JP6299500B2 - Multipoint distance measuring device and method, and shape measuring device - Google Patents

Description

  The present invention relates to a multipoint distance measuring apparatus and method for measuring distances to a plurality of points on a measurement object, and a shape measuring apparatus including the multipoint distance measuring apparatus.

  As a measuring instrument that measures the surface shape of the measurement object, a shape that measures the surface shape of the measurement object by measuring the distance to multiple points on the measurement object and obtaining the relative positional relationship of these points Measuring devices are well known.

  For example, in Patent Document 1, a He-Ne laser is scanned with respect to a microlens array disposed at a position facing a measurement object, and the reflection of the He-Ne laser converged on the measurement object for each microlens. A method is disclosed in which the relative positions of a plurality of points are measured by detecting light with a two-divided photodetector and comparing the focus positions. In addition, the measurement object is scanned with white light or a He—Ne laser, and the distance to a plurality of points on the measurement object is measured using a white interference method or a laser interference method. A method for measuring the surface shape of a measurement object by obtaining the relationship is also known.

JP-A-10-300420

  By the way, as in the measurement method described in Patent Document 1, a method of measuring the relative positions of a plurality of points based on the detection result of the two-divided photodetector, that is, the surface shape of the measurement object is a white interference method or a CW laser ( There is a problem that measurement accuracy is low compared to the case of using the continuous wave laser) interferometry. Further, in the measuring method described in Patent Document 1, the He-Ne laser is scanned with respect to the microlens array, that is, the object to be measured. Since time increases, there exists a problem that shape measurement takes time. For this reason, the He-Ne laser is divided into a plurality of light beams, each light beam is irradiated toward a plurality of points of the object to be measured, and the surface shape is measured based on the detection results of the reflected light from the plurality of points. It is preferable. However, when the light beam obtained by dividing the He-Ne laser into a plurality of points is irradiated toward a plurality of points of the object to be measured, it is difficult to select and detect only the regular reflection light of the light beam at each of the plurality of points. Problems arise in measurement accuracy. Such a problem also occurs when using the white interference method or the CW laser interference method.

  An object of the present invention is to provide a multipoint distance measuring device and method capable of measuring a distance to a plurality of points on a measurement object with high accuracy and in a short time, and a shape measuring device including the multipoint distance measuring device. There is to do.

  A multi-point distance measuring apparatus for achieving the object of the present invention includes an optical frequency comb light source that emits an optical comb having a plurality of frequency components arranged at equal frequency intervals, and an optical comb emitted from the optical frequency comb light source. An optical comb splitting unit that divides the reference light and the ranging light, and the ranging light split by the optical comb splitting unit into a plurality of luminous fluxes, respectively, emitted toward a plurality of points of the measurement object; and A light incident / exit section where regular reflected light of a light beam regularly reflected at a plurality of points is incident, a reference light divided by an optical comb dividing section, and a regular reflected light for each of the plurality of points incident on the light incident / exit section And a distance calculation unit that calculates a distance from the light incident / exit unit to each of a plurality of points based on a detection result of the light detection unit.

  According to the present invention, by using an optical frequency comb light source as a light source, when the light beams obtained by dividing the distance measuring light emitted from the light incident / exit section into a plurality of points are respectively incident on a plurality of points of the measurement object, Only specularly reflected light regularly reflected at a plurality of points can be incident on the light incident / exiting portion. As a result, the distance to a plurality of points on the measurement object can be measured with high sensitivity and high accuracy.

  Preferably, a Fabry-Perot etalon is provided between the optical frequency comb light source and the optical comb divider to multiply the frequency interval of the optical comb by an arbitrary integer. As a result, the frequency interval of the optical comb can be widened. For example, when the present invention is applied to the measurement of the surface shape of the object to be measured, the spatial resolution in the surface shape measurement is reduced by reducing the interval and delay amount of each light beam. Can be improved.

  It is preferable that a plurality of types of Fabry-Perot etalons having different free spectral ranges are connected in series between the optical frequency comb light source and the optical comb splitting unit. This facilitates the identification of the order of the comb of the optical comb, so that measurement using the optical comb can be performed with higher accuracy.

  The light incident / exit section includes at least one of a diffraction grating, a lens array, a digital mirror device, an optical spatial modulator, a mask that allows passage of only a light beam directed to a plurality of points, a plurality of optical fiber cables, and a direction control element that scans the light beam. It is preferable to divide the distance measuring light using these. Thereby, a some light beam can each be radiate | emitted toward several points of a measurement object.

  It is preferable to include an optical delay unit that sequentially causes a plurality of light beams to reach a plurality of points. Thereby, it is possible to easily identify at which point of the plurality of points the regularly reflected light incident on the light incident / exiting portion is reflected.

  In addition, a shape measuring device for achieving the object of the present invention calculates the surface shape of the measurement object based on the multipoint distance measuring device according to any one of claims and the calculation result of the distance calculating unit. A shape calculating unit.

  In addition, a multipoint distance measuring method for achieving the object of the present invention includes an emission step of emitting an optical comb having a plurality of frequency components arranged at equal frequency intervals from an optical frequency comb light source, and an emission from the optical frequency comb light source. A light dividing step for dividing the optical comb into a reference light and a distance measuring light, and a plurality of points of the measuring object from the light incident / exit section by dividing the distance measuring light divided in the light dividing step into a plurality of light beams A light incident / exit step for causing the specularly reflected light of the distance measuring light to be incident on the light incident / exit part, respectively, and the reference light divided in the light dividing step, Calculates the distance from the light incident / exit part to each of the multiple points based on the light detection step that detects the optical interference signal with the specularly reflected light at each of the multiple points incident on the light incident / exit part, and the detection result of the light detection step A distance calculating step, To.

