Integrated imaging linear polarimeter (original) (raw)
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ITE Transactions on Media Technology and Applications, 2014
step) with 0.35 µm standard CMOS process 8)-9). Combined with a linearly polarized light source with fixed polarization angle, we can obtain a polarization profile covering the whole angle in single frame measurement, without rotating the polarization of Abstract A polarization-analyzing CMOS image sensor with 65 nm standard fabrication process was designed and characterized. Polarization-analyzing image sensor pixel was realized using wire grid structures designed with a metal wiring layer within the standard CMOS process. Taking advantage of sub-100 nm CMOS process, a fine grid pitch was realized. Polarization-analyzing performance significantly higher than our previous sensors with 0.35 µm CMOS process was obtained. Polarization imaging capability was demonstrated for a scene with local polarization variation. With an aim of further performance improvement, subtraction readout scheme and multiple layer stacked on-pixel polarizer were proposed and discussed.
Dual-tier thin film polymer polarization imaging sensor
Optics Express, 2010
Traditional imaging systems capture and replicate the imaged environment in terms of color and intensity. One important property of light, which the human eye is blind to and is ignored by traditional imaging systems, is polarization. In this paper we present a novel, low power imaging sensor capable of recording the optical properties of partially linearly polarized light in real-time. The imaging sensor combines polymer polarization filters with a CMOS image sensor in order to compute the first three Stokes parameters at the focal plane. The imaging array contains 100 x 100 pixels and consumes 48mW at 30 fps.
Novel micro-polarizer array patterns for CMOS polarization image sensors
2016 5th International Conference on Electronic Devices, Systems and Applications (ICEDSA), 2016
In this paper, we present two novel "quasi-Bayer" micro-polarizer (MP) patterns for the polarization imaging based on the division-of-focal-plane polarimeters (DoFP). Compared with the traditional equally-weighted MP pattern with four different micro-polarizers, the "quasi-Bayer" pattern requires less photo-lithography-based selective etching steps, leading to a significant reduction of the MP array's fabrication complexity. In addition, for the mainstream bilinear interpolation algorithm, the proposed "quasi-Bayer" pattern with three micro-polarizers exhibits the lowest mean square error (MSE) of 0.43%. Moreover, the "quasi-Bayer" patterns take advantages not only at the fixed illumination level, but also for different illumination levels. Reported experimental results validate the effectiveness of the "quasi-Bayer" patterns by varying the input light intensity from 13 lux to 213 lux.
IEEE Transactions on Biomedical Circuits and Systems, 2009
This paper proposes and demonstrates a polarization-analyzing CMOS sensor based on image sensor architecture. The sensor was designed targeting applications for chiral analysis in a microchemistry system. The sensor features a monolithically embedded polarizer. Embedded polarizers with different angles were implemented to realize a real-time absolute measurement of the incident polarization angle. Although the pixel-level performance was confirmed to be limited, estimation schemes based on the variation of the polarizer angle provided a promising performance for real-time polarization measurements. An estimation scheme using 180 pixels in a 1deg step provided an estimation accuracy of 0.04deg. Polarimetric measurements of chiral solutions were also successfully performed to demonstrate the applicability of the sensor to optical chiral analysis.
Integrated High Resolution Focal-Plane Polarization Imager
2000
The polarimetric vector is a more general descriptor of light than intensity information alone, and it con- tains physical information about the imaged objects in a scene that traditional intensity based sensors ig- nore. Polarimeters - devices that measure polarization - are used to extract physical features from an im- age such as specularities, occluding contours, and material properties. Scientists
Image and Vision Computing, 1995
Recently, polarization vision has been shown to simplify some important image understanding tasks that can be more diff'cult to perform with intensity vision alone. This, together with the more general capabilities of polarization vision for image understanding, motivates the building of camera sensors that automatically sense and process polarization information. Described in this paper are a variety of designs for polarization camera sensors that have been built to automatically sense partial linearly polarized light, and computationally process this sensed polarization information at pixel resolution to produce a visualization of reflected polarization from a scene, and/or a visualization of physical information in a scene directly related to sensed polarization. The three designs for polarization camera sensors presented utilize (i) serial acquisition of polarization components using liquid crystals, (ii) parallel acquisition of polarization components using a stereo pair of cameras and a polarizing beamsplitter, and (iii) a prototype photosensing chip with three scanlines, each scanline coated with a particular orientation of polarizing material. As the sensory input to polarization camera sensors subsumes that of standard intensity cameras, they can potentially significantly expand the application potential of computer vision. A number of images taken with polarization cameras are presented, showing potential applications to image understanding, object recognition, circuit board inspection and marine biology.
