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 12

Installing New F606W

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