Multi-point vibration measurement device

Abstract

In this multi-point vibration measurement device, high-accuracy multi-point vibration measurement is enabled by removing a measurement error caused by an unnecessary reflected component due to optical elements such as an optical combining / dividing element provided in an optical path which measurement light radiated onto a measurement surface via an interference optical system passes through mixing with interference light necessary for multi-point vibration measurement. In a multi-point vibration measurement device 100, an optical combining / dividing head 130 comprises: a combining / dividing optical system 131 that is composed of an optical dividing element 131A connected to an interference optical system 120 into which measurement light LS from a light source 110 is input, and an optical combining element 131B connected to the interference optical system 120; a projection optical system 133 that irradiates a plurality of points on a measurement surface 5 of a measurement subject with each optical comb frequency component of the measurement light LS which has been divided by the optical dividing element 131A; and a coupling optical system 132 that inputs each optical comb frequency component included in the measurement light LS which has been divided by the optical dividing element 131A into the projection optical system 133 and inputs each optical comb frequency component of the returning measurement light LS reflected by the measurement surface 5 into the optical combining element 131B.

Description

Multi-point vibration measurement device

[0001] The present invention relates to a multi-point vibration measuring device that uses light to simultaneously measure vibration information at multiple points on a measurement target. This application claims priority based on Japanese Patent Application No. 2024-2869, filed in Japan on January 11, 2024, and is incorporated herein by reference.

[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 object being measured. 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] Furthermore, while conventional laser Doppler vibrometers can generally measure vibration amplitudes in a velocity range of about 10 m / s, they cannot obtain static heights or synchronize multiple points to measure vibration distribution.

[0005] The present applicant has previously proposed a vibration measuring device and a vibration measuring method in which a vibrometer analyzes vibration information on a measurement surface of an object by detecting interference light between a coherent reference light and a measurement light, the interference light being a spectrum with a predetermined frequency interval, and determining the phase difference between the reference light and the measurement light. The vibrometer uses an optical multiplexing / demultiplexing head that separates the measurement light into frequency components and irradiates the separated light onto multiple points on the measurement surface of the object, thereby enabling vibration information at multiple points on the measurement surface to be measured simultaneously (see, for example, Patent Documents 1 to 3).

[0006] Furthermore, the center frequency f ０ (Hz) and frequency interval f ｍ The optical comb with a center frequency of f ０ (Hz) and frequency interval f ｍ +Δf ｍA vibrometer capable of multi-point measurement and having 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).

[0008] Japanese Patent No. 5336921 Japanese Patent Application Laid-Open No. 2010-203860 Japanese Patent No. 5363231 Japanese Patent Application Laid-Open No. 7276051 Japanese Patent Application Laid-Open No. 2022-47249 Japanese Patent Application Laid-Open No. 2015-072136

[0009] In a multi-point vibration 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 multiplexer / demultiplexer that demultiplexes 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 measurement light of each frequency component wavelength demultiplexed by the optical multiplexer / demultiplexer element and returns reflected light (scattered light) from the measurement surface to the optical multiplexer / demultiplexer 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, resulting in measurement errors.

[0010] Here, by modularizing the input and output of the interference optical system 2 to optical fibers and sending reference light and measurement light, as in the multipoint vibration measurement device 10 shown in Figure 1, optical elements with various functions can be used as modular elements, making the device easier to assemble and repair. In addition, by using a free-space optical system and optical fibers to form some functional element into an optical integrated circuit, the device can be made smaller.

[0011] This multipoint vibration measuring device 10 uses coherent measurement light L output from a light source 1. Ｓ and reference light L Ｒ The optical system 2 is provided with an interference optical system 2 into which the measurement light L Ｓ The frequency components of each optical comb included in the measurement light L are demultiplexed into, for example, m×n (m and n are any positive integers) kinds of frequency components by the optical demultiplexing / multiplexing element 3, Ｓand the frequency components of the measurement light S are 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 via the projection optical system 4, and the measurement light S is reflected at the m×n measurement points on the measurement surface 5 of the measurement object and returns via the projection optical system 4. １ The reflected light of each frequency component is multiplexed by the optical multiplexer / demultiplexer 3 to form a measurement light L consisting of reflected light of each frequency component reflected at the m×n measurement points on the measurement surface 5. Ｓ ' is input to the interference optical system 2.

[0012] The light source 1 emits linearly polarized measurement light L Ｓ and reference light L Ｒ The first optical comb generator (COMB1) 1A and the second optical comb generator (COMB2) 1B each output a FB using a polarization maintaining fiber (PMF). １２Ａ , F.B. １２Ｂ The first optical comb generator (COMB1) 1A and the second optical comb generator (COMB2) 1B are connected to the interference optical system 2 via the Ｓ and reference light L Ｒ The intensity or phase of each is periodically modulated to generate two types of optical combs with different modulation frequencies. Instead of PMF, polarized (PZ) fiber, which can propagate only one polarized light, can also be used.

[0013] Here, the PMF is an optical fiber that utilizes the photoelastic effect and structural changes to generate birefringence, where the effective refractive index differs between the length and width of the core, thereby improving the polarization-maintaining characteristics of the transmitted light.

[0014] The interference optical system 2 includes an optical fiber FB from the first optical comb generator (COMB1) 1A. １２Ａ Through the measurement light L Ｓ is input, and the second optical comb generator (COMB2) 1B outputs the optical fiber FB １２Ｂ via the reference light L Ｒ is entered.

[0015] The interference optical system 2 is an optical fiber FB using a PMF. ２Ａ１ , F.B. ２Ａ２ , F.B. ２Ｂ１, F.B. ２Ｂ２ , F.B. ２Ｃ Five optical couplers OC connected by Ａ , O.C. Ｂ , O.C. Ｃ , O.C. Ｄ , O.C. Ｅ The optical coupler OC Ａ Optical fiber FB externally connected to １２Ａ The measurement light L is transmitted from the first optical comb generator (COMB1) 1A via Ｓ is input, and the optical coupler OC Ｂ Optical fiber FB externally connected to １２Ｂ The reference light L is output from the second optical comb generator (COMB2) 1B via Ｒ is entered.

[0016] In this interference optical system 2, an optical coupler OC Ａ There are two optical fiber FB ２Ａ１ , F.B. ２Ａ２ Two optical couplers OC Ｄ , O.C. Ｅ Internally connected to the optical coupler OC Ｂ There are two optical fiber FB ２Ｂ１ , F.B. ２Ｂ２ Two optical couplers OC Ｃ , O.C. Ｄ are internally connected, and the optical coupler OC Ｅ Optical fiber FB ２Ｃ via the optical coupler OC Ｃ are internally connected.

[0017] The measurement light L input to the interference optical system 2 Ｓ is the optical coupler OC Ｅ Optical fiber FB using PMF externally connected to ２３ The light is input to the optical multiplexer / demultiplexer element 3 via the optical multiplexer / demultiplexer element 3.

[0018] The measurement light L input to the optical multiplexing and demultiplexing element 3 Ｓ is the measurement light L in the optical multiplexing / demultiplexing element 3. Ｓ The multiple frequency components of the optical comb included in ３４１ , F.B. ３４２ , F.B. ３４３ , ...FB３４ｎ , . . . of the projection optical system 4 are projected through a plurality of (m×n) condenser lenses 4 Ａ１ , 4 Ａ２ , 4 Ａ３ , ..., 4 Ａｎ , . . . , and multiple (m×n) types of frequency components are input to multiple (m×n) condenser lenses 4 Ａ１ , 4 Ａ２ , 4 Ａ３ , ..., 4 Ａｎ , ... are collected by the quarter-wave plates 4 Ｂ１ , 4 Ｂ２ , 4 Ｂ３ , ..., 4 Ｂｎ , . . . and irradiated onto a plurality of points on the measurement surface 5 of the measurement object.

[0019] Then, the light is reflected at a plurality of points on the measurement surface 5 of the measurement object and passes through the projection optical system 4 to the optical fiber FB ３４１ , F.B. ３４２ , F.B. ３４３ , ...FB ３４ｎ , . . . Ｓ The reflected light of each frequency component of the optical comb is multiplexed by the optical multiplexer / demultiplexer element 3, and is output from the optical multiplexer / demultiplexer element 3 to the optical fiber FB as reflected light consisting of each frequency component reflected at a plurality of points on the measurement surface 5. ２３ via the optical coupler OC of the interference optical system 2 E is entered into

[0020] Here, the optical coupler OC E The measurement light L is made up of reflected light of each frequency component of the optical comb reflected at a plurality of points on the measurement surface 5. Ｓ ' is the optical coupler OC E The measurement light L output from Ｓ Each frequency component of the quarter wave plate 4B １ , 4B ２ , 4B ３ , ...4B ｎ , ... twice, the measurement light L Ｓ The polarization of ' is perpendicular to Ls, and the optical coupler OC Ｅis a polarized beam combiner / splitter (PBC / PBS; hereinafter, a module that can be input and output via fiber is called a PBC module), and therefore the measurement light L is composed of reflected light of each frequency component reflected at multiple points on the measurement surface 5, the polarization of which is orthogonal to Ls. Ｓ ' is an optical coupler OC Ｅ From optical fiber FB ２Ｃ via the optical coupler OC Ｃ is entered into

[0021] In the interference optical system 2, a measurement light L consisting of reflected light of frequency components of each optical comb reflected at a plurality of points on the measurement surface 5 is Ｓ ' and the reference light L input from the light source 1. Ｒ The interference light with the above optical coupler OC is used as the interference light for measurement. Ｃ and the measurement light L input from the light source 1. Ｓ and reference light L Ｒ The interference light with the optical coupler OC is used as a reference interference light. Ｄ Output from

[0022] The interference light detector 6, to which the measurement interference light and the reference interference light obtained by the interference optical system 2 are input, includes a measurement interference light detector 6A and a reference interference light detector 6B, each of which is a balanced photodetector. Ｃ Two optical fibers FB externally connected to ２６Ａ１ , F.B. ２６Ａ２ via the optical coupler OC Ｃ The measurement interference light detector 6A receives the measurement interference light input from the Ｓ and the optical coupler C of the interference optical system 2 Ｄ Two optical fibers FB externally connected to ２６Ｂ１ , F.B. ２６Ｂ２ via the optical coupler OC Ｄ The reference interference light detector 6B receives the reference interference light input from the reference interference light detector 6B, detects the reference interference light, and converts it into an electrical signal to generate a reference interference signal S Ｒ Output.

