0000000000082607
AUTHOR
Martins Osis
Lasers for in-vivo skin diagnostics: some recent developments
The recent advancements of three laser-based diagnostic technologies developed at the Riga group are briefly reviewed: (i) RGB imaging of cw-laser excited skin autofluorescence intensity and photobleaching rate distributions, (ii) ps-laser excited skin autofluorescence and diffuse reflectance kinetics analysis, (iii) snapshot RGB skin chromophore mapping under triple-laser illumination. These techniques have passed preliminary laboratory and clinical tests which have demonstrated a promising potential for further implementation in portable devices for routine clinical applications. Operation principles, set-up schemes and some clinical results obtained by the above-mentioned techniques are …
Towards direct measurements of remitted photon path lengths in skin: kinetic studies in the range 520-800 nm
Skin-remitted picosecond laser pulses have been detected at variable input-output fiber distances (8 … 20 mm) in the spectral range 520-800 nm, with subsequent analysis of the pulse shape changes. Transfer functions representing the temporal responses of remitted photons to infinitely narrow δ-pulse excitation have been calculated. Parameters related to the photon path length in skin – input-output pulse peak delays, pulse FWHM, travel times of the “initial” photons and distributions of the remitted photon path lengths – are presented and analyzed. The measurement results are in general agreement with the photon propagation model expectations
Remitted photon path lengths in human skin: in-vivo measurement data
The remitted photon path lengths in human skin can be estimated by modelling; however, there are very few experimental data available to validate the simulations. This study exploited the photon time of flight method where picosecond laser pulses at seven wavelength bands in the spectral range 560-800 nm were launched into in-vivo forearm skin of 10 volunteers via an optical fiber. The pulses of back-scattered light were detected via another optical fiber placed at variable distance (1, 8, 12, 16 or 20 mm) from the input fiber, with subsequent analysis of their shapes for all 35 spectral-spatial combinations. Using a deconvolution algorithm, the distribution functions of remitted photon arr…