Radio telescope manufacturing with adaptive aluminum thermoforming and fringe projection metrology

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.