Motivation: Results: Contrast measurements

Applied Optics, 2014

In a triangular path cyclic interferometer employing a polarizing beam splitter (PBS), the two counterpropagating beams are orthogonally polarized. A sample placed almost equidistant from the PBS is imaged by a lens placed in the path of the emerging beams so that two defocused images of the sample are recorded on a CCD. Using a linear polarizer in the path of the orthogonally polarized imaging beams, it is possible to achieve amplitude subtraction between the two images, resulting in an edge-enhanced image of the sample. The proposed real-time edge-enhancement technique is experimentally demonstrated.

2021

Are we alone? In our quest to find life beyond Earth, we use our own planet to develop and verify new methods and techniques to remotely detect life. Our Life Signature Detection polarimeter (LSDpol), a snapshot full-Stokes spectropolarimeter to be deployed in the field and in space, looks for signals of life on Earth by sensing the linear and circular polarization states of reflected light. Examples of these biosignatures are linear polarization resulting from O2-A band and vegetation, e.g. the Red edge and the Green bump, as well as circular polarization resulting from the homochirality of biotic molecules. LSDpol is optimized for sensing circular polarization. To this end, LSDpol employs a spatial light modulator in the entrance slit of the spectrograph, a liquid-crystal quarter-wave retarder where the fast axis rotates as a function of slit position. The original design of LSDpol implemented a dual-beam spectropolarimeter by combining a quarter-wave plate with a polarization gra...

Applied Spectroscopy, 1994

Scientific Reports, 2017

Polarisers are one of the most widely used devices in optical setups. They are commonly used with paraxial beams that propagate in the normal direction of the polariser plane. Nevertheless, the conventional projection character of these devices may change when the beam impinges a polariser with a certain angle of incidence. This effect is more noticeable if polarisers are used in optical systems with a high numerical aperture, because multiple angles of incidence have to be taken into account. Moreover, the non-transverse character of highly focused beams makes the problem more complex and strictly speaking, the Malus' law does not apply. In this paper we develop a theoretical framework to explain how ideal polarisers affect the behavior of highly focused fields. In this model, the polarisers are considered as birefringent plates, and the vector behaviour of focused fields is described using the plane-wave angular spectrum approach. Experiments involving focused fields were conducted to verify the theoretical model and a satisfactory agreement between theoretical and experimental results was found.

Optics & Laser Technology, 2020

• A low-cost simultaneous-phase-shifting system is implemented to analyze phase samples. • The optical components were recovered from recycled electronic devices. • Results of optical phase recovery from 2, 4, 7 and 9 interferograms are presented. • An Interferometric system for measurement the dynamic phase profile is described. • The dynamic method presented can be applied to several interferometric systems.

Image Processing: Machine Vision Applications, 2008

Image Reconstruction and Restoration II, 1997

Polarization Generator Linear Rotating polarizer quarter-wave (fixed) retarder variable angle Target Scattered light m, Polarization Analyzer Rotating quarter-wave retarder Linear polarizer (fixed) Chilled 14-bit CCD, 512 x 512 pixels Calculate and display images of Mueller matrices, diattenuation, retardance, and depolarization. Obtain Mueller matrix images of radiation scattered from scenes and targets. Investigate scatter polarization relationship to object geometry. Measure images of retardance, diattenuation, and depolarization. Estimate object orientation and refractive index. Classify target texture.

Sid Symposium Digest of Technical Papers, 2004

The next generation of MURATest will be able to make a hyper spectral analysis to get a high definition image with adjustable wavelength resolution. This paper introduces the principle of the new system, based on an imaging polarizing interferometer. The phase shift is realized by two symmetrical Wollaston prisms. The system produces an interference pattern directly on the CCD camera. The phase shift is linearly changed for all pixels using a mechanical translation.

Optics Communications, 2000

A graphical representation of general non-absorbing polarization devices operating under normal plane-wave incidence is presented. The representation is based on a four-dimensional spherical parametrization of the Jones matrix of this kind of polarization devices. The graphical representation takes the form of a solid cylinder. The projection of the point representing the device over the base of the cylinder gives the corresponding polarization eigenvectors represented in the complex plane, while the height of the point in the cylinder is the phase of its eigenvalue. Some simple examples like wave-plates and rotators are discussed. The representation may represent a useful tool to identify the operation regimes of polarization modifying elements, for instance electro-optic devices. In this sense, the representation is also applied to the case of a twisted nematic liquid crystal display. q larized light. In these two descriptions, polarization devices act as linear transformations, represented by Jones or Mueller matrices, respectively.

2000

The polarimetric vector is a more general descriptor of light than intensity information alone, and it con- tains physical information about the imaged objects in a scene that traditional intensity based sensors ig- nore. Polarimeters - devices that measure polarization - are used to extract physical features from an im- age such as specularities, occluding contours, and material properties. Scientists

Optics Express, 2009

Liquid crystal polarization gratings exhibit high diffraction efficiency (~ 100%) in thin material layers comparable to the radiation wavelength. We demonstrate that they can be combined for polarizationinsensitive imaging and optical switching applications. A pair of closely spaced, parallel oriented, cycloidal polarization gratings is capable of canceling the diffractive property of an individual grating. As a result, the phase of the beam is not distorted, and holographic images can be formed through them. An anti-parallel arrangement results in a broader effective diffraction band and doubles the diffraction angle. Broadband diffraction spanning from 480 nm to beyond 900 nm wavelengths has been obtained for a pair of gratings with 500 nm and 633 nm peak diffraction wavelengths. Liquid crystal polymer cycloidal gratings were used in the study showing 98% diffraction efficiency over a large area, and allowed for the use of laser beams expanded to 25 mm. The characteristics of combined cycloidal gratings were tested with laser beams at both UV and red wavelengths.

Applied Optics, 2004

This study demonstrates a new method for simultaneously measuring both the angle of the principal axis and the phase retardation of the linear birefringence in optical materials. We used a circular commonpath interferometer ͑polariscope͒ as the basic structure modulated by an electro-optic ͑EO͒ modulator. An algorithm was developed to simultaneously measure the principal axis and the phase retardation of a ͞4 or ͞8 plate as a sample. In the case of a ͞4 plate, the average absolute error of the principal axis is approximately 3.77°, and that of the phase retardation is approximately 1.03°͑1.09%͒. The retardation error is within the 5% uncertainty range of a commercial wave plate. Fortunately, the nonlinear error caused by the reflection phase retardation of the beam splitter dose not appear in the new system. Therefore the error could be attributed to misalignment and defects in the EO modulator or the other optical components. As for the repeatability of this new common-path heterodyne interferometer, the average deviation for the principal axis is 0.186°and the phase retardation is 0.356°. For the stability, the average deviation for the principal axis is 0.405°and the phase retardation is 0.635°. The resolution of this new system is estimated to be ϳ0.5°, and the principal axis and phase retardation could be measured up to and 2, respectively, without ambiguity.

Optics Communications, 2019

According to the technical requirements of the tempo-spatially mixed modulated polarization imaging interference spectrometer (TSMMPIIS), we designed and verified the maximum optical path difference (OPD) through two different schemes, and analyzed the influences of the field of view and calcite dispersion on the OPD. When the angles between the incident plane and the principal section of the Savart left plate were 0 • , 45 • and 90 • , we simulated the variations of the OPDs changing with different parameters. We found that the variations were proportional to the thickness 𝑡 and the incident angle 𝑖. In order to reduce the influences of the Savart polariscope dispersion and field of view on the OPD, the corrected models were established, and the correctness was validated by the experiment. This work would provide theoretical and practical guidance for the design and engineering of the TSMMPIIS.

2008