Graham Myhre

Liquid crystal polymer full-stokes division of focal plane polarimeter.

A division-of-focal-plane polarimeter based on a dichroic dye and liquid crystal polymer guest-host system is presented. Two Stokes polarimeters are demonstrated: a linear Stokes and the first ever Full-Stokes division-of-focal-plane polarimeter. The fabrication, packaging, and characterization of the systems are presented. Finally, optimized polarimeter designs are discussed for future works.

Full-Stokes imaging polarimeter using an array of elliptical polarizer

In this paper, a full-Stokes imaging polarimeter operating at 580 nm using an array of elliptical polarizers is presented. The division-of-focal-plane polarimeter utilizes a set of four optimized measurements which represent a regular tetrahedron inscribed in the Poincaré sphere. Results from the device fabrication, instrument calibration and characterization are presented. The performance of the optimized full Stokes polarimeter, as defined by size of the standard deviation of the degree of circular polarization, is found to be approximately five times better than the performance of the simple full-Stokes polarimeter.

Patterned color liquid crystal polymer polarizers.

We demonstrate patterned polarizers for visible wavelengths using dichroic dye in a liquid crystal polymer (LCP) host. Contact lithography is used to pattern a thin alignment layer, which subsequently transfers the pattern to the LCP. A gray dichroic dye mixture for the visible spectrum is optimized and implemented along with LCP to fabricate this polarizer. A peak extinction ratio of 41 was measured at a 633 nm wavelength, while simultaneously showing patterns as small as 3 μm. Finally, multi layer films are demonstrated by fabricating a two layer patterned circular polarizer consisting of a quarter-wave retarder and a color polarizer. Our process has applications in three-dimensional displays, interferometry, optical storage, and polarimeters.

Imaging capability of patterned liquid crystals

We demonstrate the ability to make high resolution arbitrary patterned optical retarders using liquid crystal polymer (LCP). Contact lithography is used to define unique LCP alignment domains. Patterned LCP retarders are imaged between crossed polarizers to determine pattern visibility as a function of feature size. It was determined that patterned retarders for wavelengths between 250 nm and 2500 nm can be constructed with feature sizes as small as 4 microm. We also showed that multiple patterns can be created on the same substrate using a combination of patterned LCP and opaque features. Our process has applications in displays, double-patterning lithography, and imaging polarimetry.

Transparent and superhydrophobic Ta 2 O 5 nanostructured thin films

Transparent Ta2O5 nanostructured thin films have been fabricated using a multi-step anodization process. Obtained by a combination of the nanostructured surface and the deposition of the hydrophobic CFx coating, the transparent films can be made highly water repellent or superhydrophobic useful for self-cleaning and anti-fogging optical coatings. Contact angle measurements and optical transmittance curves of the nanostructured films are in good agreement with theoretical calculations.

Multi-mode waveguides from ultra-long self-assembled hexagonal faceted microtubules of a benzothiadiazole molecule.

Length controlled (μm-mm-cm) self-assembly of hexagonal faceted microtubules has been achieved using a phase-transfer solution processing approach from . The self-assembled structures exhibit both polarized light emission and multi-mode waveguide properties over large length scales. The multi-mode waveguide characteristics are analyzed using a combination of experiment and finite-difference-time-domain calculations.

Lens array Stokes imaging polarimeter

We have successfully constructed and tested two portable multi-lens polarization cameras whose designs differ in the ability to measure circularly polarized light. The cameras operate by acquiring multiple images of a scene at different polarizations using multiple lenses. An algorithm is used to align and combine the images, correcting for exposure and lens variation, to generate accurate Stokes images. Comparisons are made between four- and eight-lens Stokes imaging cameras. The multi-lens camera and software error corrections can be implemented at a relatively low cost.

Patterned polarized fluorescence from a thin film

Patterned polarized fluorescence from a thin film comprised of fluorescent dichroic dye dispersed in liquid crystalline polymer is demonstrated with features as small as 11 μm. Cooperative alignment of these fluorescent dichroic molecules in a liquid crystal polymer leads to films exhibiting polarized green, red, and yellow emission. The dichroic fluorescence emission ratios for these films are 10 to 16 depending on the type of the dye. This simple strategy could be utilized for generating large area linearly polarized light sources or electroluminescent displays.

Polarization sensing cameras

Color is intuitive to people, because we can perceive it visually, but polarization is a less obviou…