Replicating Existing Adaptive Optics Control Electronics

1
Replicating Existing Adaptive Optics Control
Electronics

• For NASA IRTF

A Presentation by Paul Linden
2
The Basic AO System
Light
Image
Lens
Beamsplitter
DM
2kHz
36 Channel Signal
Electronic System
Wavefront Sensor
3
Electronic System
Real Time Redhat Linux
APDs
Tx
HV
Control Crate
Rx
MM
Ethernet
User Interface (Redhat Linux)
4
The AO Control Crate
12 Channel High Voltage Amplifier
36 Segment
VME Back Plane
DM
12 Channel High Voltage Amplifier
12 Channel High Voltage Amplifier
Membrane Mirror
36 Detectors
24 Channel Counter Card
APDs
12 Channel Counter Card
50 Watt Car Amplifier
Multifunction Board
5
Some Components Involved
6
The Basics of Curvature Sensing
f
Lens
I1
I2
s
s
f
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Distorted Wavefronts- 2 Basic Possibilities
I1
I2
P1
s
s
Case 1
I2
f
I1
s
s
P2
Case 2
f
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The Mirror Membrane
I1
I2
Detector
Detector
Detector
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Machine The Parts
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Make The Connectors
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The UltraVolt HVPS

• /- 500 Volts (to control actuators on DM)
• 2 Separate Power Supplies
• 125 Watts Each
• Controlled by Resistive Programming
• Built for Pulsed and Capacitive Loads
• (Elements of DM modeled by 3 nF Capacitors)

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Control of the UltraVolt

• Voltage Divider

5 KO Potentiometer
Signal Gnd
Remote Adjust
5 V Reference
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Reduction of Pickup

• 22µF tantalum and a 1µF Capacitor

Thévenin Equivalent
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Putting it Together
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Acknowledgements

• Mark Chun
• Assistant Astronomer
• Darryl Watanabe
• Scientific Instrument Electronics Technician
• James Ah Heong
• Student Electronic Technician
• National Science Foundation and Technology Center
  for Adaptive Optics, managed by the University of
  California at Santa Cruz under cooperative
  agreement No. 9876783