • the optical fiber connected to the sensor head 300 has a larger core diameter than the optical fiber connected to the spectroscope 120, and in this respect. Is the same as the displacement sensor 13 of the third embodiment, and has the same effect as the displacement sensor 13.
  • the displacement sensor 14 is the displacement sensor 11 according to the first embodiment as shown in FIG.
  • the same effect can be achieved, and the amount of light received can be significantly increased (5.5 times) while suppressing the decrease in moving resolution.
  • the displacement sensor 14 can improve the measurement speed while suppressing the deterioration of the measurement accuracy.
  • the displacement sensor 14 has the same effect as the displacement sensor 12 according to the second embodiment as shown in FIG. It is possible to significantly improve the moving resolution (twice) while suppressing the decrease in the amount of received light. As a result, the displacement sensor 14 can improve the measurement accuracy while suppressing the decrease in the measurement speed.
  • the optical fiber connected to the sensor head 300 by providing a tapered portion in any of the optical fibers included in the light guide portion is connected to the spectroscope 120.
  • it has a core diameter larger than that of the optical fiber to be connected, it may be realized by an optical coupler.
  • the core diameter of the second optical fiber connecting the optical coupler and the sensor head 300 is 100 ⁇ m
  • the core diameter of the second optical fiber connecting the optical coupler and the spectroscope 120 is 50 ⁇ m
  • the core is formed by the optical coupler.
  • a structure that absorbs the difference in diameter may be used.
  • Sensor head (300) and A spectroscope (120) for acquiring the reflected light reflected by the measurement object and collected by the sensor head via the light guide unit and measuring the spectrum of the reflected light is provided.
  • the optical fiber (220,221,223) connected to the sensor head has a larger core diameter than the optical fiber (230,231,233) connected to the spectroscope.

Abstract

Provided is a displacement sensor that is capable of suppressing reduction in movement resolution and the amount of light received while achieving appropriate measurement accuracy and measurement speed. This displacement sensor 11 comprises: a light source 110 that outputs white light; a light guiding part 201 comprising at least one optical fiber; a sensor head 300 that accommodates a diffractive lens 310, which produces chromatic aberration along the optical axis direction in white light that has been introduced via the light guiding part 201, and emits the light that the chromatic aberration has been produced in onto an object TA under measurement; and a spectrometer 120 that acquires, via the light guiding part 201, reflected light that has been reflected by the object TA under measurement and collected by the sensor head 300 and measures the spectrum of the reflected light. Optical fiber connected to the sensor head 300 has a larger core diameter than optical fiber connected to the spectrometer 120.

Description

変位センサDisplacement sensor
　本発明は、変位センサに関する。 The present invention relates to a displacement sensor.
　従来、非接触で計測対象物の変位を計測する装置として、共焦点光学系を利用した共焦点計測装置が用いられている。 Conventionally, a confocal measuring device using a confocal optical system has been used as a device for measuring the displacement of a measurement object in a non-contact manner.
　例えば、下記特許文献１に記載の共焦点計測装置は、光源と計測対象物の間に、回折レンズを用いた共焦点光学系を有する。この共焦点計測装置では、光源からの出射光は、共焦点光学系によって、その波長に応じた焦点距離で計測対象物に照射される。そして、反射光の波長のピークを検出することで、計測対象物の変位を計測することができる。 For example, the confocal measuring device described in Patent Document 1 below has a confocal optical system using a diffractive lens between a light source and an object to be measured. In this confocal measuring device, the light emitted from the light source is applied to the object to be measured by the confocal optical system at a focal length corresponding to the wavelength. Then, by detecting the peak of the wavelength of the reflected light, the displacement of the object to be measured can be measured.
　また、下記特許文献２では、計測対象物の位置の検出精度が高められた共焦点計測装置に関する技術が開示されており、当該共焦点計測装置は、分光器に接続される第２光ファイバ及びセンサヘッドに接続される第３光ファイバのコア径が５μｍから２５μｍである。さらに、第２光ファイバと第３光ファイバとでコア径が異なっていてもよいことが記載されている。 Further, Patent Document 2 below discloses a technique relating to a confocal measuring device having improved detection accuracy of the position of a measurement object, and the confocal measuring device includes a second optical fiber connected to a spectroscope and a second optical fiber connected to the spectroscope. The core diameter of the third optical fiber connected to the sensor head is 5 μm to 25 μm. Further, it is described that the core diameter may be different between the second optical fiber and the third optical fiber.
　ところで、上述のような共焦点計測装置の計測精度の指標として、例えば、リニアリティ、静止分解能及び移動分解能等があるが、変位計測をする場合、これらが加算され、最終的な計測誤差となる。点計測の変位センサでは、一般的に、これらの計測精度の指標の中で、移動分解能による計測誤差が最も大きいため、これを向上させることが重要な課題の１つとなる。 By the way, as an index of the measurement accuracy of the confocal measuring device as described above, there are, for example, linearity, static resolution, moving resolution, etc., but when displacement measurement is performed, these are added to obtain the final measurement error. In the displacement sensor of point measurement, the measurement error due to the movement resolution is generally the largest among these measurement accuracy indexes, and it is one of the important issues to improve this.
米国特許第５７８５６５１号明細書US Pat. No. 5,785,651 特開２０１９－６６３４３号公報Japanese Unexamined Patent Publication No. 2019-66343
　しかしながら、共焦点計測装置において、移動分解能を向上させるためには、光ファイバのコア径を小さくすることが考えられるが、コア径を小さくすれば受光量が低下し、その結果、計測速度が低下してしまうという問題がある。 However, in the confocal measuring device, in order to improve the moving resolution, it is conceivable to reduce the core diameter of the optical fiber, but if the core diameter is reduced, the amount of light received decreases, and as a result, the measurement speed decreases. There is a problem of doing it.
　そこで、本発明は、移動分解能及び受光量の低下を抑止しつつ、適切な計測精度及び計測速度を実現可能な変位センサを提供することを目的とする。 Therefore, an object of the present invention is to provide a displacement sensor capable of achieving appropriate measurement accuracy and measurement speed while suppressing a decrease in moving resolution and light receiving amount.
　本発明の一態様に係る変位センサは、白色光を出力する光源と、少なくとも１つの光ファイバを含む導光部と、導光部を介して入射した白色光に対して、光軸方向に沿って色収差を生じさせる回折レンズを収容し、色収差を生じさせた光を計測対象物に照射するセンサヘッドと、計測対象物で反射されてセンサヘッドにより集光された反射光を、導光部を介して取得し、反射光のスペクトルを計測する分光器と、を備え、センサヘッドに接続される光ファイバは、分光器に接続される光ファイバよりも大きいコア径を有する。 The displacement sensor according to one aspect of the present invention has a light source that outputs white light, a light guide portion that includes at least one optical fiber, and white light that is incident through the light guide portion along the optical axis direction. A sensor head that accommodates a diffractive lens that causes chromatic aberration and irradiates the measurement object with light that causes chromatic aberration, and a light guide unit that collects the reflected light that is reflected by the measurement object and collected by the sensor head. The optical fiber connected to the sensor head, comprising a spectroscope, which is acquired through and measures the spectrum of reflected light, has a larger core diameter than the optical fiber connected to the spectroscope.
　この態様によれば、本発明の一態様に係る変位センサは、センサヘッドに接続される光ファイバが分光器に接続される光ファイバよりも大きいコア径を有するように構成されるため、移動分解能及び受光量の低下を抑止しつつ、適切な計測精度及び計測速度を実現することができる。 According to this aspect, the displacement sensor according to one aspect of the present invention is configured such that the optical fiber connected to the sensor head has a larger core diameter than the optical fiber connected to the spectroscope, and thus has a moving resolution. It is possible to realize appropriate measurement accuracy and measurement speed while suppressing a decrease in the amount of received light.
　上記態様において、センサヘッドと分光器との間に配置される光ファイバは、コア径が連続的に変化するテーパ部を含んでもよい。 In the above aspect, the optical fiber arranged between the sensor head and the spectroscope may include a tapered portion in which the core diameter continuously changes.
