Optical Detector Systems at the European Southern Observatory

Dietrich Baade & ODT: Optical Detector Systems at ESO

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Optical Detector Systems at the

European Southern ObservatoryDietrich Baade

&Optical Detector Team (ODT)

Work at ESO on infrared detectors covered in:

Dorn et al. Finger et al. Mehrgan et al. Beletic et al.


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The ODT Themes

• Shift in emphasis from scientific imaging to signal sensing: Without AO, ELTs will not bring any improvement.

• The MAD adaptive optics system tests enabling technology with bright natural guide stars.

• The OPTICON project with e2v L3 Vision technology aims to push this towards the ultra-low noise domain.

• The New General detector Controller (NGC) is a key stepping stone.

• More to come

VLT 2nd generation instruments:• X-shooter – the 0.3-to-2.4 μm rapid-response spectro-cannon• MUSE – the cosmic inventory taker

VLT projects in their own right but with an additional view of getting ready for OWL:

OmegaCAM for the VLT Survey Telescope (VST)


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Multi-conjugated Adaptive Optics Demonstrator

• MAD tests two wavefront-sensing (WFS) concepts:

Reiss et al.

o star oriented, using multiple Shack-Hartmann (SH) systemso layer oriented (LO), using multiple pyramids

• 3 SHWFS + 2 LOWFS detector systems with e2v CCD39 devices (80 x 80 pixels)• Only one method used at a time• One FIERA controller• Up to 400 frames/s (500 frames/s with 2x2 binning)• Considerably exceeds original FIERA spec of 1 Mpixel/s • Read noise: ~7 e-


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Next-generation Wavefront Sensing: OPTICON and e2v L3 Vision Technology

AO systems for 2nd-gen. VLT instruments and OWL require:• >1,000 actuators (→ >1,000 x 6x6 pixels)• ~1 kHz frame rate• negligible read noise even when photon noise ~100%• high movability (→ no real cryogenics → dark current) OPTICON project received funding from EU Commission CCD220 being developed by e2v

1 system foreseen for HAWK-I, 4 for MUSE

Downing et al.

StoreArea

Image Area

240x12024□µm

StoreArea

Image Area

240x12024□µm

OP 1

OP 2 GainRegisters

OP 3

OP 4 GainRegisters

OP 8GainRegisters

OP 7

OP 6GainRegisters

OP 5

StoreAreaStoreArea

Image Area

240x12024□µm

StoreArea

Image Area

240x12024□µm

OP 1OP 1

OP 2 GainRegisters

OP 2 GainRegisters

OP 3OP 3

OP 4 GainRegisters

OP 4 GainRegisters

OP 8GainRegisters

OP 8GainRegisters

OP 7OP 7

OP 6GainRegisters

OP 6GainRegisters

OP 5OP 5


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OmegaCAM (1° x 1° imager)

• Three FIERAs and 32 (+4) e2v CCD44-82 devices

• Very robust since first switch-on

• The coordination of autoguiding, closed-loop wavefront sensing, and shutter control is one of the show pieces.

• Built as designed

• Commissioning in 2006

• Strict attention to safety

• Extensive detector characterization on ESO’s test bench

• Innovative cooling system very effective

Iwert et al.

Lizon et al.

Christen et al. (2x)


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X-shooter

• Basically a single-mode VLT Cassegrain instrument for singular events (`point and shoot´)

• Simultaneous wavelength coverage 0.3 – 2.4 μm• First ESO instrument to bridge the 1-micron barrier• 2 optical arms (e2v CCD44-82 and MIT/LL CCID-20)• 1 IR arm (Rockwell Hawaii-2 RG)

• 1 IRACE and 1 FIERA controller each• FIERA software defines 2 fully independent virtual cameras on one common DFE• Approaching Final Design Review• Commissioning in 2008


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• First optical instrument to use NGC

• 2nd-generation cryostat head

• Prototype detector system at the end of 2006

Multi-unit Spectroscopic Explorer (MUSE)

• Twenty-four separate detector systems

• 4K x 4K CCDs (or 2 x 1 mosaics)

• 465 – 930 nm: high red response is mission critical

• Need to save mass and volume

• Must ease AIT

• Reliability will be vital

Reiss et al.


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PULPO2 housekeeping unit with enhanced • shutter ( ) and temperature control• temperature and pressure monitoring

Cryostat Cleanliness and Control

Plasma cleaning: • fast, effective, low risk, low operating cost• excellent results with big OmegaCAM cryostat

Deiries et al.

Geimer et al.

H20 exorcism• baking of CCDs in gas stream • accidental (re-)discovery

Reif et al.


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New General detector Controller (NGC)

• In the decade since 1998, a total of 30 FIERA and IRACE systems will be deployed.

• Extremely successful (nearly negligible telescope downtime) but some other limitations:

Meyer et al. Cumani et al.

• mass, volume, power dissipation

• obsolete components

• voltage range and swing

• speed, number of channels

• 2 successes (= 2 costs)

Reyes et al.

a

• Proto-type of joint successor NGC has seen `first light´• First deployments: KMOS (2009) and MUSE (2011)

Optical Detector Systems at the European Southern Observatory

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