Handheld cross‐polarised microscope for imaging individual pigmented cells in human skin in vivo

Abstract

AbstractWe present the development of a simple, handheld cross‐polarised microscope (CPM) and demonstration of imaging individual pigmented cells in human skin in vivo. In the CPM device, the cross‐polarised detection approach is used to reduce the specular reflection from the skin surface and preferentially detect multiply‐scattered light. The multiply‐scattered light works as back illumination from within the tissue towards the skin surface, and superficial pigment such as intraepidermal melanin absorbs some spectral bands of the multiply‐scattered light and cast coloured shadows. Since the light that interacted with the superficial pigment only needs to travel a short distance before it exits the skin surface, microscopic details of the pigment can be preserved. The CPM device uses a water‐immersion objective lens with a high numerical aperture to image the microscopic details with minimal spherical aberrations and a small depth of focus. Preliminary results from a pilot study of imaging skin lesions in vivo showed that the CPM device could reveal three‐dimensional distribution of pigmented cells and intracellular distribution of pigment. Co‐registered CPM and reflectance confocal microscopy images showed good correspondence between dark, brown cells in CPM images and bright, melanin‐containing cells in reflectance confocal microscopy images.