　この態様によれば、センサヘッドと分光器との間に配置される光ファイバがテーパ部を含むため、センサヘッドに接続される光ファイバが分光器に接続される光ファイバよりも大きいコア径を有するように構成することができる。 According to this aspect, since the optical fiber arranged between the sensor head and the spectroscope includes a tapered portion, the optical fiber connected to the sensor head has a larger core diameter than the optical fiber connected to the spectroscope. Can be configured to have.
　上記態様において、導光部は、光源と接続される第１光ファイバと、センサヘッドと接続される第２光ファイバと、分光器と接続される第３光ファイバと、第１光ファイバ、第２光ファイバ及び第３光ファイバが接続される光カプラと、を含んでもよい。 In the above embodiment, the light guide unit includes a first optical fiber connected to a light source, a second optical fiber connected to a sensor head, a third optical fiber connected to a spectroscope, a first optical fiber, and a first optical fiber. It may include an optical coupler to which a second optical fiber and a third optical fiber are connected.
　この態様によれば、導光部が第１光ファイバと第２光ファイバと第３光ファイバと光カプラとを含むため、センサヘッドに接続される光ファイバが分光器に接続される光ファイバよりも大きいコア径を有するように構成することができる。 According to this aspect, since the light guide portion includes the first optical fiber, the second optical fiber, the third optical fiber, and the optical coupler, the optical fiber connected to the sensor head is more than the optical fiber connected to the spectroscope. Can also be configured to have a large core diameter.
　上記態様において、第２光ファイバは、コア径が連続的に変化するテーパ部を含んでもよい。 In the above aspect, the second optical fiber may include a tapered portion in which the core diameter continuously changes.
　この態様によれば、第２光ファイバがテーパ部を含むため、センサヘッドに接続される光ファイバが分光器に接続される光ファイバよりも大きいコア径を有するように構成することができる。 According to this aspect, since the second optical fiber includes a tapered portion, the optical fiber connected to the sensor head can be configured to have a larger core diameter than the optical fiber connected to the spectroscope.
　上記態様において、第３光ファイバは、コア径が連続的に変化するテーパ部を含んでもよい。 In the above aspect, the third optical fiber may include a tapered portion in which the core diameter continuously changes.
　この態様によれば、第３光ファイバがテーパ部を含むため、センサヘッドに接続される光ファイバが分光器に接続される光ファイバよりも大きいコア径を有するように構成することができる。 According to this aspect, since the third optical fiber includes a tapered portion, the optical fiber connected to the sensor head can be configured to have a larger core diameter than the optical fiber connected to the spectroscope.
　上記態様において、第２光ファイバは、第３光ファイバよりも大きいコア径を有してもよい。 In the above aspect, the second optical fiber may have a core diameter larger than that of the third optical fiber.
　この態様によれば、第２光ファイバ及び第３光ファイバを用いて、センサヘッドに接続される光ファイバが分光器に接続される光ファイバよりも大きいコア径を有するように構成することができる。 According to this aspect, the second optical fiber and the third optical fiber can be used so that the optical fiber connected to the sensor head has a larger core diameter than the optical fiber connected to the spectroscope. ..
　上記態様において、センサヘッドに接続される光ファイバは、回折レンズと同一の開口数を有してもよい。 In the above aspect, the optical fiber connected to the sensor head may have the same numerical aperture as the diffractive lens.
　この態様によれば、センサヘッドに接続される光ファイバは、回折レンズと同一の開口数を有するため、移動分解能の低下を抑止しつつ、受光量を向上させることができる。その結果、本発明の一態様に係る変位センサは、計測精度の低下を抑止しつつ、計測速度を向上させることができる。 According to this aspect, since the optical fiber connected to the sensor head has the same numerical aperture as the diffractive lens, it is possible to improve the amount of light received while suppressing the decrease in moving resolution. As a result, the displacement sensor according to one aspect of the present invention can improve the measurement speed while suppressing the deterioration of the measurement accuracy.
　上記態様において、センサヘッドに接続される光ファイバは、回折レンズよりも大きい開口数を有してもよい。 In the above aspect, the optical fiber connected to the sensor head may have a numerical aperture larger than that of the diffractive lens.
　この態様によれば、センサヘッドに接続される光ファイバは、回折レンズよりも大きい開口数を有するため、受光量の低下を抑止しつつ、移動分解能を向上させることができる。その結果、本発明の一態様に係る変位センサは、計測速度の低下を抑止しつつ、計測精度を向上させることができる。 According to this aspect, since the optical fiber connected to the sensor head has a numerical aperture larger than that of the diffractive lens, it is possible to improve the moving resolution while suppressing a decrease in the amount of received light. As a result, the displacement sensor according to one aspect of the present invention can improve the measurement accuracy while suppressing the decrease in the measurement speed.
　本発明によれば、移動分解能及び受光量の低下を抑止しつつ、適切な計測精度及び計測速度を実現可能な変位センサを提供することができる。 According to the present invention, it is possible to provide a displacement sensor capable of achieving appropriate measurement accuracy and measurement speed while suppressing a decrease in moving resolution and light receiving amount.
本発明の各実施形態に係る変位センサ１０の概略構成の一例を示す構成図である。It is a block diagram which shows an example of the schematic structure of the displacement sensor 10 which concerns on each embodiment of this invention. 本発明の第１実施形態に係る変位センサ１１の構成を模式的に示す図である。It is a figure which shows typically the structure of the displacement sensor 11 which concerns on 1st Embodiment of this invention. テーパ部を備える光ファイバの一具体例を示す図である。It is a figure which shows a specific example of the optical fiber which has a taper part. テーパ部を備える光ファイバの内部構造を示す図である。It is a figure which shows the internal structure of the optical fiber which includes the taper part. 図２に示された変位センサ１１の評価を示す図である。It is a figure which shows the evaluation of the displacement sensor 11 shown in FIG. センサヘッド波形及び分光器波形と、受光波形との関係を示す図である。It is a figure which shows the relationship between a sensor head waveform and a spectroscope waveform, and a light-receiving waveform. センサヘッド波形の半値幅及び分光器波形の半値幅と、受光量との関係を示す図である。It is a figure which shows the relationship between the half-value width of a sensor head waveform, the half-value width of a spectroscope waveform, and the amount of received light. 本発明の第２実施形態に係る変位センサ１２の構成を模式的に示す図である。It is a figure which shows typically the structure of the displacement sensor 12 which concerns on 2nd Embodiment of this invention. 図７に示された変位センサ１２の評価を示す図である。It is a figure which shows the evaluation of the displacement sensor 12 shown in FIG. 7. 本発明の第３実施形態に係る変位センサ１３の構成を模式的に示す図である。It is a figure which shows typically the structure of the displacement sensor 13 which concerns on 3rd Embodiment of this invention. 本発明の第４実施形態に係る変位センサ１４の構成を模式的に示す図である。It is a figure which shows typically the structure of the displacement sensor 14 which concerns on 4th Embodiment of this invention.
　以下、本発明の好適な実施形態について、図面を参照しながら具体的に説明する。なお、以下で説明する実施形態は、あくまで、本発明を実施するための具体的な一例を挙げるものであって、本発明を限定的に解釈させるものではない。また、説明の理解を容易にするため、各図面において同一の構成要素に対しては可能な限り同一の符号を付して、重複する説明を省略する場合がある。 Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings. It should be noted that the embodiments described below are merely specific examples for carrying out the present invention, and do not limit the interpretation of the present invention. Further, in order to facilitate understanding of the description, the same components may be designated by the same reference numerals as much as possible in each drawing, and duplicate description may be omitted.
　先ず、本発明の各実施形態に係る変位センサの基本的な構成について説明する。 First, the basic configuration of the displacement sensor according to each embodiment of the present invention will be described.
［変位センサの基本構成］
　図１は、本発明の各実施形態に係る変位センサ１０の概略構成の一例を示す構成図である。図１に示されるように、変位センサ１０は、コントローラ１００と、導光部２００と、センサヘッド３００とを備え、共焦点光学系を利用することによって計測対象物ＴＡまでの距離を計測する。 [Basic configuration of displacement sensor]
FIG. 1 is a configuration diagram showing an example of a schematic configuration of a displacement sensor 10 according to each embodiment of the present invention. As shown in FIG. 1, the displacement sensor 10 includes a controller 100, a light guide unit 200, and a sensor head 300, and measures a distance to a measurement object TA by using a cofocal optical system.
