Development of Low Cost Set Up Microscopic Skin Imaging Using Structured Light Projection

Abstract

Microscopic measurement of skin topography is essential both in health and cosmetics industry, for example in scar healing monitoring and efficacy assessment of beauty products. Limitation of direct visual assessment using human’s eyes leads to development of many optical devices to help assessing skin condition. One of the common devices used in skin assessment is dermatoscopy, which basically is a digital microscope used to magnifies skin profile by utilizing light interaction with skin surface. However, this method has certain limitation. It cannot yield the exact depth or height information, thus it is not sufficient enough for specified needs. Another method to acquire depth information of skin topography is by measurement of light transmission through transparent skin replica made from a silicon gel. Therefore, this method requires contact with respondent’s skin during replication. Through this paper, development of a method involving projection of structured light is presented as non-contact microscopic skin imaging. The system, built of commercially available devices, consists of a projector and a camera configured in certain angles. The processing consists of phase extraction using phase shifting interferometry (PSI) and phase unwrapping process to obtain wrapped phase and absolute phase value respectively. Experimental work was done on different areas of the skin surface each represents different skin roughness to test the feasibility of the system. Quantitative analysis was done by texture analysis based on entropy calculation to compare intensity and phase images.