Evaluation of the Acousto-Optic Figure of Merit and the Maximum Value of the Elasto-Optic Constant of Liquids.

The elasto-optic properties of liquids on the basis of the first principles of acousto-optics were theoretically investigated. A relationship for calculating the elasto-optic constant of liquids using only the refractive index was obtained. The refractive index values corresponding to the maximum elasto-optic constant for polar and nonpolar liquids were determined.

Evaluation of Acoustic Waves in Acousto-Optical Devices by Ultrasonic Imaging.

The structure of the acoustic field defines the key parameters of acousto-optical (AO) devices. To confirm their compliance with the expected values in the presence of multiple real factors, AO crystalline cells require accurate experimental investigation of the acoustic field after being totally assembled. For this purpose, we propose to detect and quantify all the acoustic waves propagating in AO cells using an impulse acoustic microscopy technique.

Computational technique for field-of-view expansion in AOTF-based imagers.

A rather narrow field of view (FOV) has always been considered as an essential limitation of spectral imagers based on acousto-optical tunable filters (AOTFs). We demonstrate a computational technique to overcome this constraint. It is based on preliminary precise spectral-angular characterization of beam transformation caused by light diffraction on an acoustic wave and consequent correction of acquired stack of spectral images.

Spectral Imaging Experiments with Various Optical Schemes Based on the Same AOTF.

Spectral image filtration by means of acousto-optical tunable filters (AOTFs) has multiple applications. For its implementation, a few different optical schemes are in use. They differ in image quality, number of coupling components, dimensions and alignment complexity.

Polarizer-Free AOTF-Based SWIR Hyperspectral Imaging for Biomedical Applications.

Optical biomedical imaging in short wave infrared (SWIR) range within 0.9-1.7 μm is a rapidly developing technique.

Single-volume dual-channel acousto-optical tunable filter.

In this paper, we present a novel approach to spectral stereoscopic imaging. It is based on simultaneous spectral filtration of two light beams with a tunable acousto-optical filter (AOTF) of original design. It does not require large crystals and complicated optical relay systems, because two beams diffract in the same volume of the crystal medium but at different angles.

RGB laser based on an optical parametric oscillator for single-shot color digital holographic microscopy.

We report on the new technical realization of single-shot color digital holographic microscopy. For this application, we propose to use an original three-wavelength red, green, and blue laser based on the Nd:YAG active element with sequential parametric downconversion and upconversion of optical frequencies into red (634 nm), green (532 nm), and blue (451 nm) spectral intervals. This light source provides high-power short (∼10  ns) pulses and enables simultaneous formation of three color interference patterns in a two-path interferometer.

Multispectral phase imaging based on acousto-optic filtration of interfering light beams [Invited].

Acousto-optic spectral selection of light is an effective technique for interference imaging at multiple wavelengths. In this paper, we show that, depending on the location of the acousto-optical tunable filter relative to the interferometer, it is possible to enhance important characteristics of the whole system: spectral contrast, insensitivity to ambient light, performance stability, and measurement accuracy. We analyze theoretically and compare experimentally a quantitative phase imaging system based on a Mach-Zehnder interferometer with one and two acousto-optical filters located in the illumination or/and in the output channels.

Acousto-optic tunable spectral filtration of stereoscopic images.

We propose a new technique for three-dimensional (3-D) imaging in arbitrary spectral intervals. It is based on a simultaneous diffraction of two divergent stereoscopic light beams on a single acoustic wave propagating in a uniaxial birefringent crystal. We discuss in detail this configuration of acousto-optic (AO) interaction, derive basic relations, and experimentally demonstrate the applicability of the proposed approach to 3-D spectral imaging.

Aberration analysis of AOTF-based spectral imaging systems.

Image aberrations caused by acousto-optic (AO) anisotropic diffraction in uniaxial crystals are discussed. For their analysis, we propose a simplified ray-tracing model of an AO crystal cell (AOC). With this approach, one can assign any configuration of AO interaction, any material and geometry of the crystal, and then estimate all conventional ray aberrations, such as spherical, coma, astigmatism, distortion, etc.

Specific directions of ultrasound propagation in double potassium tungstates for light modulation.

Acousto-optical characteristics of double potassium tungstates are analyzed and specific directions for light modulation are found. First, an important subgroup of elasto-optic coefficients of KYb(WO) and KLu(WO) crystals are calculated with use of experimental data. It is revealed that with proper choice of ultrasound direction the acousto-optical figure-of-merit approximately 2 times exceeds the maximum value detected in previous experiments.

Acousto-optical tunable filter for combined wideband, spectral, and optical coherence microscopy.

A multimodal technique for inspection of microscopic objects by means of wideband optical microscopy, spectral microscopy, and optical coherence microscopy is described, implemented, and tested. The key feature is the spectral selection of light in the output arm of an interferometer with use of the specialized imaging acousto-optical tunable filter. In this filter, two interfering optical beams are diffracted via the same ultrasound wave without destruction of interference image structure.

Elastic and photo-elastic characteristics of laser crystals potassium rare-earth tungstates KRE(WO₄)₂, where RE=Y, Yb, Gd and Lu.

The elastic and photo-elastic characteristics of four laser crystals KY(WO₄)₂, KGd(WO₄)₂, KYb(WO₄)₂, and KLu(WO₄)₂ are presented. The first pair was reported early, and the last two materials have been investigated for the first time. The full matrix of elastic constants of these monoclinic crystals has been determined.

Image aberrations caused by light diffraction via ultrasonic waves in uniaxial crystals.

The problem of optical image deformations caused by the phenomenon of light beam diffraction in uniaxial crystals by ultrasonic waves is considered in the paper. A general analytical expression is derived describing a dependence of spatial deformations and transmission coefficients on incidence angles as well as on parameters of the crystal and the ultrasound. The most interesting wide-angle diffraction configurations are analyzed, and all types of spatial distortions and transfer functions are described.