Optical multipoint measuring device

Abstract

To precisely perform multipoint measurement by eliminating a measurement error because of mixture of unneeded reflection components into measurement light required for multipoint measurement.SOLUTION: Multiple pieces of measurement light are condensed by a condensing optical element and are applied to a measurement surface 5 to be measured from an optical combining element array 44 that is arranged two-dimensionally and is modularized, the multiple pieces of measurement light that are reflected by the measurement surface 5 and are returned are condensed by the set of optical system and can be inputted to the optical combining element array 44, measurement light outputted from a light source 110 via an interference optical system 120 is branched into frequency components of multiple pieces of measurement light by an optical demultiplexing element 131A, and frequency components of multiple pieces of measurement light that are reflected by multiple points on the measurement surface 5 and are returned are multiplexed by an optical multiplexing element 131B, thus forming an optical multipoint measuring device 100 in a configuration having a large directional coupling loss from an optical path in an input side of an optical combining system to an optical path in an output side.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an optical multipoint measurement device such as a multipoint vibrometer that uses light to simultaneously measure vibration information at multiple points on an object to be measured, or a multipoint rangefinder that optically measures the distance to an object to be measured at multiple points. [Background technology]

[0002] In order to investigate the causes of vibration and the load caused by vibration, it is necessary to measure the vibration distribution within the surface of the measurement object. For example, in the case of steady vibration, the vibration distribution within the surface can be measured by measuring the vibration while shifting the location in accordance with the vibration period.

[0003] However, when you want to measure transiently changing vibrations in real time, when you do not know in advance what frequency components the vibration contains, or when you need vibration information from several points simultaneously, you need a vibration measuring device that can measure vibration information from several points simultaneously.

[0004] In addition, conventional laser Doppler vibrometers can generally measure vibration amplitude in a velocity range of about 10 m / s, but cannot obtain static height, and they cannot measure vibration distribution at multiple points synchronously.

[0005] The applicant of the present application has previously proposed a vibration measuring device and a vibration measuring method that, in a vibrometer that analyzes vibration information on a measurement surface of an object to be measured by detecting interference light between reference light and measurement light, which are spectra at a predetermined frequency interval and are phase-synchronized and coherent with each other, and determining the phase difference between the reference light and measurement light, uses an optical demultiplexing / multiplexing head that demultiplexes the measurement light into frequency components and irradiates the demultiplexed light onto multiple points on the measurement surface of the object to be measured, thereby making it possible to simultaneously measure vibration information at multiple points on the measurement surface (see, for example, Patent Documents 1 to 3).

[0006] Furthermore, without using a frequency shifter, the center frequency f0 (Hz) and the frequency interval f m The optical comb is generated as a probe light, with a center frequency of f0 (Hz) and a frequency interval of fm +Δf m A vibrometer capable of multi-point measurement with a simplified device configuration has been proposed by generating an optical comb as a reference light (see, for example, Patent Document 4).

[0007] Furthermore, a multi-point measurement type laser Doppler vibrometer has been proposed that uses an optical comb generator that makes it possible to generate a wideband optical comb with multiple modes using a single modulator (Patent Document 5). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 5336921 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-203860 [Patent Document 3] Patent No. 5363231 [Patent Document 4] Patent No. 7276051 [Patent Document 5] Japanese Patent Publication No. 2022-47249 Summary of the Invention [Problem to be solved by the invention]

[0009] In an optical multi-point measurement device using an optical comb, various optical elements are provided in the optical system that propagates the reference light and measurement light through space, such as an interference optical system into which reference light and measurement light are input, an optical branching element that branches the measurement light to be irradiated onto the measurement surface into each frequency component of the optical comb, and an optical element that irradiates the measurement surface with the measurement light of each frequency component branched by the optical branching element and returns the reflected light (scattered light) from the measurement surface to the optical branching element.However, there is a risk that unnecessary reflected components will be generated in the various optical elements and will mix with the interference light required for multi-point vibration measurement, causing measurement errors.

[0010] Here, by modularizing the input and output of the interference optical system 2 to optical fiber and sending reference light and measurement light, as in the optical multipoint measurement device 1 that performs multipoint vibration measurement shown in Figure 1, it is possible to use modularized optical elements with various functions, making it easier to assemble and repair the device. In addition, by using free-space optical systems and optical fibers to make some functional elements into optical integrated circuits, the device can be made smaller.

[0011] This optical multipoint measuring device 1 uses coherent measurement light L, which has a spectrum with a predetermined frequency interval and is phase-synchronized with each other. S and reference beam L R and a light source 10 that outputs measurement light L S and reference beam L R and an interference optical system 20 into which the measurement light L S an optical multiplexing / demultiplexing head unit 30 to which the measurement interference light and the reference interference light outputted through the interference optical system 20 are inputted, an interference light detection unit 40 to which the measurement interference signal S S and the reference interference signal S R The signal processor 50 receives the signal.

[0012] In this optical multipoint measuring device 1, the light source 10 emits the measurement light (first optical comb) L S and the reference light (second optical comb) L R The intensity or phase of each is periodically modulated to generate two types of optical combs with different modulation frequencies.

[0013] The optical multiplexing / demultiplexing head unit 30 receives the measurement light L output from the light source 10 via the interference optical system 20. S is split into frequency components of the optical comb and irradiated onto a plurality of points on the measurement surface 5 of the measurement object, and the measurement light L is reflected by the measurement surface 5 and returned. S The reflected light of the frequency components is combined to form the measurement light L S Measurement light L containing each frequency component S ' is input to the interference optical system 20.

[0014] The interference optical system 20 receives the measurement light L 1 including the frequency components returned via the optical multiplexing / demultiplexing head unit 30. S ' and the reference light L output from the light source 10. R and outputs the interference light as interference light for measurement, and S and reference beam L R The light is made to interfere with one another, and the interference light is output as reference interference light.

[0015] The interference light detection unit 40 receives and detects the measurement interference light and the reference interference light output from the interference optical system 20, and converts them into an electrical signal to generate a measurement interference signal S S and the reference interference signal S R is input to the signal processing unit 50.

[0016] Then, in the signal processing unit 50, the measurement interference signal S obtained in the interference light detection unit 40 is S and the reference interference signal S R Based on this, vibration information at a plurality of points on the measurement surface 5 is analyzed, and the vibration distribution on the measurement surface 5 is measured.

[0017] Here, the optical multipoint measuring device 1 is configured to receive measurement light L output from a light source 10 via an interference optical system 20. S The measurement light L S and an optical path for multiplexing the multiple frequency components reflected and returned at multiple points on the measurement surface 5 of the measurement object and inputting them to the interference optical system 20. The optical multiplexing / demultiplexing optical system 31 is composed of an optical demultiplexing element 31A and an optical multiplexing element 31B, an optical multiplexing / demultiplexing optical system 31 having the optical demultiplexing element 31A and a coupling optical system 32, and a plurality (m×n) optical couplers OC connected to the optical multiplexing / demultiplexing optical system 31. C1 ,OC C2 ,OC C3 ,···,OC Cn , . . . , and a plurality (m×n) of projection optical elements 441, 442, 443, . . . , 44 connected to the coupling optical system 32. n, ···, and an optical multiplexing / demultiplexing head unit 30 comprising a projection optical system 33.

[0018] In this optical multipoint measurement device 1, a light source 10 emits linearly polarized measurement light (first optical comb) L S and the reference light (second optical comb) L R The first optical comb generator (C0MB1) 1A and the second optical comb generator (C0MB2) 1B each output a polarization-maintaining fiber (PMF) and an optical fiber FB 12A FB 12B The optical fiber 20 is connected to the interference optical system 20 via a polarizing fiber optic cable 21. The PMF may be replaced by a polarizing fiber optic cable that can propagate only one polarized light.

[0019] The first optical comb generator (C0MB1) 1A and the second optical comb generator (C0MB2) 1B generate the measurement light (first optical comb) L S and the reference light (second optical comb) L R The intensity or phase of each is periodically modulated to generate two types of optical combs with different modulation frequencies.

[0020] The interference optical system 20 includes an optical fiber FB using a PMF. 2A2 ,FB 2B1 ,FB 2B2 Four optical couplers connected by OC A ,OC B ,OC C ,OC D Optical coupler OC A Externally connected optical fiber FB 12A The measurement light L is emitted from the light source 10 through the S is input and the optical coupler OC B Externally connected optical fiber FB 12B Reference light L is emitted from the light source 10 via the R is entered.

[0021] In this interference optical system 20, an optical coupler OC A There are two optical fiber FB 2A2 ,FB 23via optical coupler OC D and externally connected to an optical demultiplexing element 31A provided in the optical demultiplexing / multiplexing optical system 31 of the optical demultiplexing / multiplexing head unit 30, and B There are two optical fiber FB 2B1 ,FB 2B2 Two optical couplers via OC C ,OC D is internally connected, and the optical coupler OC C Optical fiber FB 32 The optical multiplexing element 31B provided in the optical multiplexing / demultiplexing optical system 31 of the optical multiplexing / demultiplexing head unit 30 is externally connected via the optical multiplexing / demultiplexing element 31B.

[0022] Here, in the interference optical system 120, the four optical couplers OC A , O.C. B , O.C. C , O.C. D Three optical fiber FBs connecting 2A2 , F.B. 2B1 , F.B. 2B2 By making the lengths of the measurement light L output from the first optical comb generator (COMB1) 1A of the light source 110 the same, S The above optical fiber FB 2A2 Through the above optical coupler OC D The measurement light L S The optical path length through which the reference light L output from the second optical comb generator (COMB2) 1B passes is R The above optical fiber FB 2B1 , F.B. 2B2 Through the above optical coupler OC C , optical coupler OC D The reference light L R is set equal to the optical path length through which the light passes.

[0023] The measurement light L input to the interference optical system 20 S is the optical coupler OC A Optical fiber FB using PMF externally connected to 23 The light is input to the optical demultiplexer 31A via the optical demultiplexer 31B.

[0024] The optical demultiplexing element 31A and the coupling optical system 32 provided in the optical demultiplexing / multiplexing optical system 31 of the optical demultiplexing / multiplexing head unit 30 are two optical fibers FB 23 ,FB 32 The two optical couplers OC A ,OC C are individually connected externally.

[0025] The optical demultiplexing element 31A of the optical demultiplexing / multiplexing optical system 31 includes a plurality of (m×n) optical fibers FB 341 ,FB 342 ,FB 343 ,···,FB 34n , . . . , the plurality of (m×n) optical couplers OC C1 ,OC C2 ,OC C3 ,···,OC Cn , . . . , and the optical multiplexing element 31B of the optical multiplexing and demultiplexing optical system 31 is connected to a plurality of (m×n) optical fibers FB 431 ,FB 432 , F.B. 433 ,···,FB 43n , . . . , the plurality of (m×n) optical couplers OC C1 ,OC C2 ,OC C3 ,···,OC Cn ,··· is connected to.

[0026] The projection optical system 33 includes a plurality of (m×n) projection optical elements 441, 442, 443, . . . , 44 n ,... are the condenser lenses 4 A1 ,4 A2 ,4 A3 , and quarter-wave plate 4 B1 ,4 B2 ,4 B3 ,..., and multiple (m×n) optical fibers FB 441 ,FB 442 ,FB 443 ,···,FB 44n , ··· are connected to the coupling optical system 32.

[0027] The above optical fiber FB23 The measurement light L is input to the optical demultiplexing element 31A of the optical demultiplexing / multiplexing optical system 31 via S is the measurement light L in the optical demultiplexing element 31A. S The multiple frequency components of the optical comb included in are demultiplexed, and each frequency component is demultiplexed into the multiple (m×n) optical fibers FB 341 ,FB 342 ,FB 343 ,···,FB 34n , . . . , the plurality of (m×n) optical couplers OC C1 ,OC C2 ,OC C3 ,···,OC Cn , , and are input to the optical coupler OC C1 ,OC C2 ,OC C3 ,···,OC Cn ,... to multiple (m x n) optical fibers FB 441 ,FB 442 ,FB 443 ,···,FB 44n , . . . , the plurality of (m×n) condenser lenses 4 of the projection optical system 33 A1 ,4 A2 ,4 A3 ,···,4 An , , and multiple (m×n) types of frequency components are focused by a condenser lens 4 A1 ,4 A2 ,4 A3 ,···,4 An , , , and are focused by the quarter-wave plates 4 B1 ,4 B2 ,4 B3 ,···,4 Bn , ···, and is irradiated onto a plurality of points (for example, m×n measurement points arranged two-dimensionally in a matrix) on the measurement surface 5 of the measurement object.