[0023] Here, in the balanced photodetectors used as the measurement interference light detector 6A and the reference interference light detector 6B, beats having frequencies corresponding to the frequency difference between the frequency components of the optical combs of the input measurement light and reference light are combined into one, converted into an electrical signal, and output. The frequency difference between the frequency components of the optical combs of 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 not split by the optical multiplexing element or optical splitting element described below. Furthermore, the bandwidth of the balanced photodetector is sufficiently smaller than the spacing between the frequency components of the optical comb, and is sufficiently large to detect the frequency difference between the frequency components of the optical combs of the measurement light and reference light.

[0024] In the multipoint vibration measuring device 10, the signal processing unit 7 converts the measurement interference signal S obtained by the interference light detection unit 6 into Ｓ and the reference interference signal S Ｒ By calculating the phase difference between beats having frequencies corresponding to the frequency difference between the optical combs of the measurement light and reference light input through a discrete Fourier transform (DFT) (including a fast Fourier transform (FFT)) analysis, vibration information at multiple points on the measurement surface 5 is analyzed, and the vibration distribution on the measurement surface 5 is measured.

[0025] As in this multipoint vibration measuring device 10, by configuring the input and output of the interference optical system 2 with optical fibers and sending reference light and measurement light via optical fibers, optical elements with various functions can be modularized and the device can be easily assembled and repaired. ２３ The measurement light L input to the optical multiplexer / demultiplexer element 3 via Ｓ A part of the reflected light is reflected by the optical multiplexer / demultiplexer element 3 and returns to the interference optical system 2, and is mixed with the interference light required for multipoint vibration measurement, thereby causing measurement errors.

[0026] For example, when an arrayed waveguide grating (AWG) is used for the optical multiplexer / demultiplexer element 3, it is small and has high resolution, but the return loss (RL) is about 40 dB. This reflection occurs inside the optical multiplexer / demultiplexer element 3 and at the connection between the optical fiber and the optical multiplexer / demultiplexer element 3. Furthermore, if the optical path from the interference optical system 2 to the optical multiplexer / demultiplexer element is an optical fiber, reflection from the optical fiber connector, etc., cannot be ignored.

[0027] That is, the optical multiplexer / demultiplexer element 3 uses a triangular prism, a plurality of wavelength division multiplexing filters, a diffraction grating, etc., but the problem is that the RL is small.

[0028] On the other hand, the amount of reflected light returning from the measurement surface 5 to the optical multiplexer / demultiplexer element 3 is greatly attenuated depending on the properties and shape of the surface of the measurement surface 5 .

[0029] Furthermore, the insertion loss (IL) of the optical multiplexer / demultiplexer 3 is also large, about 6.5 dB for an AWG with 25 GHz spacing, and when used in both directions, the loss becomes about 13 dB, so the influence of RL becomes relatively large.

[0030] If the reflection from the measurement surface 5 is not large enough due to the RL inside the optical multiplexer / demultiplexer 3, the measurement light (first optical comb) L Ｓ It is difficult to distinguish between reflections from the measurement surface 5 and reflections from the measurement surface 5.

[0031] In such a case, there is a problem that the vibration information calculated by the signal processing unit 7 becomes erroneous.

[0032] Therefore, the present invention has been devised in consideration of the above-mentioned problems, and its purpose is to eliminate measurement errors caused by unwanted reflection components from various optical elements, such as optical multiplexing and demultiplexing elements, which are provided in the optical path through which the measurement light passes to irradiate the measurement surface via an interference optical system, and which are mixed into the interference light required for multipoint vibration measurement in a multipoint vibration measurement device, thereby enabling high-precision multipoint vibration measurement.

[0033] 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.

[0034] In the present invention, in a multi-point vibration measurement device, two optical splitter / multiplexer elements are provided, and the functions of the optical splitter element and the optical multiplexer element are operated separately, and an optical path is separated into one that splits the measurement light output from a light source through an interference optical system into multiple frequency components of an optical comb contained in the measurement light and irradiates multiple points on the measurement surface of the object to be measured, and another optical path that combines the multiple frequency components reflected and returned from multiple points on the measurement surface and inputs them into the interference optical system, thereby preventing unnecessary reflected components from the optical splitter element that splits the measurement light into the multiple frequency components from being mixed into the interference light required for multi-point vibration measurement.

[0035] That is, the present invention is a multipoint vibration measuring device, comprising: a light source that outputs coherent measurement light and reference light having spectra with a predetermined frequency interval; an optical multiplexing / demultiplexing head that separates the measurement light output from the light source into frequency components of an optical comb and irradiates each frequency component of the optical comb onto a plurality of points on a measurement surface of a measurement object; an interference optical system that receives the measurement light and reference light output from the light source, inputs the measurement light input from the light source to the optical multiplexing / demultiplexing head, and causes interference between the measurement light including each of the frequency components reflected on the measurement surface and returning via the optical multiplexing / demultiplexing head and the reference light output from the light source, outputting interference light for measurement; and a measurement light detection unit that receives the interference light obtained by the interference optical system and converts it into an electrical signal to obtain an interference signal for measurement. and a signal processing unit that analyzes vibration information at multiple points on the measurement surface based on the measurement interference signal obtained by the measurement light detection unit, and the optical multiplexing and demultiplexing head comprises an optical demultiplexing element that demultiplexes each frequency component contained in the measurement light input from the interference optical system, a projection optical system that irradiates each frequency component demultiplexed by the optical demultiplexing element onto multiple points on the measurement surface of the measurement target, an optical multiplexing element that combines each frequency component of the measurement light reflected and returned from the measurement surface and inputs the combined signal to the interference optical system, and a coupling optical system that inputs each frequency component contained in the measurement light demultiplexed by the optical demultiplexing element to the projection optical system, and inputs each frequency component of the measurement light reflected and returned from the measurement surface to the optical multiplexing element.

[0036] In the multi-point vibration measuring device according to the present invention, the interference optical system outputs the measurement interference light and causes the measurement light input from the light source to interfere with a reference light to output reference interference light, and includes a reference light detection unit that receives the reference interference light obtained by the interference optical system and converts it into an electrical signal to obtain a reference interference signal, and the signal processing unit can analyze vibration information at multiple points on the measurement surface based on the measurement interference signal obtained by the measurement light detection unit and the reference interference signal obtained by the reference light detection unit.

[0037] Furthermore, in the multi-point vibration measuring device according to the present invention, the optical multiplexing / demultiplexing head can be configured to irradiate each frequency component of the optical comb contained in the measurement light, which is separated into each frequency component of the optical comb by the optical demultiplexing element, onto multiple points on the measurement surface of the measurement object via the projection optical system, and to multiplex each frequency component of the measurement light reflected and returned by the measurement surface by an optical multiplexing element.

[0038] Furthermore, in the multi-point vibration measuring device according to the present invention, the optical multiplexing and demultiplexing head can be configured to irradiate each frequency component of the optical comb contained in the measurement light, which is separated into multiple frequency components of the optical comb by the optical demultiplexing element, onto multiple points on the measurement surface of the measurement object via the projection optical system, and to multiplex each frequency component of the multiple frequency components of the measurement light reflected and returned from the measurement surface by an optical multiplexing element.

[0039] Furthermore, the multipoint vibration measuring device according to the present invention may be configured such that the coupling optical system is built into the projection optical system.

[0040] Furthermore, in the multi-point vibration measuring device according to the present invention, the optical demultiplexing element demultiplexes each frequency component of the optical comb contained in the measurement light input from the interference optical system via one optical fiber and outputs the demultiplexed signal via multiple optical fibers, the optical combining element combines each frequency component input via multiple optical fibers and outputs the combined signal via one optical fiber, and the combining optical system can include a combining optical element that aligns the optical axes of two light beams whose polarization directions are orthogonal to each other and output from the two optical fibers.

[0041] In the multipoint vibration measuring device according to the present invention, the coupling optical element may be made of a birefringent crystal.

[0042] In the multipoint vibration measuring device according to the present invention, the coupling optical element may be a Wollaston prism.

[0043] Furthermore, in the multi-point vibration measuring device according to the present invention, the coupling optical system comprises a coupling optical element array in which the optical elements are arranged two-dimensionally, and each frequency component of the optical comb of the measurement light input via the coupling optical element array is collected by a collecting optical element and output toward the measurement surface of the measurement object, and each frequency component of the optical comb of the measurement light reflected and returned from the measurement surface is collected by the collecting optical element and input to the coupling optical element array.

[0044] Furthermore, the multi-point vibration measuring device according to the present invention can be configured such that a delay optical system is provided in the optical path through which the reference light passes, during the period in which the measurement light and reference light output from the light source are reflected by the measurement surface and returned via the coupling optical system, and the measurement light and reference light containing the respective frequency components are made to interfere with each other in the interference optical system and output as interference light for measurement, so that the optical path length of the optical path through which the measurement light and the measurement light containing the respective frequency components reflected by the measurement surface pass is made equal to the optical path length of the optical path through which the reference light passes.