　コントローラ１００は、光源１１０と、分光器１２０と、処理部１３０とを備え、さらに、当該分光器１２０は、コリメータレンズ１２１と、回折格子１２２と、調整レンズ１２３と、受光素子１２４とを有する。 The controller 100 includes a light source 110, a spectroscope 120, and a processing unit 130, and the spectroscope 120 further includes a collimator lens 121, a diffraction grating 122, an adjustment lens 123, and a light receiving element 124.
　導光部２００は、コントローラ１００とセンサヘッド３００との間に配置され、例えば、第１光ファイバ２１０と、第２光ファイバ２２０と、第３光ファイバ２３０と、光カプラ２４０とを有し、光を伝搬する。なお、導光部２００の一部は、コントローラ１００に収容されても構わない。 The light guide unit 200 is arranged between the controller 100 and the sensor head 300, and has, for example, a first optical fiber 210, a second optical fiber 220, a third optical fiber 230, and an optical coupler 240. Propagate light. A part of the light guide unit 200 may be housed in the controller 100.
　センサヘッド３００は、導光部２００を介してコントローラ１００に脱着自在に構成されており、例えば、回折レンズ３１０と、対物レンズ３２０とを有する。 The sensor head 300 is configured to be detachably attached to the controller 100 via the light guide unit 200, and has, for example, a diffractive lens 310 and an objective lens 320.
　光源１１０は、例えば、白色光を第１光ファイバ２１０に出力する。光源１１０は、処理部１３０の指令に基づいて、白色光の光量を調整してもよい。なお、光源１１０が発する光は、複数の波長成分を含む光であって、変位センサ１０に要求される測定距離範囲をカバーする波長範囲を含む光であれば、白色光に限定されるものではない。 The light source 110 outputs, for example, white light to the first optical fiber 210. The light source 110 may adjust the amount of white light based on the command of the processing unit 130. The light emitted by the light source 110 is not limited to white light as long as it is light containing a plurality of wavelength components and includes a wavelength range that covers the measurement distance range required for the displacement sensor 10. do not have.
　第１光ファイバ２１０は、その一端が光源１１０と光学的に接続されており、第２光ファイバ２２０は、その一端がセンサヘッド３００と光学的に接続しされており、第３光ファイバ２３０は、その一端が分光器１２０と光学的に接続されている。そして、第１光ファイバ２１０の他端及び第３光ファイバ２３０の他端と、第２光ファイバ２２０の他端とは、光カプラ２４０を介して光学的に結合されている。 One end of the first optical fiber 210 is optically connected to the light source 110, one end of the second optical fiber 220 is optically connected to the sensor head 300, and the third optical fiber 230 is. , One end thereof is optically connected to the spectroscope 120. The other end of the first optical fiber 210, the other end of the third optical fiber 230, and the other end of the second optical fiber 220 are optically coupled via an optical coupler 240.
　光カプラ２４０は、第１光ファイバ２１０から入射された光（照射光）を第２光ファイバ２２０に伝送するとともに、第２光ファイバ２２０から入射された光（反射光）を分割して第１光ファイバ２１０及び第３光ファイバ２３０にそれぞれ伝送する。なお、光カプラ２４０によって第２光ファイバ２２０から第１光ファイバ２１０に伝送された光は、光源１１０において終端される。 The optical coupler 240 transmits the light (irradiation light) incident from the first optical fiber 210 to the second optical fiber 220, and divides the light (reflected light) incident from the second optical fiber 220 into the first. It is transmitted to the optical fiber 210 and the third optical fiber 230, respectively. The light transmitted from the second optical fiber 220 to the first optical fiber 210 by the optical coupler 240 is terminated by the light source 110.
　センサヘッド３００には、第１光ファイバ２１０、光カプラ２４０及び第２光ファイバ２２０を介して、光源１１０から出力された白色光が入射される。センサヘッド３００は、第２光ファイバ２２０の端面から出射された白色光を、光軸方向に沿って色収差を生じさせる回折レンズ３１０と、色収差を生じさせた光を計測対象物ＴＡに集める対物レンズ３２０とを収容し、当該色収差を生じさせた光を計測対象物ＴＡに照射する。 White light output from the light source 110 is incident on the sensor head 300 via the first optical fiber 210, the optical coupler 240, and the second optical fiber 220. The sensor head 300 is a diffractive lens 310 that causes chromatic aberration along the optical axis direction of white light emitted from the end face of the second optical fiber 220, and an objective lens that collects the light that causes chromatic aberration on the measurement object TA. It accommodates 320 and irradiates the measurement object TA with the light that causes the chromatic aberration.
　図１に示される例では、焦点距離が相対的に短い順に、第１波長の光４１０、第２波長の光４２０及び第３波長の光４３０としている。第２波長の光４２０は計測対象物ＴＡの表面で焦点が合う（第２焦点位置）が、第１波長の光４１０は計測対象物ＴＡの手前側で焦点が合い（第１焦点位置）、第３波長の光４３０は計測対象物ＴＡの奥側で焦点が合う（第３焦点位置）。 In the example shown in FIG. 1, the light 410 of the first wavelength, the light 420 of the second wavelength, and the light 430 of the third wavelength are used in the order of relatively short focal lengths. The light 420 of the second wavelength is focused on the surface of the object TA to be measured (second focal position), while the light 410 of the first wavelength is focused on the front side of the object TA to be measured (first focal position). The light 430 of the third wavelength is in focus behind the measurement object TA (third focal position).
　計測対象物ＴＡの表面で反射した光は、対物レンズ３２０によって集められ、回折レンズ３１０を通って集光されて、第２光ファイバ２２０のコアに返送される。反射光のうち第２波長の光４２０は、第２光ファイバ２２０の端面で焦点が合うため、そのほとんどが第２光ファイバ２２０に入射するが、その他の波長の光は、第２光ファイバ２２０の端面で焦点が合わず、そのほとんどが第２光ファイバ２２０に入射しない。第２光ファイバ２２０に入射した反射光は、光カプラ２４０を経由して第３光ファイバ２３０に伝送され、分光器１２０に入力される。なお、第２光ファイバ２２０に入射した反射光は、光カプラ２４０を経由して第１光ファイバ２１０にも伝送されるが、光源１１０にて終端される。 The light reflected on the surface of the measurement object TA is collected by the objective lens 320, collected through the diffractive lens 310, and returned to the core of the second optical fiber 220. Most of the reflected light of the second wavelength light 420 is incident on the second optical fiber 220 because the light 420 of the second wavelength is focused on the end face of the second optical fiber 220, but the light of other wavelengths is the second optical fiber 220. The end face of the light is out of focus, and most of it does not enter the second optical fiber 220. The reflected light incident on the second optical fiber 220 is transmitted to the third optical fiber 230 via the optical coupler 240 and input to the spectroscope 120. The reflected light incident on the second optical fiber 220 is also transmitted to the first optical fiber 210 via the optical coupler 240, but is terminated by the light source 110.
　分光器１２０は、計測対象物ＴＡで反射されてセンサヘッド３００により集光された反射光を、第２光ファイバ２２０、光カプラ２４０及び第３光ファイバ２３０を介して取得し、反射光のスペクトルを計測する。分光器１２０は、第３光ファイバ２３０から出射された反射光を集めるコリメータレンズ１２１と、反射光を分光する回折格子１２２と、分光された反射光を集める調整レンズ１２３と、分光された反射光を受光する受光素子１２４とを含む。 The spectroscope 120 acquires the reflected light reflected by the measurement object TA and collected by the sensor head 300 via the second optical fiber 220, the optical coupler 240, and the third optical fiber 230, and the spectrum of the reflected light is obtained. To measure. The spectroscope 120 includes a collimeter lens 121 that collects the reflected light emitted from the third optical fiber 230, a diffraction grid 122 that disperses the reflected light, an adjustment lens 123 that collects the dispersed reflected light, and the dispersed reflected light. Includes a light receiving element 124 that receives light.
