Polarimetry

About: Polarimetry is a research topic. Over the lifetime, 4637 publications have been published within this topic receiving 72147 citations.

Plasmonic photon sorters for spectral and polarimetric imaging

Abstract: Colour cameras mimic the human eye and record only a small part of the information contained in the incoming light. Modern image sensing techniques, which subdivide the light spectrally or record information about the polarization of the incoming light, can extract much more information for applications ranging from biological studies to remote sensing1,2,3,4,5. Spectral imaging techniques6 typically rely on filters or interferometers combined with scanning or subsampling to record a spectral image ‘cube’ (which has wavelength as a third dimension). This leads to inefficient use of the incoming light and/or long recording times. Here, we show that surface plasmons enable direct recording of spectral image cubes in a single exposure. By texturing metal surfaces at the nanometre scale, incoming light is converted to surface plasmons and can then be separated according to wavelength and polarization, before being recoupled to light through subwavelength apertures that illuminate individual photodetector elements. This photon-sorting capability provides a new approach for spectral and polarimetric imaging with extremely compact device archictures.

Satellite retrieval of aerosol properties over the ocean using polarization as well as intensity of reflected sunlight

Abstract: Most current and proposed satellite remote sensing of tropospheric aerosols relies upon radiance measurements that are interpreted using algorithms that determine best fits to precalculated scattered sunlight for one or more "standard" aerosol models. However, the number of different types of aerosol and the substantial space and time variations typically encountered can pose a severe uniqueness problem even for the multiple constraints provided by multispectral radiances of a scene at a number of observation zenith angles. Experience with polarimetremote sensing on planetary missions has demonstrated that the measurement of polarization as well as the radiance can resolve such uniqueness problems. We use numerically accurate solutions of the vector radiative transfer equation for a realistic atmosphere-ocean model to theoretically simulate several types of satellite aerosol retrievals over the ocean utilizing radiance measurements alone, polarization measurements alone, and radiance and polarization measurements combined. We have restricted all simulations to a single near-infrared wavelength of 0.865 tm and assumed that aerosols are 'spherical, monomodal, and nonabsorbing. These simplifications permit a study of practical scope that tests the retrieval algorithms under exactly the same conditions, thus clearly demonstrating their relative capabilities. In agreement with previous analyses, we have found that radiance-only algorithms using multiple-viewing-angle observations perform far better than those based on single-viewing-angle measurements. However, even multiple-viewing-angle radiance measurements taken at a single wavelength are not always sufficient to determine the aerosol optical thickness, effective radius, and refractive index with high enough accuracy. In contrast, high-accuracy, single-wavelength, multiple-viewing-angle polarimetry alone is capable of uniquely retrieving all three aerosol characteristics with extremely high accuracy (+_0.015 in aerosol optical thickness, +_0.03 gm in effective radius, and +_0.01 in refractive index). Furthermore, the accuracy of the optical thickness retrieval can be slightly improved by simultaneously using radiance measurements: Our analysis demonstrates that algorithms utilizing high-accuracy polarization as well as radiance measurements are much less dependent on the availability and use of a priori information and can be expected to provide a physically based retrieval of aerosol characteristics (optical thickness, refractive index, and size) with accuracy needed for long-term monitoring of global climate forcings and feedbacks.

Polarisation: Applications In Remote Sensing

Abstract: 1. Polarised Electromagnetic Waves 2. Depolarisation and Scattering Entropy 3. Depolarisation in Surface and Volume Scattering 4. Decomposition Theorems 5. Introduction to Radar Interferometry 6. Polarimetric Interferometry 7. Coherence Variation for Surface and Volume Scattering 8. Parameter Estimation using Polarimetric Interferometry 9. Applications of Polarimetry and Interferometry Appendix 1: Introduction to Matrix Algebra Appendix 2: Unitary and Rotation Groups Appendix 3: Coherent Stochastic Signal Analysis

Spectroscopic polarimetry with a channeled spectrum.

Abstract: We describe a novel method for the spectroscopic measurement of the state of polarization (SOP) of light. A pair of thick birefringent retarders is incorporated into the spectroscopic polarimeter, so the generated channeled spectrum is composed of three quasi-cosinusoidal components carrying the information about the SOP of the light that is being measured. Fourier inversion of the channeled spectrum provides significant parameters for determination of the spectrally resolved Stokes parameters of light. No mechanically movable components for polarization control or active devices for polarization modulation are used, and all the Stokes parameters can be determined at once from only the single spectrum. The effectiveness of this method is demonstrated by the generation of elliptically polarized light whose SOP varies with wave number.