[0045] In the multi-point vibration measurement device of the present invention, two optical splitter / multiplexer elements are provided, and the functions of the optical splitter element and the optical multiplexer element are operated separately, and an optical path is separated into one that splits the measurement light output from the light source through the interference optical system 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 another optical path that combines the multiple frequency components reflected and returned from multiple points on the measurement surface and inputs them into the interference optical system, thereby preventing unnecessary reflected components from the optical splitter element that splits the multiple frequency components from being mixed into the interference light required for multi-point vibration measurement.

[0046] Therefore, according to the present invention, measurement errors caused by unnecessary reflection components from various optical elements such as optical multiplexing and splitting elements provided in the optical path through which the measurement light irradiated onto the measurement surface via the interference optical system passes are eliminated, and multi-point vibration measurement can be performed with high accuracy.

[0047] Fig. 1 is a schematic diagram showing the configuration of a multi-point vibration measurement device involving measurement errors due to unwanted reflection components from an optical demultiplexing element being mixed into the interference light required for multi-point vibration measurement. Fig. 2 is a schematic diagram showing the configuration of a multi-point vibration measurement device to which the present invention is applied. Fig. 3 (A) and (B) are diagrams explaining the functions of the optical demultiplexing element and the optical multiplexing element provided in the optical demultiplexing / multiplexing head in the multi-point vibration measurement device. Fig. 3 (A) 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. 3 (B) shows the function of multiplexing each frequency component demultiplexed into each frequency component of the optical comb by the optical multiplexing element. 4A and 4B are diagrams illustrating the functions of the optical demultiplexing element and the optical multiplexing element provided in the optical multiplexing / demultiplexing head of the multipoint vibration measurement device. (A) shows the function of demultiplexing each frequency component of the optical comb contained in the measurement light into multiple frequency components of the optical comb using the optical demultiplexing element, and (B) shows the function of multiplexing each frequency component of the optical comb, which has been demultiplexed into multiple frequency components, using the optical multiplexing element. (5) shows the results of measuring, with an optical spectrum analyzer, an optical comb demultiplexed by an optical multiplexing / demultiplexing element that demultiplexes an optical comb into three frequency components. (6) is a schematic diagram showing the configuration of a multipoint vibration measurement device equipped with a projection optical system incorporating a coupling optical element according to the present invention. (7A) and (7B) are diagrams showing an example of the configuration of the projection optical element used in the projection optical system incorporating the coupling optical element. (A) is a schematic diagram showing the configuration of the projection optical element, and (B) is a front view of a two-core capillary provided in the projection optical element. Figures 8A and 8B show another example of the configuration of the projection optical element used in the projection optical system incorporating the coupling optical element, where (A) is a schematic diagram showing the configuration of the projection optical element, and (B) is a front view of a double-core capillary provided in the projection optical element. Figure 9 is a schematic diagram showing the configuration of a multi-point vibration measurement device equipped with a projection optical system incorporating a coupling optical element using a coupling optical element array formed by a two-dimensional arrangement of multiple projection optical elements. Figures 10A and 10B show an example of the configuration of the coupling optical element array, where (A) is a vertical cross-sectional view of the coupling optical element array as seen from the side, and (B) is a vertical cross-sectional view of the coupling optical element array as seen from the front. Figure 11 is a schematic diagram showing another example of the configuration of a multi-point vibration measurement device to which the present invention is applied.Fig. 12 is a schematic diagram showing another example of the configuration of a multi-point vibration measuring device to which the present invention is applied. Fig. 13 is a schematic diagram showing another example of the configuration of a multi-point vibration measuring device to which the present invention is applied.

[0048] 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.

[0049] FIG. 2 is a schematic diagram showing the configuration of a multipoint vibration measuring device 100 to which the present invention is applied.

[0050] This multipoint vibration measuring device 100 measures a coherent measurement light L Ｓ and reference light L Ｒ and a light source 110 that outputs measurement light L Ｓ and reference light L Ｒ and an interference optical system 120 into which the measurement light L Ｓ an interference light detection unit 140 to which the measurement interference light and the reference interference light outputted via the interference optical system 120 are inputted; and a measurement interference signal S obtained by the interference light detection unit 140. Ｓ and the reference interference signal S Ｒ The signal processing unit 150 receives the signal.

[0051] In this multipoint vibration measuring device 100, the light source 110 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.

[0052] The optical multiplexing / demultiplexing head 130 receives the measurement light L output from the light source 110 via the interference optical system 120. Ｓ is divided 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 of the optical comb is combined to form the measurement light L ＳThe measurement light L includes the frequency components of each optical comb. Ｓ ' is input to the interference optical system 120.

[0053] The interference optical system 120 receives the measurement light L 1 including the frequency components returned via the optical multiplexing / demultiplexing head 130. Ｓ ' and the reference light L output from the light source 110. Ｒ and outputs the interference light as interference light for measurement, and Ｓ and reference light L Ｒ The light is made to interfere with one another, and the interference light is output as reference interference light.

[0054] The interference light detection unit 140 receives and detects the measurement interference light and the reference interference light output from the interference optical system 120, 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 150.

[0055] Then, in the signal processing section 150, the measurement interference signal S obtained in the interference light detection section 140 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 to measure the vibration distribution on the measurement surface 5.

[0056] Here, the multipoint vibration measuring device 100 is a device in which the present invention is applied to the multipoint vibration measuring device 10 shown in FIG. 1 , and two optical multiplexing and dividing elements 3 are provided, and the function of the optical multiplexing element and the function of the optical dividing element are individually performed, and the measuring light L output from the light source 110 via the interference optical system 120 is Ｓ The measurement light L Ｓ The multipoint vibration measuring device 100 has two separate optical paths: one that splits the optical comb into multiple frequency components contained in the optical comb and irradiates them at multiple points on the measurement surface 5 of the object to be measured, and the other that combines the multiple frequency components of the optical comb that are reflected at multiple points on the measurement surface 5 and return, and inputs them to the interference optical system 120. In this multipoint vibration measuring device 100, the same components as those in the multipoint vibration measuring device 10 are given the same symbols, and detailed descriptions of them will be omitted.

[0057] In this multipoint vibration measuring device 100, the light source 110 emits measurement light (first optical comb) LＳ and the reference light (second optical comb) L Ｒ The first optical comb generator (COMB1) 1A and the second optical comb generator (COMB2) 1B each output a PMF-based optical fiber FB. １２Ａ , F.B. １２Ｂ The first optical comb generator (COMB1) 1A and the second optical comb generator (COMB2) 1B are connected to the interference optical system 120 via the 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.

[0058] The interference optical system 120 is an optical fiber FB using a PMF. ２Ａ２ , F.B. ２Ｂ１ , F.B. ２Ｂ２ Four optical couplers OC connected by Ａ , O.C. Ｂ , O.C. Ｃ , O.C. Ｄ The optical coupler OC Ａ Optical fiber FB externally connected to １２Ａ The measurement light L from the light source 110 Ｓ is input, and the optical coupler OC Ｂ Optical fiber FB externally connected to １２Ｂ The reference light L Ｒ is entered.

[0059] In this interference optical system 120, an optical coupler OC Ａ Optical fiber FB ２Ａ２ via the optical coupler OC Ｄ are internally connected, and the optical coupler OC Ａ Optical fiber FB ２３ The optical demultiplexing element 131A provided in the optical demultiplexing / multiplexing optical system 131 of the optical demultiplexing / multiplexing head 130 is externally connected via Ｂ There are two optical fiber FB ２Ｂ１ , F.B. ２Ｂ２ Two optical couplers OC Ｃ , O.C. Ｄ are internally connected, and the optical coupler OC Ｃ Optical fiber FB３２ The optical multiplexing element 131B provided in the optical multiplexing / demultiplexing optical system 131 of the optical multiplexing / demultiplexing head 130 is externally connected via the optical multiplexing / demultiplexing element 131B.

[0060] Here, in the interference optical system 120, three optical couplers OC Ａ , O.C. Ｂ , O.C. Ｄ Two optical fibers FB connecting ２Ａ２ , F.B. ２Ｂ２ By making the lengths of the first and second optical comb generators (COMB1) 1A of the light source 110 the same, the measurement light L Ｓ is the optical fiber FB ２Ａ２ via the 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 is the optical fiber FB ２Ｂ２ The reference light L Ｒ is set equal to the optical path length through which the light passes.

[0061] The measurement light L input to the interference optical system 120 Ｓ is the optical coupler OC Ａ Optical fiber FB using PMF externally connected to ２３ The light is input to the optical demultiplexer 131A via the optical demultiplexer 131B.

[0062] The optical multiplexing / demultiplexing head 130 has two optical fibers FB ２３ , F.B. ３２ The two optical couplers OC of the interference optical system 120 are A , O.C. C an optical multiplexing / demultiplexing optical system 131 including an optical demultiplexing element 131A and an optical multiplexing element 131B externally connected to the optical multiplexing / demultiplexing optical system 131; and a plurality of (m×n) optical couplers OC connected to the optical multiplexing / demultiplexing optical system 131. Ｃ１ , O.C. Ｃ２ , O.C. Ｃ３ , ..., O.C. Ｃｎ , . . . , and a plurality of (m×n) projection optical elements 44 connected to the coupling optical system 132. １ , 44 ２ , 44 ３, ..., 44 ｎ , . . . The optical coupler OC Ｃ１ , O.C. Ｃ２ , O.C. Ｃ３ , ..., O.C. Ｃｎ , ... are the optical couplers OC shown in FIG. Ｅ It functions as a PBC module in the same way.

