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

Abstract

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. Visibility of the interference patterns and noise root mean square in the calculated phase maps are estimated for all cases at room temperature. It is shown that acousto-optic filtration of interfering light beams in the output channel ensures better contrast of the interference pattern and, therefore, provides better stability and higher precision of the phase measurements.

Experimental Analysis of Tunable Optical Spectral Imaging System Using a Grating in the Pupil Function

“…The proposed optical imaging system depicts their modification in the pupil function, a configuration that has been a widely used to encode the wavefront on the incident radiation. Phase objects are commonly used to extend the field, together with shadow objects, which are also commonly used for apodization and increased resolution of the resulting images [16,38,39]. In this work, we employ the above-mentioned method to separate the spectral images of a test object.…”

“…Angle diffractions are determined by the condition of the phase coincidence for reflections from adjacent grooves [34]; these techniques allow a specialized study of various applications in spectral image analysis, such as the diagnosis of biological samples, the classification of food or objects based on colorimetry, object segmentation, the monitoring of vegetation, and analysis of soil. [35][36][37][38][39][40][41][42][43].…”

Acousto-Optic Transfer Function Control by a Phased-Array Piezoelectric Transducer

“…This is the most common AOTF type, widely available and used in various hyperspectral imaging experiments [11,12]. Several previous applications of AO devices for optical image processing include image edge enhancement in coherent light [13][14][15][16][17][18][19][20] and phase imaging [21][22][23]. Novel designs of optical traps based on LBS by an AOSF have been recently demonstrated by Obydennov et al [24,25].…”

Hyperspectral holographic microscopy of bio-objects based on a modified Linnik interferometer

“…In this respect, registration of digital holograms using sources with tunable frequencies is more effective. Frequency tuning via acousto-optic filtration results in greater spectral resolution, but the signal-to-noise ratio remains relatively low because of a large loss of light [6,7].…”