We present a new and simple method to obtain ultrasound modulated optical tomography images in thick biological tissues with the use of a photorefractive crystal. The technique offers the advantage of spatially adapting the output speckle wavefront by analysing the signal diffracted by the interference pattern between this output field and a reference beam, recorded inside the photorefractive crystal. Averaging out due to random phases of the speckle grains vanishes, and we can use a fast single photodetector to measure the ultrasound modulated optical contrast. This technique offers a promising way to make direct measurements within the decorrelation time scale of living tissues.

We present a new detection scheme for acousto-optic tomography based on pulsed-wave ultrasound and illumination combined with heterodyne parallel speckle detection. This setup can perform tomographies inside several-centimeter-thick scattering samples. Test experiments confirm the suitability of this method for performing tomographies inside various types of optically scattering media, including liquids.

A new technique is presented for measuring the spectral broadening of light that has been multiply scattered from scatterers in motion. In our method the scattered light is detected by a heterodyne receiver that uses a CCD as a multipixel detector. We obtain the frequency spectrum of the scattered light by sweeping the heterodyne local oscillator frequency. Our detection scheme combines a high optical etendue (product of the surface by the detection solid angle) with an optimal detection of the scattered photons (shot noise). Using this technique, we measure, in vivo, the frequency spectrum of the light scattered through the breast of a female volunteer.

Electron spin resonance, magnetic circular dichroism, and optical absorption spectra of a paramagnetic Rh 2ϩ complex are investigated in Rh 3ϩ doped solution-grown NaCl single crystals. x irradiation of the crystals at 77 K followed by a warm-up to room temperature results in the formation of a stable low-spin Jahn-Teller distorted RhCl 6 4Ϫ complex possessing D 4h symmetry. The unpaired electron is largely localized in the 4d z 2 orbital of the Rh 2ϩ (4d 7 ) which is involved in a type molecular bond with two symmetrically placed Cl Ϫ ions along ͗001͘. The magnetic circular dichroism and optical absorption measurements at 1.4 K reveal two main bands around 12 200 cm Ϫ1 and 16 200 cm Ϫ1 . Within the octahedral Tanabe-Sugano formalism of the Rh 2ϩ these two absorptions are associated with two vibronically allowed 2 E g → 2 T 1g , 2 T 2g molecular transitions. This assignment is in quantitative agreement with the analysis of the g matrix components. A small MCD feature at 15 200 cm Ϫ1 is tentatively associated with two coinciding 2 E g → 2 T 1g , 2 T 2g transitions of another, probably a ligand-exchanged, Rh 2ϩ center.