Birefringence interferometers for ultra-high-speed FT spectrometry and hyperspectral imaging

Thermal luminescence spectroscopy chemical imaging sensor

“…2, and specified in Table 1, entries 13-46, performs UHS interferometry on the collimated iPFOV-beam incoming from SCO. POL [13][14][15][16][17][18][19][20][21][22][23][24][25][26] and POL 33-46 are, respectively, front and back Ge linear-polarizers manufactured by II-VI, Inc. (Saxonburg, PA), and VSPA 28-29 is the interferometer engine's VSPA bar PEM now under development by co-author Buican. The VSPA bar PEM is composed of a single stress-birefringence ZnSe crystal with an array of ultrasonic-frequency piezoelectric transducers (PZTs) bonded across the length of crystal.…”

“…The VSPA bar PEM is composed of a single stress-birefringence ZnSe crystal with an array of ultrasonic-frequency piezoelectric transducers (PZTs) bonded across the length of crystal. The PZT generates elastic waves (EWs) within the ZnSe medium [14][15][16][17][18]. Behaviors of these induced EWs were modeled using COMSOL multiphysics simulation software version 3.5a (COMSOL, Inc.) and MATLAB version R2009a (MathWorks, Inc.) numerical analysis software linked together.…”

“…PPMs corresponding to these equilibrium configurations (top left) show uniform vertical polarization across exit plane VSPA 29 . We expect this in the absence of birefringence since light incident to VSPA 28 is polarized vertical linear via optic POL [13][14][15][16][17][18][19][20][21][22][23][24][25][26] . Frames 21 and 61 correspond to maximum deformation on either side of the equilibrium configuration of VSPA 28-29 in piezoelectric transduction.…”

A high retardation-amplitude photoelastic modulator study for an ultra-high speed infrared spectroscopy remote sensing measurement system

“…The photoelastic modulator (PEM) is a resonant polarization modulator operating on the basis of the photoelastic effect [1], which has the advantages of no mechanical vibration, a wide range of applicable wave bands (from the UV to the IR), and a high modulation frequency (tens to hundreds of kHz) [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The PEM-based Fourier transform spectrometer (PEM-FTS) is capable of providing greater than 10 5 interferograms/ spectra scanned per second [10], as opposed to a few thousand scans per second available spectral resolutions useful in the infrared is difficult. Therefore, the PEM-FTS technology provides necessary measuring instruments for the ultra-high speed spectroscopy fields.…”

“…The drive voltage is so large with the strain becoming stronger, the nonlinear phenomena of crystal properties caused serious frequency drift, and difficult system control. Another approach is that multiple PEMs are stacked together [10]. Individual PEMs are stacked together and are driven in phase in the order that their OPDs are added.…”