A hyperspectral imager with adjustable spectral selectivity based on AOTF

Abstract

One of the advantages of acousto-optic tunable filter (AOTF) is its spectral selectivity, not only central wavelength, but also bandwidth and passband form, can be controlled by RF signals, which provides us the opportunity to develop a more flexible hyper-spectral imager. Traditional hyper-spectral imagers collect hyper-spectral images with certain spectral resolutions and spectral sampling intervals, which means a huge amount of data and low data efficiency. So, a more flexible device to meet different applications with less but more effective data is an attractive idea. The idea is brought out this year in SITP, CAS. A custom-made AOTF which can endure higher power is adopted to realize such a hyper-spectral imager. A RF generating system is designed to produce and control 12 channels of RF signals independently, and a PC is used to control the system and record the digital images obtained by a CCD camera. If the controlling RF frequencies are close enough to each other, the consecutive output passbands will combine into one wider band, and the programmable spectral resolution and passband form are available. If the RF signals are discrete, the image of several discrete spectral bands combination which can simply be treated as a fused image is available. In this paper, the theory and structure of the system is set out, some important details of design principle are introduced, some of the original test results and a few of experimental images are showed.