sylvia baggett (stsci) ray boucarut (gsfc)
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Feb 16, 2006 TIPS – S.Baggett 1
Sylvia Baggett (STScI)Ray Boucarut (GSFC)
GSFCRandal TelferManuel QuijadaPetar ArsenovicMorgan DaileyRandy KimbleJeff KirkTim MadisonSteve RiceJennie ChuBrad GreeleyJackie TownsendLori TyahlaWeijun Su
STScIJessica Kim QuijanoTom BrownGeorge HartigJohn MacKentyMassimo Robberto
Barr George AllenKevin DowningJohn Potter
WFC3 Replacement Filters
Feb 16, 2006 TIPS – S.Baggett 2
Outline
• Introduction• Procurement of replacements• Characterization of candidates• Approved filters• Replacement status
Feb 16, 2006 TIPS – S.Baggett 3
UVIS ChannelSOFA: 12 wheels, each with 4 filters + clear63 filters (includes 5 quads, 1 grism)
Excellent performance from 51 of 63 UVIS filters, majority consistent with spec but instrument level testing showed filter ghosts in some filters Procurement of replacements: new technology provides reduction in ghosts and frequently an improvement in throughput as well
Flight SOFA
IR Channel17 filters (15 filters and 2 grisms)
x12
Excellent performance from all IR filters, consistent with spec; no ghosts Procurement of replacements for two filters to add blue blocker (new substrate-removed IR detector has significant QE in blue); addition of new red edge coat to grism (G141), to block higher background seen in TV data
IntroductionWFC3 designed as a two-channel instrument
Feb 16, 2006 TIPS – S.Baggett 4
Filter ghosting due to design of element (either air-gap or multi-substrate)
UVIS filter ghosts: airgap design
UV and narrowband air-gaps• Ghosts show elaborate shapes • Strong field dependence: both position of ghost relative to source and morphology of ghost • Strength varies with wavelength and peaks outside of bandpass
~15% totalFlight F225W
Image from WFC3 ISR 2004-04
Feb 16, 2006 TIPS – S.Baggett 5
VIS/medium bands• Compact, pointlike ghosts • Strong wavelength dependence (strongest out of band)• Slight field dependence
UVIS filter ghosts: multi-substrate design
Substrate BK7Substrate BK7
Substrate GG435Substrate GG435
Substrate BK7Substrate BK7
AR coatingAR coating
AR coatingAR coating
CoatingCoating
CoatingCoating
CoatingCoating
EpoxyEpoxy
EpoxyEpoxy
F606W: multi-substrate constructionF606W: multi-substrate constructionEpoxy layer << air gap Epoxy layer << air gap
Flight – monochromatic
470nm
725nm
500nm
Brightest spot~24% peak at 470nm
Expected window ghosts
Stimulus artifact
Flight – whitelightInstrument-level results<0.1% each~0.3% total in spots
Feb 16, 2006 TIPS – S.Baggett 6
• UV (F218W, F225W, F275W, F300X)• F606W• Medium bands (F410M, F467M, F621M, F689M)• Narrowbands (F656N, F658N – plus F280N)
With Science Oversight Committee recommendation, focus has been on obtaining and testing the following new UVIS filters
Working Plan
Green: high priorityBlue: medium priorityRed: low priority
Feb 16, 2006 TIPS – S.Baggett 7
Manufacturing Process
Barr Associates, Lead: George Allen
Polish glassVerify thickness, flatness, wedge, surface quality
Polish glassVerify thickness, flatness, wedge, surface quality
Receive customerrequirements
Receive customerrequirements Design filterDesign filter
Input from GSFC/IPT/SOCInput from GSFC/IPT/SOC
Procure substrateCheck index of refraction
Radiation tests
Procure substrateCheck index of refraction
Radiation tests
Shape glassShape glass Deposit coatingsDeposit coatings Measure bandpassAnd blocking
Measure bandpassAnd blocking
Test witness samples(abrasion, adhesion,
humidity, temperature)
Test witness samples(abrasion, adhesion,
humidity, temperature)
Inspect and label selected filters
Search for blemishes, scratches, Cosmetic defects.
(UV: paint pinholes)
Inspect and label selected filters
Search for blemishes, scratches, Cosmetic defects.