  The multipoint distance measuring apparatus and method of the present invention and the shape measuring apparatus including the multipoint distance measuring apparatus can measure the distance to a plurality of points on the measurement object with high accuracy and in a short time.

It is the schematic of the shape measuring apparatus of 1st Embodiment. It is an enlarged view of a light incident / exit part. It is an enlarged view of a measuring object. It is a flowchart which shows the flow of the shape measurement process by a shape measuring apparatus. It is the schematic of the shape measuring apparatus of 2nd Embodiment. It is explanatory drawing for demonstrating the effect acquired by providing several types of Fabry-Perot etalon from which finesse differs. It is explanatory drawing for demonstrating other Embodiment 1 of the light incident / exit part which does not have a lens. It is explanatory drawing for demonstrating other Embodiment 2 of the light incident / exit part which has a lens array. It is explanatory drawing for demonstrating other Embodiment 3 of the light incident / exit part of a structure in which one part differs from the light incident / exit part of FIG. It is explanatory drawing for demonstrating other Embodiment 4 of the light incident / exit part which has two types of lens arrays. It is explanatory drawing for demonstrating other Embodiment 5 of the light incident / exit part which has a mask. It is explanatory drawing for demonstrating other Embodiment 6 of the light incident / exit part which has a digital mirror device. It is explanatory drawing for demonstrating other Embodiment 7 of the light incident / exit part which has an optical spatial modulator. It is explanatory drawing for demonstrating other Embodiment 8 of the light incident / exit part which has an optical fiber cable group. It is explanatory drawing for demonstrating other Embodiment 9 of the light incident / exit part which has an optical fiber cable group and a direction control element.

<Configuration of Shape Measuring Device of First Embodiment>
FIG. 1 is a schematic diagram of a shape measuring apparatus 10 that measures the surface shape of a measurement object 9. This shape measuring device 10 is a device that measures the surface shape of the measuring object 9 in a non-contact manner by measuring the distance to a plurality of points on the surface of the measuring object 9, and the multipoint distance of the present invention. This corresponds to a measuring device. The type of the measurement object 9 is not particularly limited, and examples thereof include a mold, a rotating body such as an automobile or an airplane engine, and the like.

  The shape measuring apparatus 10 is roughly divided into an optical frequency comb light source 19, a Fabry-Perot etalon (hereinafter simply referred to as an etalon) 20, an optical amplifier 21, a splitter (optical comb splitting unit) 22, a first optical path 23, a second The optical path 24, the mixer 25, the light detection unit 26, the interference fringe pattern detection unit 27, the distance calculation unit 28, the shape calculation unit 29, and the optical fiber cable 30 (represented by double lines in the drawing) and the light that connect these units. A connector 31 for connecting the fiber cable 30 is provided.

  The optical frequency comb light source 19 emits an optical comb (also referred to as an optical frequency comb) 34. The optical comb 34 is light having frequency components such that the frequencies are equally spaced in the frequency domain. As the optical frequency comb light source 19, for example, a femtosecond mode-locked fiber laser uses a laser oscillator configured to excite a ring resonator formed of an erbium-doped optical fiber (EDF) with a laser diode. be able to. The optical comb 34 emitted from the optical frequency comb light source 19 is input to the etalon 20 via the optical fiber cable 30.

  The etalon 20 multiplies the frequency interval of the repetition frequency of the optical comb 34 by m (m is an arbitrary natural number), that is, an arbitrary integer multiple. Thereby, the frequency interval of the optical comb 34 can be expanded as appropriate. The frequency interval of the optical comb 34 emitted from the optical frequency comb light source 19 is generally 100 MHz and 250 MHz, but this frequency interval can be increased to, for example, about 15 GHz. Thereby, the spatial resolution in the surface shape measurement of the measuring object 9 described later can be improved.

  The optical amplifier 21 amplifies the optical comb 34 input from the etalon 20 and then outputs the optical comb 34 toward the splitter 22.

  The splitter 22 is connected to the optical amplifier 21 and the first optical path 23 and the second optical path 24. The splitter 22 divides the optical comb 34 input from the optical amplifier 21 into the reference light 35 and the distance measuring light 36, outputs the reference light 35 to the first optical path 23, and outputs the distance measuring light 36 to the second optical path. 24. In addition, the splitter 22 divides | segments the optical comb 34 so that the ratio of the reference light 35 and the ranging light 36 may be set to 5:95, for example.

  A first collimator 38, a prism reflector 39, a corner reflector 40, a scanning stage 41, and a second collimator 42 are provided in the first optical path 23.

  The first collimator 38 emits the reference light 35 input from the splitter 22 as a parallel light beam toward the prism reflector 39.

  The prism reflector 39 reflects the reference light 35 input from the first collimator 38 toward the corner reflector 40 and reflects the reference light 35 incident from the corner reflector 40 toward the second collimator 42.

  The corner reflector 40 is disposed on the optical path of the reference light 35 reflected by the prism reflector 39. The corner reflector 40 reflects the reference light 35 incident from the prism reflector 39 toward the prism reflector 39 again.

