Three-dimensional microscopy using a diffraction grating primary objective

Thomas D. Ditto

doi:10.1117/12.567598

9 December 2004 Three-dimensional microscopy using a diffraction grating primary objective

Thomas D. Ditto

Proceedings Volume 5578, Photonics North 2004: Photonic Applications in Astronomy, Biomedicine, Imaging, Materials Processing, and Education; (2004) https://doi.org/10.1117/12.567598
Event: Photonics North, 2004, Ottawa, Ontario, Canada

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.

Citation Download Citation

Thomas D. Ditto "Three-dimensional microscopy using a diffraction grating primary objective", Proc. SPIE 5578, Photonics North 2004: Photonic Applications in Astronomy, Biomedicine, Imaging, Materials Processing, and Education, (9 December 2004); https://doi.org/10.1117/12.567598

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