jan 15, 2004wfc3 tips – john w. mackenty1 wfc3 tips presentation january 15, 2004 optical stimulus

Jan 15, 2004 WFC3 TIPS – John W. MacKenty 1

WFC3 TIPS PresentationJanuary 15, 2004

Optical Stimulus


Highlights

• Major Milestone: first system level testing– STScI lead instrument calibration run (ambient testing)– UVIS channel with flight detector– Successfully validated:

• 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


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– 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)


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


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).


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


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


Air-gap Ghosts (2)

• Ghosts are worst in F218W and 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

• Single substrate now possible• Change gap or use two filter

slots to realized these 2 filters

F225W

F218W


F606W Artifact

• 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 technology than UV filters)

• Scan of all filters underway that should complete next Tuesday or Wednesday

F606W

F814W


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


Hardware Flow

• UVIS Flight Detector package re-aligned 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, 2004wfc3 tips – john w. mackenty1 wfc3 tips presentation january 15, 2004 optical stimulus

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