Imagery of Diffusing Media by Heterodyne Holography
Imagery of Diffusing Media by Heterodyne Holography
physics.optics↗
arXiv subjects
Michel Gross
Publications and source records attributed to Michel Gross.
Shot-noise detection of ultrasound-tagged photons in ultrasound-modulated optical imaging
We propose a new detection method for ultrasound-modulated optical tomography that allows us to perform parallel speckle detection with optimum shot-noise sensitivity, using a CCD camera. Moreover, we show that making use of a spatial filter system allows us to fully filter out speckle decorrelation noise. This method is confirmed by a test experiment
physics.optics↗
Effect of the Photon's Brownian Doppler Shift on the Weak-Localization Coherent-Backscattering Cone
We report the first observation of the dependence of the coherent-backscattering (CBS) enhanced cone with the frequency of the backscattered photon. The experiment is performed on a diffusing liquid suspension and the Doppler broadening of light is induced by the Brownian motion of the scatterers. Heterodyne detection on a CCD camera is used to measure the complex field (i.e., the hologram) of the light that is backscattered at a given frequency. The analysis of the holograms yield the frequency and the propagation direction of the backscattered photons. We observe that the angular CBS cone becomes more narrow in the tail of the Brownian spectrum. The experimental results are in good agreement with a simple theoretical model.
physics.optics↗
Noise and aliases in off-axis and phase-shifting holography
We have compared the respective efficiencies of off-axis and phase-shifting holography in terms of noise and aliases removal. The comparison is made by analyzing holograms of an USAF target backlit with laser illumination, recorded with a charge-coupled device camera. We show that it is essential to remove the LO beam noise, especially at low illumination levels.
physics.optics↗
Digital holography with ultimate sensitivity
We propose a variant of the heterodyne holography scheme that combines the properties of off-axis and phase-shifting holography. This scheme makes it possible to filter off numerically the zero-order image alias and the technical noise of the reference. It is then possible to record and reconstruct holographic images at an extremely low signal level. We show experimentally that the sensitivity of the method is limited only by the quantum nature of photons.
physics.optics↗
Wide-field Fourier transform spectral imaging
We report experimental results of parallel measurement of spectral components of the light. The temporal fluctuations of an optical field mixed with a separate reference are recorded with a high throughput complementary metal oxide semi-conductor camera (1 Megapixel at 2 kHz framerate). A numerical Fourier transform of the time-domain recording enables wide-field coherent spectral imaging. Qualitative comparisons with frequency-domain wide-field laser Doppler imaging are provided.
physics.optics↗
Heterodyne holographic microscopy of gold particles
We report experimental results on heterodyne holographic microscopy of subwavelength-sized gold particles. The apparatus uses continuous green laser illumination of the metal beads in a total internal reflection configuration for dark-field operation. Detection of the scattered light at the illumination wavelength on a charge-coupled device array detector enables 3D localization of brownian particles in water
physics.optics↗