Polarization-Multiplexed High-Throughput AOTF-Based Spectral Imaging System

Abstract

Spectral imaging detection using acousto-optical tunable filters (AOTFs) faces a significant challenge of low throughput due to the traditional design that only receives a single polarization light. To overcome this issue, we propose a novel polarization multiplexing design and eliminate the need for crossed polarizers in the system. Our design allows for simultaneous collection of ±1 order light from the AOTF device, resulting in a more than two-fold increase in system throughput. Our analysis and experimental results validate the effectiveness of our design in improving system throughput and enhancing the imaging signal-to-noise ratio (SNR) by approximately 8 dB. In addition, AOTF devices used in polarization multiplexing applications require optimized crystal geometry parameter design that does not follow the parallel tangent principle. This paper proposes an optimization strategy for arbitrary AOTF devices which can achieve similar spectral effects. The implications of this work are significant for target detection applications.

Angular-Spectral Characteristics of Acousto-Optic Tunable Filters Based on Mercurous Halide Crystals

“…In AOTF design, the cut angle of the exit surface can be designed according to different design requirements, such as compensation for chromatic aberration of diffracted light [ 28 ] or multiplexed polarization [ 29 ]. It is also possible to further enlarge the separation angle outside the crystal by adjusting the exit surface cut angle.…”

“…Upon completion of the design and fabrication of the devices, to tune the spectral channels by adjusting the driving frequency, wavelengths other than the specially designed central wavelengths all operate with PTP unsatisfied. Furthermore, recent AOTF device designs that consider polarization or chromatic aberrations are also not limited to satisfying the PTP [ 29 ]. Hence, we provide the variations in separation angles with the acoustic angle α when the incident angle θ i = 10° ( Figure 5 ) and the variations in separation angles with the incident angle θ i when the acoustic angle α = 5° ( Figure 6 ).…”

Analysis of Phase Mismatch for Mercurous Bromide-Based Non-Collinear AOTF Design in Spectral Imaging Applications

“…Additionally, the external separation angle θ sep , which is the angle between the transmitted and diffracted light in air, is related to the wedge angle θ w of the exit surface. The θ w is also fine-tuned to compensate for the chromatic aberration of the diffracted light [24], or adjusted according to the design requirements of multiplex polarization designs [26].…”