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Proceedings Paper

Three-dimensional microscopy using a diffraction grating primary objective
Author(s): Thomas D. Ditto
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Paper Abstract

Three-dimensional magnification of a diffusing surface can be achieved using profilometry based on holographic chirped frequency gratings and laser line projection. The recently patented method being investigated both supplants earlier 3-D microscopy methods using diffraction range finders [Thomas D. DeWitt and Douglas A. Lyon, Three-dimensional microscope using diffraction gratings, Three-Dimensional and Unconventional Imaging for Industrial Inspection and Metrology, SPIE, Vol. 2599, pp. 228-239] and also competes favorably with extant confocal microscopy in coverage area, speed of acquisition and unit cost. The geometry of grazing incidence in a diffraction range finder shows an intrinsic anamorphic magnification. A narrow waist of input rays is expanded to the full width of the grating itself. The spatial magnification is simply the ratio of the length of the grating to the waist of the input column of rays. As the column of input rays approaches the grating plane, this magnification ratio approaches infinity. We develop a theory that predicts a limit to resolution as a function of illumination wave length and grating pitch of the primary objective. A simple microscope can achieve near micron resolution over several centimeters of depth in the visible light regime. An empirical demonstration is made using silver halide holograms.

Paper Details

Date Published: 9 December 2004
PDF: 12 pages
Proc. SPIE 5578, Photonics North 2004: Photonic Applications in Astronomy, Biomedicine, Imaging, Materials Processing, and Education, (9 December 2004); doi: 10.1117/12.567598
Show Author Affiliations
Thomas D. Ditto, Aspex, Inc. (United States)


Published in SPIE Proceedings Vol. 5578:
Photonics North 2004: Photonic Applications in Astronomy, Biomedicine, Imaging, Materials Processing, and Education
Marc Nantel; Glen Herriot; Graham H. McKinnon; Leonard MacEachern; Robert A. Weersink; Rejean Munger; Andrew Ridsdale, Editor(s)

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