[0028] Then, the light is reflected at each measurement point on the measurement surface 5 of the measurement object and passes through the projection optical system 33 to the FB 441 ,FB 442 ,FB 443 ,···,FB 44n , . . . , the optical coupler OC C1 ,OCC2 ,OC C3 ,···,OC Cn The measurement light L returning to S The reflected light of each frequency component of the optical comb is C1 ,OC C2 ,OC C3 ,···,OC Cn ,...to the above optical fiber FB 431 ,FB 432 ,FB 433 ,···,FB 43n , . . . , and is input to the optical multiplexing element 31B of the optical multiplexing / demultiplexing optical system 31, and is multiplexed by the optical multiplexing element 31B, and the measurement light L consisting of reflected light of each frequency component of the optical comb reflected at each measurement point on the measurement surface 5 is S ' from the optical multiplexing element 3B to the optical fiber FB 32 the optical coupler OC of the interference optical system 20 via C is entered into

[0029] Here, in this optical multipoint measuring device 1, an optical fiber using a PMF is used as the optical path, and the measuring light L S In the optical demultiplexing element 31A, the measurement light L S The frequency components of the linearly polarized light obtained by splitting the multiple frequency components of the optical comb included in A1 ,4 A2 ,4 A3 ,···,4 An , , and condensed by the quarter-wave plates 4 B1 ,4 B2 ,4 B3 ,···,4 Bn , . . . and are irradiated onto the measurement surface 5 as circularly polarized frequency components. The reflected light of the circularly polarized frequency components reflected by the measurement surface 5 is then irradiated onto the quarter wave plate 4. B1 ,4 B2 ,4 B3 ,···,4 Bn , ... A1 ,4 A2 ,4 A3 ,···,4 An ,··· will be returned.

[0030] That is, in the optical multipoint measuring device 1, the condenser lens 4 A1 ,4 A2 ,4 A3 ,···,4 An , ... B1 ,4 B2 ,4 B3 ,···,4 Bn , ... S The frequency components of the optical comb and the quarter-wave plate 4 B1 ,4 B2 ,4 B3 ,···,4 Bn ,...through a condenser lens 4 A1 ,4 A2 ,4 A3 ,···,4 An The frequency components of the reflected light input to each of the reflectors 1, 2, 3, 4 are linearly polarized light, but their polarization planes are orthogonal to each other.

[0031] From the projection optical system 33 to the optical fiber FB 441 ,FB 442 ,FB 443 ,···,FB 44n , . . . , the optical coupler OC C1 ,OC C2 ,OC C3 ,···,OC Cn , . . . is the frequency component of the reflected light returning to the optical fiber FB 341 ,FB 342 ,FB 343 ,···,FB 34n , ... C1 ,OC C2 ,OC C3 ,···,OC Cn , ... S and the optical coupler OC C1 ,OC C2 ,OC C3 ,···,OC Cn ,...to the above optical fiber FB 431 ,FB432 , F.B. 433 ,···,FB 43n , . . . and are input to the optical multiplexing element 31B of the optical multiplexing / demultiplexing optical system 31.

[0032] The optical coupler OC of the coupling optical system 32 C1 ,OC C2 ,OC C3 ,···,OC Cn , ··· are the linearly polarized measurement light L whose polarization planes are orthogonal to each other. S The frequency components of the optical comb of the reflected light reflected by the measurement surface 5 and the frequency components of the optical comb of the reflected light are input from opposite directions and output in opposite directions, and the device functions as a directional coupler, and may be a polarized beam combiner / splitter (PBC / PBS; hereafter, a module that can be used for input and output via fiber will be referred to as a PBC module) or a circulator.

[0033] The coupling optical system 32 includes the optical coupler OC C1 ,OC C2 ,OC C3 ,···,OC Cn Instead of the above, for example, a fused-type polarized beam combiner that combines two orthogonal polarized beams and outputs them to a single fiber, a fused-type PBC module that splits input light into orthogonal linearly polarized beams and outputs them to two polarization-maintaining fibers, or a PBC module using a birefringent crystal can be used.

[0034] The measurement light L is reflected at a plurality of points on the measurement surface 5 of the measurement object and returns via the projection optical system 33. S The reflected light of each frequency component of the optical comb is multiplexed by the optical multiplexing element 3B, and measurement light L consisting of reflected light of each frequency component reflected at a plurality of points on the measurement surface 5 is generated. S ' is a signal transmitted from the optical multiplexing element 31B to the optical fiber FB 32 via the optical coupler OC of the interference optical system 20. C is entered into

[0035] Here, each frequency component of the optical comb reflected at a plurality of points on the measurement surface 5 has a phase fluctuation due to a Doppler shift caused by vibrations at the plurality of points on the measurement surface 5, and the measurement light L S The reflected light of each frequency component of the optical comb is combined by the optical combining element 3B to form the measurement light L S ' is accompanied by a phase variation due to the Doppler shift.

[0036] The above optical coupler OC C is the optical coupler OC of the interference optical system 20. B From optical fiber FB 2B1 Through the above optical coupler OC C Reference light L input to R and the above measurement light L S By combining the above reference light L R and the above measurement light L S The interference light with the ' is output as interference light for measurement.

[0037] In addition, the optical coupler OC of the interference optical system 20 D is an optical coupler OC A From optical fiber FB 2A2 The measurement light L is input through S and optical coupler OC B From optical fiber FB 2B2 Reference light L input through R By combining the above-mentioned reference light L R and the above measurement light L S The interference light is output as reference interference light.

[0038] That is, in the interference optical system 20, the measurement light L 1 includes the reflected light of each frequency component of the optical comb reflected at a plurality of points on the measurement surface 5, and the reflected light is accompanied by a phase fluctuation due to the Doppler shift. S ' and the above light source 10 to the above optical coupler OC B Reference light L input to R The interference light from the optical coupler OC C and the light source 10 outputs the signal from the optical coupler OC A Measurement light L input to S and the above optical coupler OC BReference light L input to R The interference light from the optical coupler OC D Output from

[0039] The interference light detector 40, to which the measurement interference light and the reference interference light obtained by the interference optical system 20 are input, includes a measurement interference light detector 6A and a reference light detector 6B, each of which is a balanced photodetector. C Two optical fiber FBs externally connected to 26A1 ,FB 26A2 Through the above optical coupler OC C The measurement interference light detector 6A receives the measurement interference light input from the S and the optical coupler OC D Two optical fiber FBs externally connected to 26B1 ,FB 26B2 Through the above optical coupler OC D The reference interference light is detected and converted into an electrical signal, and a reference interference signal S R Output.

[0040] The balanced photodetectors used as the measurement interference light detector 6A and reference interference light detector 6B have two photodiodes connected in such a way that their photocurrents cancel each other out, canceling out the common-mode noise of the two incident light beams and converting the difference in light intensity into an electrical signal as a displacement signal, which is then output. The photodetectors combine beats with frequencies corresponding to the frequency difference between the frequency components of the optical combs of the input measurement light and reference light into a single electrical signal. The frequency difference between the measurement light and reference light described here is sufficiently small compared to the spacing between the frequency components of the optical comb, and is therefore not split by the optical multiplexing and splitting elements described below. The bandwidth of the balanced photodetector is sufficiently smaller than the spacing between the frequency components of the optical comb, yet large enough to detect the frequency difference between the measurement light and reference light.

[0041] The signal processing unit 50 then processes the measurement interference signal S obtained by the interference light detection unit 40. S and the reference interference signal S R The phase of each frequency is calculated by FFT analysis, and the above measurement interference signal S S and the reference interference signal S R By calculating the phase difference for each frequency component of the optical comb caused by the Doppler shift due to vibration at multiple points on the measurement surface 5 between the above, vibration information at multiple points on the measurement surface 5, such as vibration velocity, movement distance, acceleration, etc., is analyzed to measure the vibration distribution of the measurement surface 5.

[0042] In this way, in this optical multipoint measurement device 1, the measurement light L S The measurement light L output from the interference optical system 20 provided with the optical demultiplexing element 31A that demultiplexes the plurality of frequency components of the optical comb included in S and the measurement light L, which is provided with the optical multiplexing element 31B that multiplexes the reflected light of each frequency component reflected at a plurality of points on the measurement surface 5 of the object. S The optical path for inputting the measurement light L ′ to the interference optical system 20 is separated, and the measurement light L ′ output from the interference optical system 20 S Even if a part of the reflected light is reflected by the optical demultiplexer 31A and an unnecessary reflected component is generated, this reflected component is transmitted to the optical fiber FB 23 via the optical coupler OC of the interference optical system 20. A Return to this branch optical coupler OC A From optical fiber FB 12A Therefore, even if unwanted reflected components are generated by reflection at the optical demultiplexing element 31A, these reflected components are absorbed by the optical coupler OC C The reference light L output from R and the above measurement light L S ' interference light, that is, the measurement interference light, and the optical coupler OC D The reference light L output from R and the above measurement light L S The interference light for reference, i.e., the interference light for reference, is not affected.

[0043] Therefore, in this optical multipoint measurement device 1, the measurement light L irradiating the measurement surface 5 through the interference optical system 20 S an optical coupler OC of the coupling optical system 32; C1 ,OC C2 ,OC C3 ,···,OC Cn This eliminates measurement errors caused by unwanted reflection components from various optical elements such as ,..., which are mixed into the interference light required for multi-point vibration measurement, making it possible to perform multi-point vibration measurement with high accuracy.

[0044] However, using an element such as a PBC module as the coupling optical system 32, as in the optical multiplexing / demultiplexing head unit 30 in the optical multipoint measurement device 1, complicates the optical system and causes problems such as reflections from the lens or fiber end face inside the PBC module and the extinction ratio of the PM fiber, resulting in a loss of optical path from the input side to the output side, i.e., the optical fiber FB 34mn Optical fiber FB from the side 43mn There are problems with reflection and the extinction ratio of PM fiber. Also, using a PBC module increases the number of parts. 441 ,FB 442 ,FB 443 ,···,FB 44n Reflections from intermediate connectors and deterioration of the extinction ratio cannot be ignored.

[0045] On the other hand, the amount of reflected light returning from the measurement surface 5 to the optical multiplexing / demultiplexing head unit 30 is greatly attenuated depending on the surface properties and shape of the measurement surface 5. If the reflection from the measurement surface 5 is not sufficiently large, the measurement light (first optical comb) L S It becomes difficult to distinguish between reflections from the measurement surface 5.

[0046] In such a case, there is a problem that the vibration information calculated by the signal processing unit 50 becomes erroneous.

[0047] Therefore, the object of the present invention is to solve the various problems with the optical multiplexing / demultiplexing head of the optical multi-point measurement device 1 described above, and to eliminate measurement errors caused by unwanted reflected components being mixed into the measurement light required for multi-point measurement, by configuring it with a large directional coupling loss from the input optical path to the output optical path without using a separate PBC module or the like, thereby enabling high-precision multi-point measurement.

[0048] Other objects of the present invention and specific advantages obtained by the present invention will become more apparent from the following description of the embodiments. [Means for solving the problem]

[0049] The present invention is an optical multi-point measurement device comprising: a light source that outputs measurement light; a projection optical head to which the measurement light output from the light source is input via a plurality of optical fibers, which irradiates the input measurement light onto a plurality of points on a measurement surface of a measurement object, and which inputs the measurement light reflected and returned by the measurement surface into the plurality of optical fibers; and a signal processing unit that converts the measurement light returned from the projection optical head via the plurality of optical fibers into electrical signals and performs analytical processing, wherein the projection optical head comprises a fiber array modularizing a plurality of capillaries into which one ends of the plurality of optical fibers are inserted, and a focusing optical system that focuses the measurement light input via the fiber array with a focusing optical element and irradiates it towards the measurement surface of the measurement object, and focuses the measurement light reflected and returned by the measurement surface with the focusing optical element and inputs it into the fiber array.

