Adaptive camera calibration for a focus adjustable liquid lens in fiber optic endoscopy

Lennart Hinz; Markus Kästner; Eduard Reithmeier

doi:10.1117/12.2592653

18 April 2021 Adaptive camera calibration for a focus adjustable liquid lens in fiber optic endoscopy

Lennart Hinz, Markus Kästner, Eduard Reithmeier

Author Affiliations +

Proceedings Volume 11770, Nonlinear Optics and Applications XII; 1177014 (2021) https://doi.org/10.1117/12.2592653
Event: SPIE Optics + Optoelectronics, 2021, Online Only

Abstract

Benefitting from recent innovations in the smartphone sector, liquid optics in very compact designs have been cost-effectively introduced to the market. Without mechanical actuation, a focus variation can be adjusted within fractions of a second by curving a boundary layer between two liquids by applying a pulse width or amplitude modulated potential. Especially in the field of endoscopy, these innovative optical components open up many application possibilities. Conventional, mechanical zoom lenses are not very common in endoscopy and can only be miniaturized at considerable effort due to the necessary actuation and the complex design. In addition, the mechanical response is slow, which is a particular disadvantage in hand-held operation. A calibrated camera provides a two-dimensional camera pixel translated into a three-dimensional beam and, together with distortion correction enables the extraction of metric information. This approach is widely used in endoscopy, for example, to measure objects in the scene or to estimate the camera position and derive a trajectory accordingly. This is particularly important for triangulation-based 3D reconstruction such as photogrammetry. The use of liquid lenses requires a new data set with an adapted camera calibration for each focus adjustment. In practice, this is not feasible and would result in an extensive calibration effort. This paper therefore examines, on the basis of an experimental setup for automated endoscopic camera calibration, the extent to which certain calibration parameters can be modelled and approximated for each possible focal adjustment, and also investigates the influence of a liquid lens on the quality of the actual calibration.

Conference Presentation

Citation Download Citation

Lennart Hinz, Markus Kästner, and Eduard Reithmeier "Adaptive camera calibration for a focus adjustable liquid lens in fiber optic endoscopy", Proc. SPIE 11770, Nonlinear Optics and Applications XII, 1177014 (18 April 2021); https://doi.org/10.1117/12.2592653

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