@article{snik_rodenhuis_escuti_brickson_hornburg_kim_kievid_groenhuijsen_roosegaarde_2019, title={Producing true-color rainbows with patterned multi-layer liquid-crystal polarization gratings}, volume={9}, ISSN={["2159-3930"]}, DOI={10.1364/OME.9.001583}, abstractNote={We present the technical design of the art installation Rainbow Station, that projects a 40-m diameter true-color rainbow. The core technology is comprised of a patterned polarization grating that produces the rainbow with the correct shape and correct color order. We achieve an effective grating period as small as 1.55 µm, and obtain high diffraction efficiency over the entire visible spectral range thanks to a multi-layer liquid-crystal implementation. The -1 spectral order is suppressed by circular polarization filtering.}, number={4}, journal={OPTICAL MATERIALS EXPRESS}, author={Snik, Frans and Rodenhuis, Michiel and Escuti, Michael J. and Brickson, Leandra and Hornburg, Kathryn and Kim, Jihwan and Kievid, Chris and Groenhuijsen, Sebastiaan and Roosegaarde, Daan}, year={2019}, month={Apr}, pages={1583–1589} }
 @article{otten_snik_kenworthy_keller_males_morzinski_close_codona_hinz_hornburg_et al._2017, title={ON-SKY PERFORMANCE ANALYSIS OF THE VECTOR APODIZING PHASE PLATE CORONAGRAPH ON MagAO/Clio2}, volume={834}, ISSN={["1538-4357"]}, DOI={10.3847/1538-4357/834/2/175}, abstractNote={We report on the performance of a vector apodizing phase plate coronagraph that operates over a wavelength range of 2–5 μm and is installed in MagAO/Clio2 at the 6.5 m Magellan Clay telescope at Las Campanas Observatory, Chile. The coronagraph manipulates the phase in the pupil to produce three beams yielding two coronagraphic point-spread functions (PSFs) and one faint leakage PSF. The phase pattern is imposed through the inherently achromatic geometric phase, enabled by liquid crystal technology and polarization techniques. The coronagraphic optic is manufactured using a direct-write technique for precise control of the liquid crystal pattern and multitwist retarders for achromatization. By integrating a linear phase ramp to the coronagraphic phase pattern, two separated coronagraphic PSFs are created with a single pupil-plane optic, which makes it robust and easy to install in existing telescopes. The two coronagraphic PSFs contain a 180° dark hole on each side of a star, and these complementary copies of the star are used to correct the seeing halo close to the star. To characterize the coronagraph, we collected a data set of a bright (mL = 0–1) nearby star with ∼1.5 hr of observing time. By rotating and optimally scaling one PSF and subtracting it from the other PSF, we see a contrast improvement by 1.46 magnitudes at 3.5 λ / D . With regular angular differential imaging at 3.9 μm, the MagAO vector apodizing phase plate coronagraph delivers a 5 σ Δ mag contrast of 8.3 ( = 10 − 3.3 ) at 2 λ / D and 12.2 ( = 10 − 4.8 ) at 3.5 λ / D .}, number={2}, journal={ASTROPHYSICAL JOURNAL}, author={Otten, Gilles P. P. L. and Snik, Frans and Kenworthy, Matthew A. and Keller, Christoph U. and Males, Jared R. and Morzinski, Katie M. and Close, Laird M. and Codona, Johanan L. and Hinz, Philip M. and Hornburg, Kathryn J. and et al.}, year={2017}, month={Jan} }
 @article{maione_brickson_escuti_kudenov_2017, title={Snapshot imaging spectrometry with a heterodyned Savart plate interferometer}, volume={56}, ISSN={["1560-2303"]}, DOI={10.1117/1.oe.56.8.081806}, abstractNote={Imaging spectrometers are frequently used in remote sensing for their increased target discrimination capabilities over conventional imaging. Increasing the spectral resolution of these sensors further enables the system’s ability to discriminate certain targets and adds the potential for monitoring narrow-line spectral features. We describe a high spectral resolution (Δλ=1.1  nm full-width at half maximum) snapshot imaging spectrometer capable of distinguishing two narrowly separated bands in the red-visible spectrum. A theoretical model is provided to detail the first polarization grating-based spatial heterodyning of a Savart plate interferometer. Following this discussion, the experimental conditions of the narrow-line imaging spectrometer (NLIS) are provided. Finally, calibration and target identification methods are applied and quantified. Ultimately it is demonstrated that in a full spectral acquisition the NLIS sensor is capable of less than 3.5% error in reconstruction. Additionally, it is demonstrated that neural networks provide greater than 99% reduction in crosstalk when compared to pseudoinversion and expectation maximization in single target identification.}, number={8}, journal={OPTICAL ENGINEERING}, author={Maione, Bryan and Brickson, Leandra and Escuti, Michael and Kudenov, Michael}, year={2017}, month={Aug} }
