the vector app coronagraph - realizing new coronagraph designs
TRANSCRIPT
Vector APP Coronagraph realizing new coronagraph designs
with polarization techniques
Gilles Otten Frans Snik, Matthew Kenworthy, Christoph Keller
Leiden Observatory, Netherlands
Matthew Miskiewicz, Michael Escuti North Carolina State University, USA
Johanan Codona University of Arizona, USA
Pros and Cons of APP
Single Optic Easy alignment
Insensitive to tip-tilt variations
One-sided PSF* Chromatic
*depends on phase pattern
Vector-APP
Patterned liquid crystal encodes phase using vector-phase Half-wave plate flips handedness
Concept described in Snik et al. (Proc. SPIE 8450, 2012)
Prototype characterized in Otten et al. (Optics Express subm., 2014)
Breakthrough manufacturing techniques Direct write Miskiewicz & Escuti, OpEx, Vol. 22, Issue 10, pp. 12691-12706 (2014)
Achromatization Komanduri, Lawler & Escuti, OpEx, Vol. 21, Issue 1, pp. 404-420 (2013)
Vector-APP
Current prototype 500 – 900 nm 25 micron pixel size, 5.5 mm diameter
between crossed polarizers
Going on-sky at LBT
4 micron vAPP currently in LBT/LMIRCam with support from Phil Hinz, Manny Montoya, University of Arizona, USA
Described in Snik et al. (Proc. SPIE 9147, 2014)
Polarimetry with vAPP
Snik et al., 2014
Snik et al., 2014
Phase patterns
Phase part of complex coronagraph Carlotti et al. 2013
1e-5 contrast ~2-6 λ/D phase-only Christoph Keller
360 degree phase patterns Contrast: 1e-5 ~2-8 λ/D 19% Strehl
Contrast: 1e-8 ~6-10 λ/D 53% Strehl
John Codona Christoph Keller
Poor man's PIAA Guyon, 2003 Image credit: Martinache Replace aspheric optics by patterned vector phase elements Only works for one handedness of polarization but is order of
magnitude cheaper Only works narrowband
Aspheric pupil remapping optics