1 / 15

VLBI: Visible Light Broadband Imager

VLBI: Visible Light Broadband Imager. Instrument Conceptual Design Presentation Tom Berger Lockheed Martin Solar and Astrophysics Lab. VLBI Science Requirements.

kirk-walsh
Download Presentation

VLBI: Visible Light Broadband Imager

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. VLBI: Visible Light Broadband Imager Instrument Conceptual Design Presentation Tom Berger Lockheed Martin Solar and Astrophysics Lab

  2. VLBI Science Requirements • WBFI Mission statement: record the highest spatial and temporal resolution movies from the ATST across the visible spectrum from 330 nm to 1.1 m. • Spatial resolution: 0.03” at 330 nm • Temporal resolution: 5 – 10 seconds • Field-of-view: 3’ x 3’ minimum, 5’ x 5’ goal • Spectral resolution: 1 – 10 Å • Polarimetric requirements: none

  3. VLBI Basic Concept • Simple transfer/beam conditioning optics • Thin film interference filters • 2 or 3 cavity glass subtrate • > 60% transmission • 1 – 10 Å bandpasses • Large format, fast readout CCD or CMOS detectors • Dedicated multi-TByte storage array

  4. VLBI Preliminary Wavelengths

  5. VLBI Instrument Requirements • Spatial resolution • Plate scale: 2 pixels per Airy disk at a given  • Optical quality: < /4 per 2 cm on all elements incl. filters • Phase diversity: wavefront measurement and image restoration capability • Temporal resolution • Filter change and settle: 2 seconds • Camera readout: 3 seconds • Filter Characteristics • TFI filter diameter: 10 cm (3’ x 3’ F/20 telescope beam) • Optical • Flat focal plane over full 3’ x 3’ FOV • Telecentric beam: probably not required

  6. VLBI Plate Scales & F/#s Requirement: 2 pixels per central Airy disk of a 4-m aperture at each  Hypothetical detector: 9 m pixels, 4096 x 4096 format

  7. VLBI Design Limitations • Detector technology • 0.015” pixels: 6K x 6K format to cover 1.5’ x 1.5’ • QE > 90% • Exposure ~10 msec, Readout < 3 seconds • Such cameras do not exist • Unknown pixel size means plate scale cannot be specified • Utility and science must be balanced • Must be first-light instrument - cannot be delivered late • Must have immediate science potential - publicity quality images must be produced • Cost

  8. VLBI Design Philosophy • Modular construction • Provide subsystems that can be used individually, in sets, or in a turn-key “black box” • Major subsystems • Filterwheels • Detectors • Feed optics/focal plane conditioners • Mountable at Gregorian or Coudé focal planes • Conform to ATST controls interface • Easily accommodate detector upgrades • Room temperature operation

  9. C1: Camera 1 XYZ Stage 1 SH1: Shutter 1 C2: Camera 2 XYZ Stage 2 SH2: Shutter 2 VLBI Modular Subsystems • Detector subsystem • Two detectors mounted on x-y-z translation stages • Cube beamsplitter feeds cameras simultaneously. CBS is easily removable. • Allows small format detectors to “roam” over the ATST focal plane • Allows dual-camera phase diversity at any wavelength via adjustable defocus of one camera DCS:Detector Control System

  10. VLBI Modular Subsystems • Filterwheel subsystem • Four aperture wheel - three 10 cm filters, one blank • Brushless DC motor drive - TRACE/EPIC heritage • Optical encoder positional readout • Edge gear/worm drive mechanism • 3 wheels in series for up to 9 wavelengths • Beam height above table ~15 cm for wheel clearance

  11. VLBI Design Concepts • VLBI Level 1 • Dual detector package • Integrated single filter holder • No transfer/conditioning optics Single Filter Beam directly from ATST Detector subsystem

  12. VLBI Design Concepts • VLBI Level 2 • Dual detector subsystem • Filterwheel subsystem • Fixed focal ratio optics. L1 removable/replaceable for F/# change.

  13. VLBI Design Concepts • VLBI Level 3, Option A • Dual detector subsystem • Multiple filterwheel subsystem • Two channel (Red/Blue) transfer/conditioning optics: F/25 & F/45 ATST Focal Plane

  14. VLBI Design Concepts • VLBI Level 3, Option B • Detector subsystem • Multiple filterwheel subsystem • Varifocal zoom lens transfer/conditioning optics: F/20  F/60 ATST Focal Plane

  15. VLBI Concept Summary • Modular instrument • Will be designed to Level 3 configuration • Level 3 option TBD • Built as subsystems that can be assembled/disassembled easily to create Level 2 and Level 1 instruments

More Related