Optical design of a variable beam angle fiber light source

Henning Rehn; Marcel Wäspi; Tobias Honig; Martin Forrer

doi:10.1117/12.2599880

12 September 2021 Optical design of a variable beam angle fiber light source

Henning Rehn, Marcel Wäspi, Tobias Honig, Martin Forrer

Proceedings Volume 11874, Illumination Optics VI; 118740C (2021) https://doi.org/10.1117/12.2599880
Event: SPIE Optical Systems Design, 2021, Online Only

Abstract

In the field of endoscope optics we see more and more zoom designs, realized by tuneable lenses, micro actuators or traditional lens movement in rigid endoscopes with a camera sensor. For such devices, a lighting concept that adapts the beam angle to the current field of view of the zoom optics is desirable. In endoscopes, the light is usually transported from a source to the tip by a light guide or fiber bundle.1 Since it is not feasible to place an optical system at the fiber exit to fulfill the task, one would make use of the fact that a fiber roughly conserves the angular distribution of incident light and transfer the task of variable beam generation to the light source. We present an optical system that performs this task by conventional optical means outside the endoscope. A LED is imaged to the fiber entrance by a system of variable focal length. By choosing the source etendue equal to that of the fiber, it is ensured that the proper magnification of the imaging is accompanied by the specified angular extent. The LED light is first collimated, and the exit pupil of the collimator is imaged by a system of moving and fix lenses. In a final step, we show a design to adapt a colored light source to the variable beam optics.

Conference Presentation

Citation Download Citation

Henning Rehn, Marcel Wäspi, Tobias Honig, and Martin Forrer "Optical design of a variable beam angle fiber light source", Proc. SPIE 11874, Illumination Optics VI, 118740C (12 September 2021); https://doi.org/10.1117/12.2599880

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