1. Feb 16, 2006TIPS – S.Baggett1 Sylvia Baggett (STScI) Ray Boucarut (GSFC) GSFC Randal Telfer Manuel Quijada Petar Arsenovic Morgan Dailey Randy Kimble Jeff Kirk Tim Madison Steve Rice Jennie Chu Brad Greeley Jackie Townsend Lori Tyahla Weijun Su STScI Jessica Kim Quijano Tom Brown George Hartig John MacKenty Massimo Robberto Barr George Allen Kevin Downing John Potter WFC3 Replacement Filters

2. Feb 16, 2006TIPS – S.Baggett2 Outline Introduction Procurement of replacements Characterization of candidates Approved filters Replacement status

3. Feb 16, 2006TIPS – S.Baggett3 UVIS Channel SOFA: 12 wheels, each with 4 filters + clear 63 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 Channel 17 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 Introduction WFC3 designed as a two-channel instrument

4. Feb 16, 2006TIPS – S.Baggett4 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% total Flight F225W Image from WFC3 ISR 2004-04

5. Feb 16, 2006TIPS – S.Baggett5 VIS/medium bands Compact, pointlike ghosts Strong wavelength dependence (strongest out of band) Slight field dependence UVIS filter ghosts: multi-substrate design Substrate BK7 Substrate GG435 Substrate BK7 AR coating Coating Coating Coating Epoxy Epoxy F606W: multi-substrate construction Epoxy layer << air gap Flight – monochromatic 470nm 725nm 500nm Brightest spot ~24% peak at 470nm Expected window ghosts Stimulus artifact Flight – whitelight Instrument-level results <0.1% each ~0.3% total in spots

6. Feb 16, 2006TIPS – S.Baggett6 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 priority Blue: medium priority Red: low priority

7. Feb 16, 2006TIPS – S.Baggett7 Manufacturing Process Barr Associates, Lead: George Allen Polish glass Verify thickness, flatness, wedge, surface quality Polish glass Verify thickness, flatness, wedge, surface quality Receive customer requirements Receive customer requirements Design filter Input from GSFC/IPT/SOC Procure substrate Check index of refraction Radiation tests Procure substrate Check index of refraction Radiation tests Shape glass Deposit coatings Measure bandpass And blocking Measure bandpass And 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 GSFC for characterization tests Ship to GSFC for characterization tests Predict ghost level Predict ghost level

8. Feb 16, 2006TIPS – S.Baggett8 Characterization Test Flow Results presented and discussed (GSFC/IPT) Results presented and discussed (GSFC/IPT) Final results posted to GSFC WWW Final results posted to GSFC WWW SOC/IPT/GSFC choose flight/spare SOC/IPT/GSFC choose flight/spare Analysis by filter team Inspection Imaging Spectral Scans Spectral Scans Receipt of filter from Barr Receipt of filter from Barr Confirm dimensions; check for blemishes Whitelight + monochromatic ghost levels Wavefront and wedge verification Focal shift confirmation Inband scans in 5x5 grid Out of band scans in 5 positions Flatfields Check for coating problems Front/backlit photos Environmental tests on witness pieces Environmental tests on witness pieces 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)

9. Feb 16, 2006TIPS – S.Baggett9 200 pixels Flight – whitelight instrument-level tests Source in each quad center Brightest ghost ~10%; totals ~15%. Filter ghost <0.3% Setup ghost F225W-303 – images taken in lab at 16 UVIS field points and mosaicd together into relative positions on WFC3 FOV 1 Example: F225W BeforeAfter

10. Feb 16, 2006TIPS – S.Baggett10 Approved UV filter set 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. FilterGhost (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

11. Feb 16, 2006TIPS – S.Baggett11 Approved Medium Bands FilterGhost (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 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

12. Feb 16, 2006TIPS – S.Baggett12 Installing New F606W

13. Feb 16, 2006TIPS – S.Baggett13 UVIS Filter Status at a Glance Wheels 67319114 F467M F410M F275W F658N Made at Barr Tested @GSFC Approved by SOC Sent to Ball Slots F689M F606W fatUV = high priority Legend done in progress F218W F225W F280N 8 F547M F621M F300X F656N F600LP 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 N/A DONE = old filters removed, new installed; wheels air-cured and baked N/A