[0050] In the optical multi-point measurement device according to the present invention, the projection optical head includes a coupling optical element array in which a plurality of coupling optical elements are arranged to align the optical axes of two light beams having orthogonal polarization directions output from two adjacent optical fibers on the fiber array, and the plurality of measurement light beams input to the projection optical head via the plurality of optical fibers are irradiated onto a plurality of points on the measurement surface of the measurement object via the coupling optical element array, and the signal processing unit converts the plurality of measurement light beams reflected by the measurement surface and returning from the projection optical head via a plurality of optical fibers different from the plurality of optical fibers that input the plurality of measurement light beams to the projection optical head via the coupling optical element array into electrical signals and performs analysis processing.

[0051] In addition, in the optical multipoint measurement device according to the present invention, the light source outputs coherent measurement light and reference light, which have spectra with a predetermined frequency interval, and the measurement light and reference light output from the light source are respectively input via optical fibers, and the optical multiplexing and demultiplexing optical system is composed of an optical demultiplexing element connected to the interference optical system via one optical fiber and connected to the projection optical head via multiple optical fibers, and an optical multiplexing element connected to the projection optical head via multiple optical fibers and connected to the interference optical system via another optical fiber, and the measurement light output from the light source is input from the interference optical system via the one optical fiber to the optical demultiplexing optical system, and the measurement light is demultiplexed by the optical demultiplexing element into multiple frequency components contained in the measurement light, thereby generating the multiple optical components. A plurality of measurement beams input to the projection optical head via fibers are irradiated onto a plurality of points on the measurement surface of the measurement object via the coupling optical element array, and in the signal processing unit, the plurality of measurement beams reflected by the measurement surface and returning from the projection optical head via a plurality of optical fibers other than the plurality of optical fibers that input the plurality of measurement beams to the projection optical head via the coupling optical element array are input to the optical multiplexing / demultiplexing optical system, combined by the optical multiplexing element, and input to the interference optical system via the other optical fiber as measurement beams reflected by the measurement surface, and the interference beam for measurement obtained as interference light between the measurement beam reflected by the measurement surface and the reference beam in the interference optical system is detected, converted into an electrical signal, and subjected to analysis processing.

[0052] In the optical multipoint measuring device according to the present invention, the coupling optical element may be made of a birefringent crystal.

[0053] In the optical multipoint measuring device according to the present invention, the coupling optical element may be a Wollaston prism.

[0054] Furthermore, in the optical multipoint measurement device according to the present invention, the light source outputs measurement light and reference light, which have spectra with a predetermined frequency interval and are phase-locked and coherent with each other, and the device comprises an interference optical system into which the measurement light and reference light output from the light source are input via optical fibers, an input / output light selection unit comprising a one-input multi-output optical switch connected to the interference optical system via a single optical fiber and connected to the projection optical head via a plurality of optical fibers, and a multi-input single-output optical switch connected to the projection optical head via a plurality of optical fibers and connected to the interference optical system via a single optical fiber, and the fiber array of the projection optical head comprises a coupling optical element array in which coupling optical elements are arranged two-dimensionally to align the optical axes of two light beams whose polarization directions are orthogonal to each other and output from two optical fibers. In the signal processing unit, the measurement light output from the light source is input to the input / output light selection unit from the interference optical system via the optical fiber, and is irradiated from the projection optical head to multiple points on the measurement surface of the measurement object via multiple optical fibers to which the measurement light is distributed by the one-input, multiple-output optical switch. The multiple measurement light beams reflected by the measurement surface and returned are input from the projection optical head via multiple optical fibers to the input / output light selection unit, and the multiple measurement light beams are input to the interference optical system via the optical fibers as measurement light reflected by the measurement surface, via the multiple-input, single-output optical switch. As a result, measurement interference light obtained as interference light between the measurement light reflected by the measurement surface and the reference light in the interference optical system is detected, converted into an electrical signal, and subjected to analysis processing.

[0055] Furthermore, the optical multi-point measurement device according to the present invention may include an interference optical system group consisting of a plurality of the above-described interference optical systems, and the signal processing unit may detect a plurality of interference light beams for measurement obtained by the interference optical system group, convert them into electrical signals, and perform analytical processing.

[0056] In addition, the optical multipoint measurement device according to the present invention includes an input / output optical selection unit that includes a one-input, multi-output optical switch that is connected to the light source via one optical fiber and to the projection optical head via a plurality of optical fibers, and a multi-input, one-output optical switch that is connected to the projection optical head via a plurality of optical fibers and to the signal processing unit via one optical fiber, and the fiber array of the projection optical head includes a coupling optical element array that arranges coupling optical elements in a matrix to align the optical axes of two light beams whose polarization directions are orthogonal to each other and that are output from two optical fibers, and the measurement light output from the light source is transmitted via the optical fibers. the measurement light is input to the input / output light selection unit, the measurement light is distributed by the one-input multi-output optical switch and irradiated from the projection optical head to a plurality of points on the measurement surface of the measurement object via a plurality of optical fibers, the plurality of measurement light beams reflected by the measurement surface and returned are input from the projection optical head to the input / output light selection unit via a plurality of optical fibers, and the plurality of measurement light beams are input to the signal processing unit via the optical fibers as measurement light reflected by the measurement surface via the multi-input single-output optical switch, and the signal processing unit detects the measurement light reflected by the measurement surface, converts it into an electrical signal, and performs analysis processing.

[0057] Furthermore, in the optical multi-point measurement device according to the present invention, the light source outputs measurement light and reference light, which have spectra with a predetermined frequency interval and are phase-locked and coherent with each other, and the device comprises an interference optical system to which the measurement light and reference light output from the light source are input via optical fibers, an optical coupler connected to the interference optical system via two optical fibers, and an optical multiplexing and demultiplexing optical system consisting of an optical coupler connected to the optical coupler via optical fibers and connected to the projection optical head via a plurality of optical fibers, and the signal processing unit inputs the measurement light output from the light source from the interference optical system via the optical fibers to the optical multiplexing and demultiplexing optical system, The measurement light is demultiplexed into a plurality of frequency components of an optical comb contained in the measurement light by an optical multiplexer / demultiplexer element, and is irradiated from the projection optical head onto a plurality of points on the measurement surface of the measurement object. The plurality of measurement light beams reflected by the measurement surface and returned are input from the projection optical head to the optical multiplexer / demultiplexer optical system via the plurality of optical fibers, combined by the optical multiplexer / demultiplexer element, and input to the interference optical system via the optical fiber as measurement light reflected by the measurement surface. In the interference optical system, interference light for measurement obtained as interference light between the measurement light reflected by the measurement surface and the reference light can be detected, converted into an electrical signal, and subjected to analysis processing. [Effects of the Invention]

[0058] In the optical multi-point measurement device according to the present invention, a projection optical head that irradiates measurement light onto the measurement surface of the object to be measured is provided with a fiber array that modularizes a plurality of capillaries into which one end of a plurality of optical fibers is inserted. This allows the plurality of measurement light beams input via the fiber array to be focused by a set of optical systems consisting of focusing optical elements and irradiated toward the measurement surface of the object to be measured, and the plurality of measurement light beams that are reflected and returned by the measurement surface to be focused by the set of optical systems and input to the fiber array, thereby simplifying the structure of the projection optical head.

[0059] Furthermore, in the optical multi-point measurement device, the fiber array of the projection optical head is provided with a two-dimensionally arranged coupling optical element array in which coupling optical elements that align the optical axes of two light beams output from two optical fibers and whose polarization directions are orthogonal to each other are arranged. This separates the measurement light output from the light source via the interference optical system into an optical path that splits the measurement light into multiple frequency components of the optical comb contained in the measurement light and irradiates multiple points on the measurement surface of the object to be measured, and an optical path that combines the multiple frequency components that are reflected and returned from multiple points on the measurement surface and inputs them into the interference optical system. This eliminates the need for a separate PBC module or the like, and enables a configuration with large directional coupling loss from the input optical path to the output optical path in the coupling optical system, eliminating measurement errors caused by unwanted reflected components mixing into the measurement light required for multi-point measurement and enabling highly accurate multi-point measurement. [Brief explanation of the drawings]

[0060] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an optical multipoint measurement device that performs multipoint vibration measurement using a modularized interference optical system in which input and output are optical fibers. [Figure 2] FIG. 2 is a schematic diagram showing the configuration of an optical multipoint measurement device for performing multipoint vibration measurement and the like to which the present invention is applied. [Figure 3] 3A and 3B are diagrams explaining the functions of the optical demultiplexing element and the optical multiplexing element provided in the optical multiplexing / demultiplexing head in the optical multipoint measurement device. FIG. 3A shows the function of demultiplexing each frequency component of the optical comb contained in the measurement light into each frequency component of the optical comb by the optical demultiplexing element, and FIG. 3B shows the function of multiplexing each frequency component demultiplexed into each frequency component by the optical multiplexing element. [Figure 4] Figures 4(A) and (B) are diagrams showing an example of the configuration of a coupling optical element array, which is formed by two-dimensionally arranging multiple coupling optical units provided in the projection optical head with built-in coupling optical elements of the optical multipoint measurement device, where (A) is a longitudinal side view of the coupling optical element array, and (B) is a longitudinal front view of the coupling optical element array. [Figure 5]Figures 5(A) and (B) show an example of the configuration of a coupling optical unit used in the projection optical head with the built-in coupling optical element, where (A) is a schematic diagram showing the configuration of the coupling optical unit, and (B) is a front view of a two-core capillary provided in the coupling optical unit. [Figure 6] Figures 6(A) and (B) show another example of the configuration of the coupling optical unit used in the projection optical head with the built-in coupling optical element, where (A) is a schematic diagram showing the configuration of the coupling optical unit, and (B) is a front view of the two-core capillary provided in the coupling optical unit. [Figure 7] 7A and 7B are diagrams explaining the functions of the optical demultiplexing element and the optical multiplexing element provided in the optical multiplexing / demultiplexing head in the optical multipoint measurement device. (A) shows the function of demultiplexing each frequency component of the optical comb contained in the measurement light into multiple frequencies using the optical demultiplexing element, and (B) shows the function of multiplexing each frequency component demultiplexed into multiple frequency components using the optical multiplexing element. [Figure 8] FIG. 8 shows the results of measuring an optical comb demultiplexed by an optical multiplexer / demultiplexer that demultiplexes an optical comb into three frequency components, using an optical spectrum analyzer. [Figure 9] FIG. 9 is a schematic diagram showing a modified example of the optical multipoint measuring device. [Figure 10] FIG. 10 is a schematic diagram showing another example of the configuration of an optical multipoint measuring device to which the present invention is applied. [Figure 11] FIG. 11 is a schematic diagram showing another example of the configuration of an optical multipoint measuring device to which the present invention is applied. [Figure 12] FIG. 12 is a schematic diagram showing another example of the configuration of an optical multipoint measuring device to which the present invention is applied. [Figure 13] FIG. 13 is a schematic diagram showing another example of the configuration of an optical multipoint measuring device to which the present invention is applied. [Figure 14] Figures 14(A) and (B) show an example of the configuration of a fiber array in which one ends of multiple optical fibers provided in the projection optical head of the optical multi-point measurement device are arranged two-dimensionally, where (A) is a longitudinal side view of the fiber array and (B) is a longitudinal front view of the fiber array. DETAILED DESCRIPTION OF THE INVENTION

[0061] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Common components will be described by using common reference numerals in the drawings. Furthermore, the present invention is not limited to the following examples, and can be modified as desired without departing from the spirit of the present invention.

[0062] FIG. 2 is a schematic diagram showing the configuration of an optical multipoint measuring device 100 for performing multipoint vibration measurement and the like to which the present invention is applied.

[0063] Here, this optical multi-point measurement device 100 is the optical multi-point measurement device 1 shown in Figure 1 to which the present invention has been applied, and in this optical multi-point measurement device 100, the same components as those in the optical multi-point measurement device 1 are given the same symbols, and detailed explanations of them will be omitted.

[0064] This optical multipoint measurement device 100 uses coherent measurement light L, which has a spectrum with a predetermined frequency interval and is phase-synchronized with each other. S and reference beam L R and a light source 110 that outputs measurement light L S and reference beam L R are input via optical fibers FB12A and FB12B, respectively, and the measurement light L S an optical multiplexing / demultiplexing head unit 130 to which the measurement interference light and the reference interference light outputted via the interference optical system 120 are inputted, an interference light detection unit 140 to which the measurement interference signal S S and the reference interference signal S R The signal processor 150 receives the signal.

