Photoelastic modulator for the 055–13-μm range

Cheng, Jianchun; Nafie, Laurence A.; Allen, Susan D.; Braunstein, A.

doi:10.1364/ao.15.001960

Cited by 60 publications

(18 citation statements)

References 5 publications

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“…My task then became to confirm this reported discovery. After developing a new photoelastic modulator (PEM) and polarization scrambling technique with invaluable assistance from Dr Jack Cheng, another postdoc of Philip's group, we not only confirmed Holzwarth's discovery in the C*H stretching band near 2950 cm −1 but significantly surpassed both its signal quality and spectral range to include in addition the broad OH stretching region between 3300 and 3600 cm −1 . With a superior instrument in hand, Dr Timothy Keiderling, who was working to search for VCD further into the mid‐IR in the so‐called fingerprint region below 2000 cm −1 , joined our effort.…”

Section: Mentorsmentioning

confidence: 73%

Vibrational optical activity: From discovery and development to future challenges

Nafie

2020

Chirality

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Vibrational optical activity (VOA) consisting of infrared vibrational circular dichroism (VCD) and vibrational Raman optical activity (ROA) was predicted, discovered, and confirmed between 1971 and 1975. My path to VOA was mentored by three pioneers of chirality and vibrational spectroscopy: Professors Albert Moscowitz, Warner L. Peticolas, and Philip J. Stephens, and while they are no longer alive today, the Chirality Medal, my award address, and this paper are dedicated to each of them. Since the discovery of VOA, a number of key advances have made possible the current era of widespread applications. The principal instrumental advances were Fourier-transform VCD (FT-VCD) and multichannel charge coupled detector (CCD) ROA. Computational advances include the first complete quantum chemistry formulation of VCD leading to the magnetic field perturbation (MFP) and the nuclear velocity perturbation (NVP) theories. The strength of VOA is the comparison between measured and calculated spectra that enables the determination of absolute configuration and solution-state conformations. More recently, VCD has uncovered supramolecular chirality in amyloid fibrils and ROA to high-order protein structure. Future challenges for VOA include describing the effects of weak intermolecular interactions, transfer of chirality, solvent effects, supramolecular chirality, and the generation of nuclear velocity electron current density. K E Y W O R D S vibrational circular dichroism (VCD), Raman optical activity (ROA)

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Section: Mentorsmentioning

confidence: 73%

Vibrational optical activity: From discovery and development to future challenges

Nafie

2020

Chirality

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“…It consists of only even harmonics of modulation frequency. A number of features can be used to calibrate the modulation amplitude φ A : (1) the distinctive waveform on the oscilloscope with φ A being an integral multiple of π radians [22][23][24]; (2) the Bessel function zeros, such as J 0 φ A , being zero when φ A is equal to 2.405, and J 2 φ A being zero when φ A is equal to 5.136; and (3) the Bessel function maxima with J 1 φ A being maximized when φ A is equal to 1.841 [25]. These are singlepoint calibration techniques.…”

Section: Calibration Of the Photo-elastic Modulatormentioning

confidence: 99%

Calibration of oblique-incidence reflectivity difference for label-free detection of a molecular layer

et al. 2016

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Oblique-incidence reflectivity difference (OI-RD) is a form of polarization-modulation ellipsometry that measures properties of thin films on a solid surface through the change in polarization state of light upon reflection from the surface. The measurement accuracy depends on the precision of the phase modulation amplitude and azimuthal alignments of key polarizing optical elements and, thus, requires careful calibration. In the present work, we describe robust methods of such calibrations that enable precise determination of the modulation amplitude and static retardation of a phase modulator and azimuths of key polarizing optics in an OI-RD system.

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“…Current devices available for variable retardation in various wavelength regions include mechanical devices such as Babinet-Soleil compensators, 7 electro-optic (EO) devices such as liquid crystals 8,9 and Pockels cells, 10 and photoelastic modulators. 11 Among these, Babinet-Soleil compensators and EO devices are capable of providing a fixed, yet tunable retardation.…”

Section: Introductionmentioning

confidence: 99%

Cadmium zinc telluride as a mid-infrared variable retarder

Fitzgerald

Taherion

Kumar

et al. 2018

Journal of Applied Physics

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The electro-optic behavior of cadmium zinc telluride is examined in the mid-infrared region between 3 and 11 lm, for applied DC field strengths of up to 10 6 V/m. The measurements performed here include full characterization of the polarization state of the transmitted light by means of the Stokes vector. We demonstrate the suitability of this material for DC variable retarder applications such as those achieved by quarter-or half-wave retardation. A comparison of two different metallic coatings for electrodes, gold and indium, reveals important differences in performance that are attributed to the homogeneity of the field through the bulk of the crystal. We illustrate that, in the case of both metals, the same electro-optic coefficients are measured, but regions of higher and lower retardation result in significant depolarization in the case of gold. Such depolarization may adversely affect the contrast ratio in a light valve, or increase the voltage necessary for the operation of an arbitrary polarization state generator.

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Photoelastic modulator for the 055–13-μm range

Cited by 60 publications

References 5 publications

Vibrational optical activity: From discovery and development to future challenges

Vibrational optical activity: From discovery and development to future challenges

Calibration of oblique-incidence reflectivity difference for label-free detection of a molecular layer

Cadmium zinc telluride as a mid-infrared variable retarder

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