MMT-AO performances: discussion

G. Brusa

Outline

• Interaction matrix• AO system model• Calibration issues• Performance estimation• Tip-tilt error• Accelerometer data

Interaction matrix

AO system model

DM

t

CREC

WFS

Dhrg wfs)( 0

nD ch dmh

sin

soff sout+ -

+

+

AO Block Diagram

WFSC

Turbulence

AdaptiveSecondary

WFSI

SSC

RTR

DMI

DDS

spo slo rtr com, pos, cur

Seeing vs. g’ factor

Best performances

• H band• Seeing 0.4” • SR

– 40% (SE)– 20-30% (LE)

Uncorrected tip-tilt

10mas

;

Total 30mas(single axis)

Secondary Tilt and Decenter (I)

dax = 300 nm rms

day = 300 nm rms

dlx = 1600 nm rms

dly = 300 nm rms

da = 15.4 nm/mas dl = 43.1 nm/mas

Secondary Tilt and Decenter (II)

dax = 170 nm rms

day = 130 nm rms

dlx = 310 nm rms

dly = 120 nm rms

da = 15.4 nm/mas dl = 43.1 nm/mas

Conclusions

• How are we going to measure the interaction matrix ?

• Is there an equivalent g’ for the pyramid sensor ?

• How are we going to setup the diagnostics both from WFC and technical camera ?

• Do we need to implement a feedforward correction of vibrations ?