  The scanning stage 41 is attached to the corner reflector 40. The scanning stage 41 reciprocates the corner reflector 40 along a direction parallel to the optical path of the reference light 35 reflected by the prism reflector 39. For example, the scanning stage 41 reciprocates the corner reflector 40 with a stroke of several mm to several cm. Thereby, the amplitude of the optical interference signal 53 between the reference light 35 and the distance measuring light 36, which will be described later, can be temporally varied. By integrating the measurement data of the optical interference signal 53 that varies with time, the accuracy of the measurement data can be increased. Instead of the scanning stage 41, for example, a PZT stage (voltage actuator) may be used.

  The second collimator 42 collects the reference light 35 incident from the prism reflector 39 and outputs it to the optical fiber cable 30. The second collimator 42 can be moved in a direction parallel to the optical path of the reference light 35 incident from the prism reflector 39 by a moving mechanism (not shown). Thereby, the optical path length of the reference light 35 in the first optical path 23 can be varied. The reference light 35 output from the second collimator 42 is input to the mixer 25.

  A circulator 44 and a light incident / exit section 45 are provided in the second optical path 24. The circulator 44 outputs the distance measuring light 36 input from the splitter 22 toward the light incident / exiting unit 45, and returns light (regular reflection distance measuring light 36b described later) from the light incident / exiting unit 45 to the mixer 25. Output to.

  The light incident / exit section 45 divides the distance measuring light 36 input from the circulator 44 into a plurality of light beams 36 a, and emits each light beam 36 a toward a plurality of points on the measurement object 9. The light incident / exit section 45 roughly includes an optical fiber cable 47, a diffraction grating 48, and a lens 49.

  In FIG. 2 showing an enlarged view of the light incident / exiting portion 45, the proximal end portion of the optical fiber cable 47 is connected to the circulator 44. A collimator 50 is attached to the tip of the optical fiber cable 47. The collimator 50 collimates the distance measuring light 36 diverges and emits conically from the tip of the optical fiber cable 47.

  The diffraction grating 48 is provided on the light exit surface of the collimator 50. The diffraction grating 48 divides the distance measuring light 36 input from the collimator 50 into a plurality of light beams 36a (diffracted light) for each diffraction order and emits them. The type of the diffraction grating 48 to be used is not particularly limited, and various known diffraction gratings may be used.

  The lens 49 is provided so as to be movable along the optical axis direction of the lens at a position on the front side of the light emission direction of the diffraction grating 48. By appropriately adjusting the position of the lens 49 in the optical axis direction of the lens 49 according to the distance to the measurement object 9, the lens 49 causes each of the plurality of light beams 36 a emitted from the diffraction grating 48 to be on the surface of the measurement object 9. Is focused (imaged). That is, a plurality of light beams 36 a are incident on a plurality of points of the measurement object 9.

  Further, between the lens 49 and the measuring object 9, a plurality of light beams 36a sequentially reach a plurality of points on the measuring object 9 (that is, reach with a time difference) (in FIG. 1, the optical delay unit 51). (Not shown) is provided. The optical delay unit 51 is configured by, for example, glass plates having different thicknesses that are appropriately disposed in the optical path of the plurality of light beams 36a. As a result, the light beams 36a transmitted through the respective glass plates can be delayed by different times, so that each light beam 36a can sequentially reach a plurality of points on the measuring object 9. As a result, it is possible to make the time during which the later-described specularly reflected light of each light beam 36 a is incident on the tip of the optical fiber cable 47 different. For this reason, it is possible to easily identify at which point the specularly reflected light incident on the tip of the optical fiber cable 47 is reflected. In addition, as the optical delay part 51, you may use the various members and methods which can delay the light beam 36a instead of a glass plate.

  In FIG. 3, which shows an enlarged view of the measurement object 9, light beams 36 a incident on a plurality of points of the measurement object 9 are optical combs 34. Here, since the optical comb 34 has a high S / N ratio, among the reflected light that is incident and reflected at a plurality of points of the measurement object 9, the specularly reflected light (hereinafter referred to as specular reflection) that is specularly reflected at the plurality of points. Only 36b (referred to as distance measuring light) enters the tip of the optical fiber cable 47 through the lens 49, the diffraction grating 48, and the like. Here, the regular reflection light is the reflection light from the portion where the light beam 36a is incident vertically, and is the reflected light returning along the optical path of the light beam 36a. Then, the regular reflection ranging light 36b for each of the plurality of points is incident on the distal end portion of the optical fiber cable 47 at different timings due to the delay by the optical delay unit 51 described above.

  Returning to FIG. 1, the regular reflection ranging light 36 b incident on the tip of the optical fiber cable 47 is input to the mixer 25 via the optical fiber cable 47, the circulator 44, and the like.

  For example, an optical mixer is used as the mixer 25. For example, the mixer 25 optically multiplies the reference light 35 input from the first optical path 23 and the regular reflection ranging light 36b for each of a plurality of points sequentially input from the second optical path 24. By mixing, the optical interference signal 53 of the reference light 35 and the regular reflection distance measuring light 36b is generated for each of a plurality of points. Then, the mixer 25 outputs an optical interference signal 53 for each of the plurality of points to the light detection unit 26.