　処理部１３０は、受光素子１２４によって受光された光の波長及び光量を示す受光量分布信号に基づいて、計測対象物ＴＡの位置を検出する。具体的には、分光器１２０によって受光波形における波長のピークを検出することで計測対象物ＴＡの位置を計測することができるが、本例の場合、計測対象物ＴＡで反射された光のうち、光ファイバで焦点が合う第２波長の光４２０が分光器１２０においてピークとして表われ、計測対象物ＴＡの位置を検出することができる。 The processing unit 130 detects the position of the measurement target TA based on the light receiving amount distribution signal indicating the wavelength and the light amount of the light received by the light receiving element 124. Specifically, the position of the measurement target TA can be measured by detecting the peak of the wavelength in the received light waveform with the spectroscope 120, but in the case of this example, among the light reflected by the measurement target TA. The light 420 of the second wavelength, which is focused on the optical fiber, appears as a peak in the spectroscope 120, and the position of the measurement target TA can be detected.
［移動分解能と受光量］
　ここで、変位センサ１０の計測精度に関して、計測誤差に与える影響が大きい移動分解能について、説明する。移動分解能は、被写界深度及び平均化効果に影響されることから、光ファイバのコア径や回折レンズ３１０の開口数（以下、「ＮＡ（numerical aperture）」と称する場合もある。）を小さく設定すれば、改善すると考えられる。 [Movement resolution and light reception amount]
Here, regarding the measurement accuracy of the displacement sensor 10, the movement resolution having a large influence on the measurement error will be described. Since the moving resolution is affected by the depth of field and the averaging effect, the core diameter of the optical fiber and the numerical aperture of the diffractive lens 310 (hereinafter, may be referred to as "NA (numerical aperture)") are reduced. If set, it will be improved.
　一方、変位センサ１０の計測速度に影響を与える受光量は、センサヘッド３００の結合効率に影響されることから、回折レンズ３１０の開口数（ＮＡ）を大きく設定すれば、改善すると考えられ、上記移動分解能の改善策とは相反するものである。また、センサヘッド３００によって集光された光の波形（以下、「センサヘッド波形」等と称する場合もある。）に、分光器１２０等のデバイスに起因するデバイス特性波形（以下、「分光器波形」等と称する場合もある。）が合成される畳み込み演算によって受光波形（受光量分布信号）が求められる際に、受光量が低下する場合もある。 On the other hand, since the amount of light received that affects the measurement speed of the displacement sensor 10 is affected by the coupling efficiency of the sensor head 300, it is considered that it can be improved by setting a large numerical aperture (NA) of the diffractive lens 310. This is contrary to the measures for improving the movement resolution. Further, the waveform of the light focused by the sensor head 300 (hereinafter, may be referred to as “sensor head waveform” or the like) is combined with the device characteristic waveform (hereinafter, “spectrometer waveform”) caused by a device such as the spectroscope 120. When the light receiving waveform (light receiving amount distribution signal) is obtained by the convolution calculation in which the light receiving amount is synthesized, the light receiving amount may decrease.
　そこで、本発明の発明者らは、センサヘッド３００に接続される第２光ファイバ２２０は、分光器１２０に接続される第３光ファイバ２３０よりも大きいコア径を有すること見出した。 Therefore, the inventors of the present invention have found that the second optical fiber 220 connected to the sensor head 300 has a larger core diameter than the third optical fiber 230 connected to the spectroscope 120.
　以下、導光部２００を構成する光ファイバ等の具体的な実施形態について、詳細に説明する。 Hereinafter, specific embodiments of the optical fiber and the like constituting the light guide unit 200 will be described in detail.
　＜第１実施形態＞
　図２は、本発明の第１実施形態に係る変位センサ１１の構成を模式的に示す図である。図２において、変位センサ１１は、光源１１０と分光器１２０とセンサヘッド３００とを備え、それぞれ導光部２０１を介して光が伝搬される。導光部２０１は、第１光ファイバ２１１と、第２光ファイバ２２１と、第３光ファイバ２３１と、光カプラ２４１とを有し、各光ファイバは、以下のコア径及び開口数（ＮＡ）を有する。 <First Embodiment>
FIG. 2 is a diagram schematically showing the configuration of the displacement sensor 11 according to the first embodiment of the present invention. In FIG. 2, the displacement sensor 11 includes a light source 110, a spectroscope 120, and a sensor head 300, and light is propagated through the light guide unit 201, respectively. The light guide unit 201 includes a first optical fiber 211, a second optical fiber 221 and a third optical fiber 231 and an optical coupler 241. Each optical fiber has the following core diameter and numerical aperture (NA). Has.
　第１光ファイバ２１１：コア径＝５０μｍ、ＮＡ＝０．２
　第２光ファイバ２２１：コア径＝５０μｍ、ＮＡ＝０．２（光カプラ２４１側）
　　　　　　　　　　　：コア径＝１００μｍ、ＮＡ＝０．１（センサヘッド３００側）
　第３光ファイバ２３１：コア径＝５０μｍ、ＮＡ＝０．２ First optical fiber 211: core diameter = 50 μm, NA = 0.2
2nd optical fiber 221: Core diameter = 50 μm, NA = 0.2 (optical coupler 241 side)
: Core diameter = 100 μm, NA = 0.1 (sensor head 300 side)
Third optical fiber 231: Core diameter = 50 μm, NA = 0.2
　ここで、第２光ファイバ２２１は、光カプラ２４１側では、コア径＝５０μｍであり、センサヘッド３００側では、コア径＝１００μｍであり、光カプラ２４１とセンサヘッド３００との間のうち、一部、コア径が連続的に変化するテーパ部を備える。 Here, the second optical fiber 221 has a core diameter = 50 μm on the optical coupler 241 side and a core diameter = 100 μm on the sensor head 300 side, and one of between the optical coupler 241 and the sensor head 300. A tapered portion whose core diameter changes continuously is provided.
　図３Ａは、テーパ部を備える光ファイバの一具体例を示す図であり、図３Ｂは、テーパ部を備える光ファイバの内部構造を示す図である。図３Ａに示されるように、３ｍの光ファイバのうち１ｍの範囲に亘って光ファイバの径が連続的に徐々に変化することによってテーパ部が形成されている。 FIG. 3A is a diagram showing a specific example of an optical fiber provided with a tapered portion, and FIG. 3B is a diagram showing an internal structure of the optical fiber provided with the tapered portion. As shown in FIG. 3A, the tapered portion is formed by continuously and gradually changing the diameter of the optical fiber over a range of 1 m out of the 3 m optical fiber.
　なお、図３Ａに示される一具体例では、光ファイバの端部にテーパ部が形成されているが、これに限定されるものではなく、例えば、中央部等にテーパ部を形成し、両端部は、それぞれ５０μｍ及び１００μｍの円柱形状であっても構わない。 In one specific example shown in FIG. 3A, a tapered portion is formed at the end portion of the optical fiber, but the present invention is not limited to this. May have a cylindrical shape of 50 μm and 100 μm, respectively.
　また、テーパ部を形成する範囲について、光ファイバの長さの１／３程度又は１ｍに限定されるものではなく、両端のコア径等に応じて適宜設定されるようにしても構わない。 Further, the range in which the tapered portion is formed is not limited to about 1/3 or 1 m of the length of the optical fiber, and may be appropriately set according to the core diameters at both ends and the like.
　また、図２に示されたように、第２光ファイバ２２１は、光カプラ２４１側では、コア径＝５０μｍであり、センサヘッド３００側では、コア径＝１００μｍであることから、光カプラ２４１側では、ＮＡ＝０．２であり、センサヘッド３００側ではＮＡ＝０．１となる（ラグランジュの不変量）。 Further, as shown in FIG. 2, since the second optical fiber 221 has a core diameter = 50 μm on the optical coupler 241 side and a core diameter = 100 μm on the sensor head 300 side, the optical coupler 241 side. Then, NA = 0.2, and NA = 0.1 on the sensor head 300 side (invariant amount of Lagrange).
　さらに、本実施形態では、センサヘッド３００に収容される回折レンズ３１０について、ＮＡ＝０．１であり、当該センサヘッド３００に接続される第２光ファイバ２２１のＮＡと同一に設定されている。 Further, in the present embodiment, the diffractive lens 310 housed in the sensor head 300 has NA = 0.1, which is set to be the same as the NA of the second optical fiber 221 connected to the sensor head 300.