[0063] The optical demultiplexing element 131A of the optical demultiplexing / multiplexing optical system 131 includes a plurality of (m×n) optical fibers FB ３４１ , F.B. ３４２ , F.B. ３４３ , ..., FB ３４ｎ , . . . , the plurality of (m×n) optical couplers OC Ｃ１ , O.C. Ｃ２ , O.C. Ｃ３ , ..., O.C. Ｃｎ , . . . , and the optical multiplexing element 131B of the optical multiplexing and demultiplexing optical system 131 is connected to a plurality of (m×n) optical fibers FB ４３１ , F.B. ４３２ , F.B. ４３３ , ..., FB ４３ｎ , . . . , the plurality of (m×n) optical couplers OC Ｃ１ , O.C. Ｃ２ , O.C. Ｃ３ , ..., O.C. Ｃｎ , ... are connected.

[0064] The plurality of (m×n) projection optical elements 44 of the projection optical system 133 １ , 44 ２ , 44 ３ , ..., 44 ｎ , ... respectively represent the condenser lenses 4 Ａ１ , 4 Ａ２ , 4 Ａ３ , ..., 4 Ａｎ , ... and quarter-wave plate 4 Ｂ１ , 4 Ｂ２ , 4 Ｂ３ , ..., 4 Ｂｎ , ..., and a plurality of (m x n) optical fibers FB ４４１ , F.B. ４４２ , F.B. ４４３ , ..., FB ４４ｎ, . . . are connected to the coupling optical system 132 .

[0065] The optical fiber FB ２３ The measurement light L is input to the optical branching element 131A of the optical branching / combining optical system 131 via the Ｓ is the measurement light L in the optical demultiplexing element 131A. Ｓ The plurality of frequency components of the optical comb included in the optical comb are demultiplexed, and each frequency component of the optical comb is demultiplexed through the plurality of (m×n) optical fibers FB ３４１ , F.B. ３４２ , F.B. ３４３ , ..., FB ３４ｎ , . . . , the plurality of (m×n) optical couplers OC Ｃ１ , O.C. Ｃ２ , O.C. Ｃ３ , ..., O.C. Ｃｎ , ..., and are input to the optical couplers OC Ｃ１ , O.C. Ｃ２ , O.C. Ｃ３ , ..., O.C. Ｃｎ , ..., a plurality of (m × n) optical fibers FB ４４１ , F.B. ４４２ , F.B. ４４３ , ..., FB ４４ｎ , . . . through the plurality of (m×n) condenser lenses 4 of the projection optical system 133. Ａ１ , 4 Ａ２ , 4 Ａ３ , ..., 4 Ａｎ , . . . and multiple (m×n) types of frequency components are condensed into a condenser lens 4 Ａ１ , 4 Ａ２ , 4 Ａ３ , ..., 4 Ａｎ , ... are collected by the quarter-wave plates 4 Ｂ１ , 4 Ｂ２ , 4 Ｂ３ , ..., 4 Ｂｎ , . . . 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.

[0066] 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 133 and the optical fiber FB ４４１ , F.B. ４４２ , F.B. ４４３, F.B. ４４ｎ , . . . Ｃ１ , O.C. Ｃ２ , O.C. Ｃ３ , ..., O.C. Ｃｎ , . . . Ｓ The reflected light of each frequency component is Ｃ１ , O.C. Ｃ２ , O.C. Ｃ３ , ..., O.C. Ｃｎ , ... to the optical fiber FB ４３１ , F.B. ４３２ , F.B. ４３３ , ..., FB ４３ｎ , . . . , are input to the optical multiplexing element 131B of the optical multiplexing / demultiplexing optical system 131, and are multiplexed by the optical multiplexing element 131B, and the measurement light L consisting of reflected light of each frequency component reflected at each measurement point on the measurement surface 5 is Ｓ ' from the optical multiplexing element 131B to the optical fiber FB ３２ the optical coupler OC of the interference optical system 120 via Ｃ is entered into

[0067] 3A and 3B are diagrams illustrating the functions of an optical branching element 131A and an optical multiplexing element 131B provided in the optical branching / multiplexing head 130 in the multipoint vibration measuring device 100. The optical branching element 131A divides the measurement light L 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 of the optical comb, and combines each frequency component demultiplexed into the measurement light L Ｓ It has the function of '.

[0068] Here, in this multipoint vibration measuring device 100, an optical fiber using a PMF is used as the optical path, and the measurement light L Ｓ In the optical demultiplexing element 131A, the measurement light L Ｓ The frequency components of the linearly polarized optical comb obtained by splitting the multiple frequency components of the optical comb included in Ａ１ , 4 Ａ２ , 4 Ａ３ , ..., 4 Ａｎ, ... are collected by the quarter-wave plates 4 Ｂ１ , 4 Ｂ２ , 4 Ｂ３ , ..., 4 Ｂｎ , ... and are irradiated onto the measurement surface 5 as circularly polarized light components of each frequency. The reflected light of each of the circularly polarized light components reflected by the measurement surface 5 is then incident on the quarter wave plate 4. Ｂ１ , 4 Ｂ２ , 4 Ｂ３ , ..., 4 Ｂｎ , . . . are converted into linearly polarized frequency components by the respective condenser lenses 4 Ａ１ , 4 Ａ２ , 4 Ａ３ , ..., 4 Ａｎ , ...and are returned to

[0069] That is, in the multipoint vibration measuring device 100, the condenser lens 4 in the projection optical system 133 is Ａ１ , 4 Ａ２ , 4 Ａ３ , ..., 4 Ａｎ , . . . through the quarter-wave plate 4 Ｂ１ , 4 Ｂ２ , 4 Ｂ３ , ..., 4 Ｂｎ , . . . the measurement light L output from Ｓ Each frequency component of the optical comb is circularly polarized and irradiated onto the target. The reflected light from the target is then incident on the quarter-wave plate 4. Ｂ１ , 4 Ｂ２ , 4 Ｂ３ , ..., 4 Ｂｎ , . . . through the condenser lens 4 Ａ１ , 4 Ａ２ , 4 Ａ３ , ..., 4 Ａｎ Each frequency component of the optical comb of the reflected light input to the condenser lens 4 is linearly polarized. Ａ１ , 4 Ａ２ , 4 Ａ３ , ..., 4 Ａｎ , ..., the output light is collected by a condenser lens 4 Ａ１ , 4 Ａ２ , 4 Ａ３ , ..., 4 Ａｎ , . . . , the polarization planes of the frequency components of the optical comb of the reflected light are orthogonal to each other.

[0070] From the projection optical system 133 to the optical fiber FB ４４１ , F.B. ４４２ , F.B. ４４３ , ..., FB ４４ｎ , . . . Ｃ１ , O.C. Ｃ２ , O.C. Ｃ３ , ..., O.C. Ｃｎ , . . . are the frequency components of the optical comb of the reflected light returning to the optical fiber FB ３４１ , F.B. ３４２ , F.B. ３４３ , ..., FB ３４ｎ , . . . through the optical coupler OC Ｃ１ , O.C. Ｃ２ , O.C. Ｃ３ , ..., O.C. Ｃｎ , . . . Ｓ and the optical coupler OC has a polarization plane orthogonal to the polarization plane of each frequency component of Ｃ１ , O.C. Ｃ２ , O.C. Ｃ３ , ..., O.C. Ｃｎ , ... to the optical fiber FB ４３１ , F.B. ４３２ , F.B. ４３３ , ..., FB ４３ｎ , . . . and are input to the optical multiplexing element 131B of the optical multiplexing / demultiplexing optical system 131.

[0071] In this way, the optical coupler OC of the coupling optical system 132 Ｃ１ , O.C. Ｃ２ , O.C. Ｃ３ , ..., O.C. Ｃｎ , ... are the linearly polarized measurement light L whose polarization planes are orthogonal to each other. Ｓ and the frequency components of the reflected light reflected by the measurement surface 5 and returning are input from opposite directions to each other, and function as a directional coupler that outputs in opposite directions to each other, and may be a PBC module or a circulator. Ｃ１ , O.C. Ｃ２ , O.C. Ｃ３ , ..., O.C. ＣｎInstead of the above, for example, a fused PBC module that combines two orthogonal polarized beams and outputs them to one fiber, a fused PBC module that splits input light into orthogonal linearly polarized beams and outputs them to two PMFs, a PBC module using birefringent crystals, etc. can be used.

[0072] 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 133. Ｓ The reflected light of each frequency component is combined by the optical combining element 131B, and measurement light L consisting of reflected light of each frequency component reflected at a plurality of points on the measurement surface 5 is obtained. Ｓ ' is a signal transmitted from the optical multiplexing element 131B to the optical fiber FB ３２ via the optical coupler OC of the interference optical system 120 Ｃ is entered into

[0073] Here, each frequency component 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 131B to form the measurement light L Ｓ ' is accompanied by a phase variation due to the Doppler shift.

[0074] The above optical coupler OC Ｃ is the optical coupler OC of the interference optical system 120. Ｂ From optical fiber FB ２Ｂ１ via the optical coupler OC Ｃ Reference light L input to Ｒ and the above optical coupler OC Ｃ The measurement light L input to Ｓ ' are combined with the reference light L Ｒ and the measurement light L Ｓ The interference light with the ' is output as interference light for measurement.

[0075] In addition, the optical coupler OC of the interference optical system 120 Ｄ is an optical coupler OC Ａ From optical fiber FB ２Ａ２ The measurement light L is input via Ｓ and optical coupler OC ＢFrom optical fiber FB ２Ｂ２ The reference light L is input via Ｒ By combining the reference light L Ｒ and the measurement light L Ｓ The interference light is output as reference interference light.

