PALM-3000 Systems Engineering R. Dekany, A. Bouchez 9/22/10 Integration & Testing Review
PALM-3000 Outline 1.Performance Predictions 2.Requirements 3.Error Budgets 4.Operations Concepts Development 5.Servo Control 6.Work during I&T phase 2
PALM-3000 Strehl vs. Observing Wavelength (for various levels of RMS wavefront error in nm) HH
PALM Reference Science Cases
PALM Performance Summary
PALM-3000 Error Budget Example V = 6.5 NGS Median seeing and wind 30 deg zenith (r 0 = 8.4 cm) Includes: 21 nm RMS anisoplanatism (1.0 arcsec) 35 nm RMS margin Total effective WFE = 104 nm RMS 1-D TT error = 2.3 mas RMS H-Strehl = 85% 6
PALM-3000 Error Budget Example V = 4.5 NGS Median seeing and wind 10 deg zenith (r 0 = 9.1 cm) Includes: 18 nm RMS anisoplanatism (1.0 arcsec) 35 nm RMS margin Total effective WFE = 92 nm RMS 1-D TT error = 1.9 mas RMS H-Strehl = 88% 7
PALM-3000 Error Budget Example V = 6.5 NGS Median seeing and wind 60 deg zenith (r 0 = 6.1 cm) Includes: 44 nm RMS anisoplanatism (1.0 arcsec) 35 nm RMS margin Total effective WFE = 145 nm RMS 1-D TT error = 2.4 mas RMS H-Strehl = 72% Large (and unreliable) contribution from Dispersion Displacement Error 8
PALM-3000 Error Budget Example V = 16.5 NGS Median seeing and wind 20 deg zenith (r 0 = 8.9 cm) Includes: 181 nm RMS anisoplanatism (15 arcsec) 35 nm RMS margin Total effective WFE = 465 nm RMS 1-D TT error = 33 mas RMS K-Strehl = 17% ~2% sky fraction at b = 30 (Same performance achieved for r 0 = 15 cm V = 17.5 NGS located 30 arcsec off-axis ~6% sky fraction at b = 30) 9
PALM-3000 Well-Corrected Subaperture (WCS) Pathfinder Experiment (Serabyn, et al.) Use of an off-axis subaperture with 8cm projected actuator spacing to validate PALM-3000 performance on bright NGS WCS AO stimulus
PALM-3000 WCS experiment confirms PALM-3000 performance predictions B-band ( nm) Strehl ratio 0.10 – 0.12 /D (B) = 59 mas SAO V = 5.1, 6.3 Sep = 0.34” (G. Serabyn) K-band Strehl ratio RMS WFE nm Strehl stability: ~1% RMS
PALM-3000 Requirements Science requirements Instrument requirements Subsystem requirements –Software –Stimulus –HOWFS –Electronics –Optical Bench –Real-time Processor 12
PALM Error Budgets Wavefront Error Transmission & Emissivity –Model of trans./emissivity with degraded coatings eg. after 1 year Flexure –Allocations to optical bench, optics mounts, HWFS Acquisition Time –Dominated by hardware, drives software automations & GUI design System Downtime –Allocations to software and hardware failures
PALM Operations Concepts We have developed an Observing Scenarios Document, which covers –Lab procedures (alignment, calibration) –Observing procedures (acquisition, dithering) –Project 1640 survey observing Effectively provided detailed requirements flowdown from Science to Software Used as starting point for lab I&T test plans
PALM-3000 Servo Control Design Flexible control of 2 DMs in a woofer-tweeter arrangement: 1.Direct control of HODM with offload to LODM 2.Modal splitting between DMs Use leaky integrator & regularized reconstructors to control blind modes Calibration WFS updates HOWFS centroid offsets every ~60s
PALM Camera & Servo Modes Currently operating the testbed in camera mode 0, servo mode 3 Developing reconstructors for servo modes 0, 1, and 4
PALM-3000 Systems Engineering tasks in I&T phase Verify requirements compliance (IRD) Complete the development of reconstructors for woofer-tweeter control Develop test plans for system-level performance validation (eg. Plant function measurement) –Revisions of 1999/2003/2005 upgrade test plans 17
PALM-3000 Backup Slides 18
PALM-3000 HOWFS Subaperture Alignment 63 6332 3216 168 8 In the 63x63 subaperture mode the pupil alignment preserve Fried geometry. In the other modes, we will use use modal control.