Abstract
Due to the high energy transfer efficiency, LED (Light Emitting Diode) is now considered to be a good light source of the surgical operating lamp. The usage of halogen light source in traditional surgical operating lamp has several disadvantages such as big spot size and low efficiency, and most importantly, the high intensity of the infrared ray which would cause the illness of both Doctors and patients. It is found that during the process of surgery, illuminations for different wound depth and light field area are required, therefore, the adjustable lighting focus or spot size of surgical operating lamp could offer better operating qualities without relocate the operating lamp. In this research we design a LED surgical operating lamp which be able to change focus by rotating the lens of the surgical light. We analyze the ray paths and generate corresponding lens profile using Tailored freeform method. After analysis, we design the lens arrangement according to projection point requirement by using the edge ray principle, which could redirect the direction of the light rays when rotating the lens. This ray redirection can change the focus point of the light. Then, together with LED model, we simulate and analyze the overall lightening distribution. The final design meets both the objective of focus-changing and specifications of surgical operating lamp in IEC-60601-2-41.