Holographic image of a point source in the presence of misalignment

Abstract

The imaging of a point source by high numerical aperture holograms was studied theoretically and experimentally in the presence of aberrations caused by inaccurate adjustment of the plane reference and plane reconstructing waves or by inaccurate positioning of the hologram. The accuracy requirement is defined by the angular resolution allowed by an aperture equal to the hologram size. Any deviation from this limit leads to deformation of the point transfer function defined by the unavoidable diffraction. For coarse mismatch (>10(-3) rad for the actual case), clearly demonstrable geometrical-type aberrations occur; for smaller angles, appreciable broadening of the diffraction pattern and rapid fall of the Strehl ratio diminish the applicability of the holographic method. The calculations and the photographic and photometric measurements are in good agreement.

Evaluation of the Direct Effect of the Film MTF on the Holographic Image

“…The philosophy of the following calculations is similar to those presented in two earlier papers of the author [10,11] . The calculations are based on the scalar diffraction theory, without any further approximation .…”

“…For the case of the geometry shown in figure 1, the diffraction-limited complex amplitude distribution of the reconstructed image is the following [10] 2 f°2 cos 0 cos p and r l and r 2 are the separations of the source and observation points at the first and the second diffraction . It is assumed that there is no wavelength change at reconstruction .…”

Accurate three-dimensional metrology of underwater objects using replayed real images from in-line and off-axis holograms

“…In-line holograms are comparatively insensitive to small angular misalignment. Banyasz et al [23] analysed the replayed image structure of a point source in a general offaxis geometry. Making reasonable assumptions about the smallness of the angles in a misaligned in-line hologram, and assuming that the recording and replay beams are plane waves of identical wavelength, an estimate of how much misalignment would cause the geometric ray-traced image to be larger than the diffraction-limited resolution spot size can be obtained.…”

Direct measurement of the refractive index profile of phase gratings, recorded in silver halide holographic materials by phase-contrast microscopy

“…14,15 Semiphysically developed phase holograms in Agfa 8E75HD emulsion were also studied by the author using phase-contrast microscopy. 16 The aim of the present work was to measure the ⌬n(E 0 ,V) characteristics of a holographic material, i.e., the dependence of the refractive index modulation of the holographic gratings on bias exposure and fringe visibility for fixed spatial frequency and processing, using phase-contrast microscopy.…”