Analysis and Simulation of the Illumination Optics of Rigid Medical Endoscopes

Abstract

Our work focuses on enhancing the illumination optics of a rigid medical endoscope using optomechanical simulation. We aim on improving the efficiency of the illumination optics to provide more light in the surgeon’s field of view (FOV) and therefore better image quality. We conducted an extensive market analysis and measured several rigid endoscopes and their external light sources in the lighting technology laboratory. Surprisingly, all endoscopes showed a degree of efficiency below 20 %. Our optimization approach is based first on a photometric and colorimetric analysis carried out with an integrating sphere and a goniophotometer. Secondly, the results obtained are implemented in a 3Doptomechanical simulation model developed with the raytracing software LightTools (Synopsis©). In the simulation model both the geometrical components as well as the critical interfaces are examined considering light coupling at boundary surfaces and light transfer within the illumination optics. Moreover, the optimization takes into account spectral power distribution (SPD) and angular light distribution (ALD) of the light provided from the fiberoptic cable connected to an external light source as well as additional interfering factors like gluing, dispersive absorption and total reflection at critical angles.

Keywords

• endoscopy
• illumination
• illumination optics
• raytracing simulation