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System Performance Metrics and Current Performance Status. George Angeli. Performance Metrics. *. Updated estimates. Calibration update in - progress. Integrated É tendue. Basic definition Extended definition Sensitivity Integrated étendue - PowerPoint PPT Presentation
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System Performance Metrics and Current Performance Status
George Angeli
Performance Metrics
Image Quality
Image DepthPhotometric Repatability
Astrometric Repeatability
Ellipticity
Image Quality
Throughput
Read Noise
Integrated Étendue
Fill Factor (fF)
Observing Efficiency (fO)
Technical Performance Measures
Measures of Performance:
SRD Data Properties
Measures of Effectiveness
*
Calibration update in-progress
Updated estimates
Integrated Étendue
− Basic definition
− Extended definition• Sensitivity• Integrated étendue
- Fill Factor (fF ) - accounts for losses in the field due to masks, bad pixels, charge stops
- Sensitivity Factor (fS ) – accounts for sensitivity losses or gains due to throughput, image quality, read noise
- Observing Efficiency Factor (fO ) – accounts for losses or gains in open shutter efficiency over the entire survey
FieldOfView CollectionArea OpenShutterTime
real P nom F nom S nom O nom
E
E f E f FOV f CA f OST
55
1S CAt
real F nom S nom O nom
P F S O
E f FOV f S f OST
f f f f
Sensitivity Factor• Not allocated - driven by allocable Technical Performance Metrics:
– Image Quality– Throughput– Read noise
• For each band:
• Overall fs as time weighted sum
Observing band (filter) Time Allocation
e2v mAR Depth
Margin over SRD Des. fS
u band 6.7 % 23.7 - 0.184 0.712
g band 9.7 % 24.9 - 0.064 0.888
r band 22.3 % 24.5 - 0.242 0.641
i band 22.3 % 24.0 - 0.001 0.997
z band 19.4 % 23.4 0.149 1.317
y band 19.4 % 22.5 0.433 2.219
Overall 1.185
margin 10 101.25 log 1.25 logrealS
nom
tm f
t
Evolution of Image Depth ReserveReserve in LSR above SRD Minimum Specification
See Chuck’s presentation for details
Sensitivity factor relative to SRD minimum specs:
1.69 1.83
FDR LSST20140.000
0.050
0.100
0.150
0.200
0.250
0.300
0.350
0.400
0.450
u bandg bandr bandi bandz bandy band
Imag
e De
pth
Rese
rve
abov
e SR
D M
in-
imum
[m
ag]
P R O P O S E D
Image Depth Dependencies
• For each band:Image QualityThroughput and read noise
2
5 101.25 log 0.69 0.310.4mm C
350 360 370 380 390 400 410 420 430 440 450
-50
-40
-30
-20
-10
0
10
20
30
40
50
Image quality [mas]
5 [
]Dm
mmag
7.0 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0
-60
-40
-20
0
20
40
60
Read noise [e-]
5 [
] Dm
mmag
r band
Change since JIM Review
Image Quality Error Budget
Optical designM1M3 shape
M2 shapeTelescope collimation
Active opticsTelescope dynamicCamera optical fab.
Camera assemblyCamera gravity
Camera thermalCamera pressureCamera vibration
Camera sensor flatnessCamera raft height
Camera cryostat heightCamera charge diff.
Total system reserve
0 50 100 150 200 250
milliarcsecond (mas)
Telescope reserve: 105 masCamera reserve: 102 mas
See Bo’s presentation for details of meeting this budget
Evolution of IQ System Reserve
Charge diffusion contribution estimate reduced before FDR from 259 mas to 186 mas
milliarcsecond (mas)
PDR JIM FDR LSST20140
50
100
150
200
250
Optical System
Structural System
Detector
Atmosphere
Sky Objects
Optics position & shapeTe
mpe
ratu
re,
Tem
pera
ture
gra
dien
ts,
Tele
scop
e el
evati
on,
Air p
ress
ure
ControllerA
Actuators
Supe
rvis
ory
cont
rol,
Tele
scop
e el
evati
on
TCS
Temperature
Force balance
WF & State Estimator WF & Guider Data
ControllerB
Temperature
System Behavior
PSF size and shape
Integrated System Model
Optical Kernel
TelescopeStructural
ModelImage Metrics
Tem
pera
ture
, Te
mpe
ratu
re g
radi
ents
, Te
lesc
ope
elev
ation
,Ai
r pre
ssur
e
ControllerA
Actuators
WF & State Estimator
WF & Guider Data
Camera optics position & shape
Camera Structural
Model
Detector temperature
Tem
pera
ture
, Te
mpe
ratu
re g
radi
ents
, Te
lesc
ope
elev
ation
PSF size and shape
Currently ZEMAXPreferably PhoSim
• Deterministic effects– Optical design residual errors, – Diffraction effects due to the finite aperture and pupil obscuration,
• Deterministic effects randomized by environmental and operational parameters– Mirror support print through and lens gravitational deformations randomized
through telescope zenith angle– Thermal deformations of optical surfaces and support structures randomized
through ambient and local temperature• Random processes
– Dome and mirror seeing– Local actuator and sensor noise and drift (non-optical sensors)– Counting statistics– CCD sensor effects (solid state effects: diffusion, field dependencies, penetration
depth, QE variations)– WFS measurement, estimation, and control errors– Material, fabrication, and installation errors; these become deterministic once
the “as built” system is available
Input Parameters (Perturbations)
• FWHM across the field• Ellipticity across the field
Output Parameters (Metrics)
• Area weighted mean of 31 samples– Diffraction (FFT) PSF– Also track geometric PSF
derived from spot RMS
• Fiducial atmospheres (3) – Scaled to 0.44”, 0.6”, and 0.8” FWHM seeing on the aperture of
LSST.• • Zenith angle range of 0˚- 65˚
– Statistical distribution derived from “standard” OpSim simulations.
• Temperature and pressure ranges as defined in the OSS as Normal Operating Conditions. – The temperature inside enclosed volumes, like the Camera, needs
to be estimated from these environmental parameters.
• The expected temperature range of the detector, with assumed statistics
Environmental Conditions
• Transition the optical kernel to PhoSim
• Include missing instrumental perturbations– Most prominently sensor effects– In the process of implemented in PhoSim
• Improve AOS control laws and performance
• Establish a configuration adequate for science simulations– Linked or emulated AOS
Future Work