 @article{maione_brickson_kudenov_escuti_2016, title={Narrowband emission line imaging spectrometry using Savart plates}, volume={9853}, ISSN={["0277-786X"]}, DOI={10.1117/12.2224275}, abstractNote={Polarization spatial heterodyne interferometry (PSHI) allows for the development of compact, vibration insensitive, high spectral resolution sensors. Introducing the imaging qualities of a lenslet array extends the advantages of PSHI to imaging interferometers. The use of Savart plates enables a birefringent interferometer that obtains higher spectral resolution with fewer optical aberrations when compared to alternative designs. In this paper, we describe the design, construction, calibration and validation of a narrowband emission line imaging spectrometer (NELIS), based on Savart plates and liquid crystal polarization gratings, along with its associated theoretical model. This sensor is advantageous for spectral imaging in the areas of remote sensing, biomedical imaging and machine vision.}, journal={POLARIZATION: MEASUREMENT, ANALYSIS, AND REMOTE SENSING XII}, author={Maione, Bryan and Brickson, Leandra and Kudenov, Michael and Escuti, Michael}, year={2016} }
 @article{homburg_brickson_escuti_2015, title={Wide color gamut multi-twist retarders}, volume={9384}, ISSN={["1996-756X"]}, DOI={10.1117/12.2084853}, abstractNote={We show how highly chromatic Multi-Twist Retarder (MTR) films can be used to create a single-film color filter wherein the color may be selected only by the MTR orientation angle. By this approach, we can create multi- color images with just an MTR between polarizers. We study the design method and limits of the available color gamut possibilities in this approach, and experimentally demonstrate several designs of continuous and discrete patterns. This technique may be useful in art, displays, microscopy, and remote sensing.}, journal={EMERGING LIQUID CRYSTAL TECHNOLOGIES X}, author={Homburg, Kathryn J. and Brickson, Leandra L. and Escuti, Michael J.}, year={2015} }
 @article{dhawan_sharma_brickson_muth_2014, title={Incorporation of vanadium oxide films in optical fibers for temperature sensing and optical switching applications}, volume={4}, ISSN={["2159-3930"]}, DOI={10.1364/ome.4.001128}, abstractNote={Fiber optic temperature sensors were fabricated by depositing vanadium oxide thin films on the tips of optical fibers, and by incorporating vanadium oxide materials into the core of optical fibers. It was found that the properties of the initially amorphous vanadium oxide can be controllably converted to those of crystalline VOx compounds via the plasma arc of a fiber fusion splicer. These crystalline VOx compounds can then be over-coated with SiO2, and subsequently fused with another fiber to form an in-line fiber optic sensor. It was found that a well defined optical absorption edge was formed when the vanadium oxide (VOx) thin films were annealed using the plasma arc of a fusion splicer, suggesting the formation of crystalline VOx. Moreover, it was observed that the spectral position of this absorption edge varied with temperature in a reproducible way. The optical fiber devices described in this paper could also be employed for optical switching applications. Based on the spectral position of the band edge and the Raman spectra of the VOx films, deposited on the fiber optic tips, it was found that these annealed VOx films contained a mixture of different phases of vanadium oxide (VOx), in particular V2O5 and VO2. Furthermore, similar in-line optical fiber switches, based only on the insulator to metal phase transitions of VO2, can be fabricated by following the techniques described in this paper.}, number={6}, journal={OPTICAL MATERIALS EXPRESS}, author={Dhawan, Anuj and Sharma, Yashna and Brickson, Leandra and Muth, John F.}, year={2014}, month={Jun}, pages={1128–1139} }