  The light detection unit 26 receives the light interference signals 53 for each of the plurality of points input from the mixer 25 and converts them into electrical signals, and outputs the light interference signals 53 for each of the plurality of points to the interference fringe pattern detection unit 27. Note that the correspondence between each point of the plurality of points and the optical interference signal 53 (that is, which point among the plurality of points the optical interference signal 53 corresponds to) is clear from the design of the optical delay unit 51 described above. is there.

  The interference fringe pattern detection unit 27 functions as a distance calculation unit of the present invention together with a distance calculation unit 28 described later. The interference fringe pattern detection unit 27 and the distance calculation unit 28 specify the light incident / exit unit 45 using a known pulse interference position measurement technique based on the optical interference signal 53 for each of a plurality of points input from the light detection unit 26. The distance from the point to each of a plurality of points is calculated. And the shape calculation part 29 calculates the surface shape of the measuring object 9 based on the distance calculation result to each point of multiple points. Hereinafter, an example of distance calculation to a plurality of points and surface shape calculation will be described.

  The interference fringe pattern detection unit 27 detects the interference fringe pattern of the optical interference signal 53 input from the light detection unit 26 described above, and outputs the detection result of the interference fringe pattern to the distance calculation unit 28.

  The distance calculation unit 28 calculates the distance L from the specific point of the light incident / exit unit 45 to each of a plurality of points based on the detection result of the interference fringe pattern input from the interference fringe pattern detection unit 27, and The calculation result of the distance L is output to the shape calculation unit 29. In addition, since the method of calculating each distance L from an interference fringe pattern is well-known, concrete description is abbreviate | omitted here.

  The shape calculation unit 29 calculates the surface shape of the measurement object 9 based on the calculation result of the distance L for each of a plurality of points input from the distance calculation unit 28. Since the type of the optical comb 34, the performance of the diffraction grating 48 and the lens 49, etc. are known, the interval between the light beams 36a can be obtained from experiments and simulations. Further, based on the calculation result of each distance L input from the distance calculation unit 28, the distance L from the specific point of the light incident / exiting unit 45 to each of a plurality of points is also obtained. Thereby, since the position coordinates of each of the plurality of points when the specific point of the light incident / exiting part 45 is used as a reference, that is, the relative positional relationship of the plurality of points can be calculated, the surface shape of the measurement object 9 is calculated. can do.

<Operation of shape measuring device>
Next, the operation (multi-point distance measuring method of the present invention) of the shape measuring apparatus 10 having the above configuration will be described using the flowchart shown in FIG. When the inspector sets the measuring object 9 in the measurement space of the shape measuring apparatus 10 and then performs a shape measurement start operation via an operation unit (not shown), an optical comb 34 is emitted from the optical frequency comb light source 19 ( Step S1, emission step).

  The optical comb 34 emitted from the optical frequency comb light source 19 is amplified by the optical amplifier 21 after the frequency interval of the repetition frequency is expanded by the etalon 20 (that is, after being increased in frequency), and is further referenced by the splitter 22. The light 35 and the distance measuring light 36 are divided (step S2, light dividing step). The reference light 35 is output from the splitter 22 to the first optical path 23 and then input to the mixer 25 via the first collimator 38 and the like.

  On the other hand, the distance measuring light 36 is output from the splitter 22 to the second optical path 24 and then input to the optical fiber cable 47 of the light incident / exit section 45 through the circulator 44. The distance measuring light 36 input to the optical fiber cable 47 is converted into parallel light by the collimator 50 and then divided into a plurality of light beams 36 a for each wavelength by the diffraction grating 48. Then, the plurality of light beams 36a emitted from the diffraction grating 48 are condensed on a plurality of points of the measurement object 9 by the lens 49 (step S3, light incident / exit step). At this time, since the light beam 36a transmitted through the optical delay unit 51 is delayed, the plurality of light beams 36a can sequentially reach a plurality of points.

  When a plurality of light beams 36a are respectively incident on a plurality of points of the measurement object 9, only the regular reflection ranging light 36b regularly reflected at the plurality of points is sequentially passed through the lens 49, the diffraction grating 48, and the like one by one. The light enters the front end of the cable 47 (step S4, light incident / exit step). The regular reflection ranging light 36b for each of the plurality of points is input to the mixer 25 via the optical fiber cable 47, the circulator 44, and the like.

  The reference light 35 and the regular reflection ranging light 36b for each of a plurality of points are sequentially mixed by the mixer 25, and the light interference signal 53 for each of the plurality of points is input from the mixer 25 to the light detection unit 26. Then, the light detection unit 26 detects the light interference signal 53 for each of a plurality of points (step S5, light detection step). The light detection unit 26 sequentially outputs the light interference signals 53 for each of the plurality of points to the interference fringe pattern detection unit 27.

  The interference fringe pattern detection unit 27 detects the interference fringe pattern of the optical interference signal 53 for each of a plurality of points, and sequentially outputs the detection result of each interference fringe pattern to the distance calculation unit 28. Then, the distance calculating unit 28 calculates the distance L from the specific point of the light incident / exiting unit 45 to each of a plurality of points based on the detection result of the interference fringe pattern input from the interference fringe pattern detecting unit 27, and each distance The calculation result of L is output to the shape calculation unit 29 (step S6, distance calculation step).

