WFC3 TIPS Presentation
January 15, 2004
Optical
Stimulus
Jan 15, 2004
WFC3 TIPS – John W. MacKenty
1
Highlights
• Major Milestone: first system level testing
– STScI lead instrument calibration run (ambient testing)
– UVIS channel with flight detector
– Successfully validated:
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Image quality and throughput of UVIS channel (1st look at UV)
Instrument operation with full flight electronics and SITS system
STScI pipeline(s) and ability to work with data volume
WFC3 ambient test environment (CASTLE system and warm det)
WFC3 ICAL team preparedness (proposals/SMS/staffing)
– Testing found two significant anomalies (filter ghosts and Xtalk)
• Program schedule has slipped several months
– Optical alignment issue with detector packages (now resolved)
– Need for expanded science testing
• WFC3 Science Oversight Committee @ STScI 5-6 Feb
Jan 15, 2004
WFC3 TIPS – John W. MacKenty
2
Optics Testing and TEC Power
• Optics testing found significant mis-alignment of flight
CCD package
– No harm/risk to detector focal plane (external mounting ring)
– Cause traced to Ball Aerospace alignment step (details still under
investigation but understood sufficiently to proceed)
– Has resulted in hold on UVIS Flight Spare and IR Flight packages
– Much credit to George Hartig and Sylvia Baggett
• Anomalous behavior of CCD TEC controller during
cooldown observed during optics testing
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Jan 15, 2004
Problem tracked by GSFC electronics team to LVPS component
Ball substituted hollow core transformer
Fix in process (3-4 months for parts fab/test)
Operational workaround in place for ambient testing (no impact)
WFC3 TIPS – John W. MacKenty
3
Test Environment
• CASTLE system working well
– Flats and point sources
– Interleaved with SMS running
on the SITS system
– Driven by STScI scientist
generated proposals
– ICAL team working very well
together
– Kudo’s to Neill Reid, Ray
Kutina and the rest of the
ICAL team
Jan 15, 2004
WFC3 TIPS – John W. MacKenty
4
Flat Fields and Point Sources
• F814W Flat field shows good
performance with low level
flare in corner (not a problem)
• Point sources can show oval
ghosts from chip to window
reflections (modeled previously
and within expectations).
Jan 15, 2004
WFC3 TIPS – John W. MacKenty
5
System Throughput (Preliminary)
• System throughput tested with a
set of wide and medium filters
• Meets expectations
– Validates SI component level
measurements
– First test of UV image quality
and throughput
Jan 15, 2004
WFC3 TIPS – John W. MacKenty
6
Air-gap Filter Ghosts
• Ghost intensity is a function of
wavelength
– Most pronounced at edges of
bandpass
– Present at both blue and red
sides of bandpass
– Initial attempts to sum flux
have not yet succeeded
• Images at left show F225W
with 4nm input at 10nm steps
on red side of the passband
Jan 15, 2004
WFC3 TIPS – John W. MacKenty
7
Air-gap Ghosts (2)
• Ghosts are worst in F218W and
F225W
F225W
– Far exceed 0.2% CEI Spec
– Can contain 30+% of total flux
for very red sources
– Morphology is highly position
dependent within field
• Team working with Barr
Associates and JPL to
– Model cause
– Duplicate behavior with spares
in optical test setup at GSFC
– Fabricate alternate filters
F218W
• Single substrate now possible
• Change gap or use two filter
slots to realized these 2 filters
Jan 15, 2004
WFC3 TIPS – John W. MacKenty
8
F606W Artifact
F606W
• Unexplained compact ghosts in
F606W
• White light features few 0.1%
• Monochromatic light
– Very faint in band center
– 10% at edges of band
• Not seen in F625W, F814W
• Filter manufactured by Omega
on single substrate (different
F814W
technology than UV filters)
• Scan of all filters underway that
should complete next Tuesday
or Wednesday
Jan 15, 2004
WFC3 TIPS – John W. MacKenty
9
CCD Electronics Cross-talk
• Image in one quadrant of the UVIS field of view can create
features in the other three quadrants.
– Seen in ACS (but WFC3 effect is few times more pronounced)
– Can suppress features in other chip using slower timing pattern
• Isolates source to limited part of signal chain
Jan 15, 2004
WFC3 TIPS – John W. MacKenty
10
Hardware Flow
• UVIS Flight Detector package realigned at Ball this month
• Mini-ambient calibration (validates
realignment and established SOFA
position)
• SOFA removal to fix electronics
redundancy issue – filter swap??
• Full ambient test of UVIS channel
(CSM removed to replace
motor/resolver set)
• IR detector delivery and noise tests in
ambient
• System level thermal vacuum testing
(first calibration of IR channel)
Jan 15, 2004
WFC3 TIPS – John W. MacKenty
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