mcao laser coordination and salsa jacques sebag / corinne boyer

MCAOMCAO

Laser Coordination and Laser Coordination and SALSASALSA

Jacques Sebag / Corinne Boyer

May 24-25, 2001 MCAO Preliminary Design Review

2

MCAOMCAO

Laser CoordinationLaser Coordination

• Avoid interference during night observations

SOAR

CTIO

• By defining an agreed policy between observatories• By implementing a Laser Traffic Control System (LTCS)


3

MCAOMCAO

Laser CoordinationLaser Coordination

Gemini South

D (m)

Z (m)

SOARTOLOLO

46012000

14505

Gemini North

D (m) Z (m)

CFHTKECK IISUBARU

160680825

32103174

• 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


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MCAOMCAO

SALSA ElementsSALSA 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)


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MCAOMCAO

SALSA: risk of illuminationSALSA: 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 1.2 50 W

Above 1.2

3x10W

•MPE for CW laser

MPE (10-5 J/cm2)

MCAO (10-5 J/cm2)

4.8 25

11 15

V=200km/h


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MCAOMCAO

SALSA: Aircraft detectionSALSA: Aircraft detection

•In the Visible

•In the IR

Intensity(candelas)

MagnitudeAt Zenith

MagnitudeAt 80 deg

400 -1.2 2.5

80 0.5 4.3

20 2 5.8

AntiCollision Lights

Position Lights

Engines @ 2-5 microns

Body @ 10-12 microns

Anti-collision lights (h=7km)


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MCAOMCAO

SALSA: Detection timeSALSA: Detection time

•For All-Sky Cameras

m (deg)

Distance to laser (km)

Time (min)

5 67.9 5

10 27.6 2

15 14 1

m

30

Laser beam

v=800km/h and h=7km


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MCAOMCAO

SALSA: Detection timeSALSA: 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 HA Time (sec) for LA

5 2.8 0.5

15 4.1 0.7

20 5.5 1


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MCAOMCAO

SALSA: Detection methodSALSA: 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


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MCAOMCAO

SALSA: SpecificationsSALSA: 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


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MCAOMCAO

SALSA: BOC LayoutSALSA: 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


12

MCAOMCAO

SALSA: ASC LayoutSALSA: 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


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MCAOMCAOSALSA Controller requirements SALSA Controller requirements - 1- 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


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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:• 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


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– 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


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– 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 14. .If no aircraft are present

Go back to step 1.

– stop the two all sky cameras loop


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MCAOMCAO

SALSA Controller DesignSALSA 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.


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MCAOMCAO

PDR AgendaPDR Agenda

Friday, 5/250800 Laser System 0900 CTIO Sodium Studies0915 Control System0945 Break1000 RTC Electronics1045 Safety System1100 Availability analysis1130 Closed vendor

Sessions1200 Lunch

1300 Cost and schedule1400 Committee session1700 Committee report1800 Adjourn

mcao laser coordination and salsa jacques sebag / corinne boyer

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