A two-polarization Michelson interferometer with a low-retardance beam splitter and digital signal processing is used to measure the retardance of optical devices. Error analysis of the improved optical system and data processing shows that the measurement has an uncertainty of 0.039 degrees for measurements of nominally 90 degrees retarders. Retardance variations arising from coherent reflections in the retarder used for intercomparison add an uncertainty of from 0.005 degrees to 0.03 degrees , increasing the combined measurement uncertainty to as much as 0.049 degrees .

Accurate Interferometric Retardance Measurements

Myocardial infarction (MI), a cause of significant morbidity and mortality, is typically followed by microstructural alterations where the necrotic myocardium is steadily replaced with a collagen scar. Engineered remodeling of the fibrotic scar via stem cell regeneration has been shown to improve/restore the myocardium function after MI. Nevertheless, the heterogeneous nature of the scar patch may impair the myocardial electrical integrity, leading to the formation of arrhythmogenesis. Radiofrequency ablation (RFA) offers an effective treatment for focal arrhythmias where local heating generated via electric current at specific spots in the myocardium ablate the arrhythmogenic foci. Characterization of these myocardial pathologies (i.e., infarcted, stem cell regenerated, and RFA-ablated myocardial tissues) is of potential clinical importance. Optical polarimetry, the use of light to map and characterize the polarization signatures of a sample, has emerged as a powerful imaging tool for structural characterization of myocardial tissues, exploiting the underlying highly fibrous tissue nature. This study aims to review the recent progress in optical polarimetry pertaining to the characterization of myocardial pathologies while describing the underlying biological rationales that give rise to the optical imaging contrast in various pathologies of the myocardium. Future possibilities of and challenges to optical polarimetry in cardiac imaging clinics are also discussed.

https://www.spiedigitallibrary.org/journals/journal-of-biomedical-optics/volume-22/issue-10/100901/Review-of-the-emerging-role-of-optical-polarimetry-in-characterization/10.1117/1.JBO.22.10.100901.pdf

Review of the Emerging Role of Optical Polarimetry in Characterization of Pathological Myocardium

The invention discloses a fast polarization detector and a detecting method adopting the detector. The fast polarization detector comprises a polarization detecting module, a light intensity detector and a signal processing device connected with the output end of the light intensity detector, the polarization detecting module, the light intensity detector and the signal processing device are sequentially arranged on a light path, the polarization detecting module comprises at least three polarization detecting channels, and the polarization detecting channels carry out simultaneous split beam polarization detection on the same polarization light beam to be detected, so that emergent light split beams passing through the polarization detecting channels comprise different polarization information. The light intensity detector can detect the light beams with the number not smaller than that of the polarization detecting channels, the light intensity detector records the light intensity information of the emergent light beams and outputs the light intensity information of the emergent light beams to the signal processing device, and the signal processing device determines the polarization state of the polarization light beam to be detected according to the light intensity information of the emergent light beams and the polarization character of the polarization detecting channels. The fast polarization detector can measure the polarization state of light simultaneously, fast and accurately, and is simple in structure and low in cost.

Fast polarization detector and detecting method

An image capture device includes an electro-optics arrangement having an arrangement of polarizers, polarization sensitive optical elements, and polarization modulating elements. First and second polarization sensitive optical elements are provided having an edge displaced relative to a plane normal to an optical axis of the electro-optics arrangement. A control system coupled to the electro-optics arrangement controls the application of voltages to the polarization modulating elements to control the polarization rotation of the light input to the polarization sensitive optical elements, such that the optical path length of the polarization sensitive optical elements is changed to provide for capture of the object images at each of the different focal planes. The first and second polarization sensitive optical elements generate lateral image shifts between respective object images captured at the different focal planes responsive to the polarization rotation of the light input thereto.

Apparatus and method for image super-resolution using integral shifting optics

The invention relates to a double refraction realtime measuring device and method. The device is characterized by comprising an alignment light source, a circular polarizer, a spectroscope, a first Wollaston prism, a second Wollaston prism, a first double quadrant detector, a second double quadrant detector and a signal processing unit. According to the device and the method, double refraction of a sample can be measured in real time, and the measurement result is not affected by light-intensity variation.

Double refraction realtime measuring device and method

Device and method for measuring phase retardation distribution and fast axis azimuth angle distribution of birefringence sample in real time The device consists of a collimating light source, a circular polarizer, a diffractive beam-splitting component, a quarter-wave plate, an analyzer array, a charge coupled device (CCD) image sensor and a computer with an image acquisition card The method can measure the phase retardation distribution and the fast axis azimuth angle distribution of the birefringence sample in real time and has large measurement range The measurement result is immune to the light-intensity fluctuation of the light source

Device and method for measuring phase retardation distribution and fast axis azimuth angle distribution in real time

The utility model discloses a spatial phase-shifting Fizeau spherical interferometer, which is characterized in that the incident plane of a standard mirror is plated with a birefringent film, the incident plane of the standard mirror is a flat surface, and the emergent plane of the standard mirror is a spherical surface; a reflected light path of a first beam splitter is provided with a second beam splitter, a second collimation lens, a dammann grating, an analyzer array, a second image sensor and a computer; a first image sensor is arranged in the reflected light direction of the second beam splitter so as to facilitate the adjustment on a to-be-measured spherical surface; and the computer facilitates the processing on image data. By using the spatial phase-shifting Fizeau spherical interferometer disclosed by the utility model, the surface shape measurement on a measured spherical element can be realized; multiple phase-shifting interference images with a certain phase-shifting amount can be obtained; because circularly polarized reference light and measuring light are adopted, the influence of residual birefringence of the collimation lens and the standard mirror is reduced; and a quarter wave plate is not used in a phase-shifting light path, and therefore, the surface shape measurement accuracy is improved.

Longhai Liu

Papers

Device and method for measuring phase retardation distribution and fast axis azimuth angle distribution in real time

Spatial phase-shifting Fizeau spherical interferometer

Double refraction realtime measuring device and method

Stable, high power, high efficiency picosecond ultraviolet generation at 355 nm in K3B6O10Br crystal

Simultaneous measurement of small birefringence magnitude and direction in real time