Improving the speckle noise attenuation of simultaneous spectral differential imaging with a focal plane holographic diffuser
| Autor: | David Lafreniere, Rene Doyon, Daniel Nadeau, Etienne Artigau, Christian Marois, Mathilde Beaulieu |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
Point spread function
Physics Channel (digital image) business.industry Attenuation Astrophysics (astro-ph) Holography Astrophysics::Instrumentation and Methods for Astrophysics FOS: Physical sciences Astronomy and Astrophysics Speckle noise Astrophysics Spectral bands 01 natural sciences Noise (electronics) law.invention 010309 optics Optics Cardinal point Space and Planetary Science law 0103 physical sciences business 010303 astronomy & astrophysics |
| DOI: | 10.48550/arxiv.astro-ph/0703093 |
| Popis: | Direct exoplanet detection is limited by speckle noise in the point spread function (PSF) of the central star. This noise can be reduced by subtracting PSF images obtained simultaneously in adjacent narrow spectral bands using a multi-channel camera (MCC), but only to a limit imposed by differential optical aberrations in the MCC. To alleviate this problem, we suggest the introduction of a holographic diffuser at the focal plane of the MCC to convert the PSF image into an incoherent illumination scene that is then re-imaged with the MCC. The re-imaging is equivalent to a convolution of the scene with the PSF of each spectral channel of the camera. Optical aberrations in the MCC affect only the convolution kernel of each channel and not the PSF globally, resulting in better correlated images. We report laboratory measurements with a dual channel prototype (1.575 micron and 1.625 micron) to validate this approach. A speckle noise suppression factor of 12-14 was achieved, an improvement by a factor ~5 over that obtained without the holographic diffuser. Simulations of realistic exoplanet populations for three representative target samples show that the increase in speckle noise attenuation achieved in the laboratory would roughly double the number of planets that could be detected with current adaptive optics systems on 8-m telescopes. Comment: 9 pages, 8 figure, to be published in ApJ June 20, 2007 |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|