Phase measurement accuracy in digital holographic microscopy using a wavelength-stabilized laser diode

Abstract

This work describes the influence of coherent illumination on phase measurement accuracy in digital holographic microscopy (DHM). To improve net phase accuracy in a DHM system, the phase referencing and temporal averaging techniques are applied simultaneously to suppress the phase noises caused by the laser source and image sensor. A comparison between a laser diode operated in single- and multi-modes is given to demonstrate the coherence effect on the fringe visibility and the reconstructed phase accuracy of digital holograms. Axial sub-nanometer accuracy in DHM with the fewest successive hologram recordings is performed using a wavelength-stabilized laser diode in single-mode operation.

Hologram authentication based on a secure watermarking algorithm using cellular automata

“…7. They are produced by an off-axis digital holographic microscope [22] system. The zero-order and conjugate images can be spatially separated and removed by a window function after Fourier analysis.…”

Resolution enhancement of spectrum normalization in synthetic aperture digital holographic microscopy

“…Subsequently, the effect of the number of holograms on the reconstructed phase sensitivity when SA with multiple angles of incidence was applied was examined. In general, increasing the number of holograms retrieved and adding a synthetic spectrum are equivalent to performing a spatial average noise operation, which enhances phase sensitivity [23]. Randomly distributed phase noises were added to the plane waves at varying angles of incidence for assessing the signal and background noise ratio of the reconstructed images in order to determine the phase sensitivity.…”

“…Next, when the objects were scanned using object beams striking from various angles, the scanning angles and spatial bandwidth of each hologram were estimated. The phase sensitivity of each reconstructed image was increased using the phase referencing technique [23]. Finally, holograms captured from various angles underwent superposition to produce the synthetic spectrum.…”

A compact synthetic aperture digital holographic microscope with mechanical movement-free beam scanning and optimized active aberration compensation for isotropic resolution enhancement

“…The synthetic aperture (SA) is achieved by superimposing the holograms of different illumination angles recorded in the spectral domain, so that the spatial frequency coverage can be expanded. The synthesized spectrum can reduce the phase noise of the holographic reconstructed images and enhance its spatial resolution [8][9][10][11], but the number of scans required is relatively large, usually several hundred digital holograms are recorded for enhanced resolutions [12]. Separately, the spectrum swelling during frequency overlapping process brings in distortion.…”