1 / 16

FM FPU Subunits

FM FPU Subunits. A. Poglitsch. 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

ferris
Download Presentation

FM FPU Subunits

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. FM FPU Subunits A. Poglitsch PACS FPU Subunits

  2. 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) PACS FPU Subunits

  3. Performance of FPU and Subunits (II) • Filters • In-band transmission • Out-of-band suppression • Calibration Sources • Absolute emissivity • Homogeneity PACS FPU Subunits

  4. 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 PACS FPU Subunits

  5. 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 PACS FPU Subunits

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

  7. 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 0th order diffraction efficiency indicates no major deviation of grating profile from spec PACS FPU Subunits

  8. 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 PACS FPU Subunits

  9. 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 PACS FPU Subunits

  10. Filters: “Red” Photometer PACS FPU Subunits

  11. Filters: “Green” Photometer PACS FPU Subunits

  12. Filters: “Blue” Photometer PACS FPU Subunits

  13. Filters: “Red” Spectrometer PACS FPU Subunits

  14. Filters: “Green” Spectrometer PACS FPU Subunits

  15. Filters: “Blue” Spectrometer PACS FPU Subunits

  16. 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 QM CS2 CS1 PACS FPU Subunits

More Related