PIAA Coronagraph Development at NASA Ames: High Contrast Laboratory Demonstration at 2 l/D
Abstract
Coronagraph technology is advancing and promises to directly image and spectrally characterize extrasolar Earth-like planets in the foreseeable future (such as the 2020 decade) with a telescope as small as 1.5m. A small Explorer-sized telescope can also be launched in the 2010 decade capable of seeing debris disks as small as 10s of zodis and potentially a few large planets. The Phase Induced Amplitude Apodization (PIAA) coronagraph makes such aggressive performance possible. We report on the latest results from a testbed at NASA Ames that is focused on developing and testing the PIAA coronagraph. This laboratory facility was built in 2008 and is designed to be flexible, operated in an actively thermally stabilized air environment, and to complement collaborative efforts at NASA JPL's High Contrast Imaging Testbed. For our wavefront control we are using small Micro-Electro-Mechanical-System deformable mirrors (MEMS DMs), which promise to reduce the size of the beam and overall instrument, a consideration that becomes very important for small telescopes. We describe our lab efforts and results, which include: the operation of our new active thermal control system; the demonstration of 5.4x10-8 (at time of this writing) average raw contrast in a dark zone from 2.0 - 5.2 λ/D in monochromatic light with a refractive PIAA system; preliminary results with an innovative low-cost set of reflective PIAA from JPL; preliminary results with a set of next-generation reflective PIAA built by Tinsley and designed to have the best theoretical broadband performance so far; and finally, an innovative design for a chromatically compensated focal plane occulter that promises to enhance broadband performance by matching the wavelength-dependent inner working angle of coronagraphs such as PIAA.
- Publication:
-
American Astronomical Society Meeting Abstracts #217
- Pub Date:
- January 2011
- Bibcode:
- 2011AAS...21725406B