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Here are the basic transmission factors for the NGAO point design (as currently envisioned):

Telescope transmission (H-band)

# of mirrors (exposed) 3 @ 0.85 = 0.614 (<-- replace w/ measured value)

NGAO Optical Relay

# of mirrors (Al) 5 @ 0.97 = 0.859 (4 mirror relay + 1 turning mirror)

# of air/glass 6 @ 0.98 = 0.886 (double input window + dichroic)

(assume AR coat for NIR)

Subtotal 0.761

IR-MOS (IR multi-object AO spectrograph)

# of mirrors (Al) 4 @ 0.97 = 0.885 (object-selection mechanism)

# of mirrors (Au) 7 @ 0.985 = 0.900 (cryostat)

# of vacuum/glass 10 @ 0.988 = 0.886 (5 lenses, NIR coated)

Grating efficiency 1 @ 0.60 = 0.600

Filter efficiency 1 @ 0.90 = 0.900

Subtotal 0.381

IR array H-band QE 0.850 (2.5um cut-off HgCdTe)

Subtotal 0.324

Visible Imager

# of mirrors (Al) 2 @ 0.97 = 0.941 (OAP relay)

# of air/glass 8 @ 0.98 = 0.851 (1 window + 1 filter + 2 ADC prism)

ADC glass/glass 2 @ 0.99 = 0.980

ADC absorption 1 @ 0.98 = 0.980

Filter efficiency 1 @ 0.95 = 0.950

Subtotal 0.730 CCD red QE 0.850 (deep depletion CCD) Subtotal 0.621

Summary

Transmission thru Telescope & Relay 0.47

Total for IR-MOS (incl. QE) 0.15 (H-band science)

Total for Visible Imager (incl. QE) 0.29 (R-band science)

-- RichardDekany - 20 Apr 2006

Topic revision: r1 - 2006-04-21 - RichardDekany
 
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