No abstract

Fluorescence and phosphorescence lifetime imaging are powerful techniques for studying intracellular protein interactions and for diagnosing tissue pathophysiology. While lifetime-resolved microscopy has long been in the repertoire of the biophotonics community, current implementations fall short in terms of simultaneously providing 3D resolution, high throughput, and good tissue penetration. This report describes a new highly efficient lifetime-resolved imaging method that combines temporal focusing wide-field multiphoton excitation and simultaneous acquisition of lifetime information in frequency domain using a nanosecond gated imager from a 3D-resolved plane. This approach is scalable allowing fast volumetric imaging limited only by the available laser peak power. The accuracy and performance of the proposed method is demonstrated in several imaging studies important for understanding peripheral nerve regeneration processes. Most importantly, the parallelism of this approach may enhance the imaging speed of long lifetime processes such as phosphorescence by several orders of magnitude. 291-295 (1996). 6. K. König, P. T. So, W. W. Mantulin, B. J. Tromberg, and E. Gratton, "Two-photon excited lifetime imaging of autofluorescence in cells during UVA and NIR photostress," J. Microsc. 183(Pt 3), 197-204 (1996). 7. J. R. Lakowicz, "Emerging applications of fluorescence spectroscopy to cellular imaging: lifetime imaging, metal-ligand probes, multi-photon excitation and light quenching," Scanning Microsc. Suppl. 10, 213-224 (1996 high-resolution measurements reveal a lack of correlation," Nat. Med. 3(2), 177-182 (1997). 14. I. P. Torres Filho, M. Leunig, F. Yuan, M. Intaglietta, and R. K. Jain, "Noninvasive measurement of microvascular and interstitial oxygen profiles in a human tumor in SCID mice," Proc. Natl. Acad. Sci. U.S.A. French, "Excitation-resolved hyperspectral fluorescence lifetime imaging using a UV-extended supercontinuum source," Opt. Lett. 32(23), 3408-3410 (2007). 32.

SynopsisHair luster is one of the most important parameters of visual appearance perceived by consumers. Current luster formulae (TRI, Reich-Robbins, ...) are optimized for goniophotometric measurements. They are based on a mathematical decomposition of reflected light into specular and diffused light and the measurement of the shine peak width on the fitted angular distributions. In this expose, we are describing a polarization imaging system measuring luster of hair tresses with an innovative algorithm. Using polarization imaging allows to physically separating the specular light from the diffused light for each pixel of the imaged tress. Angular distributions of the specular and diffused light are obtained in a few seconds. Where conventional methods calculate the shine peak width on the angular distribution, the imaging system imitates the human eye and calculates the shine width directly on the image. The new formula combines different measured parameters to objectively quantify luster. It was designed to exhibit a higher correlation with visual perception along with a higher sensitivity. Results obtained with conventional formulae are compared on different hair tresses, treated and untreated. The new formula is found to be consistent for a whole range of hair colors, from light to dark.

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We present the concept of a Polarization Diversity Active Imager operating at ? = 810 rim. Each pixel of the image is encoded by the polarization degree Pd (0% < Pd < 100%) given by its Mueller Matrix. The measurement of the Mueller matrices is obtained using the Dual Rotation Retarder Technique (DRRT). A theoretical analysis and an experimental validation of this technique are presented. The device is operating in a monostatic configuration, using a semiconductor laser (X = 810 tim) to illuminate the target and a telescope to create the image on a CCD matrix. The experiment is controlled by a computer that drives the rotation of the retarders, the digitalization and the encoding of the image. The measured intensily and polarization images are compared and the information contained in the polarization degree are analyzed. Dual images (intensity-polarization) of different targets are presented, showing the experimental validation of the technique. The application of this active imager to the detection and the decamouflage of target buried in the background (same albedo but different polarization degree) is proposed.