Polarization-independent imaging with an acousto-optic tandem system

Abstract

We propose a method for filtering convergent light beams with arbitrary polarization. For this purpose, a tandem of similar acousto-optic tunable filters was applied. Owing to the special mutual orientation of the cells, two coincident beams with ordinary and extraordinary polarizations were diffracted by the first crystal and the second crystal, respectively.

Two regimes of wide angle acousto-optic interaction in tellurium dioxide single crystals

“…Wide angle AO tunable filters based on TeO 2 crystals have been widely used in the analysis of images in the ultraviolet, visible, and IR range of electromagnetic radiation [4][5][6][9][10][11][12][13][14][15][16][17]. Traditionally, the design of the imaging AOTFs using the paratellurite crystals is based on the AO interaction in the 110 plane when a slow shear acoustic wave propagates in the material and modulates its refractive index, n. A direction of the acoustic wave propagation in the 110 plane is described by the tilt angle, α, measured between the acoustic phase velocity vector K and the axis 110; of the crystal.…”

“…The second case [labeled (b)] is realized if the AO interaction is close to the collinear with light propagating far away from the optical axis. The first regime of diffraction is described in literature in detail [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Moreover, the majority of current imaging devices is based on the diffraction observed in the crystal near the optical axis [4][5][6]9,10,[13][14][15]17].…”

“…The other modification is represented by wide angle AOTFs capable of image processing [3][4][5][6][7][8][9][10]. One of the practical problems that may be solved by the wide angle AOTFs is the spectral analysis of images [3][4][5][6][8][9][10][11][12][13][14][15][16][17]. Moreover, wide angle AOTFs can also produce spatial filtering of light beams forming images in monochromatic light [7,18].…”

Contrast enhancement in microscopy of human thyroid tumors by means of acousto-optic adaptive spatial filtering

“…[14][15][16][17] In the case of monochromatic coherent input light, AOTFs perform spatial filtering of optical beams and can be used for such image processing operations as optical phase detection, edge enhancement, and low-pass and high-pass spatial filtering. [18][19][20][21][22][23][24][25] Optical phase detection by means of AOTFs is based on the angular selectivity of acousto-optic Bragg diffraction. 19,24 Diffraction efficiency varies for different fragments of the curved wavefront after the phase object, resulting in amplitude modulation of diffracted light.…”

The narrow band AOTF based hyperspectral microscopic imaging on the rat skin stratum configuration

“…Its function is based on the acousto-optic interaction in the birefringent material and possesses many attractive features: real-time electronic tuning with wide tuning range, large throughput etc. The AOTF had been widely used in the tuning dye lasers, optical calculation, spectral analysis, hyperspectral imaging and other related areas [1]- [6]. Although many kinds of AOTF (based on the crystal or optical fiber) were commercial available, scientists have been working hard on developing an AOTF with better performance.…”