[0065] The optical multiplexing / demultiplexing head unit 130 in this optical multipoint measuring device 100 is configured to connect the optical fiber FB 23 The optical demultiplexer 131A and the interference optical system 120 are connected via an optical fiber FB 32and a light multiplexing / demultiplexing optical system 131 including a light multiplexing element 131B connected via a plurality of (m×n) coupling optical elements 44 of the projection optical system 33 in the optical multipoint measurement device 1. A1 ,44 A2 ,44 A3 ,···,44 An ,···,44 Amn a coupling optical element array 44 in which the above-mentioned lenses are arranged two-dimensionally and modularized, and a condenser lens 4 of the projection optical system 33. A1 ,4 A2 ,4 A3 ,···,4 An , i.e., the light-collecting optical element 4A functioning as a projection optical element. a ,4A b A set of optical systems 4A consisting of ab and the quarter-wave plate 4 of the projection optical system 33. B1 ,4 B2 ,4 B3 ,···,4 Bn , . . . , the projection optical head 133 includes a coupling optical element formed of a quarter-wave plate 4B. ab is a simplified representation of a double-telecentric optical system. In reality, it is made up of many lenses. A double-telecentric optical system can project and focus the measurement light output vertically from the coupling optical element array 44 vertically onto a horizontal target. This is the most sensitive projection optical system when the target is flat. For large targets, it is possible to use a telecentric optical system on only one side and an fθ optical system on the other side. It is also not necessary to use a telecentric optical system; select an optical system that suits the size and shape of the target.

[0066] 3A and 3B are diagrams illustrating the functions of the optical demultiplexing element 131A and the optical multiplexing element 131B provided in the optical demultiplexing / multiplexing head unit 130 in the optical multipoint measuring device 100. The optical demultiplexing element 131A is a S 3B, the optical demultiplexing element 131A has a function of demultiplexing each frequency component of the optical comb included in the optical comb into each frequency component, and combines the frequency components demultiplexed into the measurement light LS It has the function of '.

[0067] 4A and 4B are diagrams showing an example of the configuration of the coupling optical element array 44, where (A) is a vertical cross-sectional side view of the coupling optical element array 44 and (B) is a vertical cross-sectional front view of the coupling optical element array 44.

[0068] That is, the projection optical head 133 with built-in coupling optical elements has a plurality of (m×n) coupling optical elements 44 as shown in FIGS. 4A and 4B. A1 ,44 A2 ,44 A3 ,···,44 An ,···,44 Amn The optical coupling element array 44 is a modular combination of two-dimensionally arranged optical elements.

[0069] The plurality of (m×n) coupling optical elements 44 in the coupling optical element array 44 A1 ,44 A2 ,44 A3 ,···,44 An ,···,44 Amn For example, the coupling optical unit 4C having the configuration shown in (A) and (B) of FIG. A are used respectively.

[0070] 5A and 5B show the coupling optical unit 4C used in the projection optical head 133 incorporating the coupling optical element. A 1A is a diagram showing an example of the configuration of the coupling optical unit 4C. A 1B is a schematic diagram showing the configuration of the coupling optical unit 4C. A 4C1。 FIG. 4C1 is a front view of the two-core capillary.

[0071] This coupling optical unit 4C A The optical coupling element 4C2 has optical properties that allow the axes of the light beams whose polarization directions are orthogonal to each other and output from the tips of the two optical fibers inserted into the two-core capillary 4C1 to coincide with each other. 34 and output optical fiber FB 43is externally derived.

[0072] In this coupling optical element array 44, the input side FB 341 ,FB 342 ,FB 343 ,···,FB 34n , and the output optical fiber FB 431 ,FB 432 ,FB 433 ,···,FB 43n ,... are each led out to the outside from the two-core capillary 4C1, but it is also possible to adopt a structure in which multiple optical fibers are precisely positioned and the direction of the PMF can be controlled, such as a structure in which multiple optical fibers are led out to the outside through multiple insertion holes provided in a substrate, without using a two-core capillary.

[0073] Furthermore, in the projection optical head 133 with built-in coupling optical elements, a plurality of (m×n) coupling optical elements 44 are arranged so that each frequency component of the optical comb of the measurement light is irradiated onto m×n measurement points arranged two-dimensionally in a matrix. A1 ,44 A2 ,44 A3 ,···,44 An ,···,44 Amn However, depending on the object to be measured, a plurality of coupling optical elements 44 may be used. A1 ,44 A2 ,44 A3 ,···,44 An ,···,44 Amn Alternatively, a modularized coupling optical element array may be employed in which the optical elements are arranged two-dimensionally in a fine lattice pattern (for example, a hexagonal fine lattice pattern).

[0074] The above coupling optical unit 4C A The directions of the stress-applying portions of the polarization-maintaining fibers inserted into the two-core capillary 4C1 provided in the optical fiber 4C1 are arranged to be orthogonal to each other, as shown in FIG. 5(B).

[0075] The input optical fiber FB led out from the two-core capillary 4C1 to the outside 34is connected to the optical demultiplexing element 131A of the optical demultiplexing / multiplexing optical system 131, and is connected to the output side optical fiber FB led out from the two-core capillary 4C1 to the outside. 43 is connected to the optical demultiplexing element 131A of the optical demultiplexing / multiplexing optical system 131.

[0076] And, this coupling optical unit 4C A Then, the optical fiber FB 34 The measurement light L is input through S The frequency component of l S The light-collecting optical element 4A functions as a projection optical element via the coupling optical element 4C2. a ,4A b A set of optical systems 4A consisting of ab This set of optical systems 4A ab The frequency component l focused by S is irradiated onto the measurement surface 5 of the measurement object through the quarter-wave plate 4B. The light reflected by the measurement surface 5 is converted into the frequency component l through the quarter-wave plate 4B. S is the frequency component l of the polarization plane that is perpendicular to the polarization direction. S 'The above set of optical systems 4A ab will be returned to

[0077] The above frequency component l S is the frequency component l of the polarization plane that is perpendicular to the polarization direction. S ' denotes the set of optical systems 4A ab and the light is collected by the coupling optical unit 4C. A The output optical fiber FB 43 and the output side of this optical fiber FB 43 The light is input to the optical multiplexing element 131B of the optical multiplexing / demultiplexing optical system 131 via the optical multiplexing element 131B.

[0078] The coupling optical element 4C2 may be made of a birefringent crystal for separating light beams by using walk-off, for example.

[0079] Furthermore, in the projection optical head 133 with a built-in coupling optical element, a Wollaston prism 4C as shown in (A) and (B) of FIG. 6 is used instead of the coupling optical element 4C2 using the birefringent crystal. b The coupling optical unit 4C using the coupling optical element 4C2' configured by the above B can also be adopted.

[0080] When a birefringent crystal is used for the coupling optical element 4C2, it is possible to arrange the double-core capillaries 4C1 in an array as shown in Figure 4(B), and then attach a birefringent crystal large enough to cover the entire coupling optical element array, thereby replacing the entire coupling optical element 4C2 with a single birefringent crystal. This reduces the number of parts compared to when a Wollaston prism is used.

[0081] 6A and 6B show the coupling optical unit 4C used in the projection optical head 133 incorporating the coupling optical element. B 1A is a diagram showing an example of the configuration of the coupling optical unit 4C. B 1B is a schematic diagram showing the configuration of the coupling optical unit 4C. B 4C1。 FIG. 4C1 is a front view of the two-core capillary.

[0082] This coupling optical unit 4C B The optical coupling element 4C2' has optical characteristics that allow the axes of the light beams whose polarization directions are orthogonal to each other and output from the tips of the two optical fibers inserted into the two-core capillary 4C1 to coincide with each other. The optical coupling element 4C2' is connected to the optical fiber FB 34 and the output optical fiber FB 43 is externally derived.

[0083] The above coupling optical unit 4C B The directions of the stress applying portions of the polarization-maintaining fibers inserted into the stress applying portions of the two-core capillary 4C1 provided in the optical fiber 4C1 are arranged to be orthogonal to each other as shown in FIG. 6(B).

[0084] The coupling optical element 4C2' includes two collimator lenses 4C a ,4Cc Between Wollaston prism 4C b It is made by arranging the following.

[0085] This coupling optical unit 4C B In this case, the optical fiber FB 34 The measurement light L is input through S The frequency component l of the optical comb S The light-collecting optical element 4A functions as a projection optical element via the coupling optical element 4C2'. a ,4A b A set of optical systems 4A consisting of ab The optical system 4A ab The frequency component l focused by S is irradiated onto the measurement surface 5 of the measurement object through the quarter-wave plate 4B. The reflected light from the measurement surface 5 is then irradiated onto the measurement surface 5 through the quarter-wave plate 4B. S is the frequency component l of the polarization plane whose polarization direction is orthogonal to the S 'The above set of optical systems 4A ab will be returned to

[0086] The above frequency component l S is the frequency component l of the polarization plane whose polarization direction is orthogonal to the S ' denotes the set of optical systems 4A ab and is transmitted to the output side optical fiber FB via the coupling optical element 4C2'. 43 and the output side of this optical fiber FB 43 The light is input to the optical multiplexing element 131B of the optical multiplexing / demultiplexing optical system 131 via the optical multiplexing element 131B.

[0087] The above coupling optical unit 4C B , 4C B As shown in FIG. 5B and FIG. 6B, the optical input whose polarization plane is in the direction of the stress applying part of the inserted polarization-maintaining (PM) fiber from fiber end faces Port1 and Port2 in the two-core capillary 4C1 arranged so that the stress applying part is perpendicular to the fiber end faces Port2 and Port2 and input to the coupling optical elements 4C2 and 4C2' is as follows: By passing through the coupling optical elements 4C2 and 4C2', the optical axes of the measurement light beams L become coaxial and are output in the same direction. S The frequency component l of the optical comb S Port1 (input side optical fiber FB 34 The frequency component l is input from the direction of the stress applying part and reflected by the measurement surface 5. S ' to Port2 (output optical fiber FB 43 The light can be received in the direction of the stress applying part.

[0088] Here, in the optical multiplexing / demultiplexing head unit 30 in the optical multipoint measurement device 1, the optical multiplexing / demultiplexing optical system 31 is configured to be connected to the projection optical system 33 via the coupling optical system 32, but in this optical multipoint measurement device 100, the coupling optical system 32 and the projection optical system 33 in the optical multipoint measurement device 1 are replaced with a coupling optical element-integrated projection optical head 133 that has the function of the coupling optical system 32, so that the fiber FB connecting the coupling optical system 32 and the projection optical head 133 is 431 ,FB 432 ,FB 433 ,···,FB 43n , . . . are no longer necessary, and the optical multiplexing / demultiplexing head unit 130 can be configured with two optical systems, the optical multiplexing / demultiplexing optical system 131 and the projection optical head 133 with a built-in coupling optical element. This not only simplifies the configuration, but also reduces the need for the above-mentioned fiber FB 431 ,FB 432 ,FB 433 ,···,FB 43n , . . . does not involve the generation of unnecessary reflected light by the end faces of the optical fiber.

[0089] That is, using an element such as a PBC module as the coupling optical system 32, as in the optical multiplexing / demultiplexing head unit 30 in the optical multipoint measurement device 1, complicates the optical system and raises problems such as reflections inside the PBC module and the extinction ratio of the PM fiber. Furthermore, using a separate PBC module or the like increases the number of components. Reflections from multiple lenses and fiber end faces inside the PBC module can also be problematic. However, in the optical multipoint measurement device 100, by providing the optical multiplexing / demultiplexing head unit 130 with the projection optical head 133 with a built-in coupling optical element, it is not necessary to use a separate PBC module or the like. This allows for a configuration with a larger directional coupling loss from Port 1 to Port 2. By increasing the directional coupling loss from the input optical path to the output optical path in the coupling optical system, these problems are resolved.

[0090] In the Wollaston prism type projection optical head 133 with built-in coupling optical element provided in the optical multiplexing / demultiplexing head unit 130, a directional coupling loss from Port 1 to Port 2 of 80 dB to 90 dB was actually measured.

[0091] The plurality of modularized (m×n) coupling optical elements 44 A1 ,44 A2 ,44 A3 ,···,44 An ,···,44 Amn There are multiple (m×n) optical fibers FB 341 ,FB 342 ,FB 343 ,···,FB 34n , . . . connected to the optical demultiplexing element 131A of the optical demultiplexing / multiplexing optical system 131, and a plurality of (m×n) optical fibers FB 431 ,FB 432 ,FB 433 ,···,FB 43n , ···, and are connected to the optical multiplexing element 131B of the optical multiplexing and demultiplexing optical system 131.

