scholarly journals Polarimetric Imaging vs. Conventional Imaging: Evaluation of Image Contrast in Fog

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 813
Author(s):  
Maria Ballesta-Garcia ◽  
Sara Peña-Gutiérrez ◽  
Aina Val-Martí ◽  
Santiago Royo
Keyword(s):  
Linear Polarization ◽  
Focal Plane ◽  
Polarized Light ◽  
Image Contrast ◽  
Small Scale ◽  
Conventional Imaging ◽  
Imaging Evaluation ◽  
Polarimetric Imaging ◽  
Linearly Polarized ◽  
Intensity Images

We compare conventional intensity imaging against different modes of polarimetric imaging by evaluating the image contrast of images taken in a controlled foggy environment. A small-scale fog chamber has been designed and constructed to create the necessary controlled foggy environment. A division-of-focal-plane camera of linear polarization and a linearly polarized light source has been used for performing the experiments with polarized light. In order to evaluate the image contrast of the different imaging modes, the Michelson contrast of samples of different materials relative to their background has been calculated. The higher the image contrast, the easier it is to detect and segment the targets of interest that are surrounded by fog. It has been quantitatively demonstrated that polarimetric images present an improvement in contrast compared to conventional intensity images in the situations studied.

Applications of Dispersion Staining Technique in Image Analysis of Colorless Particles

2001 ◽  
Vol 7 (S2) ◽  
pp. 836-837
Author(s):  
Shu-Chun Su
Keyword(s):  
Image Analysis ◽  
Focal Plane ◽  
Imaging Techniques ◽  
Polarized Light ◽  
Staining Technique ◽  
Visible Range ◽  
Objective Lens ◽  
Conventional Imaging ◽  
Immersion Liquid ◽  
Staining Techniques

particles and their surrounding immersion liquid medium into a color in the When analyzing particle size distribution of colorless, translucent or transparent particles by image analysis, a major challenge is to obtain images of particles that ensure proper object detection, especially if the particles are amorphous or non-crystalline. Conventional imaging techniques, such as brightfield, darkfield, cross-polarized light, etc., might not applicable for these types of materials.Dispersion staining (DS) is a technique that coverts the refractive index (RI) difference between visible range and renders particles optically stained with that particular color. There are two modes of dispersion staining techniques: central stop (CS) and annular Stop (AS). For image analysis, CS is preferred.In the CS mode, the matching wavelength λm, i.e., the wavelength at which the RI of a particle equals that of liquid, is not refracted at the particle/liquid interface and therefore blocked by a 3-4 mm opaque round disk located at the center of the back focal plane of objective lens.

scholarly journals Polarization perception in humans: on the origin of and relationship between Maxwell’s spot and Haidinger’s brushes

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Gary P. Misson ◽  
Shelby E. Temple ◽  
Stephen J. Anderson
Keyword(s):  
Linear Polarization ◽  
Light Absorption ◽  
Polarized Light ◽  
Retinal Images ◽  
Clinical Use ◽  
Differential Absorption ◽  
Model Simulations ◽  
Eye Disorders ◽  
Absorption Of Light ◽  
Linearly Polarized

AbstractUnder specific conditions of illumination and polarization, differential absorption of light by macular pigments is perceived as the entoptic phenomena of Maxwell’s spot (MS) or Haidinger’s brushes (HB). To simulate MS and HB, an existing computational model of polarization-dependent properties of the human macula was extended by incorporating neuronal adaptation to stabilized retinal images. The model predicted that polarized light modifies the appearance of MS leading to the perception of a novel phenomenon. The model also predicted a correlation between the observed diameters of MS and HB. Predictions were tested psychophysically in human observers, whose measured differences in the diameters of each entoptic phenomenon generated with depolarized and linearly polarized light were consistent with the model simulations. These findings support a common origin of each phenomenon, and are relevant to the clinical use of polarization stimuli in detecting and monitoring human eye disorders, including macular degeneration. We conclude: (i) MS and HB both result from differential light absorption through a radial diattenuator, compatible with the arrangement of macular pigments in Henle fibres; (ii) the morphology of MS is dependent on the degree of linear polarization; (iii) perceptual differences between MS and HB result from different states of neural adaptation.

scholarly journals Interstellar Circular Polarization and the Composition of Interstellar Dust

1973 ◽  
Vol 52 ◽  
pp. 161-167 ◽  
Author(s):  
P. G. Martin
Keyword(s):  
Circular Polarization ◽  
Linear Polarization ◽  
Interstellar Dust ◽  
Principal Axis ◽  
Complex Refractive Index ◽  
Polarized Light ◽  
Position Angle ◽  
Optical Observations ◽  
Small Component ◽  
Linearly Polarized

This paper shows that optical observations of circular polarization produced by aligned interstellar grains could yield valuable information about the grain material. The interstellar medium is known to be linearly dichroic from observations of interstellar linear polarization; many different grain models using a large variety of compositions can be found to reproduce these observations. Since the same aligned grains make the medium linearly birefringent, a small component of circular polarization can result from incident linearly polarized light if the position angle of the linear polarization does not coincide with either principal axis of the medium. Here calculations are presented to demonstrate that the wavelength of the circular polarization is sensitive to the imaginary part of the complex refractive index of the grain material. This provides an opportunity of investigating whether the grains are characteristically dielectric or metallic. Some possible observations are suggested.

scholarly journals Neural processing of linearly and circularly polarized light signal in a mantis shrimp Haptosquilla pulchella