  The shape calculation unit 29 has a plurality of points based on a specific point of the light incident / exit unit 45 based on the calculation result of the distance L for each of the plurality of points input from the distance calculation unit 28 and the known interval between the light beams 36a. The surface shape of the measuring object 9 is calculated by calculating the relative positional relationship (step S7). The calculation result of the surface shape is stored in a storage unit (not shown).

<Effect of the present invention>
As described above, in the shape measuring apparatus 10 of the present invention, the optical comb 34 is used as the distance measuring light 36 when the light beams 36a obtained by dividing the distance measuring light 36 into a plurality of points are emitted toward a plurality of points on the measuring object 9, respectively. Therefore, only the regular reflection light (regular reflection ranging light 36b) of the light beam 36a at each of a plurality of points can be selected and made incident on the optical fiber cable 47. For this reason, even if the regular reflection ranging light 36b incident on the optical fiber cable 47 interferes with the strong reference light 35 even if it is weak, interference fringes with a good S / N ratio can be generated. Each distance L to the point can be measured with high sensitivity and high accuracy. Further, since the distance measuring light 36 is divided into a plurality of light beams 36a and emitted toward a plurality of points on the measuring object 9, it is not necessary to scan the distance measuring light 36 on the measuring object 9, and measurement can be performed in a short time. It can be performed. As a result, the surface shape of the measuring object 9 can be calculated with high accuracy.

  In the shape measuring apparatus 10 of the present invention, the frequency interval of the optical comb 34 is widened by providing the etalon 20 on the optical path of the optical comb 34 emitted from the optical frequency comb light source 19 (that is, the comb of the optical comb 34 ( Com) can be thinned out. As a result, it is possible to improve the spatial resolution in the measurement of the surface shape of the measurement object 9 by making the intervals and delay amounts of the light beams 36a dense.

<Shape Measuring Device of Second Embodiment>
Next, the shape measuring apparatus 60 according to the second embodiment of the present invention will be described with reference to FIG. The shape measuring apparatus 10 of the first embodiment is provided with one type of etalon 20, but the shape measuring apparatus 60 includes a free spectral line between the optical frequency comb light source 19 and the optical amplifier 21 (splitter 22). A first etalon 20A and a second etalon 20B having different ranges are provided. Here, the characteristics of the etalon are represented by, for example, “finesse: Δf / fr” [Δf: free spectral range (FSR), fr: repetition frequency of optical comb].

  The shape measuring device 60 has basically the same configuration as the shape measuring device 10 of the first embodiment except that the shape measuring device 60 includes the first etalon 20A and the second etalon 20B. The same components are denoted by the same reference numerals, and the description thereof is omitted.

  The first etalon 20A has a higher finesse than the second etalon 20B, and conversely, the second etalon 20B has a lower finesse than the first etalon 20A. The first etalon 20A and the second etalon 20B are connected in series.

  As shown in FIG. 6, the first etalon 20A and the second etalon 20B having different free spectral ranges are connected in series, so that the order of the comb of the optical comb 34 can be easily identified. For example, when the signal strength of each comb of the optical comb 34 is substantially the same, it is difficult to identify the order of the comb (which number is the comb). For this reason, since the signal strength of some combs is weakened by connecting the first etalon 20A and the second etalon 20B in series, for example, the order of each comb can be easily determined based on a comb having a high signal strength. Can be identified. As a result, measurement using the optical comb 34 can be performed with higher accuracy.

  In the first embodiment, the frequency interval of the optical comb 34 is widened by providing the etalon 20 (for example, 100 MHz to 15 GHz). At this time, it is easy to produce an etalon finesse with a frequency interval of 1 GHz. However, it is difficult to produce finesse of etalon corresponding to a frequency interval of 15 GHz. On the other hand, in the second embodiment, the frequency interval of the optical comb 34 having a frequency interval of 100 MHz emitted from the optical frequency comb light source 19 is increased to 1 GHz by the first etalon 20A, for example, and then increased to 15 GHz by the second etalon 20B. Can be spread. This eliminates the need to produce an etalon corresponding to a frequency interval of 15 GHz, which is difficult to produce. In the above embodiment, two types of etalon are connected in series, but three or more types of etalon may be connected in series.

<Other Embodiments of Light Incident / Exit Portion>
In the above embodiment, the light incident / exiting part 45 shown in FIG. 2 has been described as an example of the light incident / exiting part of the present invention, but the configuration of the light incident / exiting part may be changed as appropriate. Hereinafter, other embodiments of the light incident / exit section will be described. In addition, about the same thing as the said embodiment on a function and a structure, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

(Other embodiment 1 of light incident / exit part)
As shown in FIG. 7, the light incident / exit section 45 (1) is obtained by removing the lens 49 from the light incident / exit section 45 of the above embodiment, and directly measures a plurality of light beams 36 a divided by the diffraction grating 48. Output toward multiple points of interest. Since each light beam 36a is an optical comb 34, only the regular reflection ranging light 36b regularly reflected at a plurality of points can be made incident on the distal end portion of the optical fiber cable 47, as in the above embodiment. .

(Other embodiment 2 of light incident / exit part)
As shown in FIG. 8, in addition to the optical fiber cable 47, the light incident / exit section 45 (2) is arranged in order along the optical path of the distance measuring light 36 emitted from the optical fiber cable 47. , A lens array 66, and an optical delay unit 51. The collimator lens 65 converts the distance measuring light 36 divergently emitted from the tip of the optical fiber cable 47 into parallel light, and emits the distance measuring light 36 toward the lens array 66.

