Johann Kolb, Norbert Hubin Mark Downing, Olaf Iwert, Dietrich Baade Simulation results: Richard...
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Transcript of Johann Kolb, Norbert Hubin Mark Downing, Olaf Iwert, Dietrich Baade Simulation results: Richard...
Johann Kolb, Norbert Hubin Mark Downing, Olaf Iwert, Dietrich BaadeSimulation results: Richard Clare
Detectors for LGS WF sensing on the E-ELT
1AO for ELTs, Paris, 22-26 June 2009
AO needs for detectors Derived specifications Solutions
IR detectors development
Large visible fast low-noise detector for Shack-Hartmann based AO WFS
Existing visible high performance detector (i.e. CCD220)
3kHz low-noise detector
AO Detectors needs on the E-ELT
AO for ELTs, Paris, 22-26 June 2009
LGS GLAO
NGS GLAO NGS
SCAO
LGS MCAO LTAO MOAO
XAO
IR Low
order WFS
Low order AO
SH quad -cell
PYR Other WFS…
Vis TT sensors
IR TT sensors
2
Guiding
AO Detectors needs
on the E-ELT
Adaptive Optics WFS detectors
3AO for ELTs, Paris, 22-26 June 2009
Existing system (MAD):8x8 sub-apertures on an e2v CCD39
In development (VLT AO Facility):40x40 sub-apertures on an e2v CCD220
Future (all EELT AO
modules):84x84 sub-
apertures
Specifications / Spatial resolution I
4AO for ELTs, Paris, 22-26 June 2009
¤ Number of pixels: 84x84 sub-apertures of 20x20 pixels = 1680 x 1680 pixels
LLT
Sodium layer
Detector plane
Pupil plane
Side launch
flux
Need 14-20 pixels per sub-aperture
To cover spot elongation in the most demanding AO systems
Specifications
Large visible fast low-noise detector for Shack-Hartmann based AO WFS
¤ Spatial resolution¤ Temporal resolution¤ Image quality
Specifications / Spatial resolution II
5AO for ELTs, Paris, 22-26 June 2009
¤ Pixel size: 24 µm Detector size ~ 40x40 mmCompromise between reasonable detector size (for yield) and easiness of alignment with small pixels
¤ PSF = charge diffusion = optical cross-talk: 0.8 pixels “Blurs” the image Simulations PSF should be kept small
Specifications / Temporal resolution I
6AO for ELTs, Paris, 22-26 June 2009
¤ Exposure time: variable between 1.4 and 5 / 10 (LGS / NGS) ms.
Corresponds to frame rates from 100 / 200 (NGS / LGS) to 700 Hz All specifications should be met at any value in this range
¤ Latency 1: synchronicity within a sub-aperture All pixels from a same sub-aperture should be exposed within 20 µs
¤ Latency 2: prompt and continuous transfer of pixel data to the detector output pins
¤ Read-out scheme : Either snapshot (frame-transfer CCD) or rolling-line (CMOS, NAOS IR sensor).
Rolling-line read-out = lines of pixels or of sub-apertures are read-out while the rest of the detector is integrating
Specifications / Temporal resolution II
7AO for ELTs, Paris, 22-26 June 2009
¤ Image lag = “charges left behind”: < 2% per pixel at the next frame.
Is an issue for some technologies Is equivalent to reduction of AO bandwidth
¤ Full-well capacity: > 4000 electrons
¤ Linearity: < 5% peak-to-peak
Specifications / Image quality I
8AO for ELTs, Paris, 22-26 June 2009
¤ Average Read-Out Noise: < 3 e- rms/pixel/frame (goal <1e-) Simulations in this range, required laser power increases linearly with RON
¤ Average Dark current: < 0.5 e-/pixel/frame Important at low frame rates
Specifications / Image quality II
9AO for ELTs, Paris, 22-26 June 2009
¤ Read-Out Noise and dark current variation: 95%ile < twice the average value
Important in some technologies (CMOS) where all pixels don’t have the same RON and dark current
¤ Simulations decreases performance with CoG, not much with Matched Filter
Specifications / Image quality III
10AO for ELTs, Paris, 22-26 June 2009
¤ Quantum Efficiency: LGS mode: > 85% at 589 nm NGS mode:
¤ The same detector shall be used either for LGS or NGS WF sensing
Specifications / Image quality IV
11AO for ELTs, Paris, 22-26 June 2009
¤ One cannot always have large full-well capacity and very-low read-out noise CMOS allows regions of programmable gain.
