TY - GEN
T1 - Experimental study of a low-order wavefront sensor for a high-contrast coronagraphic imager at 1.2 λ/D
AU - Lozi, Julien
AU - Belikov, Ruslan
AU - Schneider, Glenn
AU - Guyon, Olivier
AU - Pluzhnik, Eugene
AU - Thomas, Sandrine J.
AU - Martinache, Frantz
PY - 2013
Y1 - 2013
N2 - High-contrast imaging will be a challenge for future ELTs, because their vibrations create low-order aberrations - mostly tip/tilt - that reduce coronagraphic performances at 1.2 λ/D and above. A Low-Order WaveFront Sensor (LOWFS) is essential to measure and control those aberrations. An experiment simulating a starlight suppression system is currently developed at NASA Ames Research Center, and includes a LOWFS controlling tip/tilt modes in real-time at 500 Hz. The LOWFS allowed us to reduce the tip/tilt disturbances to 10-3 λ/D rms, enhancing the previous contrast by a decade, to 8×10-7 between 1.2 and 2 λ/D. A Linear Quadratic Gaussian (LQG) controller is currently implemented to improve even more that result by reducing residual vibrations. This testbed is developed for the mission EXCEDE (EXoplanetary Circumstellar Environments and Disk Explorer), selected by NASA for technology development, and designed to study the formation, evolution and architectures of exoplanetary systems and characterize circumstellar environments into stellar habitable zones. It is composed of a 0.7 m telescope equipped with a Phase-Induced Amplitude Apodization Coronagraph (PIAA-C) and a 2000-element MEMS deformable mirror, capable of raw contrasts of 10-6 at 1.2 λ/D and 10-7 above 2 λ/D. Although the testbed simulates space conditions, its LOWFS has the same design than on the SCExAO instrument at Subaru telescope, with whom it shares the same kind of problematic. Experimental results show that a good knowledge of the low-order disturbances is a key asset for high contrast imaging, whether for real-time control or for post processing, both in space and on ground telescopes.
AB - High-contrast imaging will be a challenge for future ELTs, because their vibrations create low-order aberrations - mostly tip/tilt - that reduce coronagraphic performances at 1.2 λ/D and above. A Low-Order WaveFront Sensor (LOWFS) is essential to measure and control those aberrations. An experiment simulating a starlight suppression system is currently developed at NASA Ames Research Center, and includes a LOWFS controlling tip/tilt modes in real-time at 500 Hz. The LOWFS allowed us to reduce the tip/tilt disturbances to 10-3 λ/D rms, enhancing the previous contrast by a decade, to 8×10-7 between 1.2 and 2 λ/D. A Linear Quadratic Gaussian (LQG) controller is currently implemented to improve even more that result by reducing residual vibrations. This testbed is developed for the mission EXCEDE (EXoplanetary Circumstellar Environments and Disk Explorer), selected by NASA for technology development, and designed to study the formation, evolution and architectures of exoplanetary systems and characterize circumstellar environments into stellar habitable zones. It is composed of a 0.7 m telescope equipped with a Phase-Induced Amplitude Apodization Coronagraph (PIAA-C) and a 2000-element MEMS deformable mirror, capable of raw contrasts of 10-6 at 1.2 λ/D and 10-7 above 2 λ/D. Although the testbed simulates space conditions, its LOWFS has the same design than on the SCExAO instrument at Subaru telescope, with whom it shares the same kind of problematic. Experimental results show that a good knowledge of the low-order disturbances is a key asset for high contrast imaging, whether for real-time control or for post processing, both in space and on ground telescopes.
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U2 - 10.12839/AO4ELT3.13323
DO - 10.12839/AO4ELT3.13323
M3 - Conference contribution
AN - SCOPUS:84901934775
SN - 9788890887604
T3 - 3rd AO4ELT Conference - Adaptive Optics for Extremely Large Telescopes
BT - 3rd AO4ELT Conference - Adaptive Optics for Extremely Large Telescopes
PB - INAF - Osservatorio Astrofisico di Arcetri Largo Enrico Fermi
T2 - 3rd Conference on Adaptive Optics for Extremely Large Telescopes, AO4ELT 2013
Y2 - 26 May 2013 through 31 May 2013
ER -