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SENSORS

In-line digital holographic sensor for monitoring and characterizing marine particulates

[+] Author Affiliations
Robert B. Owen

Owen Research, Inc., 2525 Arapahoe Avenue, Bldg. E4/#262, Boulder, Colorado?80302-6720

Alex A. Zozulya

Worcester Polytechnic Institute, Department of Physics, 100 Institute Road, Worcester, Massachusetts?01609-2280

Opt. Eng. 39(8), 2187-2197 (Aug 01, 2000). doi:10.1117/1.1305542
History: Received Oct. 25, 1999; Revised Feb. 10, 2000; Accepted Feb. 10, 2000
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Abstract

We report an in-line digital holographic sensor (DHS) for monitoring and characterizing marine particulates. This system images individual particles over a deep depth of field (>25 cm) with a resolution of 5 μm. The DHS projects a collimated beam through the water column and onto a lensless CCD array. Some light is diffracted by particulates and forms an object beam; the undeflected remainder constitutes the reference beam. The two beams combine at the CCD array and create an in-line hologram, which is then numerically reconstructed. The DHS eliminates many problems traditionally associated with holography. The CCD recording material considerably lowers the exposure time and eliminates most vibration problems. The laser power needs are low; the DHS uses a small 10-mW diode laser. Rapid numerical reconstruction eliminates photographic processing and optical reconstruction. We successfully operated the DHS underwater on a remotely operated vehicle; our test results include tracing a single particle from one hologram to the next, thus deriving a velocity vector for marine mass transport. We outline our digital holographic reconstruction procedure, and present our graphical user interface and user software tools. The DHS is particularly useful for providing in situ ground-truth measurements for environmental remote sensing. © 2000 Society of Photo-Optical Instrumentation Engineers.

© 2000 Society of Photo-Optical Instrumentation Engineers

Topics

Holography ; Sensors

Citation

Robert B. Owen and Alex A. Zozulya
"In-line digital holographic sensor for monitoring and characterizing marine particulates", Opt. Eng. 39(8), 2187-2197 (Aug 01, 2000). ; http://dx.doi.org/10.1117/1.1305542


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