[0076] That is, in the interference optical system 120, the measurement light L 1 includes reflected light of each frequency component reflected at a plurality of points on the measurement surface 5 and is accompanied by a phase fluctuation due to a Doppler shift. Ｓ ' and the light source 110 to the optical coupler OC Ｂ Reference light L input to Ｒ The interference light with the above optical coupler OC is used as the interference light for measurement. Ｃ and outputs from the light source 110 to the optical coupler OC Ａ The measurement light L input to Ｓ and the above optical coupler OC Ｂ Reference light L input to Ｒ The interference light with the optical coupler OC is used as a reference interference light. Ｄ Output from

[0077] The interference light detection unit 140 to which the measurement interference light and the reference interference light obtained by the interference optical system 120 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 fibers FB externally connected to ２６Ａ１ , F.B. ２６Ａ２ via the optical coupler OC Ｃ The measurement interference light detector 6A receives the measurement interference light input from the Ｓ and outputs the signal from the optical coupler OC of the interference optical system 120. Ｄ Two optical fibers FB externally connected to ２６Ｂ１ , F.B. ２６Ｂ２ via the optical coupler OC Ｄ The reference interference light is detected and converted into an electrical signal, and a reference interference signal S Ｒ Output.

[0078] The signal processing unit 150 then processes the measurement interference signal S obtained by the interference light detection unit 140. Ｓ and the reference interference signal S Ｒ The phase difference for each frequency component of the measurement light and the reference light, which are optical combs, is calculated by DFT analysis, and the measurement interference signal S Ｓ and the reference interference signal S Ｒ By calculating the phase difference for each frequency component of the interference signal resulting from the Doppler shift caused by 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, and the vibration distribution on the measurement surface 5 is measured.

[0079] In this way, in the multipoint vibration measuring 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 Ｓ and the measurement light L, which is provided with the optical multiplexing element 131B 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 120 is separated, and the measurement light L ′ output from the interference optical system 120 is Ｓ Even if a part of the reflected light is reflected by the optical demultiplexer 131A and an unnecessary reflected component is generated, this reflected component is ２３ via the optical coupler OC of the interference optical system 120 Ａ Returning to this branching optical coupler OC Ａ From optical fiber FB １２Ａ Therefore, even if unnecessary reflected components are generated by reflection at the optical demultiplexing element 131A, these reflected components are absorbed by the optical coupler OC of the interference optical system 120. Ｃ The reference light L output from Ｒ and the 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 measurement light L Ｓ The interference light for reference, i.e., the interference light for reference, is not affected.

[0080] Therefore, in the multipoint vibration measuring device 100, the measurement light L irradiating the measurement surface 5 through the interference optical system 120 Ｓ an optical coupler OC of the coupling optical system 132; Ｃ１ , O.C. Ｃ２ , O.C. Ｃ３ , ..., O.C. Ｃｎ This eliminates measurement errors caused by unwanted reflection components from various optical elements such as , . . . being mixed into the interference light required for multi-point vibration measurement, thereby enabling highly accurate multi-point vibration measurement.

[0081] Here, in the optical multiplexing / demultiplexing head 130 in the multipoint vibration 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 wave separating 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 system 133. 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. Ｓ Each frequency component included in is demultiplexed into a plurality of frequency components, and as shown in FIG. 4B, measurement light L is generated, which is made up of reflected light of each of the frequency components demultiplexed into the plurality of frequency components that are reflected and returned by the measurement surface 5. Ｓ ' may be multiplexed by the multiplexing element 131B.

[0082] 4A and 4B are diagrams illustrating the functions of the optical branching element 131A and the optical multiplexing element 131B provided in the optical branching / multiplexing head 130 in the multipoint vibration measuring device 100. As shown in FIG. 4A, the optical branching element 131A divides the measurement light L Ｓ 4B, the optical multiplexing element 131B has a function of multiplexing the frequency components separated into a plurality of frequency components to generate the measurement light L Ｓ It can have the function of '.

[0083] In this way, the measurement light L Ｓ By splitting each frequency component of the optical comb included in into a plurality of frequency components, the frequency components of each optical comb including the split multiple frequency components are reflected at multiple points on the measurement surface 5 and return through the same optical path, so that the measurement light L consisting of the reflected light of each frequency component of the optical comb split into the plurality of frequency components Ｓ ' can be used to measure distances to a plurality of points on the measurement surface 5.

[0084] Measuring light L Ｓ When the frequency components of each optical comb included in the measurement light L are demultiplexed into multiple frequency components of the optical comb by an optical demultiplexing / multiplexing element, the frequency components of the optical comb in the frequency band of each channel demultiplexed into multiple frequency components of the optical comb are demultiplexed into single frequency components of the optical comb to perform multi-point vibration measurement. Ｓ Although the number of divisions is reduced, it is possible to measure the displacement and distance at a plurality of points on the measurement surface 5.

[0085] For example, when an optical multiplexer / demultiplexer for 100 GHz wavelength division multiplexing (WDM) demultiplexes an optical comb with 25 GHz spacing generated to overlap the ITU grid, it can demultiplex each of the 25 GHz optical combs into three frequency components in eight channel frequency bands (ch1 to ch8) centered at 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 Figure 5. Because this optical multiplexer / demultiplexer is designed specifically for 100 GHz frequency spacing, the frequency components of the intermediate optical combs between channels 100 GHz apart have a large loss, so it can demultiplex into three frequency components.

[0086] The multipoint vibration measuring device 100 employs the 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 130, respectively, so that it can handle both multipoint vibration measurement and multipoint distance measurement. ＳIn the multipoint vibration measurement device 100, which separates each frequency component of the optical comb included in the frequency band of the same channel into multiple components, the phase of any one frequency component can be analyzed, or since each frequency component included in the frequency band of the same channel is a component that has been reflected from the same point on the same optical path, if phase information is obtained for multiple frequency components of each frequency component, the vibrometer will measure the same point, and the S / N ratio can be improved by performing processing such as averaging. Also, since each frequency component included in 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 of each frequency component.

[0087] In other words, the multi-point vibration measuring 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 130.

[0088] Here, in the interference optical system 120 of the multipoint vibration measuring device 100, the reference light L is output from the second optical comb generator (COMB2) 1B of the light source 110. Ｒ is output and then the optical coupler OC Ｃ is the time required for the measurement light L to be input from the first optical comb generator (COMB1) 1A of the light source 110. 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 so that the delay is equal to the time required for the reference light L to be input to the Ｒ The delay fiber FB is a delay optical system that provides ２Ｂ１ ' is the reference light L from the second optical comb generator (COMB2) 1B of the light source 110. Ｒ The optical coupler OC Ｂ and an optical coupler OC that outputs interference light for measurement. Ｃ and the optical fiber FB that internally connects ２Ｂ１ It is set up in.

[0089] That is, the above four optical couplers OC Ａ , O.C. Ｂ , O.C. Ｃ , O.C. ＤThree optical fibers FB with the same length between them ２Ａ２ , F.B. ２Ｂ１ , F.B. ２Ｂ２ In the interference optical system 120 connected via the optical fiber FB ２Ｂ１ The delay optical system is a 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 is the measurement light L reflected by the reflecting surface 5 of the measurement object. Ｓ ' and the optical coupler OC of the interference optical system 120. Ｃ The measurement light L Ｓ , L Ｓ and 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 That is, the optical path lengths through which the measurement light L output from the first optical comb generator (COMB1) 1A of the light source 110 pass are made equal. Ｓ is the optical coupler OC of the interference optical system 120. Ｄ The measurement light L Ｓ 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. Ｄ The reference light L Ｒ The optical path lengths through which the light passes are made equal.

[0090] In this way, the measurement light L output from the light source 110 Ｓ and reference light L Ｒ However, the above optical fiber FB ３２ The measurement light L containing the above frequency components returns via Ｓ ' and the 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 A delay fiber FB, which is a delay optical system, is provided in the optical path through which the ２Ｂ１ ' is provided, and the measurement light L Ｓand the measurement light L containing the above-mentioned 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 which detects the measurement interference light and the reference interference light is Ｒ , the measurement interference signal S Ｓ Measurement light L Ｓ and reference light L Ｒ The difference in phase noise between the measurement light L Ｓ and reference light L Ｒ It is possible to reduce the measurement error caused by the phase noise of the delay fiber FB. ２Ｂ１ Instead of the above, a space propagation delay optical system having the required optical path length can be adopted.

[0091] 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.

[0092] 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 Φ ｆｍ１ (t), Φ ｆｍ２ (t), and consider the vibration information component ΦBn(t) due to the phase fluctuation caused by this phase noise component and the Doppler shift.

[0093] The measurement light L output from the first optical comb generator (COMB1) 1A Ｓ The phase noise Φ of the optical comb component of index n relative to the carrier of the comb is Ｓｎ (t) is and 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 Here, Φ ｆｍ１ (t), ｆｍ２Since (t) is a harmonic, it is multiplied by n, where n is the sideband index and the carrier is set to 0.

[0094] Measurement light L returning via the target Ｓ 's phase noise of the optical comb component Φ Ｓｎ '(t) is the vibration information component due to the phase fluctuation caused by the Doppler shift due to vibration, with the delay of the optical system being τ. Ｂｎ When (t) is used, 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 only the return time for one trip has been experienced.

[0095] 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 detected 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., This becomes:

[0096] 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), i.e., This becomes:

[0097] 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 of (t) (Equation (1)-Equation (2)) is calculated by the signal processing unit 150, This becomes:

[0098] where Φ Ｓｎ '(t)-Φ Ｓｎ Since there is no simultaneity in (t), the noise component does not become zero.

