r11 - 27 Jul 2012 - 22:35:18 - RichardDekanyYou are here: TWiki >  Palomar/TMAS Web > ArchitectureDefinition

TMAS Visible Light AO Instrument Observing Candidate Observing Modes

Note all numbers on this page has yet to be verified!

Input focal plane
  • F/15.4 (or so?) implies 2.637 "/mm
    • 25.4 mm window = 67 arc sec diameter = big enough for any Channel described below
    • 12.7 mm window = 33.5 arc sec diameter = slightly too small for Channel 1
TMAS cameras
  • Leading option
    • 2 ea. Andor 5 MPix (2560 x 2160) NEO sCMOS cameras from Gregg Hallinan
      • 6.5 micron pixels; 16.64 mm x 14.04 mm; Max rate = 100Hz; QE (400nm) = 0.3, QE (550nm) = 0.57, QE (900nm) = 0.14
  • Backup options
    • Andor 1 MPix (1024 x 1024) 888 iXon EMCCD camera from Christoph Baranec (with 'BV' quantum efficiency option)
      • 13 um pixels; 13.31 mm x 13.31 mm; Max rate = 10Hz (full frame); QE (400nm) = 0.6; QE (550nm) = 0.96, QE (900nm) = 0.48
    • CCD21 (1024 x 1024) custom former DBSP red channel camera
      • ? um pixel; Max rate = Slow; Mature science GUI; pretty good CCD QE, but not particularly red-sensitive

TMAS foci
  • Channel 1 (ZMX Config 2): F/26.392; f = 134.072m; 10 mas / pixel = 10 mas / 6.5 um = 1.5385 mas/um = 1.5385 "/mm or 0.65 mm/ " (assuming NEO camera)
    • Nyquist at lambda = 492nm; FoV = 25.6" x 21.6"
  • Channel 2 (ZMX Config 1): F/16.495; f = 83.796m; 16 mas / pixel = 16 mas / 6.5 um = 2.4615 mas / um = 2.4615 "/mm or 0.406 mm/ " (assuming NEO camera)
    • Nyquist at lambda = 788nm, FoV = 41.0" x 34.6"
    • Same focus would have 32 mas / pixel = 32 mas / 13 um; FoV = 32" x 32" assuming 888 iXon camera

  • Alt focus 1: (ZMX Config 3) F/52.784; f = 268.144m; 10 mas / pixel = 10 mas / 13 um = 0.7693 mas/um = 0.7693 "/mm or 1.3 mm/ " (assuming 888 iXon camera)
    • Nyquist at lambda = 492nm; FoV = 12.8" x 10.8"
  • Alt focus 2a: F/32.990; f = 167.592m; 16 has / pixel = 16 mas / 13 um = 1.2308 mas / um = 1.2308 " / mm or 0.813 mm / " (assuming 888 iXon camera)
    • Nyquist at lambda = 788nm, FoV = 20.5" x 17.3"
  • Alt focus 2b: F/26.392; f = 134.072m; 10 mas / pixel = 10 mas / 6.5 um = 1.5385 mas/um = 1.5385 "/mm or 0.65 mm/ " (assuming NEO camera)
    • Nyquist at lambda = 492nm; FoV = 25.6" x 21.6"
      • Alt focus 2b is identical to Channel 1.

MGS Calibration Defocus Requirement
  • We'd like to be able to move one of the cameras in and out of focus enough to generate > 200 pixels across the image. With the larger 13um pixels, this means a spot size that is > 2.6 mm in diameter. At the slower F/42 focus, this would be about +- 100 mm of travel. Newport makes a UTS 150, which could do +- 75 mm, which would give ~ 150 pixels across. I think this will be okay to calibrate our 64 actuators across the pupil (and at F/26 would be more than enough). So, we decide on the UTS 150.

AO modes
  • S64 = 64 x 64 subaperture AO correction, limiting mag R ~ 7 provides 0.6um SR ~ 10%, 0.8um SR ~ 20%, FWHM < 0.2" at 35" off-axis
  • S32 = 32 x 32 subaperture AO correction, limiting mag R ~ 10 provides visible FWHM < 0.2" on-axis, ~0.3" at 35" off-axis
  • S8 = 8 x 8 subaperture AO correction, limiting mag R ~ 17 provides visible FWHM ~ 0.4" on- or off-axis

AO beamsplitters
  • 50/50 beamsplitter
  • 80/20 visible (trans/refl) + long pass beyond 970nm (TBC)
  • 650 nm long pass
  • 750 nm long pass (TBC)
  • 970 nm long pass

SNR calculations
  • Are captured in spreadsheet megyeri:\\My Documents\COO\Projects\TMAS\Systems Engineering\SNR calculator.xls
    • 1 hr Neo integration captured at 30Hz; 1 e- read noise; 20% spectral bandwidth; r' band; 10% Strehl ratio; 25% total efficiency (incl. qe)
      • Implies SNR = 10 on AB = 23.7 (4700 source cnts / sqrt(108,000) noise cnts)

TMAS observing modes
Mode Number AO config F/43 focus F/11 focus Science Case
1 S64 Imaging filter Acquisition 12 mas/pixel imaging for all visible wavelengths
AO-assisted speckle (Lucky) imaging (Hildebrandt)
Lowest R imaging of faintest targets
2 S64 or S32 Imaging filter 1 Imaging filter 2 Dual-color photometry on different plate scales
Narrow field PSF reference for wider-field astrometry
Scattered light subtraction for extragalactic emission line science (Dekany)
3 S64 or S32 Flexure and exp. meter Single-mode fiber 10 cm/s precision radial velocity for exoplanet study (Johnson)
> 650nm for WFS < 500nm for Andor feeding precision RV spectrograph (need to identify)
4 S32 or S64 Flexure compensation Imaging filter 2 Deep (long-exposure) visible imagery / galaxy morphology / UDF
Red-channel coronagraphy (e.g. Serabyn (vortex coronagraphy))
5 S8 TBD GLAO w/ ~0.3" FWHM across moderate field Astrometry survey / identification of transients contexts
across visible wavelength
6 S8 Flexure & DAR Dual, scrambled multi-mode fiber 5 m/s RV of close (<2") binary stars (Johnson)
compensation w/ one on 2-axis stage
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