IEEE Transactions on Electron Devices, 2022
In this article, We demonstrated an image sensor for detecting changes in polarization with high sensitivity. For this purpose, we constructed an optical system with a two-layer structure, comprising an external polarizer and polarizers on a pixel array. An external polarizer is used to enhance the polarization rotation while reducing the intensity to avoid pixel saturation of the image sensor. Using a two-layer structure, the two polarizers can be arranged under optimal conditions and the image sensor can achieve high polarization-change detection performance. We fabricated the polarization image sensor using a 0.35-µm CMOS process and, by averaging 50 × 50 pixels and 96 frames, achieved a polarization rotation detection limit of 5.2 × 10 −4 • at a wavelength of 625 nm. We also demonstrated the applicability of electric-field distribution imaging using an electrooptic crystal (ZnTe) for weak-polarization-change distribution measurements. Index Terms-CMOS image sensor, electric-field imaging, ON-chip polarizer, polarization image sensor, polarization modulation imaging. I. INTRODUCTION O PTICAL polarization detection can provide information that cannot be obtained by ordinary light intensity detection, such as the angle of the incident surface [1], differences in materials [2], distortions in a transparent material [3], and separation of reflected and transmitted components in
Polarization imaging: principles and integrated polarimeters
IEEE Sensors Journal, 2002
Polarization is a general descriptor of light and contains information about reflecting objects that traditional intensity-based sensors ignore. Difficult computer vision tasks such as image segmentation and object orientation are made tractable with polarization vision techniques. Specularities, occluding contours, and material properties can be readily extracted if the Stokes polarization parameters are available. Astrophysicists employ polarization information to measure the spatial distribution of magnetic fields on the surface of the sun. In the medical field, analysis of the polarization allows the diagnose of disease in the eyes. The retinae of most insect and certain vertebrate species are sensitive to polarization in their environment, but humans are blind to this property of light. Biologists use polarimeters to investigate behaviors of animals-vis-à-vis polarization-in their natural habitats. In this paper, we first present the basics of polarization sensing and then discuss integrated polarization imaging sensors developed in our laboratory.
Liquid crystal polarization camera
IEEE Transactions on Robotics and Automation, 1997
We present a fully automated system which unites CCD camera technology with liquid crystal technology to create a polarization camera capable of sensing the partial linear polarization of reflected light from objects at pixel resolution. As polarization sensing not only measures intensity but also additional physical parameters of light, it can therefore provide a richer set of descriptive physical constraints for the understanding of images. Recently it has been shown that polarization cues can be used to perform dielectric/metal material identification, specular and diffuse reflection component analysis, as well as complex image segmentations that would be significantly more complicated or even infeasible using intensity and color alone. Such analysis has so far been done with a linear polarizer mechanically rotated in front of a CCD camera. The full automation of resolving polarization components using liquid crystals not only affords an elegant application, but significantly speeds up the sensing of polarization components and reduces the amount of optical distortion present in the wobbling of a mechanically rotating polarizer. In our system two twisted nematic liquid crystals are placed in front of a fixed linear polarizer placed in front of a CCD camera. The application of a series of electrical pulses to the liquid crystals in synchronization with the CCD camera video frame rate produces a controlled sequence of polarization component images that are stored and processed on Datacube boards. We present a scheme for mapping a partial linear polarization state measured at a pixel into hue, saturation and intensity producing a representation for a partial linear polarization image. Our polarization camera currently senses partial linear polarization and outputs such a color representation image at 5 Hz. The unique vision understanding capabilities of our polarization camera system are demonstrated with experimental results showing polarization-based dielectric/metal material classification, specular reflection and occluding contour segmentations in a fairly complex scene, and surface orientation constraints. I. INTRODUCTION A S HUMAN BEINGS we naturally think of vision in terms of perception of intensity and color. Polarization of light might appear to be of little relevance or benefit to automated vision systems simply because the human visual system is almost completely oblivious to this property of light. In fact the use of the polarization of light for automated vision systems is an augmentation of sensed light parameters from Manuscript