  The lens array 66 has a light emitting surface on which a plurality of microlenses 66a are two-dimensionally arranged. The distance measuring light 36 incident on each microlens 66a is condensed at different points on the measurement object 9 for each microlens 66a. That is, the lens array 66 divides the distance measuring light 36 into a plurality of light beams 36 a and emits the light toward a plurality of points on the measurement object 9. Since each light beam 36a is an optical comb 34, only the regular reflection distance measuring light 36b regularly reflected at a plurality of points is passed through the lens array 66, the collimator lens 65, and the like, as in the above embodiment. It can be incident on the tip.

(Other embodiment 3 of light incident / exit part)
As shown in FIG. 9, the light incident / exit section 45 (3) is obtained by removing the collimator lens 65 from the light incident / exit section 45 (2) described above. The light incident / exit section 45 (3) condenses the distance measuring light 36 divergence emitted from the tip end of the optical fiber cable 47 by each micro lens 66 a of the lens array 66 at different points on the measurement object 9. Thereby, the distance measuring light 36 can be divided into a plurality of light beams 36 a and emitted toward a plurality of points on the measurement object 9. Since each light beam 36a is an optical comb 34, only the regular reflection ranging light 36b regularly reflected at a plurality of points can be made incident on the distal end portion of the optical fiber cable 47, as in the above embodiment. .

(Other embodiment 4 of light incident / exit part)
As shown in FIG. 10, the light incident / exiting portion 45 (4) has a lens array 68 disposed between the collimator lens 65 and the lens array 66 of the light incident / exiting portion 45 (2). . The lens array 68 has a light incident surface on which a plurality of microlenses 68a are two-dimensionally arranged. The distance measuring light 36 (parallel light) incident on each microlens 68a is condensed at different points on the lens array 66 for each microlens 68a, and further, at different points on the measurement object 9 for each microlens 66a. Focused. The lens arrays 66 and 68 that are commercially available generally have a short focal length, but by combining the two types of lens arrays 66 and 68, the light beams 36 a are condensed at a plurality of points on the object 9 to be distant. Can be made.

  Similarly to the above-described light incident / exit section 45 (2), a plurality of light beams 36a are respectively emitted toward a plurality of points on the measurement target 9, and are regularly reflected at a plurality of points. Only the light 36 b can enter the tip of the optical fiber cable 47.

(Other embodiment 5 of light incident / exit part)
As shown in FIG. 11, in addition to the optical fiber cable 47, the light incident / exit section 45 (5) is a mask 70 arranged in order along the optical path of the distance measuring light 36 emitted from the optical fiber cable 47. And a lens 71.

  The mask 70 allows passage of only the light beam 36a directed to a plurality of points on the measurement object 9, and has a plurality of through holes 70a respectively corresponding to the plurality of light beams 36a. Thereby, a part of the distance measuring light 36 incident on the mask 70 passes through each through hole 70 a and is emitted toward the lens 71, and the other distance measuring light 36 is blocked by the mask 70. Thereby, the ranging light 36 is divided into a plurality of light beams 36a.

  The lens 71 condenses the plurality of light beams 36 a incident from the mask 70 at a plurality of points on the measurement object 9, respectively. Thereby, the distance measuring light 36 can be divided into a plurality of light beams 36 a and emitted toward a plurality of points on the measurement object 9. Further, since each light beam 36a is an optical comb 34, only the regular reflection ranging light 36b regularly reflected at a plurality of points is passed through the lens 71, the mask 70, etc., as in the above-described embodiment. It can be incident on the tip.

(Other embodiment 6 of a light incident / exit part)
As shown in FIG. 12A, the light incident / exit section 45 (6) includes an optical fiber cable 47, a collimator lens 73, a beam splitter 74, and a digital mirror device (hereinafter simply abbreviated as DMD). ) 75 and a reflecting mirror 76. The arrangement of these parts is not particularly limited, but in this embodiment, the beam splitter 74 is arranged at a position facing the measurement object 9, and the direction opposite to the direction of the beam splitter 74 facing the measurement object 9 (see FIG. A DMD 75 is disposed on the middle right direction) side. Further, the collimator lens 73 and the optical fiber cable 47 are disposed on the upper side of the beam splitter 74 in the drawing, and the reflecting mirror 76 is disposed on the lower side of the drawing.

  The collimator lens 73 converts the distance measuring light 36 divergently emitted from the distal end portion of the optical fiber cable 47 into parallel light, and then emits it toward the beam splitter 74 (see the number (1) in parentheses in the figure). The beam splitter 74 reflects the distance measuring light 36 incident from the collimator lens 73 toward the DMD 75 (see the number in parentheses (2) in the figure).

  The DMD 75 is a so-called MEMS device, and has a light reflecting surface in which a large number of micromirrors 75a are two-dimensionally arranged. Each micromirror 75a has a first inclined position that reflects the distance measuring light 36 incident from the beam splitter 74 toward the beam splitter 74 (measurement object 9), and the distance measurement light 36 as the beam splitter 74 (measurement object 9). ) Can be switched to a second inclined position that reflects in a different direction. In FIGS. 12A and 12B, the arrangement of the DMD 75 and the inclination of the micromirror 75a are simplified in order to prevent complication of the drawing.

