# US 2021/0239458 A1 · Displacement amount measuring device, displacement amount measuring method, and recording medium > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0239458 A1 - Document ID: US20210239458A1 - Status: Published application - Kind: A1 - Application number: 16/972,279 - Filed: 2019-06-03 - Published: 2021-08-05 - Earliest claimed: 2018-06-05 - Assignees: NEC Corporation - Applicants: NEC Corporation - Inventors: Hiroshi IMAI - Web page: https://patentgrep.com/patent/US20210239458A1 ## CPC - G01B 11/16: for measuring the deformation in a solid, e.g. optical strain gauge - G06T 7/571: from focus - G01B 11/026: {by measuring distance between sensor and object (G01B11/0608 takes precedence)} - G01M 5/0008: {of bridges} - G01M 5/0033: {by determining damage, crack or wear} - G02B 17/08: Catadioptric systems {(used in non-imaging applications G02B19/00)} - G06T 7/0002: {Inspection of images, e.g. flaw detection} - G06T 7/50: Depth or shape recovery - G06T 7/70: Determining position or orientation of objects or cameras (camera calibration G06T7/80) - G06T 2207/10016: Video; Image sequence - G06T 2207/20076: Probabilistic image processing - G06T 2207/30132: Masonry; Concrete - G06T 2207/30184: Infrastructure - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL - G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract The objective of the present invention is to detect defects in a structure accurately in a non-contact manner. An optical path length converting unit (320) is disposed between a specimen being inspected and an image capturing element (310) in such a way as to cover part of a field of view of the image capturing element (310). An image analyzing unit (330) uses images captured by the image capturing element (310) to calculate amounts of displacement within the surface of the specimen, obtained using two fields of view of the image capturing element (310) not covered/covered by the optical path length converting unit (320). An out-of-plane displacement calculating unit (340) calculates an out-of-plane displacement of the specimen on the basis of the calculated amounts of displacement. ## Claims ### Claim 1 A displacement amount measuring device comprising: an image capturing element configured to capture an image of a surface of a specimen; optical path length converting material being disposed between the specimen and the image capturing element in such a way as to cover a part of a field of view of the image capturing element; an image analyzer configured to calculate a first displacement amount in the surface of the specimen obtained in a field of view of the image capturing element that is not covered by the optical path length converting material and a second displacement amount in the surface of the specimen obtained in a field of view of the image capturing element, by using the image captured by the image capturing element; and an out-of-plane displacement calculator configured to calculate a distance from the specimen to the image capturing element and an out-of-plane displacement of the specimen based on the first displacement amount and the second displacement amount. ### Claim 2 (depends on 1) The displacement amount measuring device according to claim 1, wherein the optical path length converting material includes a transparent material having a refractive index larger than one. ### Claim 3 (depends on 1) The displacement amount measuring device according to claim 1, wherein the optical path length converting material has a shape of a flat plate parallel to an imaging surface of the image capturing element. ### Claim 4 (depends on 1) The displacement amount measuring device according to claim 1, further comprising: an in-plane displacement calculator configured to calculate an in-plane displacement of the specimen based on the first displacement amount and the second displacement amount and the out-of-plane displacement. ### Claim 5 (depends on 4) The displacement amount measuring device according to claim 4, further comprising: a memory storing a program; and at least one processor configured to run the program to perform: determining a state of the specimen based on a displacement of the distance and the out-of-plane displacement and the in-plane displacement. ### Claim 6 (depends on 5) The displacement amount measuring device according to claim 5, wherein the at least one processor is configured to run the program to perform: determining whether the specimen is sound or has a defect based on a characteristic pattern of an impulse response. ### Claim 7 A displacement amount measuring method performed by using a device including an image capturing element that captures an image of a surface of a specimen and optical path length converting material being disposed between the specimen and the image capturing element in such a way as to cover a part of a field of view of the image capturing element, the displacement amount measuring method comprising: calculating a first displacement amount in the surface of the specimen obtained in a field of view of the image capturing element that is not covered by the optical path length converting material and a second displacement amount in the surface of the specimen obtained in a field of view of the image capturing element covered by the optical path length converting material, by using the image captured by the image capturing element; and calculating a distance from the specimen to the image capturing element and an out-of-plane displacement of the specimen based on the first displacement amount and the second displacement amount. ### Claim 8 A non-transitory recording medium that stores a program for causing a computer to execute processing, the processing comprising: by using a device including an image capturing element that captures an image of a surface of a specimen and optical path length converting material being disposed between the specimen and the image capturing element in such a way as to cover a part of a field of view of the image capturing element, calculating a first displacement amount in the surface of the specimen obtained in a field of view of the image capturing element that is not covered by the optical path length converting material and a second displacement amount in the surface of the specimen obtained in a field of view of the image capturing element covered by the optical path length converting material, by using the image captured by the image capturing element; and calculating a distance from the specimen to the image capturing element and an out-of-plane displacement of the specimen based on the first displacement amount and the second displacement amount.