［変位センサ１１の評価］
　図４は、図２に示された変位センサ１１の評価を示す図である。図４に示されるように、変位センサ１１では、比較例（全てコア径＝５０μｍ及びＮＡ＝０．２の光ファイバ）と比べて、移動分解能の低下を抑止しつつ、受光量を大幅に増加させている（５．５倍）。 [Evaluation of displacement sensor 11]
FIG. 4 is a diagram showing an evaluation of the displacement sensor 11 shown in FIG. As shown in FIG. 4, the displacement sensor 11 significantly increases the amount of light received while suppressing the decrease in moving resolution as compared with the comparative example (all optical fibers having a core diameter of 50 μm and NA = 0.2). (5.5 times).
　より詳細には、センサヘッド３００の半値幅は、センサヘッド３００側の光ファイバのコア径と回折レンズ３１０のＮＡにより影響され、移動分解能は、センサヘッド３００の半値幅及びスポット径により影響されるところ、変位センサ１１では、比較例と比べて、回折レンズ３１０のＮＡ＝０．１で同一である。また、変位センサ１１は、センサヘッド３００側の光ファイバのコア径＝１００μｍであり、比較例に比べて２倍であるが、それに伴い、スポット径も２倍になる。これにより、変位センサ１１は、比較例と比べて、移動分解能の低下を抑止することができている。 More specifically, the half-price width of the sensor head 300 is affected by the core diameter of the optical fiber on the sensor head 300 side and the NA of the diffractive lens 310, and the moving resolution is affected by the half-price width and spot diameter of the sensor head 300. However, in the displacement sensor 11, the NA of the diffractive lens 310 is the same as that of the comparative example. Further, the displacement sensor 11 has a core diameter of 100 μm of the optical fiber on the sensor head 300 side, which is twice that of the comparative example, but the spot diameter is also doubled accordingly. As a result, the displacement sensor 11 is able to suppress a decrease in movement resolution as compared with the comparative example.
　ここで、受光波形（受光量分布信号）、センサヘッド３００によって集光された光の波形（センサヘッド波形）、及び分光器１２０等のデバイスに起因するデバイス特性波形（分光器波形）の半値幅について説明する。 Here, the half-value width of the light receiving waveform (light receiving amount distribution signal), the waveform of the light focused by the sensor head 300 (sensor head waveform), and the device characteristic waveform (spectrometer waveform) caused by a device such as the spectroscope 120. Will be explained.
　図５は、センサヘッド波形及び分光器波形と、受光波形との関係を示す図である。図５において、各波形は、縦軸に光量を示し、横軸に波長を示している。そして、図５に示されるように、受光波形は、センサヘッド波形に分光器波形が合成される畳み込み演算によって求められ、受光波形の半値幅は、概ねセンサヘッド波形の半値幅と分光器波形の半値幅とに基づいて算出される。 FIG. 5 is a diagram showing the relationship between the sensor head waveform and the spectroscope waveform and the received light waveform. In FIG. 5, each waveform shows the amount of light on the vertical axis and the wavelength on the horizontal axis. Then, as shown in FIG. 5, the received light waveform is obtained by a convolution operation in which the spectroscope waveform is synthesized with the sensor head waveform, and the half width of the received light waveform is approximately the half width of the sensor head waveform and the spectroscope waveform. Calculated based on the full width at half maximum.
　半値幅とは、受光量のピーク（最大値）の５０％の受光量の線と受光量分布信号との２つの交点の長さ（幅）であり、ガウス分布の広がりの程度を表す指標である。受光波形は、計測対象物ＴＡで焦点が合った光の波長がピークとなって表われるため、当該ピークがより鮮明に表われることにより、計測対象物ＴＡの位置を適切に計測することができる。すなわち、半値幅が小さければ、計測精度は高いと言える。 The full width at half maximum is the length (width) of the intersection of the light receiving amount line of 50% of the light receiving amount peak (maximum value) and the light receiving amount distribution signal, and is an index showing the degree of spread of the Gaussian distribution. be. Since the received light waveform appears as a peak at the wavelength of the light focused on the measurement target TA, the position of the measurement target TA can be appropriately measured by the peak appearing more clearly. .. That is, if the full width at half maximum is small, it can be said that the measurement accuracy is high.
　一方、センサヘッド波形の半値幅と分光器波形の半値幅との関係において、受光量が低下する場合がある。 On the other hand, the amount of light received may decrease in the relationship between the half-value width of the sensor head waveform and the half-value width of the spectroscope waveform.
　図６は、センサヘッド波形の半値幅及び分光器波形の半値幅と、受光量との関係を示す図である。図６に示されるように、センサヘッド波形の半値幅／分光器波形の半値幅が小さくなるに従って、受光量が低下している。例えば、図５（Ｂ）に示されるように、センサヘッド波形の半値幅を小さくなると、受光波形の半値幅が小さくなるとともに、センサヘッド波形の半値幅／分光器波形の半値幅も小さくなる。これにより、受光量が著しく低下することになる。 FIG. 6 is a diagram showing the relationship between the half-value width of the sensor head waveform, the half-value width of the spectroscope waveform, and the amount of received light. As shown in FIG. 6, the amount of received light decreases as the half-value width of the sensor head waveform / half-value width of the spectroscope waveform decreases. For example, as shown in FIG. 5B, when the half width of the sensor head waveform is reduced, the half width of the received light waveform is reduced and the half width of the sensor head waveform / half width of the spectroscope waveform is also reduced. As a result, the amount of light received is significantly reduced.
　なお、図４において、変位センサ１１を評価する際に、全て、コア径＝５０μｍ、ＮＡ＝０．２の光ファイバを用いた比較例を示したが、全て、コア径＝１００μｍ、ＮＡ＝０．１の光ファイバを用いることも考えられる。しかし、この場合、センサヘッド波形の半値幅及び分光器波形の半値幅の両方が大きくなるため、受光波形の半値幅は、図４に示した比較例と比べて概ね２倍になる。これにより、リニアリティ及び静止分解能が悪化し、計測精度が著しく低下することになる。 In FIG. 4, when evaluating the displacement sensor 11, comparative examples using optical fibers having a core diameter of 50 μm and NA = 0.2 are shown, but all of them have a core diameter of 100 μm and NA = 0. It is also conceivable to use the optical fiber of 1.1. However, in this case, since both the half-value width of the sensor head waveform and the half-value width of the spectroscope waveform are large, the half-value width of the received light waveform is approximately double that of the comparative example shown in FIG. As a result, the linearity and the static resolution are deteriorated, and the measurement accuracy is remarkably lowered.
　以上のように、本発明の第１実施形態に係る変位センサ１１によれば、導光部２０１がテーパ部を備える第２光ファイバ２２１を含むため、センサヘッド３００に接続される光ファイバは、分光器１２０に接続される光ファイバよりも大きいコア径を有する。これにより、移動分解能の低下を抑止しつつ、受光量を大幅に増加させることができる。その結果、変位センサ１１は、計測精度の低下を抑止しつつ、計測速度を向上させることができる。 As described above, according to the displacement sensor 11 according to the first embodiment of the present invention, since the light guide portion 201 includes the second optical fiber 221 provided with the tapered portion, the optical fiber connected to the sensor head 300 is It has a larger core diameter than the optical fiber connected to the spectroscope 120. As a result, the amount of light received can be significantly increased while suppressing the decrease in moving resolution. As a result, the displacement sensor 11 can improve the measurement speed while suppressing the deterioration of the measurement accuracy.
　なお、本実施形態で用いられる光ファイバは、単一のコアを有するシングルコアであっても、複数のコアを有するマルチコアであっても構わないが、シングルコアを適用した場合であっても上述した効果が得られるため、マルチコアを適用することによるコスト負担を軽減することにも繋がる。 The optical fiber used in the present embodiment may be a single core having a single core or a multi-core having a plurality of cores, but the above may be applied even when the single core is applied. Since the effect is obtained, it also leads to the reduction of the cost burden due to the application of multi-core.
　以降、第２～第４実施形態について説明するが、各実施形態では、主に、本発明の第１実施形態と異なる構成について詳しく説明し、第１実施形態と共通の事柄についての記述を省略又は簡略化する。 Hereinafter, the second to fourth embodiments will be described, but in each embodiment, the configuration different from the first embodiment of the present invention will be mainly described, and the description of matters common to the first embodiment will be omitted. Or simplify.
