Monocular passive ranging through a PQ:PMMA holographic wavelength division demultiplexer

Julian Gamboa; Tabassom Hamidfar; Xi Shen; Jason Bonacum; Selim M. Shahriar

doi:10.1117/12.2648402

8 March 2023 Monocular passive ranging through a PQ:PMMA holographic wavelength division demultiplexer

Julian Gamboa, Tabassom Hamidfar, Xi Shen, Jason Bonacum, Selim M. Shahriar

Proceedings Volume 12445, Practical Holography XXXVII: Displays, Materials, and Applications; 124450P (2023) https://doi.org/10.1117/12.2648402
Event: SPIE OPTO, 2023, San Francisco, California, United States

Abstract

Distance estimation is an important yet challenging part of any tracking system, as being able to quickly locate an object in 3D space allows for the automated targeting of communication, delivery, and interception systems, as well as providing important telemetry about fast moving objects. A monocular passive ranging system is defined as that which only requires one observation point through which it measures some outside signal to estimate range. The approach presented here simultaneously observes the intensity of light emitted by the target at three wavelength bands with ~10nm FWHM, centered at 750, 762, and 780 nm. The light is separated using a PQ:PMMA holographic optical element (HOE) configured as a wavelength division demultiplexer. Light at the two outer bands experiences negligible absorption in the atmosphere, while light at ~762 nm is strongly absorbed by O₂. By comparing the intensity of the two unabsorbed bands, we may interpolate the expected intensity of the 762 nm band if there is no O₂ in the path. This is then used in conjunction with the 762 nm band measurement to approximate the total O₂ transmissivity. Finally, Beer’s law and the HITRAN database provide us with the tools to convert a transmissivity into a distance estimation. The use of an HOE is pivotal in the practicality of such a system, as it allows us to measure all three signals simultaneously, thus eliminating the effects of turbulence and reducing overall noise.

Conference Presentation

Citation Download Citation

Julian Gamboa, Tabassom Hamidfar, Xi Shen, Jason Bonacum, and Selim M. Shahriar "Monocular passive ranging through a PQ:PMMA holographic wavelength division demultiplexer", Proc. SPIE 12445, Practical Holography XXXVII: Displays, Materials, and Applications, 124450P (8 March 2023); https://doi.org/10.1117/12.2648402

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