MCAO Laser Coordination and SALSA Jacques Sebag / Corinne Boyer

MCAO May 24-25, 2001MCAO Preliminary Design Review2 Laser Coordination Avoid interference during night observations SOAR CTIO By defining an agreed policy between observatories By implementing a Laser Traffic Control System (LTCS)

MCAO May 24-25, 2001MCAO Preliminary Design Review3 Laser Coordination Gemini South  D (m)  Z (m) SOAR TOLOLO Gemini North  D (m)  Z (m) CFHT KECK II SUBARU LTCS is an anti-collision algorithm TCS information from telescopes + instrument flag (URL address) Laser characteristics + geometrical model Output = Predicted collision Use MK software developed with Keck Distance  D and altitude  Z differences Comparison Gemini South and North

MCAO May 24-25, 2001MCAO Preliminary Design Review4 SALSA Elements Same design as Gemini-North: –Boresited IR aircraft camera –All-sky aircraft cameras –Available radar feeds from air traffic control agencies (TBD) –Satellites: US Laser Clearinghouse interface (TBD)

MCAO May 24-25, 2001MCAO Preliminary Design Review5 SALSA: risk of illumination d a MPE: maximum permissible exposure ANSI Z136.1 With a = 42.5” and d=45cm: h0 = 1.2km h0 Altitude (km) Model Below W Above 1.23x10W MPE for CW laser MPE (10-5 J/cm2) MCAO (10-5 J/cm2) V=200km/h

MCAO May 24-25, 2001MCAO Preliminary Design Review6 SALSA: Aircraft detection In the Visible In the IR Intensity (candelas) Magnitude At Zenith Magnitude At 80 deg AntiCollision Lights Position Lights 2-5 microns microns Anti-collision lights (h=7km)

MCAO May 24-25, 2001MCAO Preliminary Design Review7 SALSA: Detection time For All-Sky Cameras m (deg)Distance to laser (km)Time (min) m 30 Laser beam v=800km/h and h=7km

MCAO May 24-25, 2001MCAO Preliminary Design Review8 SALSA: Detection time For Boresited Camera (BOC) 30 Laser beam HA: v=800km/h and h=7km LA: v=200km/h and h=0.3km FOV (deg)Time (sec) for HATime (sec) for LA

MCAO May 24-25, 2001MCAO Preliminary Design Review9 SALSA: Detection method Method based on comparing consecutive frames –For Visible images –Subtraction to remove fixed objects –Use anti-collision lights flashing trait (freq of 1 to 2 Hz) Method based on threshold limit –For IR images False Alarm –Meteor shower, tracking errors –presence of the Moon, laser beam –testing on the sky

MCAO May 24-25, 2001MCAO Preliminary Design Review10 SALSA: Specifications Boresited camera (BOC) –1sec shutdown FOV = 20 deg HZ video rate –Aircraft Angular size 7km) : between 0.4° and 0.2° pixel scale of 0.1° or less All-Sky Cameras (ASC) –2min warning FOV = 165 deg + 1min for aircraft detection –Size of detectors/pixels pixel scale between 0.1° and 0.3° –Trail of 5 pixels variable exposure time ( 1 to 30sec) read out time less than 30sec

MCAO May 24-25, 2001MCAO Preliminary Design Review11 SALSA: BOC Layout BOC mounted on telescope top ring-Y side GIS Shutter in front of laser Shutter control Instrument sequencer MCAO subsystems Acquisition and analysis electronics

MCAO May 24-25, 2001MCAO Preliminary Design Review12 SALSA: ASC Layout ASC#1 and ASC#2 Server to share airplane detection information Image analysis and airplane detection Server to share ASC images Acquisition and control electronics User display

MCAO May 24-25, 2001MCAO Preliminary Design Review13 SALSA Controller requirements - 1 The SALSA Controller must perform the following functions: –start the bore-sited camera loop (executed at a high rate): 1.Read the camera. 2.Do the signal analysis (aircraft in the field of view ?) 3.If an aircraft is present  If the shutter is open Send first a digital signal to the AOM, BTO/LLT and RTC controllers to pause all control loops Close the safety shutter Send a status back that the safety shutter is now closed Exit the loop  If the shutter is closed Go back to step 1

MCAO May 24-25, 2001MCAO Preliminary Design Review14 SALSA Controller requirements If no aircraft  If the shutter is open Go back to step 1  If the shutter is closed Open the shutter Send a digital signal to the sub-systems AOM CC, BTO/LLT CC and RTC to indicate that the safety shutter is now open Send a status back that the safety shutter is now open –stop the bore-sited camera loop: Send first a digital signal to the AOM, BTO/LLT and RTC controllers to pause all closed loops Close the safety shutter Send a status back that the safety shutter is now closed Stop reading the camera

MCAO May 24-25, 2001MCAO Preliminary Design Review15 SALSA Controller requirements - 3 –open the shutter (engineering command): Open the safety shutter Send a digital signal to the sub-systems AOM CC, BTO/LLT CC and RTC to indicate that the safety shutter is now open Send a status back that the safety shutter is now open –close the shutter (engineering command): Send first a digital signal to the AOM, BTO/LLT and RTC controllers Close the safety shutter Send a status back that the safety shutter is now closed

MCAO May 24-25, 2001MCAO Preliminary Design Review16 SALSA Controller requirements - 4 –start the two all sky cameras loop: 1.Read the camera. 2.Do the signal analysis to determine (aircraft in the field of view ?) 3.If an aircraft is present  Compute the estimated time when the aircraft will cross our beam and display a warning message with this time information  Go back to step 1 4..If no aircraft are present  Go back to step 1. –stop the two all sky cameras loop

MCAO May 24-25, 2001MCAO Preliminary Design Review17 SALSA Controller Design The cameras and hardware of the SALSA system are not defined yet: no software design presented in this review. Interfaces with MCAO sub-systems and GIS have been defined and are described in the ICDs. Goal is to design an all-EPICS system.

MCAO May 24-25, 2001MCAO Preliminary Design Review18 PDR Agenda Friday, 5/ Laser System 0900 CTIO Sodium Studies 0915 Control System 0945 Break 1000 RTC Electronics 1045 Safety System 1100 Availability analysis 1130 Closed vendor Sessions 1200 Lunch 1300 Cost and schedule 1400 Committee session 1700 Committee report 1800 Adjourn