Multi-point vibration measurement system

Abstract

This technology solves the problem of electrical crosstalk, where the shifted portions of adjacent frequencies overlap in the electrical signal domain, causing measurement errors, and enables high-precision (high S / N) simultaneous multi-point measurement. [Solution] The optical path is configured to separate the optical path through which the measurement light output from the interference optical system 120, which is equipped with an optical demultiplexing element 130A of the optical demultiplexing optical system 130 that demultiplexes multiple frequency components of an optical comb contained in the measurement light, passes, and the optical path that inputs the measurement reflected light, which is equipped with an optical multiplexing element 130B that combines the demultiplexed measurement light of the frequency components reflected at n measurement points S1, S2, ..., Sn on the measurement surface 5 of the object to be measured, into the interference optical system 120. In addition, a connector section 131 is provided in the measurement light transmission path 134 that connects the optical demultiplexing optical system 130 and the projection optical system 4, and functions as a measurement light transmission path selection means that changes the connection relationship between the optical demultiplexing optical system 130 and the projection optical system 4 by selective channel blocking.

Claims

1. A light source that outputs coherent measurement light and reference light, having a spectrum with multiple modes in the shape of an optical comb at predetermined frequency intervals, An interference optical system receives measurement light and reference light output from the above light source, as well as measurement reflected light that is returned when the measurement light irradiated onto the measurement surface of the object to be measured is reflected by the measurement surface, and outputs measurement interference light by interfering the above reference light and the above measurement reflected light. The optical optical splitter and multiplexer optical system receives the measurement light output from the above light source via the above interference optical system, splits the measurement light into multiple delimited measurement light of one or more mode orders of the optical comb and outputs them to multiple channel measurement light transmission lines, and receives the multiple delimited measurement light reflected back from the multiple measurement points of the measurement surface of the object to be measured via multiple channel measurement light transmission lines, and combines the multiple delimited measurement light reflected light and inputs it to the above interference optical system as the measurement reflected light. Multiple single-point irradiation heads that receive the multiple delimited measurement lights separated by the above optical splitter / multiplexer optical system via the multiple-channel measurement light transmission path, assign and irradiate multiple measurement points on the measurement surface of the object to be measured with the delimited measurement lights, and input the multiple delimited measurement reflected lights that are reflected back from the multiple measurement points on the measurement surface to the above optical splitter / multiplexer optical system via the multiple-channel measurement light transmission path, The above-mentioned optical splitter and multiplexer optical system and the above-mentioned multiple optical fiber cables connecting the multiple single-point irradiation heads comprise the above-mentioned multi-channel measurement optical transmission path, A measurement optical transmission path selection means for changing the connection relationship between the optical splitter / multiplexer optical system and the multiple single-point irradiation heads connected via the above-mentioned multiple-channel measurement optical transmission path, A measuring interference photodetector that receives the measuring interference light obtained by the above interference optical system and converts it into an electrical signal to obtain a measuring interference signal, A signal processing unit analyzes the vibration information of the measurement surface based on the interference signal obtained by the above-mentioned interference photodetector. Equipped with, A multi-point vibration measurement system characterized by using the above-described measurement optical transmission path selection means to change the connection relationship between the optical dispersive and multiplexing optical system and the plurality of single-point irradiation heads connected via the plurality of measurement optical transmission paths by selective channel blocking, thereby performing multi-point vibration measurement with a plurality of demultiplexed measurement lights obtained by decimating the comb modes of frequency components that are more than one mode order apart of the optical comb.

2. The multipoint vibration measurement system according to claim 1, characterized in that the optical splitter / multiplexer optical system splits the measurement light into multiple delimited measurement lights of frequency components for at least one mode order of the optical comb and outputs them via a multi-channel measurement light transmission path, and combines the multiple delimited measurement reflected lights input via the multi-channel measurement light transmission path and inputs them to the interference optical system as the measurement reflected light.

3. The multi-point vibration measurement system according to claim 2, wherein the measurement optical transmission path selection means comprises a detachable mechanism provided at one end of each of the plurality of optical fiber cables constituting the plurality of channel measurement optical transmission paths, and the detachable mechanism provided at least at one end switches the connection of the plurality of optical fiber cables, thereby allowing the connection relationship between the optical dispersive wave optical system connected via the plurality of channel measurement optical transmission paths and the plurality of single-point irradiation heads to be changed by selective channel blocking.