[0099] However, it cannot be applied to a range finder that requires a large dynamic range, but as a means that can be applied when the distance to the target object is almost fixed, such as in a vibrometer, the reference light L Ｒ A delay fiber FB that imparts a delay corresponding to +τ in the optical path through which the ２Ｂ１ ' is the reference light L Ｒ The optical fiber FB through which ２Ｂ１ By inserting into, the above formula (1) becomes 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.

[0100] The difference between the above formula (4) and formula (2) (formula (4) - formula (2)) is calculated by the signal processing unit 150, In this equation (5), the phase noise of the laser is cancelled, but the phase noise of the oscillator cannot be completely removed because it is uncorrelated.

[0101] Therefore, the time for comparing the phases of the reference interference signal SR and the measurement interference signal SS is set to a difference of τ. For example, the cable of the reference interference signal SR or the optical fiber FB ２６Ｂ１ and FB ２６Ｂ２ , or FB ２Ａ２ and FB ２Ｂ２ By adding the length of the signal by the time τ to increase the delay of the reference interference signal SR, the above equation (2) becomes The phase obtained by the difference between the above equations (4) and (6) (equation (4) - equation (6)) is Thus, the phase noise of the oscillator is cancelled out, and what remains is the phase change component due to vibration.

[0102] Here, the cable for the reference interference signal SR or the optical fiber FB ２６Ｂ１ and FB ２６Ｂ２ , or FB ２Ａ２ and FB ２Ｂ２However, since the reference interference signal SR and the measurement interference signal SS are digitized by the signal processing unit 150, it is possible to digitally adjust the delay by adding a time delay by shifting the calculation start point. By adjusting the delay to the component with the largest delay and making all other delays the same, it is possible to minimize the influence of phase noise of the laser and oscillator.

[0103] Here, in the multipoint vibration measuring device 100, the reference light L Ｒ and measurement light L Ｓ , L Ｓ The light source 110, the interference optical system 120, the optical multiplexing / demultiplexing optical system 131, and the projection optical system 133 are connected to each other through optical fibers. Ｒ and measurement light L Ｓ , L Ｓ However, the interference optical system 120 may be configured as a spatial optical system using an optical element that propagates in space, for example, a trapezoidal prism as disclosed in Patent Document 6, and input and output may be optical fibers. Also, without using optical fibers, the reference light L may be transmitted by spatial propagation between the light source 110, the interference optical system 120, the optical multiplexing and demultiplexing optical system 131, and the projection optical system 133. Ｒ and measurement light L Ｓ , L Ｓ ' may be sent.

[0104] Next, FIG. 6 is a schematic diagram showing the configuration of a multipoint vibration measuring apparatus 100A having a light multiplexing / demultiplexing head 130A equipped with a projection optical system 133A incorporating a coupling optical element to which the present invention is applied.

[0105] This multipoint vibration measuring device 100A is a device in which the coupling optical system 132 and projection optical system 133 of the optical demultiplexing / multiplexing head 130 in the multipoint vibration measuring device 100 are replaced with a projection optical system 133A with a coupling optical element that has the function of the coupling optical system 132.In this multipoint vibration measuring device 100A, the same components as those in the multipoint vibration measuring device 100 are given the same symbols in the figures, and detailed explanations of them will be omitted.

[0106] This multipoint vibration measuring device 100A has a light dividing element 131A of a light dividing / combining optical system 131, and a plurality of optical fibers FB ３４１, F.B. ３４２ , F.B. ３４３ , ..., FB ３４ｎ , . . . and a plurality of optical fibers FB ４３１ , F.B. ４３２ , F.B. ４３３ , ..., FB ４３ｎ , . . . are connected to the optical splitter element 131A of the optical splitter / multiplexer optical system 131. Ａ１ , 44 Ａ２ , 44 Ａ３ , ..., 44 Ａｎ The optical multiplexing / demultiplexing head 130A is provided with a projection optical system 133A incorporating a coupling optical element, which is made up of the optical components 133A, . . .

[0107] The plurality of projection optical elements 44 Ａ１ , 44 Ａ２ , 44 Ａ３ , ..., 44 Ａｎ , . . . , the projection optical element 44A having the configuration shown in FIGS. 7A and 7B is used, for example.

[0108] 7A and 7B are diagrams showing an example of the configuration of the projection optical element 44A used in the projection optical system 133A incorporating the coupling optical element, where FIG. 7A is a schematic diagram showing the configuration of the projection optical element 44A, and FIG. 7B is a diagram showing the configuration of the two-core capillary 4C provided in the projection optical element 44A. １ FIG.

[0109] This projection optical element 44A is a double-core capillary 4C １ And this two-core capillary 4C １ A coupling optical element 4C having an optical characteristic of aligning the axes of light beams whose polarization directions are orthogonal to each other and output from the tips of two optical fibers inserted in the ２ The coupling optical unit 4C consists of Ａ The two-core capillary 4C １ from the input side optical fiber FB ３４ and the output optical fiber FB ４３ is externally derived.

[0110] The coupling optical unit 4C Ａ Two-core capillary 4C provided in １The stress-applying parts of the polarization-maintaining fiber inserted into the optical fiber are arranged orthogonal to each other, as shown in Figure 7(B), and in this document, all optical module elements connected to optical fibers are manufactured according to a unified standard so that the direction of the stress-applying parts becomes the polarization plane.

[0111] The above two-core capillary 4C １ The input optical fiber FB is led out from the ３４ is connected to the optical demultiplexing element 131A of the optical demultiplexing / multiplexing optical system 131, and the two-core capillary 4C １ The output optical fiber FB is led out from the ４３ is connected to the optical multiplexing element 131B of the optical multiplexing / demultiplexing optical system 131.

[0112] In the projection optical element 44A, the light beam from the optical branching element 131A to the input side optical fiber FB ３４ The measurement light L is input via Ｓ Frequency component l Ｓ is the coupling optical element 4C ２ The frequency component l condensed by this condenser lens 4A is input to the condenser lens 4A via 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 Ｓ is the frequency component l of the polarization plane whose polarization direction is orthogonal to Ｓ The light is returned to the condenser lens 4A as a beam '.

[0113] The above frequency component l Ｓ is the frequency component l of the polarization plane whose polarization direction is orthogonal to Ｓ ' is condensed by the condenser lens 4A and is Ａ The coupling optical element 4C ２ via the output optical fiber FB ４３ and the output side of the 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.

[0114] The coupling optical element 4C ２For example, a birefringent crystal can be used to separate the light beams using walk-off.

[0115] The projection optical system 133A incorporating the coupling optical element includes the coupling optical element 4C using the birefringent crystal. ２ Instead, a Wollaston prism 4C as shown in FIGS. ｂ A coupling optical element 4C configured by the above ２ It is also possible to employ a projection optical element 44B using the '.

[0116] 8A and 8B are diagrams showing an example of the configuration of the projection optical element 44B used in the projection optical system 133A incorporating the coupling optical element, where (A) is a schematic diagram showing the configuration of the projection optical element 44B, and (B) is a diagram showing the configuration of the two-core capillary 4C provided in the projection optical element 44B. １ FIG.

[0117] This projection optical element 44B is a two-core capillary 4C １ And this two-core capillary 4C １ A coupling optical element 4C having an optical characteristic of aligning the axes of light beams whose polarization directions are orthogonal to each other and output from the tips of two optical fibers inserted in the ２ ', the coupling optical unit 4C Ｂ The two-core capillary 4C １ from the input side optical fiber FB ３４ and the output optical fiber FB ４３ is externally derived.

[0118] The coupling optical unit 4C Ｂ Two-core capillary 4C provided in １ The polarization-maintaining fibers inserted into the stress-applying portion are arranged so as to be orthogonal to each other, as shown in FIG. 8B.

[0119] The coupling optical element 4C ２ ' is two collimator lenses 4C ａ , 4C ｃ Between the Wollaston prism 4C ｂ It is made by arranging the following.

[0120] In this projection optical element 44B, too, the optical fiber FB ３４ The measurement light L is input via Ｓ The frequency component of the optical comb l Ｓ is the coupling optical element 4C ２ ' is input to the condenser lens 4A, and the frequency component l 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 Ｓ is the frequency component l of the polarization plane whose polarization direction is orthogonal to Ｓ The light is returned to the condenser lens 4A as a beam '.

[0121] The above frequency component l Ｓ is the frequency component l of the polarization plane whose polarization direction is orthogonal to Ｓ ' is condensed by the condenser lens 4A and is ２ ', and the output optical fiber FB ４３ and the output side of the 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.

[0122] In the projection optical elements 44A and 44B, as shown in FIG. 7B and FIG. 8B, the stress applying portions of the two-core capillaries 4C are arranged so as to be perpendicular to each other. １ The coupling optical element 4C ２ , 4C ２ The light input whose polarization plane is in the direction of the stress applying portion and is input to the coupling optical element 4C ２ , 4C ２ By passing through the measuring light L', the optical axes become coaxial and are output in the same direction. Ｓ Frequency component l Ｓ The polarization plane is in the same direction as the stress applying part of Port 1 (the input side optical fiber FB ３４ ) and reflected by the measurement surface 5. Ｓ ' is polarized in the same direction as the stress applying portion of Port 2, and Port 2 (output side optical fiber FB ４３) can receive light.

