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Proceedings Paper

All-optical optoacoustic microscopy system based on probe beam deflection technique
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Paper Abstract

It is difficult to achieve sub-micron resolution in backward mode OA microscopy using conventional piezoelectric detectors, because of wavefront distortions caused by components placed in the optical path, between the sample and the objective lens, that are required to separate the acoustic wave from the optical beam. As an alternate approach, an optoacoustic microscope (OAM) was constructed using the probe beam deflection technique (PBDT) to detect laserinduced acoustic signals. The all-optical OAM detects laser-generated pressure waves using a probe beam passing through a coupling medium, such as water, filling the space between the microscope objective lens and sample. The acoustic waves generated in the sample propagate through the coupling medium, causing transient changes in the refractive index that deflect the probe beam. These deflections are measured with a high-speed, balanced photodiode position detector. The deflection amplitude is directly proportional to the magnitude of the acoustic pressure wave, and provides the data required for image reconstruction. The sensitivity of the PBDT detector expressed as noise equivalent pressure was 12 Pa, comparable to that of existing high-performance ultrasound detectors. Because of the unimpeded working distance, a high numerical aperture objective lens, i.e. NA = 1, was employed in the OAM to achieve near diffraction-limited lateral resolution of 0.5 μm at 532nm. The all-optical OAM provides several benefits over current piezoelectric detector-based systems, such as increased lateral and axial resolution, higher sensitivity, robustness, and potentially more compatibility with multimodal instruments.

Paper Details

Date Published: 15 March 2016
PDF: 7 pages
Proc. SPIE 9708, Photons Plus Ultrasound: Imaging and Sensing 2016, 970818 (15 March 2016); doi: 10.1117/12.2217690
Show Author Affiliations
Saher M. Maswadi, Oak Ridge Institute for Science and Education (United States)
Univ. of Texas at San Antonio (United States)
EchoLase, Inc. (United States)
Dmitri Tsyboulskic, TomoWave Labs, Inc. (United States)
Caleb C. Roth, Univ. of Texas Health Science Ctr. at San Antonio (United States)
Randolph D. Glickman, Univ. of Texas Health Science Ctr. at San Antonio (United States)
EchoLase, Inc. (United States)
Hope T. Beier, Air Force Research Lab. (United States)
Alexander A. Oraevsky, TomoWave Labs, Inc. (United States)
Bennett L. Ibey, Air Force Research Lab. (United States)

Published in SPIE Proceedings Vol. 9708:
Photons Plus Ultrasound: Imaging and Sensing 2016
Alexander A. Oraevsky; Lihong V. Wang, Editor(s)

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