The MIRI Sensor Chip Assembly (SCA) simulator
description
Transcript of The MIRI Sensor Chip Assembly (SCA) simulator
The MIRI Sensor Chip Assembly (SCA) simulator
Steven BeardUK Astronomy Technology CentreRoyal Observatory, Edinburgh, UK
ROE Workshop “Following the Photon”, 10-12 October 2011
JWST Instruments and Detectors
MIRI NIRCAM NIRSPEC FGS-TFI
3 Si:As detectors 2 HgCdTe detectors 2 HgCdTe detectors10 HgCdTe detectors
JWST Detector Readout
Integration
Time
Dropped Framesbetween Groups
Signal onDetector
F0
G0
G1
G2
G3
G4
5 Groupsin this
Integration
Averaged Frameswithin Groups
ResetDetector
Each integration is made from several non-destructive reads, divided into groups.
MIRI Summary
ImagerCoronagraphLow Res. Spectrograph
Medium Res. Spectrograph• Short wavelength• Long wavelength
MIRI Modes to be Simulated
MIRI has a number of different modes to be simulated, each of which include several common requirements:
Simulate Targets
Simulate Background
Simulate Instrument
Transmission
Simulate Distortion & Dispersion
Simulate Detector
Simulate Targets
Simulate Background
Simulate Instrument
Transmission
Simulate Distortion
Simulate Detector
Simulate Target(s)
Simulate Background
Simulate Instrument
Transmission
Simulate Distortion & Dispersion
Simulate Detector
Simulate Target
Simulate Background
Simulate Phase Mask
Transmission
Simulate Distortion
Simulate Detector
Simulate Test Sources
Simulate Telescope Simulator
MTS Sim MRS Imaging LRSCoronagraphy
MIRI Modes to be Simulated
MIRI has a number of different modes to be simulated, each of which include several common requirements:
MRS mode is simulated by Specsim.
Simulate Targets
Simulate Background
Simulate Instrument
Transmission
Simulate Distortion & Dispersion
Simulate Detector
Simulate Targets
Simulate Background
Simulate Instrument
Transmission
Simulate Distortion
Simulate Detector
Simulate Target(s)
Simulate Background
Simulate Instrument
Transmission
Simulate Distortion & Dispersion
Simulate Detector
Simulate Target
Simulate Background
Simulate Phase Mask
Transmission
Simulate Distortion
Simulate Detector
Simulate Test Sources
Simulate Telescope Simulator
MTS Sim MRS Imaging LRSCoronagraphy
MIRI Modes to be Simulated
MIRI has a number of different modes to be simulated, each of which include several common requirements:
MRS mode is simulated by Specsim.
All the imager modes are simulated by Mirim Sim (Rene Gastaud’s presentation?).
Simulate Targets
Simulate Background
Simulate Instrument
Transmission
Simulate Distortion & Dispersion
Simulate Detector
Simulate Targets
Simulate Background
Simulate Instrument
Transmission
Simulate Distortion
Simulate Detector
Simulate Target(s)
Simulate Background
Simulate Instrument
Transmission
Simulate Distortion & Dispersion
Simulate Detector
Simulate Target
Simulate Background
Simulate Phase Mask
Transmission
Simulate Distortion
Simulate Detector
Simulate Test Sources
Simulate Telescope Simulator
MTS Sim MRS Imaging LRSCoronagraphy
MIRI Modes to be Simulated
MIRI has a number of different modes to be simulated, each of which include several common requirements:
MRS mode is simulated by Specsim.
All the imager modes are simulated by Mirim Sim (Rene Gastaud’s presentation).
MTS Sim simulates the telescope simulator used for Flight Model (FM) testing.
Simulate Targets
Simulate Background
Simulate Instrument
Transmission
Simulate Distortion & Dispersion
Simulate Detector
Simulate Targets
Simulate Background
Simulate Instrument
Transmission
Simulate Distortion
Simulate Detector
Simulate Target(s)
Simulate Background
Simulate Instrument
Transmission
Simulate Distortion & Dispersion
Simulate Detector
Simulate Target
Simulate Background
Simulate Phase Mask
Transmission
Simulate Distortion
Simulate Detector
Simulate Test Sources
Simulate Telescope Simulator
MTS Sim MRS Imaging LRSCoronagraphy
MIRI Modes to be Simulated
MIRI has a number of different modes to be simulated, each of which include several common requirements:
MRS mode is simulated by Specsim.
