AOTF (Acousto-Optic Tunable Filter) spectral imaging devices is widely utilized in remote sensing applications due to its advantages of no moving parts, rapid response, and robust reliability. TeO2 (Tellurium dioxide)-based AOTF, currently represent as the most commonly employed acousto-optic crystals owing to TeO2 excellent acousto-optic figures of merit. The effect of heat in acousto-optic devices is a persistent problem because acousto-optic interactions necessitate maintaining a specific acoustic power within the crystal. Various efforts have been applied to analyze and obtain the temperature field of acousto-optic devices. Various efforts have been applied to measurement of the temperature distribution of AOTF devices. However, there is still lack the research of accurate thermal modeling for AOTF devices. This paper presents a thermodynamic model based on finite element-based approach to simulated the thermal characteristics of AOTF device. Approach considerations include the impact of device impedance matching on actual electrical power consumption, as well as factors like acoustic anisotropy and the heating effect of the acoustic absorber. Simulation model conducted on the entire device, encompassing the shell. Experimental validation was carried out by measuring the surface temperature of AO crystals under various thermodynamic conditions.
We propose here a design of Lyot-Solc composite structure for liquid crystal tunable filter (LCTF) using nematic liquid crystal, which is with high efficiency, narrow bandwidth and electrical tunability. LCTF with high efficiency has many important applications in the fields of optical communication, spectral imaging, and displays. However, most LCTFs adopt cascaded Lyot-type or Solc-type structure, in which multiple pieces of polarizing optical elements exist, causing intensive loss of light intensity. The Lyot-type filter has narrower full width at half maximum (FWHM), but the transmittance is lower. The Solc-type filter has high transmittance and larger free spectral range (FSR) but broader FWHM. We propose a new structure of LCTF composed of Solc-type and Lyot-type structure. The composite 3-levelSolc and 2-level-Lyot LCTF transmission spectrum is a combination of the advantages of the two structures. Through the reasonable structural design, the spectral transmittance is improved, and the secondary transmission peak in the visible spectrum is effectively minimized. At the same time, the output central wavelength can be electrically tunable in the range from 400nm to 650nm by loading different amplitude of driving signals. When the driving signals with amplitude of 1.61V, 1.45V and 1.25V are respectively loaded on the liquid crystal cells of the LCTF, the central wavelengths of the output spectrum are respectively 433nm, 510nm and 595nm, corresponding to the FWHM of 13nm, 16nm and 22nm.
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