[0092] The projection optical head 133 with built-in coupling optical elements in this optical multipoint measurement device 100 includes a plurality of (m×n) coupling optical elements 44 A1,44 A2 ,44 A3 ,···,44 An ,···,44 Amn By adopting the coupling optical element array 44 in which the optical fibers FB are arranged two-dimensionally and modularized, 341 ,FB 342 ,FB 343 ,···,FB 34n ,···,FB 34mn The measurement light L is input through S The plurality of frequency components of the optical comb are focused by the focusing optical element 4A a ,4A b A set of optical systems 4A consisting of ab The light can be collected by the optical fiber 4 and irradiated onto a plurality of points on the measurement surface 5 of the object to be measured via one quarter-wave plate 4B.

[0093] The reflected light reflected at a plurality of points on the measurement surface 5 is converted into frequency components of a polarization plane perpendicular to the polarization direction of the irradiated frequency components via the quarter-wave plate 4B, and is then passed through the set of optical systems 4A ab and the light is collected by the coupling optical element array 44 and output to a plurality of optical fibers FB 341 ,FB 342 ,FB 343 ,···,FB 34n ,···,FB 34mn The light is input to the optical multiplexing element 131B of the optical multiplexing / demultiplexing optical system 131 via the optical multiplexing element 131B.

[0094] The optical multiplexing element 131B of the optical multiplexing / demultiplexing optical system 131 receives the measurement light L 1 reflected at a plurality of points on the measurement surface 5 of the measurement object and returning via the projection optical head 133. S The frequency components of the optical comb are combined and reflected at multiple points on the measurement surface 5 to form a measurement light L S ' is the optical fiber FB 32 via the optical coupler OC of the interference optical system 120. C is entered into

[0095] That is, in the optical multiplexing / demultiplexing head unit 130 in this optical multipoint measuring device 100, as shown in FIG. 3A, the measurement light L S The optical comb frequency components included in the optical comb are separated into individual frequency components by the optical demultiplexing element 131A, and each frequency component is irradiated onto a plurality of points on the measurement surface 5 of the measurement object via the projection optical head 133 with the built-in coupling optical element. As shown in FIG. 3B, the reflected light of each frequency component reflected by the measurement surface 5 and returning via the projection optical head 133 with the built-in coupling optical element is combined by the optical combining element 131B to generate measurement light L consisting of the reflected light of each frequency component for each frequency component. S 'Let's say.

[0096] The optical coupler OC of the interference optical system 120 C is the measurement light L consisting of reflected light of each frequency component of the optical comb reflected at multiple points on the measurement surface 5. S ' is the above optical fiber FB 32 and the second optical comb generator (COMB2) 1B of the light source 110 is inputted via the optical fiber FB 12B via optical coupler OC B Reference light L input to R Optical fiber FB 2B1 The measurement light L is input through S ' and the reference beam L R The optical coupler OC of the interference optical system 120 outputs the interference light with the optical coupler OC as interference light for measurement. D is transmitted from the first optical comb generator (COMB1) 1A of the light source 110 to the optical fiber FB 12A via optical coupler OC A Measurement light L input to S Optical fiber FB 2A2 and the second optical comb generator (COMB2) 1B of the light source 110 is inputted via the optical fiber FB 12B via optical coupler OC B Reference light L input to R Optical fiber FB 2B2 The measurement light L is input through S and reference beam L R The interference light with the reference light is output as reference interference light.

[0097] Here, each frequency component of the optical comb reflected at a plurality of points on the measurement surface 5 has a phase fluctuation due to a Doppler shift caused by vibrations at the plurality of points on the measurement surface 5, and the measurement light L S The reflected light of each frequency component is combined by the optical combining element 3B to form the measurement light L S ' is accompanied by a phase variation due to the Doppler shift.

[0098] The interference light detector 140 receives the interference light for measurement and the interference light for reference obtained by the interference optical system 120. C Two optical fibers externally connected to 26A1 ,FB 26A2 The measurement interference light detector 6A receives the measurement interference light via the S and the optical coupler OC D Two optical fiber FBs externally connected to 26B1 ,FB 26B2 The reference interference light is detected by an interference light detector 6B that receives the reference interference light via the R Output.

[0099] Then, in the signal processing unit 150, the measurement interference signal S obtained in the interference light detection unit 140 is S and the reference interference signal S R The phase for each frequency is calculated by FFT analysis, and the phase difference for each frequency component of the optical comb caused by the Doppler shift due to vibration at multiple points on the measurement surface 5 is obtained, thereby analyzing vibration information at multiple points on the measurement surface 5 and measuring the vibration distribution on the measurement surface 5.

[0100] In this optical multipoint measurement device 100, the measurement light L S The measurement light L output from the interference optical system 120 provided with the optical demultiplexing element 131A that demultiplexes the plurality of frequency components of the optical comb included in Sand the measurement light L, which is provided with the optical multiplexing element 131B that multiplexes the reflected light of each frequency component of the optical comb reflected at multiple points on the measurement surface 5 of the object. S Since the optical path for inputting the measurement light L ′ to the interference optical system 120 is separated, the measurement light L ′ irradiated onto the measurement surface 5 via the interference optical system 120 S This eliminates measurement errors caused by unwanted reflection components from the optical demultiplexer 131A provided in the optical path through which the light passes, which are mixed into the interference light required for multi-point vibration measurement, thereby enabling high-precision multi-point vibration measurement.

[0101] In the interference optical system 120 of the optical multipoint measuring device 100, the reference light LR is output from the second optical comb generator (COMB2) 1B of the light source 110, and then the optical coupler OC C is calculated by dividing the time required for the measurement light L from the first optical comb generator (COMB1) 1A of the light source 110 to be input to the S is output and then the measurement light L S ' is the optical coupler OC of the interference optical system 120. C The delay is set to the reference light L R Delay given to fiber FB 2B1 ' is the reference light L from the second optical comb generator (COMB2) 1B of the light source 110. R is input to the optical coupler OC B and an optical coupler OC that outputs interference light for measurement. C and the optical fiber FB that is internally connected 2B1 It is set up in.

[0102] That is, the optical fiber FB 2B1 Delay fiber FB 2B1 ' is provided, the measurement light L output from the first optical comb generator (COMB1) 1A of the light source 110 S The measurement light L is reflected by the reflecting surface 5 of the measurement object. S The optical coupler OC of the interference optical system 120 is C The measurement light L S ,L Sand the optical path length through which the reference light L′ passes, and the reference light L output from the second optical comb generator (COMB2) 1B of the light source 110. R is the optical coupler OC of the interference optical system 120. C The reference light L R The optical path lengths through which the light passes are made equal.

[0103] In this way, the measurement light L output from the light source 110 S and reference beam L R However, the above optical fiber FB 32 The measurement light L containing the above frequency components returns via S ' and the above reference light L R and the reference light L are made to interfere with each other in the interference optical system 120 and output as interference light for measurement. R The delay fiber FB is inserted into the optical path through which 2B1 ' is provided to receive the measurement light LS and the measurement light L including the frequency components reflected by the measurement surface 5. S The optical path length of the optical path through which the reference light L R By making the optical path lengths of the optical paths through which the measurement interference light and the reference interference light obtained by the interference optical system 120 are equal, the reference interference signal S output from the interference light detection unit 160 that detects the measurement interference light and the reference interference light is R , the measurement interference signal S S Measurement light L S and reference beam L R The difference in the phase noise of the measurement light L S and reference beam L R This can reduce measurement errors caused by phase noise.

[0104] Here, assuming that the first optical comb generator (COMB1) 1A and the second optical comb generator (COMB2) 1B of the light source 110 generate optical combs by electro-optic modulation, the effect of the delay optical system will be explained using mathematical formulas.

[0105] The phase noise of the laser that is the seed light source of the light source 110 is Φ Laser (t), the phase noise of the oscillators modulating the first optical comb generator (COMB1) 1A and the second optical comb generator (COMB2) 1B is Φfm1 (t), Φ fm2 (t), and the vibration information component Φ due to the phase fluctuation caused by this phase noise component and Doppler shift Bn Consider (t).

[0106] The measurement light L output from the first optical comb generator (COMB1) 1A S The phase noise Φ of the optical comb component with index n relative to the carrier of the comb is Sn (t) is Φ Sn (t)=Φ Laser (t)+nΦ fm1 (t) Formula (A) The reference light L output from the second optical comb generator (COMB2) 1A is R The phase noise Φ of the optical comb component Rn (t) is Φ Rn (t)=Φ Laser (t)+nΦ fm2 (t) Formula (B) Here, Φ fm1 (t), fm2 Since (t) is a harmonic, it is multiplied by n, where n is the sideband index and the carrier is set to 0.

[0107] Measurement light L returning via the target S 's phase noise of the optical comb component Φ Sn '(t) is the delay of the optical system, and Φ is the vibration information component due to the phase fluctuation caused by the Doppler shift due to vibration. Bn When (t) is used, Φ Sn '(t)=Φ Bn (t+τ / 2)+Φ Laser (t+τ)+nΦ fm1 (t+τ) Formula (C) τ is the incremental delay component when traveling back and forth to the target, and the phase component Φ Bn The delay of (t+τ / 2) is set to +τ / 2 because we only experienced the return time for one way trip.

[0108] The noise due to the phase difference between the frequency components of the index n optical comb 1 and the index n optical comb 2 included in the signal interference light detection unit 6A is expressed as the measurement interference signal S S (t) is obtained by FFT analysis, and this is Ssn (t), then equation (C) - equation (B), i.e., Φ Ssn (t)=Φ Sn '(t)-Φ Rn (t) =Φ Bn (t+τ / 2)+Φ Laser (t+τ)+nΦ fm1 (t+τ) -Φ Laser (t)-nΦ fm2 (t) Equation (1) This becomes:

[0109] On the other hand, the noise due to the phase difference between the frequency components of the index n optical comb 1 and the index n optical comb 2 included in the reference interference light detection unit 6B is expressed as the reference interference signal S R (t) is obtained by FFT analysis, and this is SRn (t), then equation (A) - equation (B), that is, Φ SRn (t)=Φ Sn (t)-Φ Rn (t) =nΦ fm1 (t) -nΦ fm2 (t) Equation (2) This becomes:

[0110] The measurement interference signal S shown in equation (1) S Noise Φ of (t) Ssn (t) and the reference interference signal S shown in equation (2) R Noise Φ of (t) SRn When the difference (equation (1)-equation (2)) of (t) is calculated by the signal processing unit 150, Φ Sn '(t)-Φ Sn (t)=Φ Bn (t+τ / 2)+Φ Laser (t+τ) +nΦ fm1 (t+τ)-Φ Laser (t)-nΦfm1 (t) Equation (3) This becomes:

[0111] where Φ Sn '(t)-Φ Sn Since (t) is not simultaneous, the noise component does not become 0.

[0112] However, it cannot be applied to a rangefinder that requires a large dynamic range, but it can be used in cases where the distance to the target object is almost fixed, such as a vibrometer, by using the reference light L. R The delay fiber FB gives a delay equivalent to +τ in the optical path through which 2B1 ' above the reference light L R The optical fiber FB through which 2B1 By inserting into, the above equation (1) becomes Φ Ssn_Delay (t)=Φ Sn '(t)-Φ Rn (t+τ) =Φ Bn (t+τ / 2)+nΦ fm1 (t+τ)-nΦ fm2 (t+τ) Equation (4) As a result, the in-phase laser phase noise disappears. Since both optical combs 1 and 2 are made from the same laser, the laser phase noise is in-phase, and the in-phase noise is eliminated.

[0113] The difference between the above formula (4) and formula (2) (formula (4) - formula (2)) is calculated by the signal processing unit 150. Φ Ssn_Delay (t)-Φ SRn (t)=Φ Bn (t+τ / 2)+nΦ fm1 (t+τ) -nΦ fm2 (t+τ)-nΦ fm1 (t)+nΦ fm2 (t) Equation (5) In this equation (5), the phase noise of the laser is cancelled out, but the phase noise of the oscillator cannot be completely removed because it is uncorrelated.

