The Vector Vortex Coronagraph (VVC) is one of the most attractive new-generation coronagraphs for ground- and
space-based exoplanet imaging/characterization instruments, as recently demonstrated on sky at Palomar and
in the laboratory at JPL, and Hokkaido University. Manufacturing technologies for devices covering wavelength
ranges from the optical to the mid-infrared, have been maturing quickly. We will review the current status of
technology developments supported by NASA in the USA (Jet Propulsion Laboratory-California Institute of
Technology, University of Arizona, JDSU and BEAMCo), Europe (University of Li`ege, Observatoire de Paris-
Meudon, University of Uppsala) and Japan (Hokkaido University, and Photonics Lattice Inc.), using liquid
crystal polymers, subwavelength gratings, and photonics crystals, respectively. We will then browse concrete
perspectives for the use of the VVC on upcoming ground-based facilities with or without (extreme) adaptive
optics, extremely large ground-based telescopes, and space-based internal coronagraphs.
The Vector Vortex Coronagraph (VVC) is an attractive internal coronagraph solution to image and characterize
exoplanets. It provides four key pillars on which efficient high contrast imaging instruments can be built for
ground- and space-based telescopes: small inner working angle, high throughput, clear off-axis discovery space,
and simple layout. We present the status of the VVC technology development supported by NASA. We will
review recent results of the optical tests of the second-generation topological charge 4 VVC on the actively
corrected High Contrast Imaging Testbed (HCIT) at the Jet Propulsion Laboratory (JPL). New VVC contrast
records have been established.
The U.S. military has a continued interest in the development of handheld, field-usable sensors and test kits for a variety
of diagnostic applications, such as traumatic brain injury (TBI) and infectious diseases. Field-use presents unique
challenges for biosensor design, both for the readout unit and for the biological assay platform. We have developed
robust biosensor devices that offer ultra-high sensitivity and also meet field-use needs. The systems under development
include a multiplexed quantitative lateral flow test strip for TBI diagnostics, a field test kit for the diagnosis of pathogens
endemic to the Middle East, and a microfluidic assay platform with a label-free reader for performing complex
biological automated assays in the field.
A new technique is introduced to replace DOEs that are used for illumination in lithographic
projectors with polarization computer generated holograms (PCGHs) that produce both arbitrary
intensity and arbitrary polarization state in the illumination pupil. The additional capability of
arbitrary polarization state adds an additional degree of freedom for source-mask optimization.
The PCGHs are similar in design and construction to DOEs, but they incorporate polarizationsensitive
elements. Three experiments are described that demonstrate different configurations of
PCGHs deigned to produce a tangentially polarized ring. Measurements of ratio of polarization
and polarization orientation indicate that all three configurations performed well. Experimetns
are performed with visible (λ = 632.8nm) light.
Algorithms for polarization ray tracing biaxial materials and calculating the directions of ray propagation and
energy flow, the refractive indices, and the coupling coefficients for all four resultant reflected and transmitted
rays are presented. Examples of polarization state maps, retardance maps and diattenuation maps are generated
as a function of angle of incidence for comparing plane parallel plate systems with uniaxial and biaxial
materials.
Special enhanced silver mirror coatings were designed and fabricated to minimize the polarization introduced by a three-mirror
off-axis high-accuracy telescope. A system diattenuation of approximately 1% in the VIS-NIR was achieved by
both reducing the diattenuation from each mirror individually and by balancing the diattenuations introduced by the
three mirrors over the spectral range. This process of low-polarization engineering involves minimizing system
polarization introduced by surface geometry, thin film coatings and birefringent elements, and measuring the system. In
this report we will outline a methodology to minimize instrumental polarization aberrations, with an emphasis on
achieving low diattenuation in the MSPI camera, given its off-axis geometry and coating design constraints imposed by
the space-based application. This polarization balancing technique for mirror coatings can be applied to astrophysics
applications.
Understanding the interaction of polarized light with materials is critical to applications such as remote
sensing, laser radar, and quality control. The availability of angular and spatial information add additional dimensions
to this understanding.
A facility is constructed for Mueller Matrix Bidirectional Reflectance Distribution (MMBRDF) imaging.
Polarized light at near infrared and visible wavelengths is scattered from samples ranging from bare metals to complex
organic structures with various textures and orientations. The resulting scattered polarized light is measured with a
Mueller matrix active imaging polarimeter.
The in-plane MMBRDF is measured for a sanded aluminum sample as a demonstration of the facility. The
aluminum is found to be a weak depolarizer, with a somewhat higher depolarization index at specular angles.
Retardance is dominated by its linear component and is close to 180° for the majority of angles. Diattenuation is weak,
especially in the specular region, and increases in the region further away from specular angles.
An illuminated Solar Diffuser is the calibration source for the VIS/NIR bands on the NPOESS/VIIRS sensor. We
completed a set of BRF measurements to fully characterize the distribution of scattered light from the solar diffuser.
NPOESS/VIIRS has an overall VIS/NIR radiometric calibration uncertainty requirement of 2%(1 sigma), of which
1.32% was allocated to the characterization of the BRF. In order to meet this requirement, we modified the existing
goniometer and measurement procedure used on MODIS. Modifications include sample yoke redesign, periodic
measurements of the lamp polarization coupled with stability measurements, modifications to source optics, and stray
light reduction. We measured BRF in 6 spectral wavebands for 9 out-of-plane illumination angles and 2 view angles.
We achieved NIST traceable measurements with an uncertainty ranging from 1.09% to 1.32%. Our measurements of a
smaller SpectralonTM sample match NIST measurements of the same sample to better than 0.5%. These requirements
are nominally the same as achieved on MODIS. As a result of instrument upgrades, we currently meet this overall
uncertainty while having included additional uncertainty terms.
The in-plane Mueller matrix bidirectional reflectance distribution function (MMBRDF) is measured for a Spectralon
calibration target with a reflectance of 99%. Measurements are acquired using a Mueller matrix active imaging,
goniometric polarimeter operated in the near infrared at 1550nm. The Spectralon is measured for both incident and
scattering angles from -80 degrees to 80 degrees to within 20 degrees of retro-reflection. A range of polarization states
is generated and scattered polarization states are analyzed by means of a dual rotating retarder Mueller matrix
polarimeter. Complete Mueller matrix data is measured with a high-resolution camera in image form.
Polarization scatter data is presented in Mueller matrix angular arrays. As expected the Spectralon is a strong
depolarizer and weak s-plane oriented diattenuator. It was also a weak retarder. Diattenuation and retardance are
strongest at horizontal and vertical polarizations, and weakest for circular polarization states.
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