Abstract : Using soft radiation like light and ultrasound, the tissue activities such as metabolism, blood flow in tissue can be measured by correlating them with chromophores (haemoglobin, Melanin, water, lipid etc) concentration. Laser light based diagnostic methodologies are getting more important at present century due to its diagnostic potential in biophysic research and medical physics. As an example we can point out optical tomography where the tissue activity image is obtained based on absorption and scattering of light. Another example is the hybrid photoacoustic diagnostic modality where we see the conversion of optical energy into mechanical sound wave through molecular level physical phenomena which has potential to provide early stage disease sign