  The DMD 75 divides the distance measuring light 36 into a plurality of light beams 36 a by individually reflecting the distance measuring light 36 toward the beam splitter 74 (measurement object 9) by the individual micromirrors 75 a, thereby dividing the distance measuring light 36 into the beam splitter 74 ( The light can be emitted toward the measuring object 9). Further, the DMD 75 sequentially reaches each beam 36a to the beam splitter 74 (a plurality of points of the measurement object 9) by shifting the timing of switching the individual micromirrors 75a from the second tilt position to the first tilt position. Can do. That is, the DMD 75 also functions as an optical delay unit of the present invention.

  The beam splitter 74 transmits the plurality of light beams 36a incident from the DMD 75 as they are. Thereby, a plurality of light beams 36a can be sequentially incident on a plurality of points of the measuring object 9 (see the number in parentheses (3) in the figure).

  As shown in FIG. 12B, since each light beam 36a is an optical comb 34, only the regular reflection distance measuring light 36b specularly reflected at a plurality of points of the measuring object 9 is obtained as in the above embodiment. Sequentially enters the beam splitter 74 (see the number in parentheses (4) in the figure). Then, the beam splitter 74 reflects the regular reflection ranging light 36b for each of the plurality of points toward the reflecting mirror 76 (see the number (5) in parentheses in the figure).

  The reflecting mirror 76 reflects the regular reflection ranging light 36b incident from the beam splitter 74 for each of the plurality of points toward the beam splitter 74 (collimator lens 73). The specularly reflected distance measuring light 36b reflected toward the beam splitter 74 is transmitted through the beam splitter 74 as it is and enters the collimator lens 73, and the tip of the optical fiber cable 47 is passed through the collimator lens 73. (See the number in parentheses (6) in the figure).

  As described above, also in the light incident / exit section 45 (6), only the regular reflection ranging light 36 b that is regularly reflected at a plurality of points can be incident on the distal end portion of the optical fiber cable 47 as in the above embodiment. it can. A reflective spatial light modulator may be used instead of the DMD 75.

(Other embodiment 7 of a light incident / exit part)
As shown in FIG. 13, in addition to the optical fiber cable 47, the light incident / exit section 45 (7) is a collimator lens arranged in order along the optical path of the distance measuring light 36 emitted from the optical fiber cable 47. 65 and a transmissive spatial light modulator 79.

  The spatial light modulator 79 can individually control the transmittance, the polarization direction, and the like for each pixel. For this reason, the spatial light modulator 79 divides the distance measuring light 36 input via the optical fiber cable 47 and the collimator lens 65 into a plurality of light beams 36 a and emits the light toward the plurality of points on the measurement object 9. can do. At this time, by shifting the control timing of the transmittance, the polarization direction, etc., each light beam 36a can be made to reach a plurality of points of the measuring object 9 sequentially. That is, the spatial light modulator 79 also functions as an optical delay unit of the present invention. Similarly to the above embodiment, since each light beam 36a is an optical comb 34, only specular reflection ranging light 36b specularly reflected at a plurality of points is transmitted through an optical spatial modulator 79, a collimator lens 65, and the like. The light can enter the tip of the fiber cable 47. Instead of the spatial light modulator 79, a transmission type micro optical device may be used.

(Other embodiment 8 of light incident / exit part)
As illustrated in FIG. 14, the light incident / exit section 45 (8) includes an optical fiber cable 47, an optical fiber cable group 81, a lens 82, and the optical delay section 51 described above. The optical fiber cable group 81 includes a plurality of optical fiber cables 81 a connected to the distal end portion of the optical fiber cable 47. Each optical fiber cable 81 a emits the distance measuring light 36 input from the optical fiber cable 47 toward the lens 82. That is, the optical fiber cable group 81 divides the distance measuring light 36 into a plurality of light beams 36a and emits the light toward the lenses 82 (a plurality of points on the measurement object 9).

  The lens 82 condenses a plurality of light beams incident from the respective optical fiber cables 81a at a plurality of points on the measurement object 9, respectively. Thereby, the distance measuring light 36 can be divided into a plurality of light beams 36 a and emitted toward a plurality of points on the measurement object 9. Further, since each light beam 36a is an optical comb 34, as in the above-described embodiment, only regular reflection ranging light 36b specularly reflected at a plurality of points is passed through a lens 82, an optical fiber cable group 81, and the like. The light can enter the tip of the cable 47. Instead of providing the optical delay unit 51, an optical switch may be interposed between the optical fiber cable group 81 and the optical fiber cable 47, and the light flux 36a may be emitted in order from each optical fiber cable 81a.

(Other embodiment 9 of light incident / exit part)
As shown in FIG. 15, the light incident / exit section 45 (9) has an optical fiber cable group 85 and direction control instead of the optical fiber cable group 81 and the optical delay section 51 of the light incident / exit section 45 (8). The element 86 is arranged. The optical fiber cable group 85 includes a plurality of optical fiber cables 85 a connected to the distal end portion of the optical fiber cable 47. Thereby, like the above-described optical fiber cable group 81, the distance measuring light 36 can be divided into a plurality of light beams 36a and emitted.

