Achromatic interfero-coronagraph with variable rotational shear: reducing of star leakage effect, white light nulling with lab prototype

Stellar coronagraphs with a small inner working angle have limited possibilities to detect exoplanets due to the star leakage effect caused by incomplete suppression of the star of finite angular size. We consider an improved instrument for direct imaging of exoplanets: common-path achromatic interfero-coronagraph with variable rotational shear (CP-ARC). CP-ARC reduces the star leakage effect by several orders of magnitude (with small angles of rotational shear relative to a fixed angle of 180 deg) with telescope size more than 1 m. Operation capacity of CP-ARC was experimentally verified by laser light nulling and white light nulling with lab prototype treated. (c) 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)