Characterization of optical polarization properties for liquid crystal-based retarders

López-Téllez, Juan Manuel; Bruce, Neil C.; Rodríguez-Herrera, Oscar G.

doi:10.1364/ao.55.006025

Cited by 26 publications

(6 citation statements)

References 11 publications

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“…In the results presented in this paper we used a range of 20 ±° in each of the parameters of the polarimeter (two axes angles and two retardance values), with a step of 2°, giving a total of 4 21 194481 = sample points for each case studied. This error range was found to be adequate for the possible systematic axes errors found in the characterization of our liquidcrystal variable retarders [17] and in the retardance errors due to temperature and voltage variations. They also allowed us to have accurate fits to Gaussian functions to obtain estimations of the overall error limits for each parameter.…”

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confidence: 86%

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Permitted experimental errors for optimized variable-retarder Mueller-matrix polarimeters

et al. 2018

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An optimized Mueller-matrix polarimeter is simulated. The polarimeter is optimized by finding the configurations of the polarization state generator and polarization state analyzer that give the minimum condition number. Noise is included in the measurement of the polarimeter intensities, and the eigenvalue calibration procedure is used to reduce the errors in the final Mueller matrix. Controlled errors are introduced to the polarimeter configuration, and the error in the final measured Mueller matrix is calculated as a function of these configuration errors. It is found that the alignment of the retarder axes in the polarimeter is much more important than the use of the ideal, optimized retardance values. In particular, the misalignment of the retarders farthest from the sample is the error source with the highest impact in the precision of the polarimeter.

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confidence: 86%

“…The Mueller matrices for the four calibration samples are reconstructed using Eq. (17) and the ideal polarimeter parameters.…”

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confidence: 99%

Permitted experimental errors for optimized variable-retarder Mueller-matrix polarimeters

et al. 2018

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“…According to the observations under the metallographic microscope, it has been confirmed the LCVRs exhibit both LB and CB properties during the modulation processes. It is worth emphasizing that there is little LD property in the modulation processes of the LCVRs [23]. In order to simplify the calibration model, the LD property is not considered in the characterization experiments.…”

Section: Characterization Of the Lcvrs Based On Mueller Matrixmentioning

confidence: 99%

“…Terrier et al additionally considered the driving voltage dependence of the azimuth based on previous characterization methods with the objective to improve the performance of an imaging spectrometer [22]. López-Téllez et al characterized the optical polarization properties of the LCVRs with consideration of LB, linear diattenuation (LD) and depolarization, but there is little discussion about the dynamic characteristics of LCVRs [23]. Heredero et al investigated the correlation between the response times and temperature under different applied voltage changes [24].…”

Section: Introductionmentioning

confidence: 99%

Dynamic characteristics of nematic liquid crystal variable retarders investigated by a high-speed polarimetry

Zhang

Chen

Jiang

et al. 2019

J. Opt.

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Liquid crystal variable retarders (LCVRs) have been widely used as a transmissive element with electrically tunable optical phase retardance in polarimetric optical systems. Since the responsive characteristics of the LCVRs depend on the modulation processes, accurately and rapidly characterizing LCVRs is of great significance for the performance improvement of the optical system with LCVRs. Firstly, we proposed a Mueller matrix based model to characterize an LCVRs with considerations of both linear birefringence (LB) and circular birefringence (CB), with which the LCVRs is described by several driving voltage-dependent optical parameters such as retardance, azimuth, relative transmittance and optical rotation angle. The experimental results show that the Mueller matrices of the LCVRs measured by a commercial Mueller matrix ellipsometer are consistently fitted by the proposed method, and the improvement of the proposed characterization method can be read from the 15 times reduced average residual errors of the reconstructed Muller matrix compared to the matrix reconstructed with the conventional characterization methods. Through several typical dynamic measurement experiments using a high-speed Stokes polarimeter with a temporal resolution of several nanoseconds, we demonstrated the driving-voltage-dependence of these optical parameters as well as the existence of both LB, CB and depolarization properties in the LCVRs modulation processes. Based on the analysis of the extracted optical parameters, we have obtained the continuous modulation characteristics and step response characteristics of LCVRs. Additionally, a comparison between the Mueller matrices of air measured with the proposed and conventional characterization method has been carried out to demonstrate the fidelity of the proposed method as well.

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“…One liquid-crystsal variable retarder and Peinado et al, 14 Gendre et al, 15 Woźniak et al, 16 López-Téllez et al 17 [✓] [ ✓]…”

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An FPGA‐based pipeline for micropolarizer array imaging

Lapray

Gendre

Foulonneau

et al. 2018

Circuit Theory & Apps

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The enhancement of current camera performances, in terms of framerate, image resolution, and pixel width, has direct consequences on the amount of resources needed to process video data. Stokes imaging permits to estimate polarization of light and create multiple polarization descriptors of the scene. Therefore, such video cameras need fast processing for critical applications like overseeing, defect detection or surface characterization. A field-programmable gate array hardware implementation of Stokes processing is presented here that embeds dedicated pipeline for micropolarizer array sensors. An optimized fixed-point pipeline is used to compute polarimetric images, ie, Stokes vector, degree of polarization, and angle of polarization. Simulation and experimental studies are done. The hardware design contains parallel processing, low latency, and low power and could meet actual real-time and embeddable requirements for smart camera systems. KEYWORDSFPGA, hardware implementation, micropolarizer array, stokes imaging INTRODUCTIONAnalyzing the polarization of the light coming directly from a source or scattered by an object, using an efficient polarimeter instrument, has become of great interest. Because of their nature, polarimeters provide information that are not available with conventional imaging systems. It is used for example in astrophysics, 1-3 remote sensing, 4 interferometry, 5 biomedical applications, 6-8 or nanostructures and metamaterials characterization. 9,10 Their benefits are growing bigger as the technology allows faster, more detailed, and more precise measurements. 11 Polarization of light is linked to the wave-propagation vector of the electromagnetic waves. Stokes theory 12 is a method for describing polarization properties of light. In this formalism, the polarization is totally described by a 4-component vector, called Stokes vector and commonly denoted as S = [s 0 s 1 s 2 s 3 ] T .Stokes imaging is done by using 1 imaging sensor (or several sensors, depending on the technology) and several optical elements, like linear polarizers, wave plates or retarders, prisms, and liquid crystals. Each pixel of the imaging system needs to be processed in order to bring out, finally, the 4 components of the Stokes vector. Linear polarimeter is the class of device that is designed to measure only the first 3 polarization Stokes parameters: s 0 , s 1 , and s 2 . These parameters are stored in full-resolution images and are used to calculate other useful descriptors like degree of linear polarization (DOLP) or angles of linear polarization (AOLP).There are different imaging device architectures that allow the polarization to be analyzed, each of which has its own drawbacks and advantages. A review of recent acquisition systems for polarimetric imaging is done in Table 1. The same diversity of instruments exists for multispectral acquisition systems. 34 There are 2 main methods to acquire multichannel polarimetric images: the scanning technique and the snapshot technique. The scanning technique implies that...

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Characterization of optical polarization properties for liquid crystal-based retarders

Cited by 26 publications

References 11 publications

Permitted experimental errors for optimized variable-retarder Mueller-matrix polarimeters

Permitted experimental errors for optimized variable-retarder Mueller-matrix polarimeters

Dynamic characteristics of nematic liquid crystal variable retarders investigated by a high-speed polarimetry

An FPGA‐based pipeline for micropolarizer array imaging

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