Endoscope with distal LED for illumination

Abstract

Nowadays, surgical sites observed by an endoscope during minimally invasive surgery are illuminated by external cold-light sources. That procedure causes several disadvantages as cold-light sources are expensive, their lamps have a low durability as well as poor efficiency and the fiber-optic cable to transport the light to the endoscope leads to a cumbersome handling of the device. Within technical endoscopy, cold-light sources are often replaced by LEDs, which are mounted at the tip of the device. Today’s High-Power-LEDs are able to substitute cold-light sources for illumination. However, the heat development is too high. An LED mounted at the tip of the endoscope produces so much thermal energy that it becomes too hot for medical approval. The heat of an LED mounted in the endoscope handle could be dissipated by the larger surface of the handle, but the generated light still has to be transported to the tip of the device. Consequently, the optimal setup is a source of radiation at the distal end of the endoscope with a system for transferring the thermal energy to the handle of the instrument. This is done by a High-Power-LED with a “white spectrum” and a heat transfer system consisting of heat pipes and copper connectors. Research showed that heat pipes are the optimal heat transfer system for an endoscope, as they have a very high thermal conductivity and there is no need for extra elements like pumps to circulate a cooling fluid. Measurements on two laboratory prototypes proved that they comply with the temperatures specified in IEC 60601 at different alignments. Thus, a conventional endoscope with a cold-light source including all its disadvantages can be replaced by an endoscope with an integrated light source consisting of an LED and adequate heat transfer system made of heat pipes.