Gemini Observatory. Multi-Conjugate Adaptive Optics Control System. The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 1

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1 Gemini Observatory Multi-Conjugate Adaptive Optics Control System The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 1

2 The Gemini MCAO System Andy Foster Observatory Sciences Ltd William James House, Cowley Road CAMBRIDGE, UK. CB4 0WX. The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 2

3 Classical Adaptive Optics The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 3

4 Classical AO Comparison The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 4

5 The plague of Classical AO Limited Field of View Wavefront sensors measure perturbations along line of sight to guide star. These will differ along line of sight to the science target. See images below taken 20 arcseconds apart. The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 5

6 The plague of Classical AO Sky Coverage Need bright stars close to science target for AO. Only 5% of the sky is accessible. Use Laser Guide Stars (LGS) to get round this. Fluorescence of sodium atoms at 90/100km. But not without problems. Cannot determine Tip/Tilt information from an LGS. This is where most of the phase correction comes from. Finite height of LGS leads to The Cone Effect. The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 6

7 The plague of Classical AO The Cone Effect 90 km Missing Data The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 7

8 The Solution MCAO Multi-Conjugate Adaptive Optics Turbulence Layers #2 #1 Telescope DM1 DM2 WFS Atmosphere UP The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 8

9 MCAO & the Cone Effect 90 km The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 9

10 The MCAO Subsystems MCAO contains the following subsystems: The Laser System (LS) The Real-Time Controller (RTC) The Safe Aircraft Localization and Satellite Acquisition System (SALSA) The Beam Transfer Optics and Laser Launch Telescope Systems (BTO/LLT)» The Beam Diagnostics Sensor System (BDSS) The Adaptive Optics Module (AOM) The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 10

11 The BTO/LLT Subsystem The BTO/LLT subsystem is responsible for taking the laser beams from the centre section of the telescope and transferring them up the telescope truss, across the secondary vanes and then launching them from behind the secondary mirror. VME based EPICS with the Gemini extensions vxworks Control System designed and developed by OSL. Commissioning this week! The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 11

12 Laser path z z Five 14-W beams Laser System location: On center section (A) z On-axis LLT A The Gemini MCAO System (ICALEPCS, Geneva, October 2005) A 12

13 BTO/LLT: Main Engineering Screen The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 13

14 BTO/LLT VME architecture Synchro bus BDSS Time bus Control LAN MCAO BTO/LLT VME MVME 2700 CPU board MVME 2700 CPU board Bancom 635 time board VMIVME5588 RM board OMS58-8S motor controller OMS58-8S motor controller OMS58-8S motor controller OMS58-4S motor controller XYCOM XIP To servo motor electronics To TT mirrors From sensors To switches, relays, DC motors The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 14

15 BTO/LLT EPICS Additions EPICS driver for Xycom 9660 carrier board (following Andrew Johnson s drvipac approach) Device and driver support for XIP-2440, Digital Input bi, mbbi, mbbidirect records, interrupt support Device and driver support for XIP-2445, Digital Output bo, mbbo, mbbodirect records Device and driver support for XIP-5320, Analogue Input ai, waveform records Supports on-board calibration through a vxworks task every 30 minutes Device and driver support for XIP-5230, Analogue Output ao record Drivers can be compiled without EPICS ao driver, drives piezo-electric actuators at up to 1 khz for FSA control The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 15

16 BTO/LLT EPICS Additions Velocity and acceleration of tip and tilt axis motors must provide smooth, linear travel between mirror positions Multi-axis linear coordinated moves are supported by OMS 58 hardware As far as we could tell, this feature is not supported by any current EPICS records, so Coordinated Motion Record developed to handle multiple axis moves The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 16

17 The Beam Diagnostics Sensor System Uses two commercial (Pixelfly) CCD cameras to image the near and far fields of the laser Measures offsets from pre-determined positions of laser spots Corrections applied to truss pointing and centering mirrors by BTO Provides measurements of the beam quality of the laser at the top-end times diffraction limit (1 for a Gaussian beam) The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 17

18 The Beam Diagnostic Sensor System Runs on a Linux (Red Hat 9.0) target Running EPICS with Gemini extensions Use ESO s Skycat tool to display images Interface to cameras is through PCIbus, came with linux driver Wrote a SCAM (Simulated Camera) driver which manipulates memory buffers to test without cameras Using a 2.66 GHz Pentium 4 (512 MB RAM), can read out both cameras (1390x1024 pixels) at 8.6Hz. The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 18

19 The Beam Diagnostics Sensor System Software Design epicsthreadcreate called to create tasks which analyse and manipulate the image data. This is done through a gensub INIT routine at iocinit. Standard EPICS records used to control functions of the cameras such as: Binning Exposure time Reading the temperature Commands are sent to the BDSS through Gemini CAD records. Being able to use EPICS under Linux has allowed us to fully integrate this system with the rest of the Gemini Control System. This is very positive and we have seen no major problems using a Linux target. The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 19

20 BDSS: Main Engineering Screen The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 20

21 BDSS: Simulated Far Field and Phase Retrieval Plots Skycat Display of Simulated Far Field Phase Retrieval Plots The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 21

22 DMs AOM Schematic Science ADC LGS source simulator NGS source simulator shutter TTM NGS WFS Beamsplitter Diagnostic WFS NGS ADC LGS WFS LGS zoom corrector The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 22

23 AOM: Main Engineering Screen The Gemini MCAO System (ICALEPCS, Geneva, October 2005) 23