　＜第２実施形態＞
　図７は、本発明の第２実施形態に係る変位センサ１２の構成を模式的に示す図である。図７において、変位センサ１２は、第１実施形態に係る変位センサ１１と比べて、センサヘッド３００における回折レンズ３１０のＮＡが異なる。本実施形態では、回折レンズ３１０のＮＡ＝０．０５である。 <Second Embodiment>
FIG. 7 is a diagram schematically showing the configuration of the displacement sensor 12 according to the second embodiment of the present invention. In FIG. 7, the displacement sensor 12 has a different NA of the diffractive lens 310 in the sensor head 300 as compared with the displacement sensor 11 according to the first embodiment. In this embodiment, the NA of the diffractive lens 310 is 0.05.
　図８は、図７に示された変位センサ１２の評価を示す図である。図８に示されるように、変位センサ１２では、比較例（全てコア径＝５０μｍ及びＮＡ＝０．２の光ファイバ）と比べて、受光量の低下を抑止しつつ、移動分解能を大幅に改善させている（２倍）。 FIG. 8 is a diagram showing the evaluation of the displacement sensor 12 shown in FIG. 7. As shown in FIG. 8, the displacement sensor 12 significantly improves the moving resolution while suppressing a decrease in the amount of received light as compared with the comparative example (all optical fibers having a core diameter of 50 μm and NA = 0.2). (Double).
　より詳細には、変位センサ１２では、センサヘッド３００側の光ファイバのＮＡに対する回折レンズ３１０のＮＡは１／２であって、比較例と同一である。このため、変位センサ１２と比較例とは、センサヘッドの結合効率（比）も同一であり、受光量の低下を抑止している。一方、変位センサ１２では、センサヘッド３００側の光ファイバのコア径が１００μｍで、比較例と比べて２倍であり、回折レンズ３１０のＮＡ＝０．０５で、比較例と比べて１／２であるため、センサヘッド３００の半値幅は、比較例と比べて同一となる。また、センサヘッド３００側の光ファイバのコア径が２倍であり、比較例と比べてスポット径が２倍になるため、スポット内での平均化により、移動分解能は大幅に改善している。 More specifically, in the displacement sensor 12, the NA of the diffractive lens 310 with respect to the NA of the optical fiber on the sensor head 300 side is 1/2, which is the same as the comparative example. Therefore, the displacement sensor 12 and the comparative example have the same coupling efficiency (ratio) of the sensor head, and suppress the decrease in the amount of received light. On the other hand, in the displacement sensor 12, the core diameter of the optical fiber on the sensor head 300 side is 100 μm, which is twice that of the comparative example, and the NA of the diffractive lens 310 is 0.05, which is 1/2 that of the comparative example. Therefore, the half price width of the sensor head 300 is the same as that of the comparative example. Further, since the core diameter of the optical fiber on the sensor head 300 side is doubled and the spot diameter is doubled as compared with the comparative example, the moving resolution is greatly improved by averaging within the spot.
　以上のように、本発明の第２実施形態に係る変位センサ１２によれば、第１実施形態に係る変位センサ１１における導光部２０１と同一の構成を備えつつ、センサヘッド３００の回折レンズのＮＡを、センサヘッド３００側の光ファイバのＮＡよりも小さく設定する。これにより、受光量の低下を抑止しつつ、移動分解能を大幅に改善させることができる。その結果、変位センサ１２は、計測速度の低下を抑止しつつ、計測精度を向上させることができる。 As described above, according to the displacement sensor 12 according to the second embodiment of the present invention, the diffractive lens of the sensor head 300 has the same configuration as the light guide unit 201 in the displacement sensor 11 according to the first embodiment. The NA is set smaller than the NA of the optical fiber on the sensor head 300 side. This makes it possible to significantly improve the moving resolution while suppressing a decrease in the amount of received light. As a result, the displacement sensor 12 can improve the measurement accuracy while suppressing the decrease in the measurement speed.
　＜第３実施形態＞
　図９は、本発明の第３実施形態に係る変位センサ１３の構成を模式的に示す図である。図９において、変位センサ１３は、光源１１０と分光器１２０とセンサヘッド３００とを備え、それぞれ導光部２０３を介して光が伝搬される。導光部２０３は、第１光ファイバ２１３と、第２光ファイバ２２３と、第３光ファイバ２３３と、光カプラ２４３とを有し、各光ファイバは、以下のコア径及び開口数（ＮＡ）を有する。 <Third Embodiment>
FIG. 9 is a diagram schematically showing the configuration of the displacement sensor 13 according to the third embodiment of the present invention. In FIG. 9, the displacement sensor 13 includes a light source 110, a spectroscope 120, and a sensor head 300, and light is propagated through the light guide unit 203, respectively. The light guide unit 203 includes a first optical fiber 213, a second optical fiber 223, a third optical fiber 233, and an optical coupler 243, and each optical fiber has the following core diameter and numerical aperture (NA). Has.
　第１光ファイバ２１３：コア径＝１００μｍ、ＮＡ＝０．１
　第２光ファイバ２２３：コア径＝１００μｍ、ＮＡ＝０．１
　第３光ファイバ２３３：コア径＝１００μｍ、ＮＡ＝０．１（光カプラ２４３側）
　　　　　　　　　　　：コア径＝５０μｍ、ＮＡ＝０．２（分光器１２０側） First optical fiber 213: core diameter = 100 μm, NA = 0.1
Second optical fiber 223: core diameter = 100 μm, NA = 0.1
Third optical fiber 233: core diameter = 100 μm, NA = 0.1 (optical coupler 243 side)
: Core diameter = 50 μm, NA = 0.2 (spectroscope 120 side)
　図９に示されるように、変位センサ１３における導光部２０３に含まれる光ファイバのうちテーパ部を備える光ファイバが第３光ファイバ２３３である点で、図２に示された第１実施形態に係る変位センサ１１（第２光ファイバ２２１にテーパ部を備える）と異なる。 As shown in FIG. 9, among the optical fibers included in the light guide portion 203 of the displacement sensor 13, the optical fiber provided with the tapered portion is the third optical fiber 233, that is, the first embodiment shown in FIG. It is different from the displacement sensor 11 (the second optical fiber 221 is provided with a tapered portion).
　より詳細には、第３光ファイバ２３３は、光カプラ２４３側では、コア径＝１００μｍであり、分光器１２０側では、コア径＝５０μｍであり、光カプラ２４３と分光器１２０との間のうち、一部、コア径が連続的に変化するテーパ部を備える。また、第３光ファイバ２３３は、光カプラ２４３側では、ＮＡ＝０．１であり、分光器１２０側ではＮＡ＝０．２となる（ラグランジュの不変量）。 More specifically, the third optical fiber 233 has a core diameter = 100 μm on the optical coupler 243 side and a core diameter = 50 μm on the spectroscope 120 side, and is between the optical coupler 243 and the spectroscope 120. , Partly provided with a tapered portion in which the core diameter changes continuously. Further, in the third optical fiber 233, NA = 0.1 on the optical coupler 243 side and NA = 0.2 on the spectroscope 120 side (invariant amount of Lagrange).
　また、第１光ファイバ２１３は、図２に示された第１実施形態に係る変位センサ１１における第１光ファイバ２１１と比べて、コア径が２倍であることにより、断面積は４倍になるが、ＮＡは１／２である。これにより、光源１１０が出力されて第１光ファイバ２１３によって伝搬される光量は、第１実施形態に係る変位センサ１１と同一である。 Further, the first optical fiber 213 has a core diameter twice as large as that of the first optical fiber 211 in the displacement sensor 11 according to the first embodiment shown in FIG. 2, so that the cross-sectional area is quadrupled. However, NA is 1/2. As a result, the amount of light output from the light source 110 and propagated by the first optical fiber 213 is the same as that of the displacement sensor 11 according to the first embodiment.
　なお、光カプラ２４３は、コア径１００μｍの２本の光ファイバを結合するカプラである。 The optical coupler 243 is a coupler that connects two optical fibers having a core diameter of 100 μm.
　上述のように、第３光ファイバ２３３がテーパ部を備えることにより、センサヘッド３００に接続される光ファイバは、分光器１２０に接続される光ファイバよりも大きいコア径を有するように構成される。 As described above, the third optical fiber 233 is configured to have a tapered portion so that the optical fiber connected to the sensor head 300 has a larger core diameter than the optical fiber connected to the spectroscope 120. ..
