mendillo 2019 spie poster - umass lowell | umass lowell 2019 spie poster... · hodm probe patterns...
TRANSCRIPT
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Decoupling the image-plane and low-order wavefront sensors for the PICTURE-C coronagraph Christopher Mendillo1, Kuravi Hewawasam1, Glenn A. Howe1, Jason Martel1, Timothy Cook1, Supriya Chakrabarti1 1: UML
Abstract: The Planetary Imaging Concept Testbed Using a Recoverable Experiment - Coronagraph (PICTURE-C) mission will directly image debris disks and exozodiacal dust around nearby stars from a high-altitude balloon using a vector vortex coronagraph. PICTURE-C employs both image-plane wavefront sensing for high-order wavefront control and a reflective Lyot-stop sensor for low-order wavefront control. Since both of these systems lie downstream from the coronagraph's deformable mirror, and since both must run simultaneously, they must be calibrated as to not interfere with each other. The deformable mirror probe patterns required for image-plane sensing appear as wavefront errors to the low-order sensor. This paper presents simulations of low and high-order wavefront sensing for PICTURE-C and calibration techniques for decoupling the two sensors.
Funded by NASA grant: NNX15AG23G
LLOWFS influence images for LODM Zernikes
HODM probe patterns for HOWFS
LLOWFS influence images for HODM probes
LLOWFS Zernike measurement of each HOWFS DM probe pattern
The Zernike on the X-axis is commanded on the LODM with a 10nm RMS amplitude. The dots show the RSS of all LLOWFS-measured Zernikes other than the commanded one.
Each dot represents one of the 8 HOWFS probe patterns. Red is uncalibrated. Black is calibrated.
Single-point calibration: Multi-point calibration:HOWFS & LOWFS cross-coupling:Use unique reference image for each HODM probe Use unique Zernike matrix for each HODM probeHODM probe patterns register as Zernikes on LLOWFS
11117-74
M1
Avionics
Star Tracker
Trim Weights
CoronagraphM2
ElectronicsWASP Hubs
POWER SUPPLY
LODM CTRL
HEX CTRL
CPUTEMP
TM
SS
HEX
CCD
POL2
POL1
OAP4
HODM 952ch
OAP2
OAP1 Dichroic pass < 540nm
M3
Acquisition Camera
VVC
Lyot Stop
24” x 48” Carbon Fiber Bench
SH LOWFS
Lyot LOWFS
CCD
From Telescope
LODM 97ch
OAP3
PICTURE-C Coronagraph
BP Filter
CCD
5 Color Science Camera