Early diagnosis by comparison between interferometry and Z-scan methods to measure NLO refraction of human skin cancer (BCC and SCC) in vitro

As the nonlinear refractive index ([Formula: see text]) of human cancerous skin tissues is an important parameter in characterizing the optical response in laser–tissue interaction, the interferometry method was applied for early diagnosis. Simple method of interferometry measurement has been applied to measure the tissues’ [Formula: see text] in vitro from cancerous human skin samples (BCC and SCCs) in three thicknesses. Also, to compare the sensitivity and accuracy of the interferometry method, the [Formula: see text]-scan method was used. The results show that in comparison with healthy skin tissue, the cancerous skin has nonlinear response and this index increases with the thickness of samples.