[0114] Therefore, the time to compare the phases is determined by the reference interference signal S Rand the measurement interference signal S S For example, the reference interference signal S R cable or optical fiber FB 26B1 and FB 26B2 , or FB 2A2 and FB 2B2 The length of the reference interference signal S R If the delay is increased, the above equation (2) is delayed by the time τ Φ SRn_Delay (t)=Φ SRn (t+τ) =nΦ fm1 (t+τ)-nΦ fm2 (t+τ) Equation (6) The phase difference between the above equations (4) and (6) (equation (4) - equation (6)) is Φ Ssn_Delay (t)-Φ SRn_Delay (t)=Φ Bn (t+τ / 2) Equation (7) Thus, the phase noise of the oscillator is cancelled out, and what remains is the phase change component due to vibration.

[0115] Here, the reference interference signal S R cable or optical fiber FB 26B1 and FB 26B2 , or FB 2A2 and FB 2B2 Although τ was adjusted by the length of the reference interference signal S R and the measurement interference signal S S is digitized by the signal processing unit 150, it can be adjusted digitally by adding a time delay by shifting the calculation start point. By matching the delay to the component with the largest delay and making all other delays the same, it is possible to minimize the effects of laser and oscillator phase noise.

[0116] In this optical multipoint measuring device 100, the coupling optical element array 44 is employed in the coupling optical element built-in projection optical head 133, so that the light beams are transmitted from the optical demultiplexing element 131A of the optical demultiplexing / multiplexing optical system 131 to the plurality of optical fibers FB 341 ,FB 342 ,FB343 ,···,FB 34n ,···,FB 34mn The measurement light L is input through S The plurality of frequency components of the optical comb are focused by the focusing optical element 4A a ,4A b A set of optical systems 4A consisting of ab The light is collected by the quarter-wave plate 4B and irradiated onto a plurality of points on the measurement surface 5 of the object to be measured. The light reflected at the plurality of points on the measurement surface 5 is converted into frequency components with a polarization plane perpendicular to the polarization direction of the irradiated frequency components via the quarter-wave plate 4B. ab and the light is collected by the coupling optical element array 44 and output to a plurality of optical fibers FB 431 ,FB 432 ,FB 433 ,···,FB 43n ,···,FB 43mn The light can be input to the optical multiplexing element 131B of the optical multiplexing and demultiplexing optical system 131 via the optical multiplexing and demultiplexing optical system 131, thereby solving various problems in the optical multiplexing and demultiplexing head unit 30 of the optical multipoint measurement device 1, and there is no need to use a separate PBC module or the like. By configuring the coupling optical system to have a large directional coupling loss from the optical path on the input side to the optical path on the output side, measurement errors caused by unnecessary reflected components being mixed into the measurement light required for multipoint measurement can be eliminated, and multipoint measurement can be performed with high precision.

[0117] Here, in the optical multiplexing / demultiplexing head unit 130 in the optical multipoint measuring device 100, as shown in FIG. 3A, the measurement light L S The frequency components of each optical comb included in are separated into one frequency component by the optical demultiplexing element 131A, and each frequency component is irradiated onto a plurality of points on the measurement surface 5 of the measurement target via the projection optical head 133 with the built-in coupling optical element. As shown in FIG. 3B, measurement light L consisting of reflected light of each frequency component for each of the frequency components is generated. S The optical multiplexing element 131B multiplexes the measurement light L′, and the optical demultiplexing element 131A multiplexes the measurement light L′ as shown in FIG. S7B, the measurement light L is a reflected light beam L2 that is made up of the reflected light of each of the frequency components that are separated into the plurality of frequency components and that are reflected and returned by the measurement surface 5. S ' may be multiplexed by the optical multiplexing element 131B.

[0118] 7A and 7B are diagrams illustrating the functions of the optical demultiplexing element 131A and the optical multiplexing element 131B provided in the optical demultiplexing / multiplexing head unit 130 in the optical multipoint measuring device 100. As shown in FIG. 7A, the optical demultiplexing element 131A divides the measurement light L S 7B, the optical multiplexing element 131B multiplexes the frequency components separated into multiple frequencies to generate the measurement light L S It can have the function of '.

[0119] In this way, the measurement light L S By splitting each frequency component of the optical comb included in each of the plurality of frequencies, each of the split frequency components is reflected at a plurality of points on the measurement surface 5 and returns through the same optical path, so that the measurement light L consisting of the reflected light of each frequency component split into each of the plurality of frequencies is S ' can be used to measure distances to a plurality of points on the measurement surface 5.

[0120] In this case, the measurement light L S The measurement light L S Although the number of divisions is reduced, it is possible to measure the displacement amount and distance at a plurality of points on the measurement surface 5.

[0121] For example, when an optical multiplexer / demultiplexer for 100GHz wavelength division multiplexing (WDM) demultiplexes an optical comb with 25GHz spacing generated so as to overlap the ITU grid, it is possible to demultiplex the 25GHz optical comb into three frequency components in each of eight channel frequency bands (ch1 to ch8) centered on 192.4 THz, 192.5 THz, 192.6 THz, 192.7 THz, 192.9 THz, 193.0 THz, 193.1 THz, and 193.2 THz, as shown in the measurement results using an optical spectrum analyzer in Figure 8. Since this optical multiplexer / demultiplexer is dedicated to 100GHz frequency spacing, there is a large loss in the intermediate frequency components of channels 100GHz apart, so it can only be demultiplexed into three frequency components.

[0122] The optical multipoint measurement device 100 employs the 100 GHz WDM optical demultiplexing / multiplexing elements as the optical demultiplexing element 131A and the optical multiplexing element 131B of the optical demultiplexing / multiplexing head 130, enabling it to perform both multipoint vibration measurement and multipoint distance measurement. In this way, the optical multipoint measurement device 100 demultiplexes the frequency components of each optical comb contained in the measurement light LS into multiple frequencies. Since each frequency component contained within the frequency band of the same channel is a component that has been reflected from the same point on the same optical path, the optical multipoint measurement device 100 can analyze the phase of one frequency component, or obtain phase information for multiple frequency components of each frequency component, thereby achieving a vibrometer that measures the same point. Therefore, the signal-to-noise ratio can be improved by performing averaging or other processing. Furthermore, since each fractional component contained within the frequency band of the same channel is a component that has been reflected from the same point on the same optical path, distance information can be obtained by utilizing the relative displacement difference between each frequency component.

[0123] That is, the optical multi-point measurement device 100 can handle both multi-point vibration measurement and multi-point distance measurement by adopting the above-mentioned 100 GHz WDM optical multiplexing and demultiplexing elements as the optical demultiplexing element 131A and the optical multiplexing element 131B of the optical multiplexing and demultiplexing head unit 130.

[0124] Here, in the interference optical system 120 of the optical multipoint measurement device 100, the measurement light L output from the light source 110 S and reference beam L R The interference light of the light source 110 is output as the reference interference light, and the measurement light L S is irradiated onto the measurement surface 5 of the measurement object through the optical demultiplexing / multiplexing head unit 130 from the interference optical system 120, and is reflected by the measurement surface 5 and returned through the optical demultiplexing / multiplexing head unit 130. S ' and the above reference light L R The interference light detecting unit 140 includes a measurement interference light detector 6A that receives the measurement interference light output from the interference optical system 120 and an interference light detector 6B that receives the reference interference light output from the interference optical system 120, and detects the measurement interference light by the measurement interference light detector 6A and converts it into an electrical signal to generate a measurement interference signal S S and a reference interference signal S obtained by detecting the reference interference light by the interference light detector 6B and converting it into an electric signal. R I try to get it.

[0125] In the optical multipoint measuring device 100, the signal processing unit 150 converts the measurement interference signal S obtained by the interference light detection unit 140 into S and the reference interference signal S R The phase of each frequency is calculated by FFT analysis for the above, and the phase difference for each frequency component of the optical comb caused by the Doppler shift due to vibration at multiple points on the measurement surface 5 is obtained, thereby analyzing vibration information at multiple points on the measurement surface 5. S is the measurement light L reflected by the measurement surface 5 and returned. S ' and the reference beam L R Since the interference signal is obtained by detecting the interference light for measurement, which is the interference light of S By calculating the phase for each frequency by FFT analysis only, it is possible to obtain the phase difference for each frequency component of the optical comb caused by the Doppler shift due to vibration at multiple points on the measurement surface 5.

[0126] FIG. 9 is a schematic diagram showing a modified example of the optical multipoint measuring device 100. In FIG.

[0127] That is, the optical multipoint measuring device 100, like the optical multipoint measuring device 100' shown in FIG. 9, includes an interference optical system 120' configured to output only interference light for measurement, an interference light detecting unit 140' that receives only interference light for measurement, and an interference signal S for measurement obtained by the interference light detecting unit 140'. S The optical comb may be provided with a signal processing unit 150′ that calculates the phase for each frequency by FFT analysis of only the optical comb and determines the phase difference for each frequency component of the optical comb caused by Doppler shift due to vibration at multiple points on the measurement surface 5.

[0128] In this optical multipoint measurement device 100', the same components as those in the optical multipoint measurement device 100 are given the same reference numerals in the drawing, and detailed description thereof will be omitted.

[0129] Here, the optical multiplexing / demultiplexing head unit 130 in the optical multipoint measuring device 100, 100′ includes an optical multiplexing / demultiplexing optical system 131 consisting of an optical demultiplexing element 131A and an optical multiplexing element 131B, and the measurement light L dispersed by the optical demultiplexing element 131A is S The frequency components of the optical comb are irradiated onto a plurality of points on the measurement surface 5 of the measurement object via a projection optical head 133 incorporating a coupling optical element, and the measurement light L is reflected by the measurement surface 5 and returns via the projection optical head 133 incorporating a coupling optical element. S By inputting each of the frequency components of the above into the optical multiplexing element 131B, measurement light L consisting of reflected light of each of the above frequency components that is reflected by the measurement surface 5 and returns via the projection optical head 133 with the built-in coupling optical element is generated. S 10, an optical multipoint measurement device 100A may be provided with an input / output optical selection unit 131' consisting of a one-input, multi-output optical switch and a multi-input, one-output optical switch, instead of the optical multiplexing / demultiplexing optical system 131 consisting of the optical demultiplexing element 131A and the optical multiplexing element 131B.

[0130] FIG. 10 is a schematic diagram showing an optical multipoint measuring device 100A to which the present invention is applied.

[0131] This optical multi-point measurement device 100A replaces the optical multiplexing / demultiplexing head unit 130 of the optical multi-point measurement device 100 with a projection optical head unit 130A equipped with an input / output light selection unit 131', and in this optical multi-point measurement device 100A, components that are the same as those in the optical multi-point measurement device 100 are given the same symbols in the figure, and detailed explanations thereof will be omitted.

[0132] This optical multipoint measuring device 100A uses measurement light L output from a light source 110. S and reference beam L R are the optical fibers FB 12A ,FB 12B The optical fiber FB23 is connected to the interference optical system 120, which receives the input through the optical fiber FB23. 341 ,FB 342 ,FB 343 ,···,FB 34n ,···,FB 34mn a one-input, multi-output optical switch 131A' connected to a projection optical head 133 incorporating a coupling optical element via a plurality of optical fibers FB 431 ,FB 432 ,FB 433 ,···,FB 43n ,···,FB 43mn and one optical fiber FB 32 The optical switch 131B' is connected to the interference optical system 120 via an input / output optical selector 131'.

[0133] In this optical multipoint measuring device 100A, the measurement light L output from the light source 110 S is input from the interference optical system 120 to the input / output light selector 131B' via the optical fiber FB23, and the measurement light is distributed by the one-input multi-output optical switch 131A' to a plurality of optical fibers FB 341 ,FB 342 ,FB 343 ,···,FB34n ,···,FB 34mn The measurement light L is projected onto a plurality of points on the measurement surface 5 of the measurement object from the projection optical head 133 with the built-in coupling optical element via the S The plurality of measurement beams scanned in time division are output from the projection optical head 133 with the built-in coupling optical element to the plurality of optical fibers FB 431 ,FB 432 ,FB 433 ,···,FB 43n , . . . to the input / output light selection unit 131′, and the plurality of measurement light beams are input to the input / output light selection unit 131′ via the multi-input, single-output optical switch 131B′, and are converted into measurement light L reflected by the measurement surface 5. S 'As above, optical fiber FB 32 The light is input to the interference optical system 120 via the optical fiber 122.