［変位センサ１３の評価］
　センサヘッド３００に収容される回折レンズ３１０について、ＮＡ＝０．１であり、当該センサヘッド３００に接続される第２光ファイバ２２３のＮＡと同一に設定される場合には、変位センサ１３は、図４で示されたように第１実施形態に係る変位センサ１１と同様の効果を奏する。 [Evaluation of displacement sensor 13]
When the NA = 0.1 for the diffractive lens 310 housed in the sensor head 300 and the NA is set to be the same as the NA of the second optical fiber 223 connected to the sensor head 300, the displacement sensor 13 is set. As shown in FIG. 4, the same effect as that of the displacement sensor 11 according to the first embodiment is obtained.
　すなわち、変位センサ１３は、移動分解能の低下を抑止しつつ、受光量を大幅に増加させることができる（５．５倍）。その結果、変位センサ１３は、計測精度の低下を抑止しつつ、計測速度を向上させることができる。 That is, the displacement sensor 13 can significantly increase the amount of light received (5.5 times) while suppressing the decrease in moving resolution. As a result, the displacement sensor 13 can improve the measurement speed while suppressing the deterioration of the measurement accuracy.
　また、センサヘッド３００に収容される回折レンズ３１０について、ＮＡ＝０．０５であり、センサヘッド３００側の光ファイバのＮＡに対する回折レンズ３１０のＮＡが１／２に設定される場合には、変位センサ１３は、図８で示されたように第２実施形態に係る変位センサ１２と同様の効果を奏する。 Further, when the NA of the diffractive lens 310 housed in the sensor head 300 is 0.05 and the NA of the diffractive lens 310 with respect to the NA of the optical fiber on the sensor head 300 side is set to 1/2, the displacement is dislocated. As shown in FIG. 8, the sensor 13 has the same effect as the displacement sensor 12 according to the second embodiment.
　すなわち、変位センサ１３は、受光量の低下を抑止しつつ、移動分解能を大幅に改善させることができる（２倍）。その結果、計測速度の低下を抑止しつつ、計測精度を向上させることができる。 That is, the displacement sensor 13 can significantly improve the moving resolution (twice) while suppressing a decrease in the amount of received light. As a result, it is possible to improve the measurement accuracy while suppressing the decrease in the measurement speed.
　＜第４実施形態＞
　図１０は、本発明の第４実施形態に係る変位センサ１４の構成を模式的に示す図である。図１０において、変位センサ１４は、光源１１０と分光器１２０とセンサヘッド３００とを備え、それぞれ導光部２０４を介して光が伝搬される。導光部２０４は、第１光ファイバ２１４と、第２光ファイバ２２３と、第３光ファイバ２３３と、光カプラ２４４とを有し、各光ファイバは、以下のコア径及び開口数（ＮＡ）を有する。 <Fourth Embodiment>
FIG. 10 is a diagram schematically showing the configuration of the displacement sensor 14 according to the fourth embodiment of the present invention. In FIG. 10, the displacement sensor 14 includes a light source 110, a spectroscope 120, and a sensor head 300, and light is propagated through the light guide unit 204, respectively. The light guide portion 204 has a first optical fiber 214, a second optical fiber 223, a third optical fiber 233, and an optical coupler 244, and each optical fiber has the following core diameter and numerical aperture (NA). Has.
　第１光ファイバ２１４：コア径＝５０μｍ、ＮＡ＝０．２
　第２光ファイバ２２３：コア径＝１００μｍ、ＮＡ＝０．１
　第３光ファイバ２３３：コア径＝１００μｍ、ＮＡ＝０．１（光カプラ２４４側）
　　　　　　　　　　　：コア径＝５０μｍ、ＮＡ＝０．２（分光器１２０側） First optical fiber 214: core diameter = 50 μm, NA = 0.2
Second optical fiber 223: core diameter = 100 μm, NA = 0.1
Third optical fiber 233: core diameter = 100 μm, NA = 0.1 (optical coupler 244 side)
: Core diameter = 50 μm, NA = 0.2 (spectroscope 120 side)
　図１０に示されるように、変位センサ１４における導光部２０４に含まれる光ファイバのうちテーパ部を備える光ファイバが第３光ファイバ２３３である点で、図２に示された第１実施形態に係る変位センサ１１（第２光ファイバ２２１にテーパ部を備える）と異なる。この点においては、第４実施形態に係る変位センサ１４は、第３実施形態に係る変位センサ１３と同様である。 As shown in FIG. 10, among the optical fibers included in the light guide portion 204 of the displacement sensor 14, the optical fiber provided with the tapered portion is the third optical fiber 233, that is, the first embodiment shown in FIG. It is different from the displacement sensor 11 (the second optical fiber 221 is provided with a tapered portion). In this respect, the displacement sensor 14 according to the fourth embodiment is the same as the displacement sensor 13 according to the third embodiment.
　一方、第１光ファイバ２１４は、図９に示された第３実施形態に係る変位センサ１３の第１光ファイバ２１３とは異なり、図２に示された第１実施形態に係る変位センサ１１における第１光ファイバ２１１と同様である。 On the other hand, the first optical fiber 214 is different from the first optical fiber 213 of the displacement sensor 13 according to the third embodiment shown in FIG. 9, in the displacement sensor 11 according to the first embodiment shown in FIG. It is the same as the first optical fiber 211.
　なお、光カプラ２４４は、コア径５０μｍの光ファイバ及びコア径１００μｍの光ファイバを結合するカプラである。 The optical coupler 244 is a coupler that couples an optical fiber having a core diameter of 50 μm and an optical fiber having a core diameter of 100 μm.
　上述のように、第３光ファイバ２３３がテーパ部を備えることにより、センサヘッド３００に接続される光ファイバは、分光器１２０に接続される光ファイバよりも大きいコア径を有し、この点においては、第３実施形態の変位センサ１３と同様であり、当該変位センサ１３と同様の効果を奏する。 As described above, by providing the third optical fiber 233 with a tapered portion, the optical fiber connected to the sensor head 300 has a larger core diameter than the optical fiber connected to the spectroscope 120, and in this respect. Is the same as the displacement sensor 13 of the third embodiment, and has the same effect as the displacement sensor 13.
　具体的には、センサヘッド３００に収容される回折レンズ３１０について、ＮＡ＝０．１の場合には、変位センサ１４は、図４で示されたように第１実施形態に係る変位センサ１１と同様の効果を奏し、移動分解能の低下を抑止しつつ、受光量を大幅に増加させることができる（５．５倍）。その結果、変位センサ１４は、計測精度の低下を抑止しつつ、計測速度を向上させることができる。 Specifically, for the diffractive lens 310 housed in the sensor head 300, when NA = 0.1, the displacement sensor 14 is the displacement sensor 11 according to the first embodiment as shown in FIG. The same effect can be achieved, and the amount of light received can be significantly increased (5.5 times) while suppressing the decrease in moving resolution. As a result, the displacement sensor 14 can improve the measurement speed while suppressing the deterioration of the measurement accuracy.
　また、センサヘッド３００に収容される回折レンズ３１０について、ＮＡ＝０．０５の場合には、変位センサ１４は、図８で示されたように第２実施形態に係る変位センサ１２と同様の効果を奏し、受光量の低下を抑止しつつ、移動分解能を大幅に改善させることができる（２倍）。その結果、変位センサ１４は、計測速度の低下を抑止しつつ、計測精度を向上させることができる。 Further, with respect to the diffractive lens 310 housed in the sensor head 300, when NA = 0.05, the displacement sensor 14 has the same effect as the displacement sensor 12 according to the second embodiment as shown in FIG. It is possible to significantly improve the moving resolution (twice) while suppressing the decrease in the amount of received light. As a result, the displacement sensor 14 can improve the measurement accuracy while suppressing the decrease in the measurement speed.
