1. the steering mirror control
c.cerna
demonstrator progress meeting 29/06/2005

2. the KMOS case The more stringent requirements : Temperature (30 °K)
Vibration (Ariane 5 launch)
Purpose of the prototype : verify the cryo conditions :
Tip-tilt range : +/- 2.5°
Pointing accuracy : 1’
Pointing stability : <= 5”
In terms of coding :
5°/5” = 3600 steps ~ 12bits

3. PC the KMOS case solution adopted in term of control : x2 axis x2 axis
Coil
INFINEON
FP212L100 PC
National Instrument
NI 7342 control board
2 axis
out : +/-10V, qq mA
in : +/- 10V, 12bits
home made ao board
AD524 ampli op.
U/I ampli : +/-10V, qq mA40 mA
out 2 : +5V, 10 mA stable
ampli op. : g=10

4. the demonstrator case The more stringent requirement :
control the dithering test at 120 °K

5. the demonstrator case qX = +/- 0.258° qY = +/- 1.15°
250 mm
2.5 mm
10 mm Z
stack
Tip-tilt :
qX = +/ °
qY = +/- 1.15°
steering
position
pointing accuracy :
dithering : moving a PSF on the slices of a known value to be sure that the image of the PSF on the detector has moved of 1/10 of pixel
1/10 of IR pixel = 39 mm on the slices  qaccuracy = 33 “
Absolute accuracy :
be able to measure 33” means have an absolute accuracy of about 3”  dqaccuracy ~ 3“

6. <12bits the demonstrator case in terms of coding :
en x : 0.516°/3” ~ 9bits
en y : 2.3°/3” ~ 11.4bits
in terms of signal amplification :
As the tip-tilt is at least twice lower than in KMOS case, AO gain have to be at least twice higher g~20-50
in terms of motor power :
As mechanical part is optimised (PEB) one can imagine than 40mA will be enough to move the actuators
<12bits

7. demonstrator solutions
Coil
INFINEON
FP212L100
500€
800€
home
expensive outside
NI 7342
ao board :
U/I converter
stable alim
ao g~10-100
4ch 16bits an. input
8ch Alim 24V
alim rack
control
1000€
~3000€ ?
Coil
INFINEON
FP212L100
ao g~10-100