All the imager modes are simulated by Mirim Sim (Rene Gastaud’s presentation).
MTS Sim simulates the telescope simulator used for Flight Model (FM) testing.
All the simulators share the same detector simulation – provided by SCA Sim.
Simulate Targets
Simulate Background
Simulate Instrument
Transmission
Simulate Distortion & Dispersion
Simulate Detector
Simulate Targets
Simulate Background
Simulate Instrument
Transmission
Simulate Distortion
Simulate Detector
Simulate Target(s)
Simulate Background
Simulate Instrument
Transmission
Simulate Distortion & Dispersion
Simulate Detector
Simulate Target
Simulate Background
Simulate Phase Mask
Transmission
Simulate Distortion
Simulate Detector
Simulate Test Sources
Simulate Telescope Simulator
MTS Sim MRS Imaging LRSCoronagraphy
The MIRI Simulator Suite
• Having a suite of simulators ensures that every problem is solved only once.– But we did miss the opportunity
to share “simulate targets” and “simulate background”.
• SCASim provides a common detector simulation service for the other simulators.
• It converts detector illumination information from any MIRI simulator and generates simulated MIRI data in a choice of formats accepted by MIRI pipeline and analysis software.
DMS MIRI Pipeline
DHASmiri_sloper
DET
Simulated FITSWriter FITS
File
SCA Simulator
Specsim (MRS)
Detector Illumination Image File
TargetInformationMTS Sim
MIRIM SimMO Sim
Coro LRS
TargetInformation
SCASCA SCA
Simulated Level 1 FITS
File
Required SCA Simulator StepsThe SCA Simulator simulates:• Quantum efficiency• Reference pixels and outputs• Bad pixels• Dark current and hot pixels• Persistence• Readout modes• Poisson noise and read noise• Bias, gain and non-linearity• Cosmic ray effects• Subarray (window) modes
The simulation is controlled by:• Input parameters
• e.g. Readout mode
• Configuration information• e.g. Detector properties
• Configuration measurements• e.g. Dark current vs temperature
• Calibration data• e.g. Bad pixel map
X
X
X
X
Integrate and Apply Poisson
Noise
Coadd and Apply QE
Fringe Map
Simulated MIRI Level 1
FITS data
Integration time or ngroups
Subarray name
Readout mode
Flux in photons/second/pixel
Detector Illumination Image File (I,λ)
DetectorProperties
QE vs λ
Bad Pixel Map
Dark & Hot Pixel Map
Dark Current vs T
Read Noise vs T
AmplifierProperties
Cosmic RayProperties
StScI Cosmic Ray Library
Apply Fringe Map
(if any)
Apply Reference
Pixels
Apply Bad Pixels
Add Dark Current
For each readout...
Apply Read Noise
Apply Bias, Gain and
Non-linearity
Hit with Cosmic
Rays
Extract Subarray
Nextreadout
Format Output
Expected electrons/second/pixel
Actual electrons/pixel
Flux in electrons/second/pixel
DN/pixel
FPA name
Cosmic Ray mode
Persistence
Measurement
Configuration Info
Data Files
Calibration Data
Input Parameters
Input file name
Output file name
Design Decisions
• I used an Object-Oriented design that would make SCASim more flexible and reusable.– I also wrote the simulator in Python – an object-oriented language with
several useful scientific and array processing add-ons (numpy, scipy, matplotlib, pyfits, etc…)
• Since the JWST detector readout modes are very similar, I chose to make the SCASim workable with any JWST detector – not just the MIRI detectors.– So ngroups ≠ nframes. Useful for NIRCAM and NIRSPEC as well?
• I also chose to encapsulate as much of the detector information in parameter files, rather than in software constants.– By modifying these parameters and/or the class methods, SCASim could
be adapted to similar kinds of detector.
• The simulator modules were developed along with unit tests.– This ensured that changes didn’t generate unwanted side effects.
SCASim Design
The SCA simulator has an object-oriented design.
The core of the simulator is a Detector Array class.
The operational interface is generic: All detectors are illuminated, reset, integrated and read out, or can be hit by a cosmic ray.
The detailed implementation of the methods simulates the effects of the MIRI detector.
This makes the design adaptable and reusable.
OperationsAttributes
Name of class
SCASim Design
The detector uses a helper class, the Poisson Integrator, which encapsulates the Poisson statistics.