  The direction control element 86 is provided at the tip of each optical fiber cable 85a. Each direction control element 86 can control the emission direction of a plurality of light beams 36a emitted from each optical fiber cable 85a. Thereby, the direction control element 86 can scan the plurality of light beams 36a condensed on the measurement object 9 through the lens 82. As a result, similar to the above-described light incident / exit section 45 (9), a plurality of light beams 36a are sequentially emitted toward a plurality of points on the measurement target 9, and are regularly reflected at a plurality of points. Only the distance measuring light 36 b can be incident on the tip of the optical fiber cable 47. The direction control element 86 also functions as an optical delay unit of the present invention by scanning the light beam 36a. Further, by scanning the light flux 36a with the direction control element 86, the number of the optical fiber cables 85a can be reduced from the number of the optical fiber cables 81a.

<Others>
In the above embodiment, the case where the multipoint distance measuring device of the present invention is applied to the shape measuring device has been described as an example. However, for example, deformation of a main body of a nuclear power plant or the like, contactless measurement of a position, other The present invention can be applied to a multipoint distance measuring device used for various purposes.

  DESCRIPTION OF SYMBOLS 10,60 ... Shape measuring apparatus, 19 ... Optical frequency comb light source, 20 ... Fabry-Perot etalon, 22 ... Splitter, 23 ... 1st optical path, 24 ... 2nd optical path, 25 ... Light incident / exit part, 26 ... Light detection , 27 ... interference fringe pattern detection unit, 28 ... distance calculation unit, 29 ... shape calculation unit, 35 ... reference light, 36 ... distance measuring light, 36a ... luminous flux, 36b ... specular reflection distance measuring light, 48 ... diffraction grating, 66, 68 ... lens array, 70 ... mask, 75 ... DMD, 79 ... spatial light modulator, 81, 85 ... optical fiber cable group, 86 ... direction control element

Claims (7)

An optical frequency comb light source that emits an optical comb having a plurality of frequency components arranged at equal frequency intervals;
An optical comb splitting unit that splits the optical comb emitted from the optical frequency comb light source into reference light and ranging light;
The distance measuring light divided by the optical comb dividing unit is divided into a plurality of light beams, respectively, emitted toward a plurality of points of the measurement object, and positively reflected by the plurality of points. A light incident / exit section where reflected light is incident;
An optical delay unit that sequentially reaches the plurality of points with the plurality of light beams emitted from the light incident / exit unit;
A light detection unit for detecting an optical interference signal between the reference light divided by the optical comb division unit and the regular reflection light at each of the plurality of points incident on the light incident / exit unit;
Based on the detection result of the light detection unit, a distance calculation unit that calculates the distance from the light incident / exit unit to each of the plurality of points;
A multipoint distance measuring device.   2. The multipoint distance measuring device according to claim 1, wherein a Fabry-Perot etalon for multiplying the frequency interval of the optical comb by an arbitrary integer is provided between the optical frequency comb light source and the optical comb divider.   The multipoint distance measuring device according to claim 2, wherein a plurality of types of Fabry-Perot etalons having different free spectral ranges are connected in series between the optical frequency comb light source and the optical comb splitting unit. An optical frequency comb light source that emits an optical comb having a plurality of frequency components arranged at equal frequency intervals;
An optical comb splitting unit that splits the optical comb emitted from the optical frequency comb light source into reference light and ranging light;
The distance measuring light divided by the optical comb dividing unit is divided into a plurality of light beams, respectively, emitted toward a plurality of points of the measurement object, and positively reflected by the plurality of points. A light incident / exit section where reflected light is incident;
A light detection unit for detecting an optical interference signal between the reference light divided by the optical comb division unit and the regular reflection light at each of the plurality of points incident on the light incident / exit unit;
Based on the detection result of the light detection unit, a distance calculation unit that calculates the distance from the light incident / exit unit to each of the plurality of points;
With
Between the optical frequency comb light source and the optical comb splitting unit, a Fabry-Perot etalon that multiplies the frequency interval of the optical comb by an arbitrary integer is provided,
A multipoint distance measuring apparatus in which a plurality of types of Fabry-Perot etalons having different free spectral ranges are connected in series between the optical frequency comb light source and the optical comb splitting unit. The light incident / exit section includes a diffraction grating, a lens array, a digital mirror device, an optical spatial modulator, a mask that allows passage of only the light beam toward the plurality of points, a plurality of optical fiber cables, and direction control for scanning the light beam. The multipoint distance measuring device according to any one of claims 1 to 4 , wherein the distance measuring light is divided using at least one of elements. The multipoint distance measuring device according to any one of claims 1 to 5,
Based on the calculation result of the distance calculation unit, a shape calculation unit that calculates the surface shape of the measurement object;
A shape measuring apparatus comprising: An emission step of emitting an optical comb having a plurality of frequency components arranged at equal frequency intervals from the optical frequency comb light source;
A light splitting step for splitting the optical comb emitted from the optical frequency comb light source into reference light and ranging light;
The distance measuring light divided in the light dividing step is divided into a plurality of light fluxes and emitted from a light incident / exit section to a plurality of points of a measurement object, and regularly reflected at the plurality of points. A light incident / exit step for causing the regular reflection light of the distance measuring light to enter the light incident / exit part;
A light delay step for sequentially reaching the plurality of points with the plurality of light beams emitted in the light incident / exit step;
A light detection step of detecting an optical interference signal between the reference light divided in the light division step and the regular reflection light for each of the plurality of points incident on the light incident / exit part;
Based on the detection result of the light detection step, a distance calculation step of calculating a distance from the light incident / exit part to each of the plurality of points;
A multipoint distance measuring method comprising:

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