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Throughput and emissivity performance budgets

Throughput and emissivity performance budgets. Antonin Bouchez NGAO Team Meeting #5 March 7, 2007. Transmission spectra. Temp. Emission spectra. Spectrum (Krisciunas 1997). Sky. N/A. Sky. . +. Telescope primary (aluminum). Spectrum (Denton). 275.5 K. Telescope primary. . +.

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Throughput and emissivity performance budgets

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  1. Throughput and emissivity performance budgets Antonin Bouchez NGAO Team Meeting #5 March 7, 2007

  2. Transmission spectra Temp Emission spectra Spectrum (Krisciunas 1997) Sky N/A Sky  + Telescope primary (aluminum) Spectrum (Denton) 275.5 K Telescope primary  + … …  + AO window 1 surface 1 (broadband AR coat) Scalar (0.02) 275.5 K AO window surface 1  + AO window 1 bulk (15 mm CaF2) Spectrum (Klocek 1991) AO window bulk 275.5 K  + AO window 1 surface 2 (broadband AR coat) Scalar (0.02) AO window surface 2 TAO … = … = Total throughput Total background Method +

  3. K2AO Optical Design K2AO = $ [{id:'Keck M1', mat:'aluminum', thk:-1.0, t:tel.t}, $ {id:'Keck M2', mat:'aluminum', thk:-1.0, t:tel.t}, $ {id:'Keck M3', mat:'aluminum', thk:-1.0, t:tel.t}, $ {id:'rotator M1', mat:'prosilver', thk:-1.0, t:ao.t}, $ {id:'rotator M2', mat:'prosilver', thk:-1.0, t:ao.t}, $ {id:'rotator M3', mat:'prosilver', thk:-1.0, t:ao.t}, $ {id:'OAP1', mat:'prosilver', thk:-1.0, t:ao.t}, $ {id:'DM', mat:'enh_alum', thk:-1.0, t:ao.t}, $ {id:'TTM', mat:'prosilver', thk:-1.0, t:ao.t}, $ {id:'OAP2', mat:'prosilver', thk:-1.0, t:ao.t}, $ {id:'IR Dich 1 S1', mat:'ir_dich_1', thk: 0.0, t:ao.t}, $ {id:'IR Dich 1 B', mat:'CaF2', thk:1.5e-2, t:ao.t}, $ {id:'IR Dich 1 S2', mat:'nir_ar', thk: 0.0, t:ao.t}, $ {id:'Inst win S1', mat:'nir_ar', thk: 0.0, t:ao.t}, $ {id:'Inst win B', mat:'CaF2', thk:1.0e-2, t:ao.t}]

  4. OAP Relay (IR) Optical Design OAPIR = $ [{id:'Keck M1', mat:'aluminum', thk:-1.0, t:tel.t}, $ {id:'Keck M2', mat:'aluminum', thk:-1.0, t:tel.t}, $ {id:'Keck M3', mat:'aluminum', thk:-1.0, t:tel.t}, $ {id:'AO win S1', mat:'opt_ar', thk: 0.0, t:tel.t}, $ {id:'AO win B', mat:'CaF2', thk:1.5e-2, t:tel.t}, $ {id:'AO win S2', mat:'opt_ar', thk: 0.0, t:ao.t}, $ {id:'rotator M1', mat:'prosilver', thk:-1.0, t:ao.t}, $ {id:'rotator M2', mat:'prosilver', thk:-1.0, t:ao.t}, $ {id:'rotator M3', mat:'prosilver', thk:-1.0, t:ao.t}, $ {id:'OAP1', mat:'prosilver', thk:-1.0, t:ao.t}, $ {id:'DM', mat:'enh_alum', thk:-1.0, t:ao.t}, $ {id:'OAP2', mat:'prosilver', thk:-1.0, t:ao.t}, $ {id:'IR Dich 1 S1', mat:'ir_dich_1', thk: 0.0, t:ao.t}, $ {id:'IR Dich 1 B', mat:'CaF2', thk:1.5e-2, t:ao.t}, $ {id:'IR Dich 1 S2', mat:'nir_ar', thk: 0.0, t:ao.t}, $ {id:'Inst win S1', mat:'nir_ar', thk: 0.0, t:ao.t}, $ {id:'Inst win B', mat:'CaF2', thk:1.0e-2, t:ao.t}]

  5. Adaptive Secondary Optical Design ADSEC = $ [{id:'Keck M1', mat:'aluminum', thk:-1.0, t:tel.t}, $ {id:'Adaptive M2', mat:'aluminum', thk:-1.0, t:tel.t}, $ {id:'Keck M3', mat:'aluminum', thk:-1.0, t:tel.t}, $ {id:'Na Dich S1', mat:'na_dich', thk:-1.0, t:ao.t}, $ {id:'Inst win S1', mat:'nir_ar', thk: 0.0, t:ao.t}, $ {id:'Inst win B', mat:'CaF2', thk:2.0e-2, t:ao.t}]

  6. Verification of the model against NIRC2 Filter Predicted Measured J 16.07 14.9 H 13.66 13.6 K 13.46 12.24 L’ 3.75 2.91 Ms 1.03 -0.12 / = 1000 TAO = 277.5 K Black: Sky background Red: Background at science focal plane Sky background (mag/arcsec2)

  7. Signal-to-noise in the K band OAP relay Adaptive Secondary OAP relay TAO Bkgd. Limiting K mag. (5, 1h, S=0.5) 277.5 13.15 25.82 273.0 13.35 25.92 263.0 13.70 26.10 253.0 13.89 26.19 Adaptive Secondary TAO Bkgd. Limiting K mag. (5, 1 hr, S=0.5) 277.5 13.77 26.13 273.0 13.89 26.19 263.0 14.07 26.28 253.0 14.16 26.33 / = 2000 TAO = 277.5 K / = 2000 TAO = 273.0 K / = 2000 TAO = 263.0 K / = 2000 TAO = 253.0 K / = 2000 TAO = 253.0 K

  8. Transmission in the visible / = 1000 TAO = 277.5 K • Transmission ~0.45 in visible, due to inclusion of an ADC in the science path. • The temperature of the AO enclosure has no effect below 1.8 µm.

  9. Preliminary conclusions • An adaptive secondary designs start with an ~0.30 limiting magnitude advantage at K band (~0.25 in L band). • Once AO is cooled to <263 K, the thermal background is dominated by the telescope. We may want to consider higher reflectivity telescope coatings. • To do: • Include better coatings data. • Adopt more realistic optical designs (incl. MOAO). • Understand K2AO performance discrepancy. • More thorough SNR calculations OAP relay design, TAO = 263 K, / = 4000 Background after telescope M3 in blue.

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