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Characterization of linear diattenuator and retarders using a two-modulator generalized ellipsometer (G.E. Jellison Jr., Oak Ridge National Lab, et.al., SPIE Proceedings, vol. 4819, July 2002)
The two-modulator generalized ellipsometer (2-MGE) is a spectroscopic polarization-sensitive optical instrument that is sensitive to both standard ellipsometric parameters from isotropic samples as well as cross polarization terms arising from anisotropic samples. In reflection mode, the 2-MGE has been used to measure the complex dielectric functions of several uniaxial crystals, including TiO2, ZnO, and BiI3. The 2-MGE can also be used in the transmission mode, in which the complete Mueller matrix of a sample can be determined (using 4 zone measurements).

Detectors with photoelastic modulators (T.Oakberg, A. Bryan, SPIE Proceedings, vol. 4819, July 2002)
Photoelastic modulators (PEMs) are polarization modulation devices used in a wide range of experiments to probe the interaction between polarized light and matter. Experimental setups using PEMs rely on common detector types (photodiodes, photomultipliers, etc.) but care must be taken with their use.

Stokes polarimeter using two photoelastic modulators (B. Wang, J. List, R. Rockwell, SPIE Proceedings, vol. 4819, July 2002)
We report in this paper an instrument for measuring the Stokes parameters of a light beam. This Stokes polarimeter employs two low birefringence photoelastic modulators (PEMs) operating at different resonant frequencies. A computer program calculates and displays the intensity parameter and the normalized Stokes parameters of the light beam measured. Common laboratory lasers are measured as examples.

Calibration of photoelastic modulators in the vacuum UV (T.Oakberg, J. Trunk, J.C. Sutherland, SPIE Proceedings, vol. 4133, 101 - 111, August 2000)
Measurements of circular dichroism (CD) in the UV and vacuum UV have used photoelastic modulators (PEMs) for high sensitivity (to about 10-6). While a simple technique for wavelength calibration of the PEMs has been used with good results, several features of these calibration curves have not been understood. The authors have calibrated a calcium fluoride PEM and a lithium fluoride PEM using the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory as a light source.

Relative variation of stress-optic coefficient with wavelength in fused silica and calcium fluoride
(T. Oakberg, SPIE Proceedings, vol. 3754, 226-234, July 1999)
Birefringence in refractive components such as lenses has become an increasingly serious problem in semiconductor lithography as exposure wavelength decreases. Most measurements of birefringence are made with visible light but the light used for photolithography is in the UV and deep UV spectral regions. The method uses photoelastic modulators with optical elements made from fused silica and calcium fluoride.

Basic Optical Properties of the Photoelastic Modulator, Part I: Useful Aperture and Acceptance Angle (Baoliang (Bob) Wang and Jennifer List, SPIE Proceedings vol. 5888, 436-443 (2005))
The photoelastic modulator (PEM) is a resonant polarization modulator. It operates at the resonant frequency of a desired mechanical vibration mode of its optical element. The PEM is made of isotropic optical materials, in contrast to the birefringent materials used in electro-optic modulators. These two characteristics, operation at resonance and the use of isotropic optical materials, give the PEM unique optical properties, such as high modulation purity and efficiency, broad spectral range, high power handling capability, large acceptance angle, large useful aperture and good retardation stability. These properties make the PEM an effective polarization modulator in a variety of high sensitivity applications. In this first paper in a series, we focus on studying two basic optical properties of the PEM: useful aperture and acceptance angle.

Measurement of Circular and Linear Birefringence in Chiral Media and Optical Materials Using the Photoelastic Modulator (B. Wang, SPIE Proceedings, vol. 3535, 294-302, Nov 1998)
Circular birefringence is also called optical rotation. An experimental set-up using the photoelastic modulator (PEM) is developed in our lab for measuring small optical rotation in chiral solutions. Sugar solutions at known concentrations are used as standards to test the feasibility of the method and the sensitivity of the instrument. The sensitivity of this current instrument is determined to be 0.001°.

An Improved Method for Measuring Low-Level Linear Birefringence in Optical Materials (B. Wang, SPIE Proceedings, vol. 3424, 120-124, Jul 1998)
The author reports in this paper a sensitive method for measuring low-level linear birefringence in optical materials. A photoelastic modulator is employed as the polarization modulation device in the set-up. The sensitivity of this method is evaluated to be at ~0.003nm (~0.002° at 632.8nm) by measuring the mechanically induced linear birefringence in a fused silica optical element. The capability of the method is demonstrated in the residual linear birefringence below 0.1nm in several high quality optical elements.

Infrared Reflection-Absorption Spectroscopy using the Photoelastic Modulator (B. Wang, Spectroscopy, vol. 12, no.1, 30-36, Jan 1997)
Infrared reflection-absorption spectroscopy (IRRAS) is an important IR technique for studying and monitoring chemical species adsorbed on a metal surface. This article describes, on the “how-to” level, double-modulation IRRAS instruments and discusses different demodulation approaches for obtaining the IRRAS signal.

Measurement of Waveplate Retardation using a Photoelastic Modulator (T.C. Oakberg, SPIE Proceedings, vol. 3121, 19-22, Aug 1997)
Measurements of low levels of strain birefringence in fused silica glass have been made using a system based on a photoelastic modulator. Measurements of sample net retardation have been made with a resolution of 0.1 nanometers. Measured values of a strain birefringence constant for fused silica are in good agreement with established data.

Measurement of Low-Level Strain Retardation in Optical Materials (T.C. Oakberg, SPIE Proceedings, vol. 3121, 19-22, Aug 1997)
A method for measurement of low-level strain birefringence in optical elements and materials will be described. This method provides for the simultaneous measurement of magnitude and direction of the net retardation without the necessity of sample rotation. Good agreement was obtained between measured retardation and independent measurements of a polymer waveplate. Measurements were also made of uncalibrated samples with retardation magnitudes down to 1.5 nanometers.

Measurement of Low-Level Strain Birefringence in Optical Elements Using a Photoelastic Modulator (T.C. Oakberg, SPIE Proceedings, vol. 2873, 17-20, Jun 1996)
A system for measurement of waveplate retardation using a photoelastic modulator will be described. The system is intended for incoming quality inspection of quarter-wave plates at 632.8 nm and 900 nm. Measurement of several polymer waveplates were in good agreement with the waveplate manufacturer's calibration data.