Optical discrimination of benign and malignant oral tissue using Z-scan technique

• Morphological change of cancerous tissue can help to discriminate malignant from benign tissues.
• Biolayers have been investigated by CW He-Ne laser.
• Z-scan technique has been used to investigate nonlinear optical behavior of micro-sized biolayers.
• Nonlinear refractive index of benign samples was negative, while positive for malignant samples.

A new optical method to discriminate benign and malignant oral tissue is reported. Twenty four tissue biopsy of patients tumor have been prepared in standard method without coloring process. The CW He-Ne laser beam interrogated the samples in optical setup. Linear absorption of tissues in laser wavelength measured and nonlinear behavior of tissue biopsies has been investigated by Z-scan setup. We used some simple optical instruments to focus on microsize region of biolayer to investigate less number of cells and to take repeatable test. Results show that the malignant samples have more attenuation than benign samples. Furthermore nonlinear refractive index (n2) of malignant biolayers has positive sign and n2 of benign biopsies has negative sign with the 10−8(cm2/W)(cm2/W) order of magnitude. So this optical method may be used to discriminate malignant from benign tissues.