Measurement of absorption and reduced scattering coefficients in Asian human epidermis, dermis, and subcutaneous fat tissues in the 400- to 1100-nm wavelength range for optical penetration depth and energy deposition analysis

SIGNIFICANCE: In laser therapy and diagnosis of skin diseases, the irradiated light distribution, which is determined by the absorption coefficient μa and reduced scattering coefficient μs' of the epidermis, dermis, and subcutaneous fat, affects the treatment outcome and diagnosis accuracy. Although values for μa and μs' have been reported, detailed analysis for Asian skin tissues is still lacking. AIM: We present μa and μs' measurements of Asian skin tissues in the 400- to 1100-nm wavelength range for evaluating optical penetration depth and energy deposition. APPROACH: The measurements with Asian human skin samples are performed employing a double integrating sphere spectrometric system and an inverse Monte Carlo technique. Using the measured parameters, the optical penetration depth and energy deposition are quantitatively analyzed. RESULTS: The μa of the epidermis layer varies among different ethnic groups, while the μa of the other layers and the μs' of all of the layers exhibit almost no differences. The analysis reveals that the optical penetration depth and the energy deposition affect the photodynamic therapy treatment depth and the heat production in skin tissue, respectively. CONCLUSIONS: The experimentally measured values of μa and μs' for Asian skin tissues are presented, and the light behavior in Asian skin tissues is analyzed using a layered tissue model.