(UV: paint pinholes)
Ship to GSFCfor
characterization tests
Ship to GSFCfor
characterization tests
Predictghost level
Predictghost level
Feb 16, 2006 TIPS – S.Baggett 8
Characterization Test Flow
Results presented anddiscussed (GSFC/IPT)Results presented anddiscussed (GSFC/IPT)
Final results postedto GSFC WWW
Final results postedto GSFC WWW
SOC/IPT/GSFCchoose flight/spareSOC/IPT/GSFC
choose flight/spare
Analysis by filter teamAnalysis by filter team
InspectionInspection
ImagingImaging
Spectral Scans
Spectral Scans
Receipt of filterfrom Barr
Receipt of filterfrom Barr
Confirm dimensions; check for blemishesConfirm dimensions; check for blemishes
Whitelight + monochromatic ghost levelsWhitelight + monochromatic ghost levels
Wavefront and wedge verificationWavefront and wedge verification
Focal shift confirmationFocal shift confirmation
Inband scans in 5x5 gridInband scans in 5x5 grid
Out of band scans in 5 positionsOut of band scans in 5 positions
FlatfieldsFlatfields Check for coating problemsCheck for coating problems
Front/backlit photosFront/backlit photos
Environmental tests onwitness pieces
Environmental tests onwitness pieces
Verify no changes Verify no changes
Tests by vendor (such as thickness, flatness, wedge, surface quality, bandpass, blocking, cosmetics)
Tests by vendor (such as thickness, flatness, wedge, surface quality, bandpass, blocking, cosmetics)
Feb 16, 2006 TIPS – S.Baggett 9
200 pixels
Flight – whitelight instrument-level testsSource in each quad centerBrightest ghost ~10%; totals ~15%.
Filter ghost <0.3%
Setup ghost
F225W-303 – images taken in lab at 16 UVIS field pointsand mosaic’d together into relative positions on WFC3 FOV
1”
Example: F225W
Before After
Feb 16, 2006 TIPS – S.Baggett 10
Approved UV filter set
0
0.1
0.2
0.3
0.4
0.5
0.6
190 210 230 250 270 290 310 330 350 370 390 410 430 450
wavelength(nm)
tran
smis
sio
n
f218w - newf218w - origf225w - newf225w - origf275w - newf275w - origf300x - newf300x - orig
Transmission curves of replacement and original flight filters
In all cases, ghosting has been reduced and in most cases, other improvements were achieved as well such as simplified ghost shapes (thanks to switch from air-gap to single substrate design), higher grasp, better uniformity.
Filter Ghost
(spec: 0.2%)
Grasp
(rel.to
flight)
F218W 10 3.3% 0.55
F225W 15 <0.3% 1.3
F275W 0.7 <0.1% 0.99
F300X 1 0.4% 1.12
Feb 16, 2006 TIPS – S.Baggett 11
Approved Medium Bands
Filter Ghost
(spec: 0.2%)
Grasp
(rel.to
flight)
F606W 0.3 <0.1% 1.08
F410M 0.6 <0.01%
1.28
F467M 0.3 <0.01%
1.02
F621M 0.3 0.02% 1.04
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
390 415 440 465 490 515 540 565 590 615 640 665 690 715
wavelength (nm)
tra
ns
mis
sio
n f606w - new
f606w - orig
f410m - new
f410m - orig
f467m - new
f467m - orig
f621m - new
f621m - orig
In all cases, ghosts have been reduced (or eliminated) and grasp improved.
Original medium band filters consisted of layers of substrates with coatings on both sides joined with epoxy – giving rise to numerous small, pointlike ghosts. In the new filters, bandpass coatings are on one side, AR coat on the other.
Transmission curves of replacement and original flight filters
Feb 16, 2006 TIPS – S.Baggett 13
UVIS Filter Status at a Glance
Wheels 6 731 9 114
F467MF467M
F410MF410M
F275WF275WF658NF658N
Madeat Barr
Tested@GSFC
Approved by SOC
Sent to Ball
SlotsF689MF689MF606WF606W
fatUV
= high priority
Legend done in progress
F218W F218W
F225WF225W F280NF280N
8
F547MF547M
F621M F621M F300X F300X
F656N F656N F600LPF600LP
Original F600LPflight spare fully tested. New filter from Barr to serve as spare.
New F280N to go into F280N slot (fatUVs not useful).
F689M, F658N replacement deemed not worth risk
F656N replacement deemed not worth risk.
DONE DONE DONEDONEN/A
DONE = old filters removed, new installed; wheels air-cured and baked
N/A
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