The acousto-optic tunable filter (AOTF) has optical sidelobes that are due to the acoustic field produced by the transducer. These sidelobes were analyzed by wave-vector phase matching between the optical and acoustic fields, which correlated with measurements made with a TeO2 AOTF. A white-light point source was filtered and imaged, showing reasonably large and slowly decreasing sidelobes covering a large spectral range. This effect reduces the image quality of an AOTF system by producing faint secondary images of bright objects. The image quality can be improved with a telecentric confocal optical arrangement in which the angular shift of the sidelobes is greatly reduced, producing a much sharper image. This effect was also demonstrated experimentally with the point source.
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http://dx.doi.org/10.1364/ao.44.005797 | DOI Listing |
Nanophotonics
March 2024
Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea.
The acousto-optic modulation over a broad near-infrared (NIR) spectrum with high speed, excellent integrability, and relatively simple scheme is crucial for the application of next-generation opto-electronic and photonic devices. This study aims to experimentally demonstrate ultrafast acousto-optic phenomena in the broad NIR spectral range of 0.77-1.
View Article and Find Full Text PDFMaterials (Basel)
November 2024
School of Instrumentation and Opto-Electronic Engineering, Beihang University, Beijing 100191, China.
For the acousto-optic tunable filter (AOTF)-based spectral imaging systems, the diffraction efficiency of the AOTF is a primary factor affecting system throughput. Moreover, the distribution of the acoustic field within the AOTF fundamentally determines the device's diffraction efficiency. Thus, the design of an AOTF device including a transducer and absorber to achieve a uniform acoustic field distribution plays an important role in improving diffraction efficiency.
View Article and Find Full Text PDFMaterials (Basel)
September 2024
School of Instrumentation and Opto-Electronic Engineering, Beihang University, Beijing 100191, China.
The spectral response of an acousto-optic tunable filter (AOTF) is crucial for an AOTF based spectral imaging system. The acousto-optic (AO) interaction within the spatial-distributed area of the acoustic field determines the spectral response of the light incidence. Assuming an ideally uniform acoustic field distribution, phase-matching geometries can be applied to calculate the anisotropic Bragg diffraction in AO interactions, determining the wavelength and direction of the diffracted light.
View Article and Find Full Text PDFJ Acoust Soc Am
September 2024
Department of Physics, M.V. Lomonosov Moscow State University, Moscow, 119991, Russia.
Quasi-collinear geometry is a special configuration of acousto-optic (AO) diffraction that applies the acoustic wave reflection from the AO cell input optical face and provides an extremely large interaction length for achieving abnormally high spectral resolution of AO tunable filters. As a result, it becomes possible to implement the multifrequency diffraction which has found important applications for laser pulse shaping. The operation of quasi-collinear AO devices in the multifrequency diffraction regimen is accompanied by the appearance of the longitudinal and transverse temperature gradients in the crystal, mainly due to the acoustic power absorption.
View Article and Find Full Text PDFJ Biomed Opt
September 2024
University of Florence, Department of Physics and Astronomy, Florence, Italy.
Significance: Histopathological examination of surgical biopsies, such as in glioma and glioblastoma resection, is hindered in current clinical practice by the long time required for the laboratory analysis and pathological screening, typically taking several days or even weeks to be completed.
Aim: We propose here a transportable, high-density, spectral scanning-based hyperspectral imaging (HSI) setup, named HyperProbe1, that can provide , fast biochemical analysis, and mapping of fresh surgical tissue samples, right after excision, and without the need for fixing, staining nor compromising the integrity of the tissue properties.
Approach: HyperProbe1 is based on spectral scanning via supercontinuum laser illumination filtered with acousto-optic tunable filters.
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