Technical Meeting #2: Optomechnical design and derived requirements

This meeting took place on Friday 7 May at 14:00. Attendees: JSY, CAH, DFB, XS, EBS, ADR, DMAW

Agenda

• Discussion of any results from high priority tasks
  • DFB & JSY: Assign working value for overall image quality requirement
  • DFB: Assign range for pixel scale
  • ADR & CAH: Think about how to apportion image quality budget
  • ADR & CAH: Nominal stability budget
  • XS: Understand space envelope, optical components & make CAD drawing
  • XS: Initial studies of achievable stability
  • MF: Thermal analysis of camera in box
• Next steps
  • Tasks
  • Next meeting(s)

Discussion Slides

Optical Tolerancing Slides as PDF

Task Assignments

Completed tasks

• DFB & JSY: Assign working value for overall image quality requirement
  • Working value is ~1 pixel independent of pixel scale (avoids aliasing of high frequencies in speckled image)
• DFB: Assign range for pixel scale
  • Working range is 0.12 to 0.2 arcsec/pixel
    • Fine limit of 0.12 arcsec/pix set by acquisition mode FOV (assuming same pixel scale for acquisition and FTT modes)
    • Coarse limit of 0.2 arcsec/pix corresponds to 2.5 pixels across FWHM of short-exposure seeing-limited image
• ADR & CAH: Optical image quality tolerancing of OAP-based layout
  • See attached slides. Converting this into a budget by component has been deferred
• ADR & CAH: Stability tolerancing of OAP-based layout
  • See attached slides. Converting this into a budget by component has been deferred
• EBS: Chase Princeton for mechanical drawings of camera
  • We (all?) need to sign NDA
• XS: Understand space envelope, optical components & make CAD drawing
  • See attached drawing
• JSY: Make corrections to appendix of FTT technical requirements document

High priority tasks

• ADR & CAH: Layout and tolerancing of lens-based optical system
• XS: Initial studies of achievable stability
• MF: Thermal analysis of camera in box
• JSY: Correct target object spectral energy distribution for limiting magnitude in FTT technical requirements document
• EBS: Draw up EMCCD camera comparison matrix

Lower priority tasks

• ADR: Dialogue with OAP manufacturer re referencing to optic axis of finished component
• ADR: Optical design using off-the-shelf components
• ADR & CAH: Use tolerancing results to assign image quality and stability budgets by component
• EBS: Liase with ADR about possible sources for off-axis paraboloids
• JSY: Photon rate calculations
• DMAW & MF: Start thinking about test arrangements

Next Meetings

Initial follow-up discussion of results from the high-priority tasks will be done informally (for example at coffee times). A first meeting to discuss the FTT software requirements and conceptual design will take place at 14:00-16:30 on Friday 14 May in the Ryle Seminar Room.