[0123] Here, in the optical multiplexing / demultiplexing head 130 in the multipoint vibration measuring device 100 described above, the optical multiplexing / demultiplexing optical system 131 is connected to the projection optical system 133 via the coupling optical system 132. However, in the multipoint vibration measuring device 100A, the coupling optical system 132 and the projection optical system 133 in the multipoint vibration measuring device 100 are replaced with a coupling optical element-integrated projection optical system 133A that has the function of the coupling optical system 132. ４４１ , F.B. ４４２ , F.B. ４４３ , ..., FB ４４ｎ , . . . are no longer necessary, and the optical multiplexing / demultiplexing head 130A can be configured with two optical systems, the optical multiplexing / demultiplexing optical system 131 and the projection optical system 133A with a built-in coupling optical element. This not only simplifies the configuration, but also reduces the need for the above-mentioned fiber FB ４４１ , F.B. ４４２ , F.B. ４４３ , ..., FB ４４ｎ , . . . does not result in the generation of unnecessary reflected light.

[0124] That is, using an element such as a PBC module as the coupling optical system 132, as in the optical multiplexing / demultiplexing head 130 in the multipoint vibration measurement device 100, complicates the optical system and causes problems such as reflections inside the PBC module and the extinction ratio of the PM fiber. Furthermore, using a 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 multipoint vibration measurement device 100A, by providing the optical multiplexing / demultiplexing head 130A with a projection optical system 133A incorporating a 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, thereby resolving these problems.

[0125] In the projection optical system 133A incorporating a Wollaston prism type coupling optical element provided in the optical multiplexing / demultiplexing head 130A, a directional coupling loss from Port 1 to Port 2 of 80 dB to 90 dB was actually measured.

[0126] Then, in the optical multiplexing element 131B of the optical multiplexing / demultiplexing optical system 131, 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 133B. Ｓ The frequency components of the optical comb are multiplexed, and the measurement light L is composed of reflected light of the frequency components of the optical comb reflected at multiple points on the measurement surface 5. Ｓ ' is a signal transmitted from the optical multiplexing element 131B to the optical fiber FB ３２ via the optical coupler OC of the interference optical system 120 Ｃ is entered into

[0127] 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 is inputted via the second optical comb generator (COMB2) 1B of the light source 110 through the optical fiber FB １２Ｂ via the optical coupler OC Ｂ Reference light L input to Ｒ Optical fiber FB ２Ｂ1 and the measurement light L Ｓ ' and the reference light L Ｒ The optical coupler OC of the interference optical system 120 outputs the interference light with the optical coupler OC as the 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 the optical coupler OC Ａ The measurement light L input to Ｓ Optical fiber FB ２Ａ２ and is inputted via the second optical comb generator (COMB2) 1B of the light source 110 through the optical fiber FB １２Ｂ via the optical coupler OC Ｂ Reference light L input to Ｒ Optical fiber FB ２Ｂ２ and the measurement light L Ｓ and reference light L Ｒ The interference light with the reference light is output as reference interference light.

[0128] 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 FB externally connected to ２６Ａ１ , F.B. ２６Ａ２ The measurement interference light detector 6A receives the measurement interference light via the Ｓ and outputs the signal from the optical coupler OC of the interference optical system 120. Ｄ Two optical fibers FB externally connected to ２６Ｂ１ , F.B. ２６Ｂ２ The reference interference light is detected by an interference light detector 6B that receives the reference interference light via the Ｒ Output.

[0129] Then, in the signal processing section 150, the measurement interference signal S obtained in the interference light detection section 140 is Ｓ and the reference interference signal S Ｒ The phase of each frequency component of the optical comb is calculated by DFT analysis, and the phase difference for each frequency component 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.

[0130] In this multipoint vibration measuring device 100A, 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 Ｓ and 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 splitter element 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.

[0131] The signal processing unit 150 then processes the measurement interference signal S obtained by the interference light detection unit 140. Ｓ and the reference interference signal S Ｒ The phase of each frequency component of the optical comb is calculated by DFT analysis, and the 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.

[0132] Next, FIG. 9 is a schematic diagram showing the configuration of a multi-point vibration measuring device 100B equipped with a projection optical system 133B incorporating a coupling optical element, which uses a coupling optical element array consisting of a plurality of (m×n) projection optical elements arranged two-dimensionally, in an optical multiplexing / demultiplexing head 130B.

[0133] In this multipoint vibration measuring apparatus 100B, the projection optical system 133A in the multipoint vibration measuring apparatus 100A is replaced with a projection optical system 133B incorporating a coupling optical element. Ａ１ , 44 Ａ２ , 44 Ａ３ , ..., 44 Ａｎ , ｎ ..., 44 Ａｍｎ a coupling optical element array 44 in which the above-mentioned components are modularized, and a condenser lens 4A of the projection optical system 4. １ , 4A ２ , 4A ３ , ..., 4A ｎ , 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 4B of the projection optical system 4. １ , 4B ２ , 4B ３ , ..., 4B ｎ , . . . is provided with a projection optical system 133B incorporating a coupling optical element, which is made up of one quarter-wave plate 4B. ａｂis 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. For large targets, a telecentric optical system may be used on only one side and an fθ optical system on the other side. It is also possible not to use a telecentric optical system, and select an optical system that suits the size and shape of the target.

[0134] In this multipoint vibration measuring apparatus 100B, the same components as those in the multipoint vibration measuring apparatus 100A are given the same reference numerals in the drawings, and detailed description thereof will be omitted.

[0135] Figures 10A and 10B are diagrams showing an example of the configuration of the above-mentioned coupling optical element array 44, where (A) is a longitudinal cross-sectional view of the coupling optical element array 44 seen from the side, and (B) is a longitudinal cross-sectional view of the coupling optical element array 44 seen from the front.

[0136] As shown in FIGS. 10A and 10B, the projection optical system 133B includes a plurality of (m×n) coupling optical elements 44 Ａ１ , 44 Ａ２ , 44 Ａ３ , ..., 44 Ａｎ , . . . are arranged two-dimensionally to form a modular coupling optical element array 44.

[0137] 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 is a coupling optical element 4C using a birefringent crystal to separate light beams by utilizing the walk-off. ２ a coupling optical element 4C consisting of a Wollaston prism or the like ２ ' is used, and the optical fiber on the input side and the optical fiber on the output side are led out from each of the two-core capillaries.

[0138] In this coupling optical element array 44, the input side FB ３４１ , F.B.３４２ , F.B. ３４３ , ..., FB ３４ｎ , ... and the output optical fiber FB ４３１ , F.B. ４３２ , F.B. ４３３ , ..., FB ４３ｎ , ... are each led out to the outside from a two-core capillary, but it is also possible to adopt a structure in which a plurality of optical fibers are precisely positioned and the direction of the PMF can be controlled, such as a structure in which a plurality of optical fibers are led out to the outside through a plurality of insertion holes provided in a substrate, without using a two-core capillary.

[0139] In addition, in the projection optical system 133B 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 , . . . are arranged two-dimensionally to form a modular coupling optical element array 44. However, depending on the object to be measured, multiple coupling optical elements 44 may be used. Ａ１ , 44 Ａ２ , 44 Ａ３ , ..., 44 Ａｎ , . . . may be arranged two-dimensionally in a fine lattice pattern (for example, a hexagonal fine lattice pattern) to form a modular coupling optical element array.

[0140] The modularized plurality of coupling optical elements 44 Ａ１ , 44 Ａ２ , 44 Ａ３ , ..., 44 Ａｎ , ... are a plurality of optical fibers FB ３４１ , F.B. ３４２ , F.B. ３４３ , ..., FB ３４ｎ , . . . and are connected to the optical demultiplexing element 131A of the optical demultiplexing / multiplexing optical system 131, and are connected to a plurality of (m×n) optical fibers FB ４３１ , F.B. ４３２ , F.B. ４３３ , ..., FB ４３ｎ , . . . are connected to the optical multiplexing element 131B of the optical multiplexing / demultiplexing optical system 131.

[0141] The projection optical system 133B with built-in coupling optical element in this multipoint vibration measuring device 100B employs a modularized coupling optical element array 44, and thereby transmits a plurality of optical fibers FB from the optical branching element 131A of the optical branching / multiplexing optical system 131. ３４１ , F.B. ３４２ , F.B. ３４３ , ..., FB ３４ｎ , . . . are input to the focusing optical element 4A. ａ , 4A ｂ A set of optical systems 4A consisting of ａｂ The light can be condensed by the condenser 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.

[0142] The reflected light reflected at a plurality of points on the measurement surface 5 is converted into frequency components of a polarization plane orthogonal to the polarization direction of the frequency components of the irradiated optical comb via the quarter-wave plate 4B, and is then input to the set of optical systems 4A. ａｂ and the light is collected by the coupling optical element array 44 and transmitted to a plurality of optical fibers FB. ４３１ , F.B. ４３２ , F.B. ４３３ , ..., FB ４３ｎ , . . . and are input to the optical multiplexing element 131B of the optical multiplexing / demultiplexing optical system 131.

[0143] In the optical multiplexing element 131B of the optical multiplexing / demultiplexing optical system 131, 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 133B. Ｓ The frequency components of the optical comb are multiplexed, and the measurement light L is composed of reflected light of the frequency components of the optical comb reflected at multiple points on the measurement surface 5. Ｓ ' is a signal transmitted from the optical multiplexing element 131B to the optical fiber FB ３２ via the optical coupler OC of the interference optical system 120 Ｃ is entered into

[0144] In the interference optical system 120, the measurement light L consisting of reflected light of each frequency component of the optical comb reflected at a plurality of points on the measurement surface 5 is Ｓ ' and the second optical comb generator (COMB2) 1B of the light source 110 is connected to the optical fiber FB１２Ｂ via the optical coupler OC Ｂ Reference light L input to Ｒ The interference light with this is used as the measurement interference light through the optical coupler OC. Ｃ and the first optical comb generator (COMB1) 1A of the light source 110 is outputted from the optical fiber FB １２Ａ via the optical coupler OC Ａ The measurement light L input to Ｓ and the above optical coupler OC Ｂ The reference light L input to Ｒ The interference light with the optical coupler OC is used as a reference interference light. Ｄ Output from

[0145] 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 FB externally connected to ２６Ａ１ , F.B. ２６Ａ２ The measurement interference light detector 6A receives the measurement interference light via the Ｓ and outputs the signal from the optical coupler OC of the interference optical system 120. Ｄ Two optical fibers FB externally connected to ２６Ｂ１ , F.B. ２６Ｂ２ The reference interference light is detected by an interference light detector 6B that receives the reference interference light via the Ｒ Output.

