An off-axis four-quadrant phase-mask coronagraph: concept and first results
Abstract
We have recently deployed a four-quadrant phase-mask coronagraph behind an unobscured, circular, off-axis section of the Palomar 200-inch telescope. To obtain very good wavefront correction across the 1.5 m subaperture, our relay optics reimage the sub-aperture onto the adaptive optics system's deformable mirror. This approach combines the advantages of low diffraction from obscuring elements, due to the off-axis aperture, with high wavefront correction, due to the magnification of the pupil, and high stellar rejection, due to the phase mask coronagraph. Our initial on-sky results include Strehl ratios exceeding 90%, peak stellar rejections of >100:1, and an improvement in contrast of 235:1 on a binary of separation 2 λ /D.
- Publication:
-
IAU Colloq. 200: Direct Imaging of Exoplanets: Science & Techniques
- Pub Date:
- 2006
- DOI:
- 10.1017/S174392130600980X
- Bibcode:
- 2006dies.conf..477S