lowest RON, small full-well (worst elongation)
low RON, average full-well
high RON (but still small w.r.t. photon noise), large full-well
System gain
(e-/ADU)
Full-well(e-)
Noise target
(e-)0.2 204 2.010.5 512 2.061 1024 2.242 2048 2.834 4096 4.278 8192 8.25
16 16384 16.12
¤ Example:
¤ Simulations (R. Clare) same performance as very low RON + large full-well, with Matched filter (degradation with CoG)
Other specifications
12AO for ELTs, Paris, 22-26 June 2009
¤ Packaging
¤ Incidence angle
¤ Interfaces
¤ Cosmetics
¤ Pixel Response Non Uniformity
¤ Lifetime
¤ Stability w/ temperature and time
13AO for ELTs, Paris, 22-26 June 2009
Large visible fast low-noise detector for Shack-Hartmann based AO WFS
Solutions that meet the specifications
E-ELT AO WFS DetectorDevelopment Plan
14AO for ELTs, Paris, 22-26 June 2009
Design Study
Design Study
Technology Validation
Development
Testing/ Acceptance
Production Phase
Technology Demonstrator
Scaled-down Demonstrator
2007
2008
2009
2010
2011
2012
2013
2014
2015
Authorize Production
Testing
30 Science Devices
Production
Full size device meeting all
specs.
Engineering exercise
Full Scale Demonstrator
Retire Architecture/ Process Risks
SDD
Retire Pixel Risks
TD
1 (2?) contract – 1xFP7, (1xother?) 24 months Highly likely CMOS and down-select of TDs Retire architectural risks by fab. ~ ¼ imager
3 contracts – 2xFP6 ELT-DS, 1xEELT Phase B: 11 months All CMOS Imagers - most likely to succeed retire pixel risk by demonstration noise x speed with good imaging capability
4 contracts - 2xFP6 ELT-DS, 2xEELT Phase A: 6 months Investigated many different technologies Most promising – CMOS Image, APD array and orthogonal EMCCD
CCD-based vs. CMOS-based concepts
15AO for ELTs, Paris, 22-26 June 2009
CCD:Charge Coupled Device
Outside chipOn chipPixels
Charges transfer
Read-out (output register)
Controller, incl. digitization (ADCs)
CMOS: Complimentary Metal Oxide Semiconductor
Charges creation
Pre-amp.
To the RTC
Charges transfer
Read-out (output register)
Controller, incl. digitization (ADCs)
Charges creation
Pre-amp.
To the RTC Read-out (pixels transistors)
Voltages transfer
Digitization (ADCs)
84x84 Sub-apertures
Analog processing
100s ADCs
Multiplexer/serializerY-a
dd
ressin
g
ControlLogic
Y-a
dd
ressin
g
ControlLogic
Analog processing
100s ADCs
Multiplexer/serializer
ControlLogic
ControlLogic
each 20x20 pixels
Vision of Full Size Device
E-ELT AO WFS Detector design
16AO for ELTs, Paris, 22-26 June 2009
Example: frame transfer CCD: CCD220
Technology Demonstrator
Scaled Down Demonstrator
Development status
17AO for ELTs, Paris, 22-26 June 2009
¤ 3 Technology Demonstrator contracts awarded in 2008 2 in manufacturing, results end of the year 1 completed:
frame rate of 1 kHzRON < 2 electronsImage lagPixel Response Non UniformityLinearity
Problems understood Forward path proposed
¤ 1 Scaled Down Demonstrator contract Call for Tender out this summer Contract start beginning 2010 Funded by EC
How to motivate detectors suppliers?
18AO for ELTs, Paris, 22-26 June 2009
The Universe
Atmosphere
Telescope
WFS in adaptor or instrument
WFS detector
Entity Provider Role
Contain objects to observe
Blur images
Deliver the best possible image quality, with the maximum throughput
?
?
EELT
Provide pixels as representative as possible of the image: high spatial and temporal resolution,
high QE
Make the best use of received pixels to compute
turbulence correction
Wave Front reconstruction / Command to the Deformable Mirror
EELT