[0146] Then, in the signal processing section 150, the measurement interference signal S obtained in the interference light detection section 140 is Ｓ and the reference interference signal S Ｒ The phase of each frequency component of the optical comb is calculated by DFT analysis, and the phase difference for each frequency component 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.

[0147] In this multipoint vibration measuring device 100B, the measurement light L ＳThe 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 Ｓ and the measurement light L, which is provided with the optical multiplexing element 131B that multiplexes the reflected light of each frequency component reflected at a plurality of 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 splitter element 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.

[0148] Here, in the interference optical system 120 of the multipoint vibration measuring apparatus 100, 100A, and 100B, the measurement light L output from the light source 110 Ｓ and reference light L Ｒ The interference light L is output as reference interference light, and the measurement light L output from the light source 110 is Ｓ is irradiated onto the measurement surface 5 of the measurement object through the optical multiplexing and demultiplexing heads 130, 130A, and 130B from the interference optical system 120, and is reflected by the measurement surface 5 and returned via the optical multiplexing and demultiplexing heads 130, 130A, and 130B. Ｓ ' and the 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 The reference interference light is detected by the interference light detector 6B and converted into an electric signal to obtain a reference interference signal S Ｒ I try to get it.

[0149] In the multipoint vibration measuring devices 100, 100A, and 100B, 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 ＲThe phase of each frequency component of the optical comb is calculated by DFT 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 light 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 of each frequency component of the optical comb using only DFT analysis, 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.

[0150] That is, the multipoint vibration measuring devices 100, 100A, and 100B include an interference optical system 120′ that outputs only interference light for measurement, an interference light detecting unit 140′ that receives only interference light for measurement, and a measurement interference signal S obtained by the interference light detecting unit 140′, as in the multipoint vibration measuring device 100′ shown in FIG. 11, the multipoint vibration measuring device 100A′ shown in FIG. 12, and the multipoint vibration measuring device 100B′ shown in FIG. Ｓ The signal processing unit 150′ can be provided with a signal processing unit 150′ that calculates the phase of each frequency component of the optical comb using DFT analysis only 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.

[0151] In the multipoint vibration measuring devices 100', 100A', and 100B', the same components as those in the multipoint vibration measuring devices 100, 100A, and 100B are given the same reference numerals in the drawings, and detailed description thereof will be omitted.

[0152] 1,110 Light source, 1A First optical comb generator (COMB1), 1B Second optical comb generator (COMB1), 2,120,120' Interference optical system, 3 Optical multiplexer / demultiplexer element, 4 Projection optical system, 4A ａ , 4A ｂ Condensing optical element, 4A ａｂ Complete optical system, 4 Ａ１ , 4 Ａ２ , 4 Ａ３, ..., 4 Ａｎ , ..., 4A condenser lens, 4 Ｂ１ , 4 Ｂ２ , 4 Ｂ３ , ..., 4 Ｂｎ ,...,4B 1 / 4 wavelength plate, 4C Ａ , 4C Ｂ Coupling optics, 4C １ 2-core capillary, 4C ２ , 4C ２ ' Coupling optics, 4C ａ , 4C ｃ Collimator lens, 4C ｂ Wollaston prism, 5 Measurement surface, 6, 140, 140' Interference light detection unit, 6A Interference light detector, 6B Reference light detector, 7, 150, 150' Signal processing unit, 10, 100, 100', 100A, 100A', 100B, 100B' Multi-point vibration measuring device, 44 １ , 44 ２ , 44 ３ , ..., 44 ｎ , 44A, 44B Projection optical element, 130A, 130B Optical demultiplexing / combining head, 131 Optical demultiplexing / combining optical system, 131A Optical demultiplexing element, 131B Optical multiplexing element, 132 Coupling optical system, 133, 133A, 133A Projection optical system, FB １２Ａ , FB １２Ｂ , FB ２Ａ１ , FB ２Ａ２ , FB ２Ｂ１ , FB ２Ｂ２ , FB ２Ｃ , FB ２３ , FB ３２ , FB ３４１ , FB ３４２ , FB ３４３ , ...FB ３４ｎ , ..., FB ２６Ａ１ , FB ２６Ａ２ , FB ４３１ , FB ４３２ , FB ４３３ , ..., FB ４３ｎ , ... Optical fiber, FB ２Ｂ１ ' Delay fiber, FB ３４ Input optical fiber, FB ４３ Output optical fiber, OC Ａ , O.C. Ｂ , O.C. Ｃ, O.C. Ｄ , O.C. Ｅ , O.C. Ｃ１ , O.C. Ｃ２ , O.C. 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 and reference light with a spectrum of a predetermined frequency interval and having interference; an optical multiplexer / demultiplexer head that divides the measurement light output from the light source into each frequency component and irradiates a plurality of points on a measurement surface of a measurement target as each frequency component; an interference optical system that receives the measurement light and the reference light output from the light source, inputs the measurement light input from the light source to the optical multiplexer / demultiplexer head, and interferes the measurement light including each frequency component reflected by the measurement surface and returned through the optical multiplexer / demultiplexer head with the reference light output from the light source to output measurement interference light; a measurement photodetector that receives the measurement interference light obtained by the interference optical system and converts it into an electrical signal to obtain a measurement interference signal; and a signal processing unit that analyzes vibration information at a plurality of points on the measurement surface based on the measurement interference signal obtained by the measurement photodetector. The optical multiplexer / demultiplexer head includes an optical demultiplexing element that demultiplexes each frequency component included in the measurement light input from the interference optical system, a projection optical system that irradiates each frequency component demultiplexed by the optical demultiplexing element to a plurality of points on a measurement surface of a measurement target, a multiplexing optical element that multiplexes each frequency component of the measurement light reflected by the measurement surface and returned and inputs it to the interference optical system, and a coupling optical system that inputs each frequency component included in the measurement light demultiplexed by the optical demultiplexing element to the projection optical system and inputs each frequency component of the measurement light reflected by the measurement surface and returned to the multiplexing optical element. The multi-point vibration measurement device is characterized by this.

2. The interference optical system outputs the measurement interference light, and interferes the measurement light and the reference light input from the light source to output reference interference light. The interference optical system includes a reference photodetector that receives the reference interference light obtained by the interference optical system and converts it into an electrical signal to obtain a reference interference signal. The signal processing unit analyzes vibration information at a plurality of points on the measurement surface based on the measurement interference signal obtained by the measurement photodetector and the reference interference signal obtained by the reference photodetector. The multi-point vibration measurement device according to claim 1 is characterized by this.

3. The multiplexer / demultiplexer head splits each frequency component included in the measurement light into individual frequency components one by one by the optical demultiplexing element, irradiates a plurality of points on the measurement surface of the measurement target through the projection optical system, and multiplexes each frequency component of each frequency component of the measurement light reflected and returned from the measurement surface by the multiplexing element. The multi-point vibration measurement device according to claim 1 or claim 2, characterized in that.

4. The multiplexer / demultiplexer head splits each frequency component included in the measurement light into a plurality of frequency components by the optical demultiplexing element, irradiates a plurality of points on the measurement surface of the measurement target through the projection optical system, and multiplexes each frequency component of each of the plurality of frequency components of the measurement light reflected and returned from the measurement surface by the multiplexing element. The multi-point vibration measurement device according to claim 1 or claim 2, characterized in that.

5. The multi-point vibration measurement device according to claim 1 or claim 2, characterized in that the coupling optical system is incorporated in the projection optical system.

6. The optical demultiplexing element splits each frequency component included in the measurement light input from the interference optical system through one optical fiber and outputs it through a plurality of optical fibers. The multiplexing element multiplexes each frequency component input through a plurality of optical fibers and outputs it through one optical fiber. The coupling optical system includes a coupling optical element that aligns the optical axes of two light beams with orthogonal polarization directions output from two optical fibers. The multi-point vibration measurement device according to claim 5, characterized in that.

7. The multi-point vibration measurement device according to claim 6, characterized in that the coupling optical element is made of a birefringent crystal.

8. The multi-point vibration measurement device according to claim 6, characterized in that the coupling optical element is a Wollaston prism.

9. The coupling optical system is composed of an array of coupling optical elements in which the coupling optical elements are arranged two-dimensionally. Each frequency component of the measurement light input through the array of coupling optical elements is condensed by a condensing optical element and output toward the measurement surface of the measurement target. At the same time, each frequency component of the measurement light reflected and returned from the measurement surface is condensed by the condensing optical element and input to the array of coupling optical elements. The multi-point vibration measurement device according to claim 6, characterized in that.

10. Before the measurement light and the reference light output from the light source are reflected by the measurement surface and return through the coupling optical system, and the measurement light and the reference light including each frequency component are interfered in the interference optical system to be output as measurement interference light, a delay optical system is provided in the optical path through which the reference light passes so that the optical path length of the optical path through which the measurement light and the measurement light including each frequency component reflected by the measurement surface pass is made equal to the optical path length of the optical path through which the reference light passes. The multi-point vibration measurement device according to claim 1 or claim 2, characterized in that.

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