　さらに、本発明の第１～第４実施形態では、導光部に含まれる光ファイバのうち、いずれかにテーパ部を備えることにより、センサヘッド３００に接続される光ファイバは、分光器１２０に接続される光ファイバよりも大きいコア径を有するようにしたが、これ以外に光カプラで実現するようにしても構わない。例えば、光カプラとセンサヘッド３００とを接続する第２光ファイバのコア径を１００μｍとし、当該光カプラと分光器１２０とを接続する第２光ファイバのコア径を５０μｍとし、当該光カプラによりコア径の差異を吸収するような構造としても構わない。 Further, in the first to fourth embodiments of the present invention, the optical fiber connected to the sensor head 300 by providing a tapered portion in any of the optical fibers included in the light guide portion is connected to the spectroscope 120. Although it has a core diameter larger than that of the optical fiber to be connected, it may be realized by an optical coupler. For example, the core diameter of the second optical fiber connecting the optical coupler and the sensor head 300 is 100 μm, the core diameter of the second optical fiber connecting the optical coupler and the spectroscope 120 is 50 μm, and the core is formed by the optical coupler. A structure that absorbs the difference in diameter may be used.
　以上説明した各実施形態は、本発明の理解を容易にするためのものであり、本発明を限定して解釈するためのものではない。各実施形態が備える各要素並びにその配置、材料、条件、形状及びサイズ等は、例示したものに限定されるわけではなく適宜変更することができる。また、異なる実施形態で示した構成同士を部分的に置換し又は組み合わせることが可能である。 Each of the embodiments described above is for facilitating the understanding of the present invention, and is not for limiting the interpretation of the present invention. Each element included in each embodiment and its arrangement, material, condition, shape, size, and the like are not limited to those exemplified, and can be appropriately changed. Further, it is possible to partially replace or combine the configurations shown in different embodiments.
［附記］
　白色光を出力する光源（１１０）と、
　少なくとも１つの光ファイバを含む導光部（２００，２０１，２０２，２０３，２０４）と、
　前記導光部を介して入射した前記白色光に対して、光軸方向に沿って色収差を生じさせる回折レンズ（３１０）を収容し、色収差を生じさせた光を計測対象物（ＴＡ）に照射するセンサヘッド（３００）と、
　前記計測対象物で反射されて前記センサヘッドにより集光された反射光を、前記導光部を介して取得し、前記反射光のスペクトルを計測する分光器（１２０）と、を備え、
　前記センサヘッドに接続される光ファイバ（２２０，２２１，２２３）は、前記分光器に接続される光ファイバ（２３０，２３１，２３３）よりも大きいコア径を有する、
　変位センサ（１０，１１，１２，１３，１４）。 [Appendix]
A light source (110) that outputs white light and
A light guide unit (200,201,202,203,204) including at least one optical fiber, and
A diffractive lens (310) that causes chromatic aberration along the optical axis direction with respect to the white light incident through the light guide unit is accommodated, and the light that causes chromatic aberration is irradiated to the measurement object (TA). Sensor head (300) and
A spectroscope (120) for acquiring the reflected light reflected by the measurement object and collected by the sensor head via the light guide unit and measuring the spectrum of the reflected light is provided.
The optical fiber (220,221,223) connected to the sensor head has a larger core diameter than the optical fiber (230,231,233) connected to the spectroscope.
Displacement sensor (10,11,12,13,14).
１０，１１，１２，１３，１４…変位センサ、１１０…光源、１２０…分光器、２００，２０１，２０２，２０３，２０４…導光部、２１０，２１１，２１３，２１４…第１光ファイバ、２２０，２２１，２２３…第２光ファイバ、２３０，２３１，２３３…第３光ファイバ、２４０，２４１，２４３，２４４…光カプラ、３００…センサヘッド、３１０…回折レンズ、４１０…第１波長の光、４２０…第２波長の光、４３０…第３波長の光、ＴＡ…計測対象物 10,11,12,13,14 ... displacement sensor, 110 ... light source, 120 ... spectroscope, 200,201,202,203,204 ... light guide unit, 210,211,213,214 ... first optical fiber, 220 , 221,223 ... 2nd optical fiber, 230, 231,233 ... 3rd optical fiber, 240, 241,243, 244 ... optical coupler, 300 ... sensor head, 310 ... diffractive lens, 410 ... first wavelength light, 420 ... Light of the second wavelength, 430 ... Light of the third wavelength, TA ... Object to be measured

Claims (8)

  1. 　白色光を出力する光源と、
    　少なくとも１つの光ファイバを含む導光部と、
    　前記導光部を介して入射した前記白色光に対して、光軸方向に沿って色収差を生じさせる回折レンズを収容し、色収差を生じさせた光を計測対象物に照射するセンサヘッドと、
    　前記計測対象物で反射されて前記センサヘッドにより集光された反射光を、前記導光部を介して取得し、前記反射光のスペクトルを計測する分光器と、を備え、
    　前記センサヘッドに接続される光ファイバは、前記分光器に接続される光ファイバよりも大きいコア径を有する、
    　変位センサ。     A light source that outputs white light and
    A light guide containing at least one optical fiber and
    A sensor head that accommodates a diffractive lens that causes chromatic aberration along the optical axis direction with respect to the white light incident through the light guide portion, and irradiates the measurement object with the light that causes chromatic aberration.
    A spectroscope for acquiring the reflected light reflected by the measurement object and collected by the sensor head via the light guide unit and measuring the spectrum of the reflected light is provided.
    The optical fiber connected to the sensor head has a larger core diameter than the optical fiber connected to the spectroscope.
    Displacement sensor.
  2. 　前記センサヘッドと前記分光器との間に配置される光ファイバは、コア径が連続的に変化するテーパ部を含む、
    　請求項１に記載の変位センサ。     The optical fiber arranged between the sensor head and the spectroscope includes a tapered portion in which the core diameter continuously changes.
    The displacement sensor according to claim 1.
  3. 　前記導光部は、
    　前記光源と接続される第１光ファイバと、
    　前記センサヘッドと接続される第２光ファイバと、
    　前記分光器と接続される第３光ファイバと、
    　前記第１光ファイバ、前記第２光ファイバ及び前記第３光ファイバが接続される光カプラと、を含む、
    　請求項１又は２に記載の変位センサ。     The light guide unit is
    The first optical fiber connected to the light source and
    The second optical fiber connected to the sensor head and
    The third optical fiber connected to the spectroscope and
    The first optical fiber, the second optical fiber, and an optical coupler to which the third optical fiber is connected are included.
    The displacement sensor according to claim 1 or 2.
  4. 　前記第２光ファイバは、コア径が連続的に変化するテーパ部を含む、
    　請求項３に記載の変位センサ。     The second optical fiber includes a tapered portion in which the core diameter changes continuously.
    The displacement sensor according to claim 3.
  5. 　前記第３光ファイバは、コア径が連続的に変化するテーパ部を含む、
    　請求項３に記載の変位センサ。     The third optical fiber includes a tapered portion in which the core diameter changes continuously.
    The displacement sensor according to claim 3.
  6. 　前記第２光ファイバは、前記第３光ファイバよりも大きいコア径を有する、
    　請求項３に記載の変位センサ。     The second optical fiber has a larger core diameter than the third optical fiber.
    The displacement sensor according to claim 3.
  7. 　前記センサヘッドに接続される光ファイバは、前記回折レンズと同一の開口数を有する、
    　請求項１から６のいずれか一項に記載の変位センサ。     The optical fiber connected to the sensor head has the same numerical aperture as the diffractive lens.
    The displacement sensor according to any one of claims 1 to 6.
  8. 　前記センサヘッドに接続される光ファイバは、前記回折レンズよりも大きい開口数を有する、
    　請求項１から６のいずれか一項に記載の変位センサ。     The optical fiber connected to the sensor head has a numerical aperture larger than that of the diffractive lens.
    The displacement sensor according to any one of claims 1 to 6.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012208102A (en) * 2011-03-14 2012-10-25 Omron Corp Confocal measuring device
JP2017102067A (en) * 2015-12-03 2017-06-08 オムロン株式会社 Optical measurement device
JP2018146279A (en) * 2017-03-02 2018-09-20 オムロン株式会社 Confocal measurement device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012208102A (en) * 2011-03-14 2012-10-25 Omron Corp Confocal measuring device
JP2017102067A (en) * 2015-12-03 2017-06-08 オムロン株式会社 Optical measurement device
JP2018146279A (en) * 2017-03-02 2018-09-20 オムロン株式会社 Confocal measurement device

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