Return-path polarimeter for two-dimensional birefringence distribution measurement
25 Oct 1999-Vol. 3754, pp 144-149
TL;DR: In this paper, a system based on the use of a laser return-path polarimeter which consists of a rotating polarizing beam splitter and a quarter wave plate is described.
Abstract: The paper covers an issue of method and device for measurement of 2D retardance and principal plane azimuth distributions. The system based on the use of a laser return-path polarimeter which consists of a rotating polarizing beam splitter and a quarter wave plate. Two or four sets from four images are used for birefringence analysis. This allows to decrease the errors caused by imperfection of a polarizing beam splitter and a quarter wave plate. The basic expressions that describe the operation of the systems are presented. The main sources of error are discussed. The measured results of the 2D birefringence distribution of a plastic and standard phase plate of retardation are shown.
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TL;DR: In this article, the authors proposed image processing algorithms for measuring two-dimensional distributions of linear birefringence using a pair of variable retarders and obtained the lowest noise level of 0.036 nm.
Abstract: We propose image processing algorithms for measuring two-dimensional distributions of linear birefringence using a pair of variable retarders. Several algorithms that use between two and five recorded frames allow us to optimize measurements for speed, sensitivity, and accuracy. We show images of asters, which consist of radial arrays of microtubule polymers recorded with a polarized light microscope equipped with a universal compensator. Our experimental results confirm our theoretical expectations. The lowest noise level of 0.036 nm was obtained when we used the five-frame technique and four-frame algorithm without extinction setting. The two-frame technique allows us to increase the speed of measurement with acceptable image quality.
398 citations
TL;DR: In this article, a theoretical and experimental study of radially symmetric aberration caused by the differential transmission and phase shift of p-and s-polarized components of an axial beam passing through spherical lenses and plane parallel plates is presented.
Abstract: We present a theoretical and experimental study of radially symmetric aberration caused by the differential transmission and phase shift of p- and s-polarized components of an axial beam passing through spherical lenses and plane parallel plates. We give a general description of the aberrations for an axial beam. The extinction is calculated as a function of the numerical aperture for uncoated lenses and for plane parallel plates. In our theoretical analysis, the polarization of output rays is described as a function of the input ray parameters, the shape factor, and refractive index of the lenses used. For rays that are inclined to the optical axis, optimal lens shape factors that minimize the rays' polariza- tion aberrations are found. Techniques for measurement of radially sym- metric birefringence in a lens system are described. Finally, we discuss strategies for polarization rectification and introduce new designs includ- ing meniscus rectifiers and a liquid crystal rectifier that can actively com- pensate a wide variety of polarization aberrations. Good correlations be- tween theory and experimental results for microscope optical systems with coated and uncoated optical elements are found. Our results enable us to suppress depolarization and remove anomalous diffraction in a modern microscope equipped with high-numerical-aperture lenses.
72 citations
TL;DR: The vastly improved throughput and quantitative analysis afforded by the light field LC‐PolScope make it the instrument of choice for measuring 3D birefringence parameters of complex structures.
Abstract: For the comprehensive analysis of anisotropic materials, a new approach, called 'polarized light field microscopy' is introduced. It uses an LC-PolScope to which a microlens array was added at the image plane of the objective lens. The system is patterned after the 'light field microscope' that achieves both lateral and axial resolution in thick specimens in a single camera exposure. In polarized light field microscopy, the microlens array generates a hybrid image consisting of an array of small conoscopic images, each sampling a different object area. Analysis of the conoscopic images reveals the birefringence of each object area as a function of the propagation direction of transmitted light rays. The principles and utility of the instrument that we are calling 'light field LC-PolScope' are demonstrated with images of a thin, polycrystalline calcite film, revealing the azimuth and inclination angle of the optic axis for many crystals simultaneously, including crystals with diameters as small as 2 microm. Compared to traditional conoscopy and related methods, the vastly improved throughput and quantitative analysis afforded by the light field LC-PolScope make it the instrument of choice for measuring 3D birefringence parameters of complex structures.
54 citations
Cites background from "Return-path polarimeter for two-dim..."
...(Otani et al., 1994; Oldenbourg & Mei, 1995; Glazer et al., 1996; Shribak et al., 1999; Massoumian et al., 2003; Kaminsky et al., 2007)....
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TL;DR: In this article, the authors report the results of measurements of the polarized hemispherical directional reflectance (HDR) which is related to the di- rectional emissivity, and bidirectional reflectance distribution function (BRDF) from two examples of leaves.
Abstract: The ability to perform polarimetric imaging throughout the vis- ible and infrared (IR) wavebands has improved considerably in the past decade. Systems now exist that enable measurements to be made of all four Stokes parameters arising from each pixel in the image. The ques- tion of whether polarimetric imaging offers an advantage over conven- tional imaging methods for discrimination of plant type in scenes of natu- ral vegetation remains to be answered. Although the size of a leaf may be below the spatial resolution of an imaging system, the polarimetric properties of individual leaves may affect the data observed from a tree or forest canopy. We report the results of measurements of the polarized hemispherical directional reflectance (HDR), which is related to the di- rectional emissivity, and bidirectional reflectance distribution function (BRDF) from two examples of leaves. To completely characterize the polarimetric properties of a leaf, and ultimately a leaf canopy, an exten- sive measurement of the polarized BRDF and HDR of individual leaves is required. This is necessary because of the large range of possible relative orientations of the illumination, leaf and observer, and the range of polarization states of incident radiation. We report a limited set of laboratory measurements designed to investigate whether any gross po- larimetric difference exist between two dissimilar types of plant leaves in the visible, near IR (NIR), and IR spectral wavebands. Laurel (prunus laurecatious) has a wax surface creating a gloss or glabrous appearance to the leaf. The surface of mullein (verbascum thapsus) is highly pubes- cent with a dense layer of hair over the adaxial surface, creating a highly diffuse surface reflectance. Significant differences are found between the two species of leaf in the measured polarized directional reflectance and emissivity. © 2002 Society of Photo-Optical Instrumentation Engineers.
53 citations
Patent•
29 Jul 2003TL;DR: In this article, a method and an apparatus for determining the influencing of the state of polarization of optical radiation by an optical system under test, wherein radiation with a defined entrance state of polarities is directed onto the optical system, the exit-side state of polarity is measured, and the determining of the polarity of the system with the aid of evaluation of the exit state with reference to the entrance state is presented.
Abstract: A method and an apparatus for determining the influencing of the state of polarization of optical radiation by an optical system under test, wherein radiation with a defined entrance state of polarization is directed onto the optical system, the exit-side state of polarization is measured, and the influencing of the state of polarization is determined by the optical system with the aid of evaluation of the exit state of polarization with reference to the entrance state of polarization. An analyser arrangement which can be used for this purpose is also disclosed. The method and the apparatus are used, e.g., to determine the influencing of the state of polarization of optical radiation by an optical imaging system of prescribable aperture, the determination being performed in a pupil-resolved fashion.
49 citations