1. PACS SVR 22/23 June 2006 PACS FPU Subunits1 FM FPU Subunits A. Poglitsch

2. PACS SVR 22/23 June 2006 PACS FPU Subunits2 Performance of FPU and Subunits (I) Structure –Temperature (stability) requirements –Mechanical/optical tolerances, alignment Mirrors –Optical performance Chopper –Pointing accuracy –Dynamic behaviour (duty cycle) Grating –Optical performance of grating –Mechanical performance of grating drive Precision of position readout/actuator; jitter Dynamic properties (scanning/dithering/frequency switching)

3. PACS SVR 22/23 June 2006 PACS FPU Subunits3 Performance of FPU and Subunits (II) Filters –In-band transmission –Out-of-band suppression Calibration Sources –Absolute emissivity –Homogeneity

4. PACS SVR 22/23 June 2006 PACS FPU Subunits4 FPU Structure Most (but not all) of the FPU structure has been used in CQM Thermal requirements fulfilled by CQM as far as tested – expect no changes with FM –More detailed tests necessary w.r.t. sensitivity to L0/L1 interface temperature tolerances/variations –Ge:Ga detector thermal interface changed for thermal curing LHe Optical Alignment Stability Test under way –CQM ILT revealed no anomalies

5. PACS SVR 22/23 June 2006 PACS FPU Subunits5 Optics: Mirrors All mirrors tested individually at ambient temperature Visible light end-to-end test –Documentation with delivery of FPU No unexplained anomalies observed in QM –But PSF measurements were hampered by telescope simulator defocus

6. PACS SVR 22/23 June 2006 PACS FPU Subunits6 Chopper Mirror optical performance –Flatness< 150 nmtested; failed but accepted –Roughness< 50 nmtested; passed –Reflectivity> 98%by verified coating process Actuator performance (static/dynamic) –Range observation ± 4.1°; accuracy ± 1 arcmintested; ok –Duty cycle observation @ 10 Hz >80%tested; ok –Range calibration± 9°; accuracy ± 2 arcmintested; ok –Duty cycle calibration >70%tested; ok ± 0.5 arcsec on sky

7. PACS SVR 22/23 June 2006 PACS FPU Subunits7 Grating (I) Groove period - spec 117.65 (± 0.7) µm –Only measured for CQM: g=117.66 ± 0.11 µm (2 sigma) Facet angles - spec 34.5° (± 1°) and 62.4° (± 1°) –Average: 34.1846°; standard deviation: 0.3455° –Average: 62.3264°; standard deviation: 0.4233° Groove regularity - spec 0.3 µm r.m.s. –Not verified  search for grating ghosts in ILT essential! –Positioning precision of machine used for ruling is 0.1 µm w.r.t. reference (reference: Heidenhain glass ruler). Measured ruler error (interferometric) over 100 mm travel: 0.15 µm (p-p); no measurement over full length available Groove depth - spec 56 µm ± 2 µm –Not measured, but 0 th order diffraction efficiency indicates no major deviation of grating profile from spec

8. PACS SVR 22/23 June 2006 PACS FPU Subunits8 Grating (II) Groove parallelism - spec ± 10” –Each groove to each other: not verified, but hard to miss with machine used for ruling –Grooves to rotation axis: no absolute measurement done, but grating drive wobble measured – uses up error entire budget!  Thorough test of position shifts and spectral shear/tilt as function of grating angle during ILT required! Overall surface flatness - spec 3 (goal 1.5) µm r.m.s. –Verification by WFE measurement with 10 µm interferometer in three grating orders partly achieved (only partial coverage of grating area by beam at a time); machining error <0.5 µm (but internal stress in grating body could lead to deformation)  Confirmation by measurement of PSF / spectral profile during ILT

9. PACS SVR 22/23 June 2006 PACS FPU Subunits9 Grating Drive Position precision within the useful angular throw: 8 arcsec (goal: 4 arcsec) –Calibration certificate: ± 3 arcsec; ± 4 arcsec (nom.; red.) Grating position “jitter” shall be < 0.1 arcsec/√Hz –verified by test Wavelength switching: amplitude of < 3 arcmin with frequencies of < 3 Hz and a duty cycle of 80% –verified by test Stabilization time for a grating step of 18 arcsec: < 23 ms –verified by test

10. PACS SVR 22/23 June 2006 PACS FPU Subunits10 Filters: “Red” Photometer

11. PACS SVR 22/23 June 2006 PACS FPU Subunits11 Filters: “Green” Photometer

12. PACS SVR 22/23 June 2006 PACS FPU Subunits12 Filters: “Blue” Photometer

13. PACS SVR 22/23 June 2006 PACS FPU Subunits13 Filters: “Red” Spectrometer

14. PACS SVR 22/23 June 2006 PACS FPU Subunits14 Filters: “Green” Spectrometer

15. PACS SVR 22/23 June 2006 PACS FPU Subunits15 Filters: “Blue” Spectrometer

16. PACS SVR 22/23 June 2006 PACS FPU Subunits16 Calibration Sources No measurements of FM CSs possible before FM ILT Cause of inhomogeneity in CS1 illumination identified in QM FPU; avoided in FM FPU Emissivity adjusted Stability expected in spec (similarity with QM) QM CS1CS2