The present invention comprises methods and systems/devices for non-invasively measuring birefringent tissues (e.g. collagen) and changes during treatment of tissue, e.g., denaturation by the application of RF energy, through linear dichroism, circular dichroism, or birefringence. The invention optionally uses polarization sensitive optical measurements to discriminate between denaturation of unidirectionally oriented strands of collagen, such as a ligament or tendon, and denaturation of planar collagen surfaces, such as the dermal layer of the skin or collagen in joint capsules.