Other associated classes are used to describe detector characteristics, such as bad pixels, hot pixels, dark current and quantum efficiency.
SCASim Design
Each detector may be read out by one or more amplifiers (4 in the case of MIRI + ref. output).
SCASim Design
Each detector may be read out by one or more amplifiers (4 in the case of MIRI + ref. output).
Each amplifier is responsible for reading a particular slice (or zone) on the detector surface.
Each amplifier has an associated gain, linearity and read noise.
Note that dark current and read noise are derived from a generic “Measured Variable” class, used to described laboratory measurements (in this case measuring how dark current and read noise vary with temperature).
Read 1
1 2 3 4 1 2 3 4
1 2 3 4 1 2 3 4
1 2 3 4 1 2 3 4
1 2 3 4 1 2 3 4
1 2 3 4 1 2 3 4
1 2 3 4 1 2 3 4
1 2 3 4 1 2 3 4
1 2 3 4 1 2 3 4
5 5
5 5
5 5
5 5
5 5
5 5
5 5
5 5
Close upBlind
referenceoutput pixels
Read 2
Read 3
Read 4
Read 5
Dark reference columns
Normal columnsDetector Surface
4+1024+4=1032 pixels
1024
pix
els
SCASim Design
Each detector may be read out by one or more amplifiers (4 in the case of MIRI + ref. output).
Each amplifier is responsible for reading a particular slice (or zone) on the detector surface.
Each amplifier has an associated gain, linearity and read noise.
Note that dark current and read noise are derived from a generic “Measured Variable” class, used to described laboratory measurements (in this case measuring how dark current and read noise vary with temperature).
SCASim Design
The detector and the amplifiers can both be hit by cosmic rays during an integration, depending on the integration time and their target area.
A Cosmic Ray Environment class describes the cosmic ray environment (solar condition etc…), and can generate Cosmic Ray events.
Cosmic ray events are selected from a library of simulated events created by Massimo Roberto at STScI (for all JWST detectors).
SCASim Design
The SCA simulator also defines classes describing how an exposure is constructed from a series of integrations.
The Integration class sequences the reset/integrate/readout operations in the Detector Array.
An illumination map describes the intensity and wavelength of the illumination across the detector surface.
SCASim Design
Finally, these additional classes show how the contents of the input file are distributed, and how the data associated with each exposure is written to an output file.
The Sensor Chip Assembly class manages the simulation and provides a selection of interfaces to the outside world (not shown here).
SCASim External Interfaces
SCASim Demonstration.Start with some test illumination data.
Intensity data Wavelength data
Add Reference Pixels and Outputs
Apply Quantum Efficiency
Add Bad Pixels
Add Dark Current & Hot Pixels
Apply Gain and Non-linearity
Add Poisson Noise (frame 2/18 shown)
Add Read Noise (frame 2/18 shown)
Add Cosmic Ray Events(frame 8/18 shown)
Build up of signal with group
Build up of signal with group
Build up of signal with group
Build up of signal with group
Build up of signal with group
Build up of signal with group
Build up of signal with group
Build up of signal with group
SCASim ExperienceGood
• OO design made SCASim highly flexible and reusable.– Rapid development time.– Additional effects (such as
variable dark current and persistence) were easy to add.
– Now a useful tool adaptable for other detectors.
• SCASim made successful predictions for MIRI FM testing.– Expected S/N and exposure
times.– Effect of cosmic ray hits.
• It also helped development and testing of analysis software.– DHAS cosmic ray detection
Bad• Too many inputs.
– Nobody has yet edited the configuration files or provided their own calibration files.
– But the simulation is only as good as the calibration and configuration info. given to it.
• Only known effects can be simulated.– The underlying causes of the
“first and last integration effect” and the “pixel lag” effect are not yet known.
• Perhaps caused by leaving detectors too long without flushing?
– Subarray vs full frame.– But the simulator can help
investigate such effects by trying out ideas.
The MIRI Sensor Chip Assembly(SCA) Simulator - Summary
• What does it do?– It simulates the behaviour of the MIRI detector chips and
focal plane electronics.– This simulation is common to all MIRI simulators, so it saves
duplication of effort.
• What is it for?– MIRI observation planning.– MIRI Flight Model test planning.– JWST Pipeline development and testing.
• Design Features– OO design, written in Python.– Highly adaptable and reusable.– Valid for all JWST detectors – could be adapted for other
instruments.
Questions?
?