Optical signal degradation study in fixed human skin using confocal microscopy and higher-harmonic optical microscopy

Confocal and nonlinear optical microscopies have been applied for dermatological studies because of their capability to provide sub-surface three-dimensional images with sub-mu m spatial resolutions. Optical signal degradation as the imaging plane being moved toward deeper regions in skin specimens is the key factor that limits the observation depth for the laser scanning based linear or nonlinear imaging modalities. In this article, we studied the signal degradation in fixed human skin specimens using reflection confocal microscopy and higher-harmonic optical microscopy based on a Cr:forsterite femtosecond laser centered at 1230-nm. By analyzing the optical properties through these linear and nonlinear imaging modalities, we found that the optical signal degradation in the studied human skin specimen is dominated by the distortion of the point spread function. (c) 2006 Optical Society of America.