1 / 9

The Hobby-Eberly Telescope Mirror Alignment Recovery System

The Hobby-Eberly Telescope Mirror Alignment Recovery System. Marsha Wolf Graduate Student UT Astronomy Department. CCAS Tower. The Primary Mirror -- 91 Telescopes. Segmented Primary Entire mirror 11 meters (36 ft) 9 meters (30 ft) used during observations 91 hexagonal segments

mansour
Télécharger la présentation

The Hobby-Eberly Telescope Mirror Alignment Recovery System

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. The Hobby-Eberly Telescope Mirror Alignment Recovery System Marsha Wolf Graduate Student UT Astronomy Department

  2. CCAS Tower The Primary Mirror-- 91 Telescopes • Segmented Primary • Entire mirror • 11 meters (36 ft) • 9 meters (30 ft) used during observations • 91 hexagonal segments • 1 meter (3.3 ft) across • All segments must be aligned to act as a single mirror • Alignment is done from the Center of Curvature Alignment Sensor (CCAS) tower

  3. laser projector in CCAS tower HET primary mirror perfectly stacked not stacked spectrograph slit Burst Stacking • Expanding beam sent down to primary from its Center of Curvature • Each segment returns its own spot • Spots are “burst out” • Computer calculates positions of spots, sends them to the center • “stacks” them • Worked, but not precisely return spots

  4. The Mirror Alignment Recovery System (MARS) • Proof-of-Concept instrument installed Summer 2001 • Now used for mirror alignment

  5. The Shack-Hartmann Technique • Incoming wavefront is sampled by an array of lenses • Each lens focuses its portion of the beam • Focused spot from a flat wavefront is at the center of its lens • Focused spot from a tilted wavefront is translated • The amount a spot is translated tells how much its portion of the wavefront was tilted • On HET, each lens is one mirror segment evenly spaced unevenly spaced

  6. fiber optic cable light source beamsplitter cube lenslet array pinhole WaveScope TO HET knife edge CCD camera shutters collimating lens reference mirror (perfect sphere) Shack-Hartmann on HET(MARS in the tower)

  7. Reference pupil image Reference spot image HET pupil image HET spot image MARS in Action

  8. Maintaining the Alignment • Important for long science observations & efficient use of telescope time • Segment Alignment Maintenance System (SAMS) • Sensors on edges of all mirror segments • More overlap of sensors, means more signal • Control system takes sensor inputs and calculates required mirror motions to keep the entire primary aligned as a spherical surface • Significantly decreased frequency of alignment during science operations segment 1 segment 2

  9. MARS Performance • Stack sizes measured at tower continue to decrease • On-sky image quality has largely been limited by “seeing” • Final MARS will incorporate improvements and be complete this Summer

More Related