Biomedical subjects
Publications and source records attributed to Vincent Loriette.
The use of a confocal detection scheme in a dual-beam thermal-lens microscope is presented. The scheme allows the measurement of absorption factors down to 1.2 x 10(-7) in a 0.35-microm3 volume by use of a heating laser power of 100 mW incident upon the sample. Results are presented that prove that a 450-nm axial resolution is possible when a 1.2 water immersion objective lens with a N.A. of 1.2 is used.
A method for measuring birefringence by use of thermal-light polarization-sensitive optical coherence tomography is presented. The use of thermal light brings to polarization-sensitive optical coherence tomography a resolution in the micrometer range in three dimensions. The instrument is based on a Linnik interference microscope and makes use of achromatic quarter-wave plates. A mathematical representation of the instrument is presented here, and the detection scheme is described, together with a discussion of the validity domain of the equations used to evaluate the birefringence in the presence of white-light illumination.
We describe an instrument for measuring the magnitude of birefringence of tomographic images and the principal directions of axes that use thermal-light polarization-sensitive optical coherence tomography. The instrument permits full-field measurements with an axial resolution of 1.5 microm and a transverse resolution limited by diffraction. We obtained a sensitivity of 84 dB, limited by shot noise, when we integrated the signal for 1 s. We verified the validity of the measurement by measuring the birefringence of a variable phase shifter. We present typical results obtained with optical samples.
A collinear photothermal detection bench is described that makes use of a position-modulated heating source instead of the classic power-modulated source. This new modulation scheme increases by almost a factor 2 the sensitivity of a standard mirage bench. This bench is then used to measure the absorption coefficient of OH-free synthetic fused silica at 1064 nm in the parts per 10(6) range, which, combined with spectrophotometric measurements, confirms that the dominant absorption source is the OH content.