1 / 17

Some General Considerations on Wide Field Telescopes

This document presents key considerations discussed during the Synoptic Network Workshop held in Boulder from April 22-24, 2013. Emphasizing crucial parameters such as detector size (4k x 4k pixels), field of view (~0.7°), and image scale (120 arcsec/mm), the workshop explored the technical requirements for successful wide field telescopes. Topics include resolution determined by sampling theorem, SNR evaluations, and the need for image stabilization to mitigate motion errors. Practical design options, including various telescope configurations, were also discussed for optimal performance.

lexine
Download Presentation

Some General Considerations on Wide Field Telescopes

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. Some General Considerations on Wide Field Telescopes Dirk Soltau Kiepenheuer-Institut für Sonnenphysik Synoptic Network Workshop, Boulder 22.-24.4.2013

  2. Basic assumptionsandimmediateconclusions • Detectorsize: 4k x 4 k pixels, 5 µm pixelsize • Field ofview:  0.7°  2500 arcsec •  pixelscale = 0.6 arcsec •  imagescale = 120 arcsec/mm •  focallength = 1720 mm Synoptic Network Workshop, Boulder 22.-24.4.2013

  3. Diameter •  resolutionaccordingtosamplingtheorem: 1.2 arcsec = 5.8 µrad •  D = 1.22 λ / 5.8E-6 •  minimum Diameter w.r.tresolution = 0.1 m Synoptic Network Workshop, Boulder 22.-24.4.2013

  4. Bandwidth, SNR • Assumedbandwidth: 5 pm ( 50 mÅ, R = 100000 @ 500 nm) • AssumedExposure time: 0.005 s F Ret Cam1 PBS Sun Telescope Cam2 Synoptic Network Workshop, Boulder 22.-24.4.2013

  5. Counts and SNR for 5 msexp. time Diameter shouldexceed 0,5 m  f/# < f/3.5 Synoptic Network Workshop, Boulder 22.-24.4.2013

  6. Mounting (commoninstrumentplatform) • May beweneed different instrumentsfor different SNR requirements (Polarimetry vs. imaging) •  Severalinstruments on oneplatformmaybe a solution SOLIS Synoptic Network Workshop, Boulder 22.-24.4.2013

  7. Image Motion and Noise 2 pixel 0.1 m 0.1 m 1 pixel 1 m 1 m Sun = 104isoplanaticpatches  Averageseeinginducedimagemotionofthewholedisk will bearound 0.01 pixel

  8. Time constant 1 m 0.1 m

  9. Image motion: Effect on imagesubtraction - Example: shiftby 0.1 pixel 10-2noise =  Image stabilizationneeded, dual beam polarimetrydesirable

  10. Image stabilization? • Main causeprobably instrumental: • spatialdimensions: 1m  1 arcsec = 5 µm atthemirroredge • Limbsensor vs. Correlationtracker • Tiptiltmirror • relayoptics? • Solar Orbiter (PHI) concept? Synoptic Network Workshop, Boulder 22.-24.4.2013

  11. Optical Design Options • Design drivingparameters: • Detector • SNR @ typicalexposure time Synoptic Network Workshop, Boulder 22.-24.4.2013

  12. Refractor • Goodperformance, limited diameter Example: Chrotel (KIS) Synoptic Network Workshop, Boulder 22.-24.4.2013

  13. Example: Maksutov D = 200 mm, FOV = 0.5 deg + Potential forevacuation - 10 µm Synoptic Network Workshop, Boulder 22.-24.4.2013

  14. Example: Ritchey-Chretien Cassegrain D = 600 mm, FOV = 0.5 deg • Mightneed a fieldcorrectorif larger • needsbaffling (daylightblindness) Synoptic Network Workshop, Boulder 22.-24.4.2013

  15. Consider different designsfor different purposes • Severaltelescopes on a commonstructure • SOLIS concept Titisee

  16. Summary • Basic requirement: SNR • Image stabilization – ifnecessary – has large impact on the design • Diameter not determinedbyresolutionarguments telescopedoesn‘tneedtobediffraction limited • Evacuationshouldbeconsidered (catadioptricsystem?) • Multiple telescopeplatformmightbeuseful • Ritchey-Chretien promising. But falselightcountermeasuresnecessary Synoptic Network Workshop, Boulder 22.-24.4.2013

  17. Photon electrons Synoptic Network Workshop, Boulder 22.-24.4.2013

More Related