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-3

Reference Pupil

MARS Design Review

PP-4

Reference Spots

MARS Design Review

PP-5

HET aligned

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-8

Pupil Plane Errors

•Affects

•Capturability

•Absolute Tip/Tilt accuracy

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-13

Stacking Time

• Total time 27-53 min

• Total time - IQ/logging 16-36 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.