[0134] The interference optical system 120 transmits the measurement light L S ' and the above reference light L R The interference light L output from the light source 110 is output as interference light for measurement. S and reference beam L R The interference light with the reference light is output as reference interference light.

[0135] Then, in an interference light detection unit 140 including a measurement interference light detector 6A that receives the measurement interference light output from the interference optical system 120 and an interference light detector 6B that receives the reference interference light output from the interference optical system 120, the measurement interference light is detected by the measurement interference light detector 6A and converted into an electrical signal, to generate a measurement interference signal S S and a reference interference signal S obtained by detecting the reference interference light by the interference light detector 6B and converting it into an electric signal. R and a signal processing unit 150A reflects the measurement light L S The measurement interference signal S obtained by time-division scanning S and the reference interference signal S R The phase for each frequency is calculated by FFT analysis, and the distances to the plurality of points on the measurement surface 5 are obtained.

[0136] That is, the optical multipoint measuring device 100A focuses the measurement surface 5 with the measurement light L S It functions as a multi-point rangefinder that performs time-division scanning and finds the distances to multiple points on the measurement surface 5.

[0137] This optical multipoint measurement device 100A does not separate the measurement light into frequency components, so it is possible to take advantage of the wide spectrum, and it is possible to perform measurements not only as a rangefinder but also spectroscopy and other analyses, including so-called dual comb spectroscopy. Furthermore, for example, if a measurement object 5 is configured with multiple samples to be measured, such as gas, liquid, or solid, arranged in an array as cells and the measurement surface is used as a reflecting surface, it is possible to automatically perform spectroscopic analysis of a large number of samples.

[0138] FIG. 11 is a schematic diagram showing an optical multipoint measuring device 100B to which the present invention is applied.

[0139] This optical multipoint measurement device 100B is equipped with a signal processing unit 150B that detects measurement light using an optical spectrum analyzer or the like that has the functions of the interference optical system 120 and interference light detection unit 140 in the optical multipoint measurement device 100A and performs analytical processing. In this optical multipoint measurement device 100B, the same components as those in the optical multipoint measurement device 100A are given the same symbols in the figure, and detailed explanations thereof will be omitted.

[0140] In this optical multi-point measurement device 100B, the light source 110 is connected to a single-input, multi-output optical switch 131A' of the input / output light selection unit 131' via a single optical fiber FB13, and the multi-input, single-output optical switch 131B' of the input / output light selection unit 131' is connected to the signal processing unit 150B via a single optical fiber FB35.

[0141] Then, the measurement light L output from the light source 110 S is connected to a plurality of optical fibers FB via the one-input multi-output optical switch 131A'. 341 ,FB 342 ,FB 343 ,···,FB 34n,···,FB 34mn and projected onto a plurality of points on the measurement surface 5 of the measurement object from the projection optical head 133 with built-in coupling optical element of the projection optical head unit 130A, and reflected at a plurality of points on the measurement surface 5 and returned, the measurement surface 5 is illuminated as the measurement light L S The plurality of measurement beams scanned in time division are output from the projection optical head 133 with the built-in coupling optical element to the plurality of optical fibers FB 431 ,FB 432 ,FB 433 ,···,FB 43n ,····,FB 43mn and the plurality of measurement beams are input to the input / output beam selector 131′ via the multi-input, single-output optical switch 131B′, and are converted into measurement beam L reflected by the measurement surface 5. S ' and is input to the signal processing unit 150B via the optical fiber FB35.

[0142] This optical multipoint measurement device 100B detects the measurement light by an optical spectrum analyzer or the like having the functions of the interference optical system 120 and the interference light detection unit 140 in the optical multipoint measurement device 100A, and performs analysis processing. S The measurement signal obtained by time-division scanning is analyzed and processed, and the measurement light L reflected and returned from the plurality of measurement points on the measurement surface 5 is S Spectroscopic analysis is performed to measure the spectrum of a substance and use that information to estimate its chemical composition and structure.

[0143] FIG. 12 is a schematic diagram showing an optical multipoint measurement device 100C to which the present invention is applied.

[0144] This optical multi-point measurement device 100C does not have the input / output light selection unit 131' in the optical multi-point measurement device 100A, and is equipped with an interference optical system group 120C consisting of a plurality of interference optical systems 120 arranged in parallel, and a signal processing unit 150C detects the plurality of interference light beams for measurement obtained by the interference optical system group 120C, converts them into electrical signals, and performs analytical processing. In this optical multi-point measurement device 100C, the same components as those in the optical multi-point measurement device 100A are given the same symbols in the figures, and detailed explanations thereof will be omitted.

[0145] In this optical multipoint measuring device 100C, measurement light L output from a light source 110 S In the interference optical system group 120C to which the measurement light L is input, an optical distributor, for example, a 1:multi optical coupler, is used to divide the measurement light L into a plurality of interference optical systems corresponding to the number of measurement points on the measurement surface 5 of the object to be measured. S are distributed from the plurality of interference optical systems to a plurality of optical fibers FB 341 ,FB 342 ,FB 343 ,···,FB 34n ,···,FB 34mn to a projection optical head 133 incorporating a plurality of coupling optical elements of the projection optical head unit 130A, and the measurement light L is projected from the projection optical head 133 incorporating a plurality of coupling optical elements onto a plurality of measurement points on the measurement surface 5 of the measurement object. S Then, a plurality of measurement beams L are irradiated onto the measurement surface 5, which are reflected and returned from the measurement points. S ' is a signal transmitted from the projection optical head 133 incorporating the plurality of coupling optical elements to the plurality of optical fibers FB 431 ,FB 432 ,FB 433 ,···,FB 43n ,····,FB 43mn and the light beams are input to the plurality of interference optical systems of the interference optical system group 120C via the optical fiber 120A.

[0146] In the interference optical system group 120C, a plurality of measurement beams L reflected and returned from a plurality of measurement points on the measurement surface 5 are S ' and the reference light L output from the light source 110. RThe interference light beams are detected as interference light beams for measurement by a plurality of interference light beam detectors for measurement, and converted into electrical signals to form a plurality of interference signals for measurement S S and outputs it to the signal processing unit 150C.

[0147] The signal processing unit 150C processes the plurality of measurement interference signals S S By the FFT analysis, spectroscopic analysis and distance measurement can be performed for a plurality of measurement points on the measurement surface 5.

[0148] This optical multi-point measurement device 100C can be used, for example, as a swept-source optical coherence tomography (SS-OCT) that uses a wavelength-swept light source or as an optical comb rangefinder.In the case of SS-OCT, multi-point information can be obtained without scanning, and it can also function as a multi-point optical comb rangefinder.

[0149] This optical multipoint measurement device 120C requires multiple interferometers, but the presence of multiple interferometers makes it possible to capture multipoint vibrations even with a single-frequency light source, and it functions as a multipoint vibrometer without using an optical comb. Furthermore, since this optical multipoint measurement device 120C does not separate the measurement light into frequency components, it is possible to perform measurements that utilize the wide spectrum, and it is possible to perform not only distance measurements but also spectroscopy and other analyses, including so-called dual comb spectroscopy, and it can be used for vibration measurement, spectroscopic analysis, and OCT. Furthermore, the measurement light L output from the light source 110 in this optical multipoint measurement device 120C S and reference beam L R The can be a single-mode laser light whose frequency has been shifted by an acousto-optic modulator (AOM) or the like, and because it is a single-wavelength laser, it can measure even large Doppler shifts (fast vibration velocities), and the signal processing unit 150D can process a large number of interference signals to obtain vibration information at multiple points.

[0150] Here, in the optical multipoint measurement devices 100, 100A, 100B, and 100C, a plurality of (m×n) coupling optical elements 44 A1 ,44 A2,44 A3 ,···,44 An ,···,44 Am n 13, instead of the projection optical head 133 with built-in coupling optical elements, a plurality of optical fibers FB 341 ,FB 342 ,FB 343 ,···FB 34n , . . . inserted into a plurality of capillaries, and a plurality of measurement beams inputted through the fiber array 44D are collected by a condensing optical element 4A. a , 4A b and irradiates the plurality of measurement beams toward the measurement surface 5 of the measurement object, and the plurality of measurement beams reflected by the measurement surface 5 and returned are collected by the light collecting optical element 4A. a ,4A b and inputting the light into the fiber array 44D. ab It is also possible to employ a projection optical head 133D comprising:

[0151] FIG. 13 is a schematic diagram showing an optical multipoint measuring device 100D to which the present invention is applied.

[0152] This optical multi-point measurement device 100D is obtained by replacing the optical multiplexing and demultiplexing head unit 130 of the optical multi-point measurement device 100 with an optical multiplexing and demultiplexing head unit 130D equipped with a projection optical head 133D. In this optical multi-point measurement device 100D, the same components as those in the optical multi-point measurement device 100 are given the same symbols in the figures, and detailed explanations thereof will be omitted.

[0153] In this optical multipoint measuring device 100D, the optical multiplexing / demultiplexing head unit 130D has two optical fibers FB 23 ,FB 32 Optical coupler OC connected via E And this optical coupler OC E Optical fiber FB 123an optical multiplexer / demultiplexer element 131D connected via a plurality of optical fibers FB connected to the optical multiplexer / demultiplexer element 131D; 341 ,FB 342 ,FB 343 ,···FB 34n ,···,FB 34mn The optical projection head 133D is provided with a fiber array 44D from which the optical projection head 133D is externally led.

[0154] 14A and 14B show a plurality of optical fibers FB provided in the projection optical head 133D of the optical multipoint measuring device 100D. 341 ,FB 342 ,FB 343 ,···FB 34n ,···,FB 34mn 10A and 10B are diagrams showing an example of the configuration of a fiber array 44D in which one end of each fiber is two-dimensionally arranged, in which (A) is a vertical cross-sectional side view of the fiber array 44D, and (B) is a vertical cross-sectional front view of the fiber array 44D.

[0155] As shown in FIG. 14A, the fiber array 44D includes a plurality of optical fibers FB 341 ,FB 342 ,FB 343 ,···FB 34n ,···,FB 34mn One end of each of the single-core capillaries 44 is inserted. B1 ,44 B2 ,44 B3 ,···,44 Bn ,···,44 Bmn The plurality of single-core capillaries 44 B1 ,44 B2 ,44 B3 ,···,44 Bn ,···,44 Bmn The plurality of optical fibers FB inserted into 341 ,FB 342 ,FB 343 ,···FB 34n ,···,FB 34mn As shown in FIG. 14(B), one end of each of the electrodes is arranged two-dimensionally in a matrix.

[0156] In this optical multipoint measuring device 100D, measurement light L output from a light source 110 S However, the optical fiber FB 23 Projection optical head 133D optical coupler OC E The measurement light L input to S The above optical coupler OC E From optical fiber FB 123 The light is input to the optical multiplexer / demultiplexer element 131D via the optical multiplexer / demultiplexer 131D.

[0157] Then, the optical multiplexer / demultiplexer 131D couples the measurement light L S is split into multiple frequency components of the optical comb and transmitted through multiple optical fibers FB 341 ,FB 342 ,FB 343 ,···FB 34n ,···,FB 34mn and input to the fiber array 44D of the projection optical head 133D via the optical fiber array 44D.

[0158] In the projection optical head 133D, the measurement light L input to the fiber array 44D S The plurality of frequency components of the optical comb are focused by the focusing optical element 4A a ,4A b A set of optical systems 4A consisting of ab The light is focused by the quarter-wave plate 4B and irradiated onto a plurality of points on the measurement surface 5 of the object to be measured. The light reflected at a plurality of points on the measurement surface 5 is then converted via the quarter-wave plate 4B into frequency components of an optical comb whose polarization plane is orthogonal to the polarization direction of the irradiated frequency components, and is then reflected by the set of optical systems 4A. ab and the light is collected by the fiber array 44D and emitted from the plurality of optical fibers FB 341 ,FB 342 ,FB 343 ,···FB 34n ,···,FB 34mn The measurement light L is input to the optical multiplexer / demultiplexer element 131D via the optical multiplexer / demultiplexer element 131D, and is multiplexed by the optical multiplexer / demultiplexer element 131D and reflected at a plurality of points on the measurement surface 5 of the measurement object. S 'Fiber optic FB 123 via optical coupler OC Eand the optical fiber FB 32 The light is input to the interference optical system 120 via the optical fiber 122.