2020 ◽  
Vol 223 (22) ◽  
pp. jeb219832
Author(s):  
Tsyr-Huei Chiou ◽  
Ching-Wen Wang
Keyword(s):  
Circular Polarization ◽  
Linear Polarization ◽  
Polarized Light ◽  
Polarization Vision ◽  
Animal Group ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Mantis Shrimp ◽  
Linearly Polarized ◽  
Vector Angle

ABSTRACTStomatopods, or mantis shrimp, are the only animal group known to possess circular polarization vision along with linear polarization vision. By using the rhabdomere of a distally located photoreceptor as a wave retarder, the eyes of mantis shrimp are able to convert circularly polarized light into linearly polarized light. As a result, their circular polarization vision is based on the linearly polarized light-sensitive photoreceptors commonly found in many arthropods. To investigate how linearly and circularly polarized light signals might be processed, we presented a dynamic polarized light stimulus while recording from photoreceptors or lamina neurons in intact mantis shrimp Haptosquilla pulchella. The results indicate that all the circularly polarized light-sensitive photoreceptors also showed differential responses to the changing e-vector angle of linearly polarized light. When stimulated with linearly polarized light of varying e-vector angle, most photoreceptors produced a concordant sinusoidal response. In contrast, some lamina neurons doubled the response frequency in reacting to linearly polarized light. These responses resembled a rectified sum of two-channel linear polarization-sensitive photoreceptors, indicating that polarization visual signals are processed at or before the first optic lobe. Noticeably, within the lamina, there was one type of neuron that showed a steady depolarization response to all stimuli except right-handed circularly polarized light. Together, our findings suggest that, between the photoreceptors and lamina neurons, linearly and circularly polarized light may be processed in parallel and differently from one another.

Linear Polarization and the Dynamics of Circumstellar Disks of Classical Be Stars

2014 ◽  
Vol 9 (S307) ◽  
pp. 377-378
Author(s):  
Robbie J. Halonen ◽  
Carol E. Jones
Keyword(s):  
Linear Polarization ◽  
Polarized Light ◽  
Circumstellar Disks ◽  
Be Stars ◽  
Stellar Radiation ◽  
Circumstellar Gas ◽  
Linearly Polarized ◽  
Spherically Symmetric Distribution ◽  
Be Star ◽  
Dynamical Nature

AbstractThe intrinsic linearly polarized light arising from electron scattering of stellar radiation in a non-spherically symmetric distribution of gas is a characterizing feature of classical Be stars. The distinct polarimetric signature provides a mean for directly probing the physical and geometric properties of the gaseous material enveloping these rapidly-rotating massive stars. Using a Monte Carlo radiative transfer computation and a self-consistent radiative equilibrium solution for the circumstellar gas, we explore the role of this observable signature in investigating the dynamical nature of classical Be star disks. In particular, we focus on the potential for using linearly polarized light to develop diagnostics of mass-loss events and to trace the evolution of the gas in a circumstellar disk. An informed context for interpreting the observed linear polarization signature can play an important role in identifying the physical process(es) which govern the formation and dissipation of the gaseous disks surrounding classical Be stars.

scholarly journals Энергетический обмен при встречном двухволновом взаимодействии в кристалле Bi-=SUB=-12-=/SUB=-GeO-=SUB=-20-=/SUB=- среза (001)

2021 ◽  
Vol 47 (13) ◽  
pp. 47
Author(s):  
В.Н. Навныко ◽  
А.В. Макаревич ◽  
В.В. Юдицкий ◽  
С.М. Шандаров
Keyword(s):  
Energy Transfer ◽  
Linear Polarization ◽  
Polarized Light ◽  
Holographic Grating ◽  
Object Wave ◽  
Crystal Thickness ◽  
Light Waves ◽  
Linearly Polarized ◽  
Volume Reflection ◽  
Bi12geo20 Crystal

The regularities of energy transfer between two linearly polarized light waves as their contra-directional mixing on a volume reflection holographic grating formed in a photorefractive Bi12GeO20 crystal of the (001)-cut are analyzed. The values of the crystal thickness and the azimuths of the linear polarization of the light waves, at which the amplification of the object wave is achieved, are determined. The change in the direction of energy transfer to the opposite, depending on the thickness of the crystal, has been experimentally demonstrated.

Split and Merge of Left–Right Circular Polarized Light through Coupled Magnetic Resonators

2012 ◽  
Vol 67 (8-9) ◽  
pp. 491-497
Author(s):  
Jijun Wang ◽  
Jing Cao ◽  
Min Zhu ◽  
Zhipan Zhu ◽  
Yun-tuan Fang
Keyword(s):  
Circular Polarization ◽  
Linear Polarization ◽  
Transfer Matrix Method ◽  
Polarized Light ◽  
Light Polarization ◽  
Transmission Properties ◽  
Left Handed ◽  
Linearly Polarized ◽  
Split And Merge ◽  
Control Light

In order to obtain the means to control light polarization, we designed a structure of coupled magnetic resonators and studied its transmission properties by the 4x4 transfer matrix method. The incidence of linearly polarized light results in two transmission resonant peaks of left-handed circular polarization at shorter wavelengths and two transmission resonant peaks of right-handed circular polarization at longer wavelengths, respectively. Through adjusting the magnetizations, the inner left-handed circular polarization and right-handed circular polarization can be merged into one linear polarization, while the two outside resonant peaks keep their circular polarization. The polarized direction of the output linearly polarized light can be controlled by the polarized direction of incidence light. The incidence light with one polarization can output light with three kinds of polarizations through the designed structure.

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