4. The multi-point vibration measurement system according to claim 2, characterized in that the measurement optical transmission path selection means allows for selective channel blocking of the connection relationship between the optical dispersive wave optical system connected via the multi-channel measurement optical transmission path and the multi-point irradiation heads by an optical switch mechanism that switches the connections of the multi-channel optical fiber cables constituting the multi-channel measurement optical transmission path.

5. The above optical splitter / multiplexer optical system consists of an optical splitter / multiplexer element that receives measurement light output from the light source via the interference optical system, splits the measurement light into at least one or more frequency components for each mode order, outputs multiple split-measurement lights for each split frequency component from multiple input / output ports, and reflects multiple split-measurement lights for each split frequency component that are irradiated onto multiple measurement points on the measurement surface of the object to be measured. These reflected lights are reflected by the measurement surface, and the returning multiple split-measurement lights for each split frequency component are input to multiple input / output ports. These multiple split-measurement lights for each split frequency component are combined and input to the interference optical system as the measurement reflected light. The multi-point vibration measurement system according to any one of claims 1 to 4, characterized in that the multiple input and output ports of the above-mentioned optical splitter / multiplexer are connected to the multiple-channel measurement optical transmission paths via the above-mentioned measurement optical transmission path selection means.

6. The above-mentioned multi-channel measurement optical transmission path comprises a first multi-channel measurement optical transmission path and a second multi-channel measurement optical transmission path. The above optical demultiplexing and multiplexing optical system comprises an optical demultiplexing element that receives measurement light output from the above light source via the above interference optical system, demultiplexes the frequency components contained in the measurement light, and outputs multiple demultiplexed measurement lights for each demultiplexed frequency component from multiple output ports via the first multi-channel measurement optical transmission path, and an optical multiplexing element that irradiates multiple measurement points on the measurement surface of the object to be measured with the multiple demultiplexed measurement lights for each demultiplexed frequency component demultiplexed by the optical demultiplexing element, and inputs the multiple demultiplexed measurement reflected lights for each demultiplexed frequency component that are reflected back by the measurement surface to multiple input ports via the second multi-channel measurement optical transmission path, and combines the multiple demultiplexed measurement reflected lights for each demultiplexed frequency component and inputs them to the above interference optical system as the measurement reflected light. A multi-point vibration measurement system according to any one of claims 1 to 4, characterized in that a coupling optical system comprising a plurality of coupling optical elements is provided, wherein a plurality of delimited measurement lights for each of the delimited frequency components delimited by the optical demultiplexing element of the optical splitter / multiplexer optical system are input via the first plurality of channels of measurement light transmission paths, delimited measurement lights are output via the plurality of single-point irradiation heads to irradiate a plurality of measurement points on the measurement surface of an object to be measured, and delimited measurement reflected light reflected by the plurality of measurement points on the measurement surface and returned via the plurality of single-point irradiation heads is input to the optical multiplexing element of the optical splitter / multiplexer optical system via the second plurality of channels of measurement light transmission paths.

7. The multi-point vibration measurement system according to claim 6, characterized in that the above-mentioned multiple single-point irradiation heads each consist of a projection optical system that incorporates the above-mentioned multiple coupled optical elements of the coupled optical system.

8. The above optical demultiplexing optical system includes an optical demultiplexing element that demultiplexes measurement light input from the above interference optical system via a single optical fiber cable and outputs multiple demultiplexed measurement lights via multiple optical fiber cables constituting the first multi-channel measurement light transmission path, and an optical multiplexing element that combines multiple demultiplexed measurement reflected lights input via multiple optical fiber cables constituting the second multi-channel measurement light transmission path and outputs them via a single optical fiber cable. The multi-point vibration measurement system according to claim 7, characterized in that the projection optical system of the above-mentioned plurality of single-point irradiation heads incorporates the coupling optical element that aligns the two optical axes of the demultiplexed measurement light and the demultiplexed measurement reflected light, which have mutually orthogonal polarization directions and pass through two optical fiber cables, on the measurement surface side.

9. The multi-point vibration measurement system according to claim 8, characterized in that the above-mentioned coupled optical element is made of a birefringent crystal.

10. The multi-point vibration measurement system according to claim 8, characterized in that the above-mentioned coupled optical element consists of a Wollaston prism.

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