New approaches to improve the illumination optics of rigid endoscopes

Alexander Gaertner; Antje Dietzel-Schaarschmidt; Paola Belloni

doi:10.1117/12.2596859

12 September 2021 New approaches to improve the illumination optics of rigid endoscopes

Alexander Gaertner, Antje Dietzel-Schaarschmidt, Paola Belloni

Proceedings Volume 11874, Illumination Optics VI; 118740J (2021) https://doi.org/10.1117/12.2596859
Event: SPIE Optical Systems Design, 2021, Online Only

Abstract

Rigid endoscopes are optical systems characterized by high light losses and poor light transfer efficiencies below 20 %. We investigated this issue first by performing a photometric analysis of three state of the art endoscopes and second by carrying out an optical analysis by means of an optomechanical model with the optical design software LightTools (Synopsys). The light losses in the material and the critical interfaces of the optomechanical model are then analyzed by considering both the spectral power distribution of the light source and the light distribution that is coupled into the endoscope’s illumination optics. To improve the illumination optics of rigid endoscopes three approaches are presented in this work: a compound parabolic concentrator and a fiber cone are first developed as alternative coupling elements but only a minor improvement could be realized, because the present optical system is highly constraint by étendue law. Therefore, an immersion element is secondly introduced between coupling element and fiberbundle to reduce backscattering between the interfaces and to increase the overall light transfer efficiency. However, it turned out that a 10 % increased light transfer efficiency can be achieved only by selecting high numerical aperture fibers combined with the immersion element. Third, the influence of the initial coupling element’s geometry on the light distribution in the surgical field is investigated. The optical simulations show that by lengthening the coupling element’s truncated cone the light can be distributed more uniformly in the surgical field.

Citation Download Citation

Alexander Gaertner, Antje Dietzel-Schaarschmidt, and Paola Belloni "New approaches to improve the illumination optics of rigid endoscopes", Proc. SPIE 11874, Illumination Optics VI, 118740J (12 September 2021); https://doi.org/10.1117/12.2596859

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