Heterodyne detection fiber confocal microscope for in vivo skin imaging
Confocal microscopy has been demonstrated to be a very effective tool for imaging in-vivo samples. The confocal imaging geometry provides a dramatic optical advantage for microscopy by discriminating against out-of-focus background with minimal loss of image-forming signal. Because of these advantages, the confocal laser scanning microscope (CLSM) can image a thin layer clearly from a thick sample without biopsy. However, current usage of CLSM is limited by the signal-to-noise ratio using conventional optical detection. In order to achieve deeper penetration into the skin in a clinical setting, a technique called heterodyne detection is incorporated into the CLSM system. This thesis describes the optical, mechanical and electrical design of the system, evaluates system noise and imaging performance, and provides initial skin images collected by the heterodyne system, comparing the results with direct detection. The heterodyne detection system is proved to have deeper penetration than the direct detection system, but the image quality is degraded.