The Research Of Spectral Imaging Based On AOTF

Acousto-optic tunable filter (AOTF) is a newly developed spectroscopic device based on acousto-optic interaction. Compared with the traditional spectroscopic components (prism or grating), it has a lot advantages, including small bulk, solid state and no moving parts; large light and angle aperture; high diffraction efficiency; fast electrical tuning speed and so on. Up to now the application of AOTF is spreading to the fields of industry, medical care, remote sensing and scientific researching, and all the applications have made favorable effects.Because of the large light and angle aperture, AOTF has quite wide potential in spectral imaging field. While since the TeO₂ has natural dispersion, it will cause scene shift and imaging blur, and hence hinder the application in imaging field.This article precisely calculates the parameters of AOTF and adds a precisely designed wedge to produce the chromatic correction with its natural dispersion. The results of numerical simulation prove this method can correct the scene shift totally and improve the spatial resolution greatly.Base on the dispersion removing AOTF design in this article, and integrating optical elements, imaging lens, CCD detector and RF power, we designed and implement a spectral imaging system. With the computer control, it can realize spectral scanning and spectral imaging collecting. The test result of spectral wavelength accuracy, spectral resolution, scene shift, imaging quality for this system is satisfactory. Using this spectral imaging system, we first study plant leaf, and verified the leaf's "red edge" phenomena. And then in the experiment of locust and grass environment spectral imaging analysis, we found the reflecting rate of locust and grass differ greatly in NIR, and this trait have a great potential application in the field of agriculture insects monitoring.