Laser Coordination and SALSA

Jacques Sebag / Corinne Boyer

MCAO

Laser Coordination

CTIO

• Avoid interference during night observations MCAO

SOAR

• By defining an

agreed policy

between observatories • By implementing a

Laser Traffic Control System (LTCS)

May 24-25, 2001 MCAO Preliminary Design Review

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MCAO

Laser Coordination

•Comparison Gemini South and North

Gemini South

SOAR TOLOLO D D (m) 460 12000 D Z (m) 14 505 •Distance D D and altitude D Z differences

Gemini North

CFHT KECK II SUBARU D D (m) 160 680 825 D Z (m) 32 103 174 • 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

May 24-25, 2001 MCAO Preliminary Design Review

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MCAO

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)

May 24-25, 2001 MCAO Preliminary Design Review

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MCAO

SALSA: risk of illumination

•MPE: maximum permissible exposure ANSI Z136.1 •With a = 42.5” and d=45cm: h0 = 1.2km

a

•MPE for CW laser Altitude (km) Model Below 1.2

50 W Above 1.2 3x10W MPE (10-5 J/cm2) 4.8

11 MCAO (10-5 J/cm2) 25 15

d h0

V=200km/h

May 24-25, 2001 MCAO Preliminary Design Review

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MCAO

SALSA: Aircraft detection

Position Lights

•In the Visible

Anti-collision lights (h=7km)

Intensity (candelas) 400 80 20 Magnitude At Zenith -1.2

0.5

2 Magnitude At 80 deg 2.5

4.3

5.8

•In the IR

AntiCollision Lights Engines @ 2-5 microns Body @ 10-12 microns

May 24-25, 2001 MCAO Preliminary Design Review

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MCAO

SALSA: Detection time

•For All-Sky Cameras

Laser beam

30

m

v=800km/h and h=7km

May 24-25, 2001

m (deg) Distance to laser (km) 5 67.9

10 15 27.6

14 Time (min) 5 2 1

MCAO Preliminary Design Review

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SALSA: Detection time

•For Boresited Camera (BOC)

Laser beam

HA: v=800km/h and h=7km LA: v=200km/h and h=0.3km

MCAO 30

May 24-25, 2001

FOV (deg) 5 15 20 Time (sec) for HA 2.8

4.1

5.5

MCAO Preliminary Design Review

Time (sec) for LA 0.5

0.7

1

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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, 2001 MCAO Preliminary Design Review

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SALSA: Specifications

• Boresited camera (BOC) – 1sec shutdown • FOV = 20 deg + 30-60 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, 2001 MCAO Preliminary Design Review

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SALSA: BOC Layout

•BOC mounted on

telescope top ring-Y side

•Shutter in

front of laser

MCAO •Acquisition and

analysis electronics

•Shutter

control

•Instrument

sequencer

•MCAO

subsystems

May 24-25, 2001 MCAO Preliminary Design Review

•GIS

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SALSA: ASC Layout

•ASC#1 and ASC#2 •User display MCAO •Acquisition and

control electronics

•Image analysis and

airplane detection

•Server to share

ASC images

May 24-25, 2001

•Server to share airplane

detection information

MCAO Preliminary Design Review

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SALSA Controller requirements - 1

MCAO • 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

May 24-25, 2001 MCAO Preliminary Design Review

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SALSA Controller requirements - 2

MCAO 4. 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 • Close the safety shutter • Stop reading the camera : • Send first a digital signal to the AOM, BTO/LLT and RTC controllers to pause all closed loops • Send a status back that the safety shutter is now closed

May 24-25, 2001 MCAO Preliminary Design Review

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SALSA Controller requirements - 3

MCAO – 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) RTC controllers • Close the safety shutter closed : • Send first a digital signal to the AOM, BTO/LLT and • Send a status back that the safety shutter is now

May 24-25, 2001 MCAO Preliminary Design Review

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SALSA Controller requirements - 4

MCAO – 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

May 24-25, 2001 MCAO Preliminary Design Review

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MCAO

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.

May 24-25, 2001 MCAO Preliminary Design Review

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PDR Agenda

Friday, 5/25

0800 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 MCAO

May 24-25, 2001 MCAO Preliminary Design Review

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