Large-scale radio telescope projects will be important in answering modern astronomical questions like those of the National Academies' Astro2020 survey. We propose an efficient and cost-effective thermoforming process with fringe projection metrology (FPM) as an alternative to current panel fabrication methods. In our thermoforming process, we use a flexure plate with actuated tiles to create an adjustable mold inside an oven. Unshaped panels are placed on the adjustable mold and heat is applied, thermoforming the panel to the mold shape. This process allows for the rapid prototyping and production of many panel shapes with sufficient accuracy and reduced recurring costs. We apply FPM to evaluate the mold and panel shapes. FPM applies phase-shifted fiducial patterns, camera stereo vision, and triangulation to measure the thermoformed panel. We applied these technologies in beginning the construction of the Public Outreach Radio Telescope (PORT) and its off-axis dish of 26, 0.5 m2, 1/8" thick panels. The PORT is designed for 30dB of gain at λ = 21 cm wavelength, and the dish was toleranced to λ = 3 cm wavelength for future observations. In this proof of concept, we have installed thermoformed panels measured with FPM on a radio telescope.
A recently proposed concept for the Next Generation Arecibo Telescope involves an array of tightly packed small dishes [1]. In support, we present mitigation methods for grating lobe effects inherent in regularly spaced aperture synthesis.
The Coronagraphic Debris Exoplanet Exploring Payload (CDEEP) is a Small-Sat mission concept for high contrast imaging of circumstellar disks. CDEEP is designed to observe disks in scattered light at visible wavelengths at a raw contrast level of 10-7 per resolution element (10-8 with post processing). This exceptional sensitivity will allow the imaging of transport dominated debris disks, quantifying the albedo, composition, and morphology of these low-surface brightness disks. CDEEP combines an off-axis telescope, microelectromechanical systems (MEMS) deformable mirror, and a vector vortex coronagraph (VVC). This system will require rigorous testing and characterization in a space environment. We report on the CDEEP mission concept, and the status of the vacuum-compatible CDEEP prototype testbed currently under development at the University of Arizona, including design development and the results of simulations to estimate performance.
Reconfigurable freeform optical systems enable greatly enhanced imaging and focusing performance within nonsymmetric, compact, and ergonomic form factors. In this paper, several improvements are presented for the design, test, and data analysis with these systems. Specific improvements include definition of a modal G and C vector basis set based on Chebyshev polynomials for the design and analysis of non-circular optical systems. This framework is then incorporated into a parametric optimization process and tested with the Tomographic Ionized-carbon Mapping Experiment (TIME), a reconfigurable optical system. Beyond design, a reconfigurable deflectometry system enhances metrology to measure a fast, f/1.26 convex optic as well as an Alvarez lens. Further improvements in an infrared deflectometry system show accuracy around λ/10 of the notoriously difficult low-order power. Working together, the mathematical vector polynomial set, the programmatic optical design approach, and various deflectometry-based optical testing technologies enable more flexible and optimal utilization of freeform optical components and design configurations.
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