The use of light for scientific investigation in biomedical research and non-invasive diagnostics has become increasingly important and popular. This course is designed to cover the principles, experimental setup and applications of optical spectroscopy and imaging techniques that are commonly used. The first part of the course introduces UV-visible absorption, fluorescence, infrared absorption, Raman scattering and functional near-infrared spectroscopies. The second part of the course introduces the fundamental principle of optical imaging and light microscopy techniques including phase contrast, darkfield, polarization, differential interference contrast (DIC), structured illumination, confocal microscopy, optical coherence tomography, , and quantitative phase microscopy/tomography. Recent applications of various optical techniques in medical diagnostics will also be discussed.