Patterned achromatic elliptical polarizer for short-wave infrared imaging polarimetry.

Short-wave infrared (SWIR) imaging polarimetry has widespread applications in telecommunication, medical imaging, surveillance, remote-sensing, and industrial metrology. In this work, we design, fabricate, and test an achromatic SWIR elliptical polarizer, which is a key component of SWIR imaging polarimetry. The elliptical polarizer is made of a patterned linear polarizer and a patterned optical elliptical retarder.

Patterned liquid crystal polymer C-plate retarder and color polarizer.

The patternability and guest-host interaction with dichroic dye and C-plate liquid crystal polymer (LCP) materials are investigated, and the optical properties of a thin film C-plate retarder and polarizer are studied and compared with theory. The C-plate retarder is a waveplate made of a uniaxial LCP where the optical axis of the LCP is parallel to the surface normal of the optic. No retardance is observed at a normal angle of incidence and retardance grows as the angle of incidence increases.

Division of focal plane red-green-blue full-Stokes imaging polarimeter.

We calibrate and test a division-of-focal-plane red-green-blue (RGB) full-Stokes imaging polarimeter in a variety of indoor and outdoor environments. The polarimeter, acting as a polarization camera, utilizes a low dispersion microretarder array on top of a sensor with Bayer filters and wire-grid linear polarizers. We also present the design and fabrication of the microretarder array and the assembly of the camera and validate the performance of the camera by taking multiple RGB full-Stokes images and videos.

Observation of elliptically polarized light from total internal reflection in bubbles.

Bubbles are ubiquitous in the natural environment, where different substances and phases of the same substance forms globules due to differences in pressure and surface tension. Total internal reflection occurs at the interface of a bubble, where light travels from the higher refractive index material outside a bubble to the lower index material inside a bubble at appropriate angles of incidence, which can lead to a phase shift in the reflected light. Linearly polarized skylight can be converted to elliptically polarized light with efficiency up to 53% by single scattering from the water-air interface.

Polarizing beam splitter cube for circularly and elliptically polarized light.

A method of designing an arbitrary polarizing beam splitter (PBS) cube using multiple layers of thin-film liquid crystal polymer is demonstrated. This methodology utilizes cholesteric phase liquid crystal polymer (Ch-LCP) to transmit one handedness of elliptically polarized light and reflect the orthogonal state when unpolarized light is incident. Using additional nematic liquid crystal polymer layers, the polarization state for the transmitted and reflected light can be controlled and output to any two orthogonal states represented on the Poincaré sphere.

Multi-wavelength quantitative polarization and phase microscope.

We introduce a snapshot multi-wavelength quantitative polarization and phase microscope (MQPPM) for measuring spectral dependent quantitative polarization and phase information. The system uniquely integrates a polarized light microscope and a snap-shot quantitative phase microscope in a single system, utilizing a novel full-Stokes camera operating in the red, green, and blue (RGB) spectrum. The linear retardance and fast axis orientation of a birefringent sample can be measured simultaneously in the visible spectra.

Snapshot multi-wavelength interference microscope.

A snapshot multi-wavelength interference microscope is proposed for high-speed measurement of large vertical range discontinuous microstructures and surface roughness. A polarization CMOS camera with a linear micro-polarizer array and Bayer filter accomplishes snapshot multi-wavelength phase-shifting measurement. Four interferograms with 𝜋/2 phase shift are captured at each wavelength for phase measurement, the 2𝜋 ambiguities are removed by using two or three wavelengths.

Division of amplitude RGB full-Stokes camera using micro-polarizer arrays: erratum.

We correct two figures showing the micro-polarizer arrangement on the RGB full-Stokes camera.

Design, fabrication and testing of achromatic elliptical polarizer.

A method of designing achromatic elliptical polarizers using a combination of multiple birefringent waveplates is demonstrated. This approach has a simple geometric interpretation and simplifies the problem of designing an achromatic elliptical polarizer to find overlapping arcs on the Poincaré sphere. The technique is applied to the design of achromatic elliptical polarizers for a broadband division-of-focal-plane full-Stokes imaging polarimeter for visible wavelength band (λ = 450nm to 650nm).

Optimized design of N optical filters for color and polarization imaging.

Designs of N optical filters for color and polarization imaging are found by minimizing detector noise, photon shot noise, and interpolation error for the image acquisition in a division of focal plane configuration. To minimize interpolation error, a general tiling procedure and an optimized tiling pattern for N filters are presented. For multispectral imaging, a general technique to find the transmission band is presented.