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Proceedings Paper

Imaging through turbulence with the volume-holographic confocal microscope
Author(s): Michal Balberg; George Barbastathis; David J. Brady
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Paper Abstract

The confocal microscope with volume-holographic collector [1] utilizes Bragg selectivity in order to achieve depth sectioning. The volume hologram is recorded by the interference of two beams, one of which originates as a point source at a reference depth. When a reconstructing Qrobe) source is at the reference depth, it is Bragg-matched and causes a strong diffracted signal; sources at different depths are rejected because of Bragg mismatch. Therefore, the use of a pinhole in front of the detector (as in traditional confocal microscopes [2]) is not required. The arguments for use of a volume hologram instead of a pinhole to achieve depth sectioning are: (i) the depth resolution of the microscope is independent of its photon-collection performance; (ii) the hologram phase conjugates aberrations and other systematic phase distortions, and hence acts as an ideal matched filter to the reference source (unlike the ad hoc filtering function performed by the pinhole). In this paper we focus on the depth-resolving properties of volume diffraction when a turbulent (scattering) medium, emulating a biological tissue, is present in the path of the light entering the microscope. In particular, we compare the depth resolution of a microscope recorded with and without precompensation for the presence of the scatterer. Precompensation extends the matched filtering principle by use of a priori information (the thickness of the turbulent medium) during the recording phase of the hologram. Our experimental results (section 2) demonstrate that precompensation increases the scatterer thickness over which confocal imaging is possible.

Paper Details

Date Published: 15 December 2000
PDF: 2 pages
Proc. SPIE 4087, Applications of Photonic Technology 4, (15 December 2000); doi: 10.1117/12.406352
Show Author Affiliations
Michal Balberg, Univ. of Illinois/Urbana-Champaign (United States)
George Barbastathis, Massachusetts Institute of Technology (United States)
David J. Brady, Univ. of Illinois/Urbana-Champaign (United States)

Published in SPIE Proceedings Vol. 4087:
Applications of Photonic Technology 4
Roger A. Lessard; George A. Lampropoulos, Editor(s)

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