A new, low-cost attachment to telescopes allows previously unachievable precision in ground-based observations of exoplanets -- planets beyond our solar system as they pass in front of their parent stars.
Created in a collaborative effort between astronomers at Penn State University and the Rochester, New York-based RPC Photonics nano-fabrication laboratories, the new technology uses custom beam-shaping diffusers to minimize distortions in images taken of objects vast distances away. Diffusers, devices which spread light evenly from a single source and reduce shadows, are inexpensive and easily adaptable, yet they strongly enhance the capabilities of ordinary telescopes. Penn State graduate student Gundmundur Stefansson, a NASA Earth and Space Science Fellow, who served as leader author of a study on the technology, says it could benefit followup studies of discoveries made by NASA's Transiting Exoplanet Survey Satellite (TESS) mission, which will be launched early next year. "This inexpensive technology delivers high photometric precision in observations of exoplanets as they transit--cross in front of--the bright stars they orbit," he stated. Photometry is a technique that measures light in regard to its brightness to the human eye. "Beam-shaping diffusers are made using a precise nano-fabrication process where a carefully designed surface pattern is precisely written on a plastic polymer on a glass surface or directly etched on the glass itself," noted study co-author Suvrath Mahadevan, also of Penn State. "The pattern consists of precise micro-scale structures, engineered to mold the varying light input from stars in a predefined broad and stable output shape spread over many pixels on the telescope camera," he added. Diffused observations yield stable, smooth images that minimize the distorting effects of Earth's atmosphere and achieve a very high degree of precision, said New York Times data scientist Ming Zhao. When the new diffuser technology was tested on Palomar Observatory's Hale telescope, the Apache Point Observatory's ARC 3.5-meter telescope, and on Davey Lab Observatory's 0.6-meter telescope, the results were images far more precise and intense than those taken using conventional methods. The developers of this technology hope to make it available to exoplanet-observing telescopes and observatories around the world.