Sensitivity enhancement in laser ultrasonics using a versatile laser array system
- Argonne National Laboratories, 9700 Cass Avenue, Bldg. 212, Argonne, Illinois 60439 (United States)
- Center for Nondestructive Evaluation, The Johns Hopkins University, Baltimore, Maryland 21218 (United States)
- Analytic Services and Materials, Inc., 107 Research Drive, Hampton, Virginia 23666 (United States)
Past investigators have predicted and, in limited cases, demonstrated the potential utility of using temporally and spatially modulated laser array sources as a means of increasing the signal-to-noise ratio in laser ultrasonic systems without causing the surface damage characteristic of a single high-power laser point source. In an effort to develop a practical and flexible laser array source, a laser system has been designed and implemented which uses a single Nd:YAG pulsed laser and an optical delay system in which the laser pulse passes repetitively through a White cell cavity being sampled by a custom beamsplitter after each pass. Up to ten spatially separated light beams exit from the system each time a single laser pulse is introduced. Time separation between the distinct pulses can be adjusted over a range from 28 to 170 ns, corresponding to a pulse repetition rate from 6 to 36 MHz. Since individual control of the beam paths is possible, one has the flexibility to implement either a single-element, temporally modulated array, or a multielement, phased'' array. From a single point, a multiple spike narrow-band acoustic signal is generated, permitting greater detection sensitivity than can be obtained with broadband detection of a single spike. Alternatively, multielement arrays can be used to increase the acoustic signal amplitude by superposition of the signals generated from each individual element, once again enhancing detection sensitivity.
- OSTI ID:
- 7071889
- Journal Information:
- Journal of the Acoustical Society of America; (United States), Vol. 97:1; ISSN 0001-4966
- Country of Publication:
- United States
- Language:
- English
Similar Records
Laser Wakefield Acceleration Driven by a CO2 Laser (STELLA-LW) - Final Report
R&D for a Soft X-Ray Free Electron Laser Facility