Heterodyne Holography with full control of both signal and reference arms

Heterodyne holography is a variant of phase shifting holography in which reference and signal arms are controlled by acousto optic modulators. In this review paper, we will briefy describe the method and its properties, and we will illustrate its advantages in experimental applications

Spatiotemporal heterodyne detection

We describe a scheme into which a camera is turned into an efficient tunable frequency filter of a few Hertz bandwidth in an off-axis, heterodyne optical mixing configuration, enabling to perform parallel, high-resolution coherent spectral imaging. This approach is made possible through the combination of a spatial and temporal modulation of the signal to reject noise contributions. Experimental data obtained with dynamically scattered light by a suspension of particles in brownian motion is interpreted

Phase-resolved heterodyne holographic vibrometry with a strobe local oscillator

We report a demonstration of phase-resolved vibrometry, in which out-of-plane sinusoidal motion is assessed by heterodyne holography. In heterodyne holography, the beam in the reference channel is an optical local oscillator (LO). It is frequency-shifted with respect to the illumination beam to enable frequency conversion within the sensor bandwidth. The proposed scheme introduces a strobe LO, where the reference beam is frequency-shifted and modulated in amplitude, to alleviate the issue of phase retrieval. The strobe LO is both tuned around the first optical modulation side band at the vibration frequency, and modulated in amplitude to freeze selected mechanical vibration states sequentially. The phase map of the vibration can then be derived from the demodulation of successive vibration states

(DH) Noise and Signal scaling factors in Digital Holography in week illumination: relationship with Shot Noise

We have performed off axis heterodyne holography with very weak illumination by recording holograms of the object with and without object illumination in the same acquisition run. We have experimentally studied, how the reconstructed image signal (with illumination) and noise background (without) scale with the holographic acquisition and reconstruction parameters that are the number of frames, and the number of pixels of the reconstruction spatial filter. The first parameter is related to the frequency bandwidth of detection in time, the second one to the bandwidth in space. The signal to background ratio varies roughly like the inverse of the bandwidth in time and space. We have also compared the noise background with the theoretical shot noise background calculated by Monte Carlo simulation. The experimental and Monte Carlo noise background agree very well together

Holographic microscopy reconstruction in both object and image half spaces with undistorted 3D grid

We propose an holographic microscopy reconstruction method, which propagates the hologram, in the object half space, in the vicinity of the object. The calibration yields reconstructions with an undistorted reconstruction grid i.e. with orthogonal $x$, $y$ and $z$ axis and constant pixels pitch. The method is validated with an USAF target imaged by a $\times$60 microscope objective, whose holograms are recorded and reconstructed for different USAF locations along the longitudinal axis: -75 to +75 $\mu$m. Since the reconstruction numerical phase mask, the reference phase curvature and MO form an afocal device, the reconstruction can be interpreted as occurring equivalently in the object or in image half space