[0159] The optical coupler OCE couples the measurement light L S The frequency components of the optical comb and the frequency components of the reflected light reflected by the measurement surface 5 are input from opposite directions and output in opposite directions, functioning as a directional coupler, and may be a PBC module or a circulator.

[0160] The interference optical system 120 is configured to S ' and the above reference light L R The interference light L output from the light source 110 is output as interference light for measurement. S and reference beam L R The interference light with the reference light is output as reference interference light.

[0161] Then, in an interference light detection unit 140 including a measurement interference light detector 6A that receives the measurement interference light output from the interference optical system 120 and an interference light detector 6B that receives the reference interference light output from the interference optical system 120, the measurement interference light is detected by the measurement interference light detector 6A and converted into an electrical signal, to generate a measurement interference signal S R and a reference interference signal S obtained by detecting the reference interference light by the interference light detector 6B and converting it into an electric signal. R get.

[0162] The signal processing unit 15 detects the interference signal S for measurement obtained by the interference light detection unit 140. S and the reference interference signal S R The phase for each frequency is calculated by FFT analysis, and the phase difference for each frequency of the optical comb caused by the Doppler shift due to vibration at multiple points on the measurement surface 5 is obtained, thereby analyzing vibration information at multiple points on the measurement surface 5.

[0163] Here, the optical multipoint measuring device 100D divides the measurement light L by an optical multiplexing / demultiplexing element 131D provided in the projection optical head 133D. S The optical comb functions as a multipoint vibrometer that separates each frequency component of the optical comb into one frequency component and combines each frequency component that is reflected back by the measurement surface 5. Also, the optical multiplexing and demultiplexing element 131D separates the measurement light L S It is also possible to make it function as a multi-point rangefinder by splitting each frequency component into multiple frequency components and combining the multiple frequency components that are reflected back by the measuring surface 5.

[0164] Furthermore, the optical multipoint measuring device 100D replaces the optical multiplexing / demultiplexing element 131D provided in the projection optical head 133D with an optical switch, thereby projecting the measurement surface 5 onto the measurement light L S The measurement signal obtained by time-division scanning is analyzed by the signal processing unit 15, and the device can function as a multi-point rangefinder that finds the distances to a plurality of points on the measurement surface 5. [Explanation of symbols]

[0165] 100, 100', 100A, 100B, 100C, 100D Optical multipoint measurement device, 1A First optical comb generator (COMB1), 1B Second optical comb generator (COMB2), 4 A1 ,4 A2 ,4 A3 ,···,4 An ,··· Condenser lens, 4A a ,4A b Concentrating optics, 4A ab Complete optical system, 4 B1 ,4 B2 ,4 B3 ,···,4 Bn ,...,4B 1 / 4 wavelength plate, 4C A ,4C B Coupling optical part, 4C1 2-core capillary, 4C2, 4C2' Coupling optical element, 4C a ,4C c Collimator lens, 4C bWollaston prism, 5 measurement surface, 6A interference light detector, 6B reference light detector, 10,110 light source, 20,120,120' interference optics, 30,130,130 (1) ,130 (2) ,130 (3) ,130D optical multiplexing / demultiplexing head unit, 130A projection optical head unit, 31, 131 optical multiplexing / demultiplexing optical system, 31A, 131A optical multiplexing element, 31B, 131B optical multiplexing element, 32 coupling optical system, 33 projection optical system, 40, 140, 140' interference light detection unit, 44 coupling optical element array, 44D fiber array, 44 B1 ,44 B2 ,44 B3 ,···,44 Bn ,···,44 Bmn 1-core capillary, 50, 150, 150', 150A, 150B, 150C, 150D signal processing unit, 120C interference optical system group, 131' input / output light selection unit, 131D optical multiplexing / demultiplexing element, 131A' 1-input multi-output optical switch, 131B' multi-input 1-output optical switch, 133 projection optical head with built-in coupling optical element, 133D projection optical head, 200 experimental apparatus, FB 12A ,FB 12B ,FB 2A2 ,FB 2B1 ,FB 2B2 ,FB 23 ,FB 26A1 ,FB 26A2 ,FB 26B1 ,FB 26B2 ,FB 32 ,FB 123 ,FB 341 ,FB 342 ,FB 343 ,···FB 34n ,···,FB 34mn ,FB 431 ,FB 432 ,FB 433 ,···,FB 43n ,···,FB 441 ,FB 442 ,FB 443 ,···,FB 44n ,··· Optical fiber, FB 2B1 ' Fiber delay, FB 34 Input optical fiber, FB 43Output optical fiber, OC A ,OC B ,OC C ,OC D ,OC E ,OC C1 ,OC C2 ,OC C3 ,···,OC Cn ,···optical coupler, L S Measuring light, L R Reference light, S S Measurement interference signal, S R Reference interference signal

Claims

1. a light source that outputs measurement light; a projection optical head in which measurement light output from the light source is input via a plurality of optical fibers, the input measurement light beams are irradiated onto a plurality of points on a measurement surface of a measurement object, and the measurement light beams reflected by the measurement surface and returned are input into the plurality of optical fibers; a signal processing unit that converts the plurality of measurement light beams returning from the projection optical head through the plurality of optical fibers into electrical signals and performs analysis processing; Equipped with The projection optical head comprises a fiber array into which one end of each of the plurality of optical fibers is inserted, and a focusing optical system that focuses the plurality of measurement beams input via the fiber array with a focusing optical element and irradiates the beams toward the measurement surface of the measurement object, and also focuses the plurality of measurement beams reflected and returned from the measurement surface with the focusing optical element and inputs the beams to the fiber array. An optical multi-point measurement device characterized by:

2. the projection optical head includes a coupling optical element array in which a plurality of coupling optical elements are arranged to align the optical axes of two light beams, the polarization directions of which are orthogonal to each other and output from two adjacent optical fibers on the fiber array; a plurality of measurement beams input to the projection optical head via the plurality of optical fibers are irradiated onto a plurality of points on a measurement surface of the measurement object via the coupling optical element array; The signal processing unit converts the plurality of measurement beams reflected by the measurement surface and returning from the projection optical head via a plurality of optical fibers different from the plurality of optical fibers that input the plurality of measurement beams to the projection optical head via the coupling optical element array into electrical signals and performs analysis processing.

2. The optical multipoint measuring device according to claim 1.

3. the light source outputs coherent measurement light and reference light, the coherent measurement light and reference light having a spectrum with a predetermined frequency interval; an interference optical system into which the measurement light and the reference light output from the light source are input via optical fibers; an optical multiplexing and demultiplexing optical system including an optical demultiplexing element connected to the interference optical system via one optical fiber and connected to the projection optical head via a plurality of optical fibers, and an optical multiplexing element connected to the projection optical head via a plurality of optical fibers and connected to the interference optical system via another optical fiber; The measurement light output from the light source is input to the optical multiplexing and demultiplexing optical system through the interference optical system and the single optical fiber, and the measurement light is demultiplexed by the optical demultiplexing element into a plurality of frequency components contained in the measurement light, and the plurality of measurement light beams are input to the projection optical head through the plurality of optical fibers, and are irradiated onto a plurality of points on the measurement surface of the measurement object through the coupling optical element array, 3. The optical multipoint measuring device according to claim 2, wherein the signal processing unit receives the plurality of measurement beams reflected by the measurement surface and returning from the projection optical head via a plurality of optical fibers other than the plurality of optical fibers that input the plurality of measurement beams to the projection optical head via the coupling optical element array, inputs the plurality of measurement beams to the optical multiplexing / demultiplexing optical system, combines the plurality of measurement beams by the optical multiplexing element, and inputs the plurality of measurement beams as the measurement beams reflected by the measurement surface to the interference optical system via the other optical fiber, thereby detecting measurement interference light obtained as interference light between the measurement beams reflected by the measurement surface and the reference beam in the interference optical system, converting the light into an electrical signal, and performing analysis processing.

4. 4. The optical multipoint measuring device according to claim 3, wherein the coupling optical element is made of a birefringent crystal.

5. 4. The optical multipoint measuring device according to claim 3, wherein the coupling optical element is a Wollaston prism.

6. the light source outputs coherent measurement light and reference light, the coherent measurement light and reference light having a spectrum with a predetermined frequency interval; an interference optical system into which the measurement light and the reference light output from the light source are input via optical fibers; an input / output optical selector including a one-input, multi-output optical switch connected to the interference optical system via a single optical fiber and connected to the projection optical head via a plurality of optical fibers, and a multi-input, one-output optical switch connected to the projection optical head via a plurality of optical fibers and connected to the interference optical system via a single optical fiber; the fiber array of the projection optical head includes a coupling optical element array in which coupling optical elements are arranged two-dimensionally to align the optical axes of two light beams whose polarization directions are orthogonal to each other and output from two adjacent fibers on the fiber array; 2. The optical multi-point measuring device according to claim 1, wherein in the signal processing unit, the measurement light output from the light source is input to the input / output light selection unit from the interference optical system via the optical fiber, the measurement light is distributed by the one-input / multi-output optical switch and irradiated from the projection optical head to a plurality of points on the measurement surface of the measurement object via a plurality of optical fibers, the plurality of measurement light beams reflected by the measurement surface and returning are input from the projection optical head via a plurality of optical fibers to the input / output light selection unit, and the plurality of measurement light beams are input to the interference optical system via the optical fibers as measurement light reflected by the measurement surface via the multi-input / one-output optical switch, thereby detecting measurement interference light obtained as interference light between the measurement light reflected by the measurement surface and the reference light in the interference optical system, converting it into an electrical signal, and performing analysis processing.

7. an interference optical system group consisting of a plurality of the interference optical systems; 3. The optical multipoint measuring device according to claim 2, wherein the signal processing unit detects a plurality of interference light beams for measurement obtained by the interference optical system group, converts the detected interference light beams into electrical signals, and performs analytical processing.

8. an input / output optical selector consisting of a one-input, multi-output optical switch connected to the light source via a single optical fiber and connected to the projection optical head via a plurality of optical fibers, and a multi-input, one-output optical switch connected to the projection optical head via a plurality of optical fibers and connected to the signal processing unit via a single optical fiber; the fiber array of the projection optical head includes a coupling optical element array in which coupling optical elements are arranged two-dimensionally to align the optical axes of two light beams whose polarization directions are orthogonal to each other and output from two adjacent optical fibers on the fiber array; The measurement light output from the light source is input to the input / output light selection unit via the optical fiber, and the measurement light is irradiated from the projection optical head to a plurality of points on the measurement surface of the measurement object via a plurality of optical fibers to which the one-input, multi-output optical switch distributes the measurement light, and the plurality of measurement light beams reflected and returned by the measurement surface are input from the projection optical head to the input / output light selection unit via a plurality of optical fibers, and the plurality of measurement light beams are input to the signal processing unit via the optical fibers as measurement light beams reflected by the measurement surface via the multi-input, single-output optical switch, thereby 2. The optical multipoint measuring device according to claim 1, wherein the signal processing unit detects the measurement light reflected by the measurement surface, converts it into an electrical signal, and performs an analysis process.

9. the light source outputs coherent measurement light and reference light, the coherent measurement light and reference light having a spectrum with a predetermined frequency interval; an interference optical system into which the measurement light and the reference light output from the light source are input via optical fibers; an optical coupler connected to the interference optical system via two optical fibers; and an optical multiplexing / demultiplexing element connected to the optical coupler via optical fibers and connected to the projection optical head via a plurality of optical fibers, 2. The optical multi-point measuring device according to claim 1, wherein the signal processing unit receives the measurement light output from the light source from the interference optical system via the optical fiber and inputs it to the optical multiplexer / demultiplexer element, where the measurement light is demultiplexed by the optical multiplexer / demultiplexer element into a plurality of frequency components contained in the measurement light, and irradiates the measurement light onto a plurality of points on the measurement surface of the measurement object from the projection optical head. The plurality of measurement light beams reflected by the measurement surface and returning are input from the projection optical head to the optical multiplexer / demultiplexer element via the plurality of optical fibers, combined by the optical multiplexer / demultiplexer element, and input to the interference optical system via the optical fiber as measurement light reflected by the measurement surface. The optical multi-point measuring device according to claim 1, wherein the signal processing unit detects measurement interference light obtained as interference light between the measurement light reflected by the measurement surface and the reference light in the interference optical system, converts it into an electrical signal, and performs analysis processing.

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