Co-aligned dual wavelength circular scanner for airborne lidar bathymetry

Nathan D. Meraz; Grady H. Tuell; Eric A. Brown; Thomas A. Craney; Joong Yong Park

doi:10.1117/12.2518978

2 May 2019 Co-aligned dual wavelength circular scanner for airborne lidar bathymetry

Nathan D. Meraz, Grady H. Tuell, Eric A. Brown, Thomas A. Craney, Joong Yong Park

Proceedings Volume 11005, Laser Radar Technology and Applications XXIV; 1100508 (2019) https://doi.org/10.1117/12.2518978
Event: SPIE Defense + Commercial Sensing, 2019, Baltimore, MD, United States

Abstract

A dual-wavelength circular scanner with collinear transmit and receive axes has been developed for use in the SEAHAWK bathymetric lidar. The scanner optics consist of an achromatic prism pair located concentrically within a 11.3” diameter dual-zone holographic optical element (HOE). This scanner achieves coaligned green and infrared beams at a 20° off- nadir scan angle when using a 50W dual-wavelength laser (30W @ 532 nm and 20W @1064 nm) as the transmitter. The main engineering challenges in achieving the design were minimizing the optical pointing error between the four optical axes (two transmit and two receive) and developing a rugged prism pair design sufficient to withstand the high laser power. The design proved sensitive to fabrication and alignment errors so success depended on analyzing optical and mechanical tolerances, acknowledging fabrication limitations, measuring critical optical components, tailoring the design to the as- built components, and utilizing a custom alignment fixture featuring a digital autocollimator. Final measurements of the deployed scanner indicate its optical pointing error has a cone half angle error of less than 0.06° (1 mrad).

Conference Presentation

Citation Download Citation

Nathan D. Meraz, Grady H. Tuell, Eric A. Brown, Thomas A. Craney, and Joong Yong Park "Co-aligned dual wavelength circular scanner for airborne lidar bathymetry", Proc. SPIE 11005, Laser Radar Technology and Applications XXIV, 1100508 (2 May 2019); https://doi.org/10.1117/12.2518978

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