mars design review pp-1 requirements definition performance: –tip/tilt error < 0.06″ rms...
TRANSCRIPT
MARS Design Review
PP-1
Requirements Definition
• Performance:– Tip/Tilt error < 0.06″ rms mirror coordinates
0.12″ rms image coodinates
0.28″ fwhm image coordinates
– Stacking Time < 10minutes requirement
5minute goal
• Operational:– Ease of Use
– Ease of Maintenance
– Full documentation
MARS Design Review
PP-2
MARS Overview
TO HET
shutters
reference sphere
light source beamsplitter
pinhole
knife edge
collimating lens
WaveScope
lenslet array
x
yz
CCD camera
TO HET
shutters
reference sphere
light source beamsplitter
pinhole
knife edge
collimating lens
WaveScope
lenslet array
x
yz
x
yz
CCD camera
Sensys camera
TO HET
shutters
reference sphere
light source beamsplitter
pinhole
knife edge
collimating lens
WaveScope
lenslet array
x
yz
CCD camera
TO HET
shutters
reference sphere
light source beamsplitter
pinhole
knife edge
collimating lens
WaveScope
lenslet array
x
yz
x
yz
CCD camera
Sensys camera
MARS Design Review
PP-6
Current Stacking Performance
•Typically stop stacking when the largest mirror move is < 0.06″.
MARS Design Review
PP-7
Causes of Poor Stacks
• Inconsistent Segment Capture– Inscrutable rejection parameters
– Poor Segment Figure, 16% of segments have double lobes
– Poor placement of pupil plane
• Poor Dome Seeing– Expands Stack
– Makes Focusing difficult
• Improperly Set GroC
MARS Design Review
PP-9
MARS II / MARS I
• Better camera– More pixels
– More dynamic range
– Analog/Digital operation
• Software enhancement– Integrated system
– Improve segment capture/rejection algorithms
• More robust mounts with more precisely controllable degrees of freedom.
• Remote operation – Light source
– Knife edge
– Pitch and Yaw.
MARS Design Review
PP-10
35mm Collimator Design
• 747:1 demagnification of primary to 14.7mm pupil image
• Tip/Tilt Angles Magnified by 747
• Camera – Pulnix TM-1040: 1024x1024, 9μm
pix , 10bit, 30Hz
• Camera Relay Lens– Telecentric, mag of 0.55 to fit
pupil on chip
• For 5″ capture range tilt is magnified to 18.1mrad
• Max displacement with spots under lenslets 535μm
• Lenslet Focal Length 29.5 mm
• Collimator/Lenslet mag 0.6
• Spot size required for Nyquist sampling 57mm
• Pixel subtends– 0.55 mrad at the lenslet image
plane
– 0.153″ on sky
• Resolution assuming 1/10pix centroiding
– 0.015″
MARS Design Review
PP-11
Optional Optical Parameters
Coll
foc len
Pupil
size
Lenslet
size
Relay
mag
Lenslet
foc len
Lenslet
f ratio
28mm (5″ cap) 11.772 1.070 .7 18.88 f/17.6
(7″ cap) 13.49 f/12.6
35mm (5″ cap) 14.715 1.338 .55 29.52 f/22
(7″ cap) 21.09 f/15
50mm (5″ cap) 21.021 1.911 .4 60.25 f/31.5
(7″ cap) 43.04 f/22
Capture Pinhole
Size
Resolution
1/10 pix
(7″ cap) 81.5 .021
(5″ cap) 58.2 .015
(1.3″ cap) 15 .004
*
*
MARS Design Review
PP-12
Current Stacking time• Find Stack (use SenSys), Align M43 (tip/tilt) 3-5 min
• Measure Stack Size ** 3-5 min
• Focus (Knife Edge) 2-12 min
• Adjust GroC (PMC allfile) 0-5 min
• Log Conditions ** 1 min
• Measure Single Mirror (M54) ** 3-5 min
• Wavescope stacking: 10 min – Measure lenslet centers 15sec 15sec
– Stack iteration 44sec x 6 264sec
» Measure+Com ~ 25sec
– PMC 32sec x 6 192sec
– Slew 40sec x 2 80sec
– Overhead ~60sec
• Place missed segments by hand with PMC 0-3 min
• Log Conditions ** 1 min
• PMC (MARS to SAMS), Set SAMS reference (35sec) 1 min
• Measure Stack Size ** 3-5 min
MARS Design Review
PP-14
Where to save time
• No or Sparse SenSys IQ testing, Automate Logging 10min– Develop IQ measure from MARS
• Setup 1-2 min– Predict Tower/Stack position
• Focus 1 min– Better dome seeing will eliminate extended times
– Automation will help
• Wavescope Stacking 6.5 min– Maximum 4 iterations, 1 slew 3min 12sec
– Faster Computer/Code efficiency 10secx4 40sec
– PMC (5sec update) 1min 48sec
– Overhead 50sec
• Integration ?
Minimum time 6.5 min
MARS Design Review
PP-15
Operations Scenario
• Initial Setup (Ops at start of night)– Move Telescope to CCAS position
– Move Tracker to nominal stacking position
– Ops should set SAMS reference for the opening TEMP.
• Position MARS with respect to the HET (3min)– Move X, Y stages to align the MARS bore-site with that of the
HET. X and Y positions are positioned by placing M43 on the reference spot. Yaw and pitch ??
– Move Z stage to set MARS to the best nominal GRoC. Focus on a segment apply any necessary offset.
• Stacking (3.5min)– Adjust GroC (allout through PMC, dihedral through SAMS)
– Run Stacking code through 2 iterations
– Move tracker
– Run Stacking code through 2 iterations
MARS Design Review
PP-16
Conclusions
• We are modeling MARS II on a relatively robust system which is now delivering to the stacking performance specifications most of the time.
• Time specifications are attainable, but will require :– Minimal follow-up measurements,
– Reliably good dome seeing,
– Faster PMC updates,
– More reliable mirror capture,
– Accurate placement in a maximum of 2 stacking iterations
• Need to tolerance the system to optimize operations.