Institute for Laser Technology

Research Project

Project/Area Number	25420495
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Research Field	Structural engineering/Earthquake engineering/Maintenance management engineering
Research Institution	Institute for Laser Technology
Principal Investigator	Kotyaev Oleg 公益財団法人レーザー技術総合研究所, その他部局等, 研究員 (80399352)
Co-Investigator(Renkei-kenkyūsha)	Yoshinori Shimada 公益財団法人レーザー技術総合研究所, レーザー計測研究チーム, 主任研究員 (80250091)
Project Period (FY)	2013-04-01 – 2016-03-31
Project Status	Completed (Fiscal Year 2015)
Budget Amount *help	¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000) Fiscal Year 2015: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000) Fiscal Year 2014: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000) Fiscal Year 2013: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Keywords	laser system / vibration measurement / laser-based system / two-beam probing / nondestructive testing / bridge / remote inspection / highway bridge / laser interferometry / bouncing bridge
Outline of Final Research Achievements	A novel approach of laser-based remote non-destructive inspection of civil structures has been tested. The approach is based on using homodyne interferometry with two-beam probing for minimization of homodyne signal instability caused by irregular bouncing of inspected structure (like highway bridges). Two-beam probing method provides more reliable information of inspected structure conditions than conventional one-beam probing approach. The system was designed, assembled and tested in laboratory. CO2 laser pulses with 4-Joule energy are used for initiation of vibration in inspected object. CW Nd:YVO4 laser with 0.5W output power is used as a source of two probing beams. Defects in the laboratory samples were recognized reliably. The system demonstrated significant benefit over conventional one-beam probing technique. A mobile prototype of the system was assembled and tested in the field conditions. The system demonstrated capability of real defect recognition in highway bridge.