|Si:As Detector||1.8-28||Boeing HF16-128 BIB array specs sheet
SiAs QE plot (Stapelbroek et al 1995)
|Sky Transmission||1.8-28||Mean PMV (Precipitable Water Vapor) measurements for Las Campanas have proved to be elusive. We assume that the PMV statistics for La Silla are representative for Las Campanas due to the similarity in location and altitude. Mean PMV values during the months of Aug 2001 (4.2mm) and May 2002 (5.8mm), suggest that 5mm is optimal. Sky transmission models come from Lord (1992) through the Gemini Observatory website. For our total transmission curve, we glue together the Lord (1992) curves for airmass = 1.5: 0.9-5.6um [3.0mm H20] and 6-28um [5.0mm H20]. We assume zero transmission from 5.6-6um, however this is irrelevant for the filters of interest to us. I can't find data for PWV > 3mm for the near-IR.||X_skytrans.dat
|KRS-5 window||1.8-28||6-mm thick -- however this matters little. The transmission from 1-30um is essentially flat, implying that the losses are completely dominated by reflection, not absorption. I calculated transmission as 1-2R, where R=(n-1)^2/(n+1)^2, and n (refractive index) as function of wavelength is calculated with a 5th-order Sellmeier equation from an optics handbook. After a minor renormalization (to 0.716 @ 10um), the resulting reflectance vs. wavelength curve closely matched the curves seen in the literature and on the web.||X_KRS-5.dat||MIRAC_KRS-5.gif|
|ZnSe window||1.8-28||A ZnSe window has been sometimes used instead of the KRS-5 one. The properties and curve of ZnSe are shown at http://www.lure.u-psud.fr/. Fortunately we have a scan of the transmission of the ZnSe window (J. Hora 4/9/90), so I digitized this plot. I assume the trans. @ 2.5um is the same blueward to 1.8um.||X_ZnSe.dat||MIRAC_ZnSe.gif|
|KBr lens||1.8-28||KBr is extremely flat from 1-20mu (presumably dominated by reflection losses, not absorption), but absorption dominates redward of 20um. KBr transmission properties are discussed elsewhere by Janos Tech and Harrick optical material info. Multiple sources on the web claim transmission is 0.916 @ 10um. We digitize Fig. 7-27 (5.0mm KBr) from the Infrared Handbook and normalize to 0.916 @ 10um.||X_KBr.dat||MIRAC_KBr.gif|
|Al mirror||1.8-28||I can't find Al reflectance redward of 10um. Table of reflectance (0.25-2.5um) is available on p. 25.15 of Handbook of Optics Vol. II. A rough, and crowded, reflectance curve is available (Fig. 7-43) of the Infrared Handbook. Values <2.5um come straight from Handbook of Optics. 2.5-10um curve is interpolated from IR Handbook curve, and normalized to 2.5um value from Handbook of Optics. Curve of 10-28um is simply held constant at extrapolated 10um value.||X_Al.dat||MIRAC_Mirror.gif|
|Au mirror||1.8-28||I can't find Au reflectance redward of 10um. Table of reflectance (0.25-2.5um) is available on p. 25.15 of Handbook of Optics Vol. II. A rough, and crowded, reflectance curve is available (Fig. 7-43) of the Infrared Handbook. Values <2.5um come straight from Handbook of Optics. IR Handbook shows reflectance to be flat and constant between 2.5-10um. We keep constant reflectance (0.977) for 2.5-28um.||X_Au.dat||MIRAC_Mirror.gif|
|BaF2 Blocking Filter (1-mm)||1.8-28||This curve should not be necessary for any calculation -- all of the OCLI silicate filters already have blocking filters included in their curves! An optical handbook gave transmission curves for 10mm and 27mm thickness BaF2 filters. We use a published Sellmeier equation to determine the reflective losses, then calculate the absorption coefficient from the remaining measured transmission (1-2*R), and extrapolate for 1-mm thickness. The response dives at 14um since the 10-mm curve reaches zero at this point. The veracity of this feature is of no consequence since we don't use the blocking filter redward of 12um.||X_BaF2_1mm.dat
|Notes||Transmission Data (Temperature given in file name)|
|A||2.2K (16%)||"W02206-7" is the only K-band curve found [2.206um, 16.0%, Amb]. Ambient curve used here.||X_OCLI_K_2.2_Amb.dat|
|B||3.8L (16%)||There are two curves which may be correct: "OCLI Astronomy L" [3.841, 16.2%, 77K] and anonymous [3.830, 16.6%, 77K]. The "OCLI Astro L" appears to be the better match, and it is the only 3.8um filter curve shown in the old "MIRAC Instruction Manual" and Hora's thesis. Only the 77K curve is available, and the type of substrate is unknown.||X_OCLI_L_3.8_77K.dat|
The best match is "OCLI W04931-8" [4.93, 16.4%; Silicon substrate]
(Hoffmann MIRAC filter list 4/12/95 & 2/24/94).
A W04944-8 filter is mentioned in Hoffmann-Orton fax dated 6/30/95, which was bought along with the "Astro M", however no curve for W04944-8 was found. I can find only a transmission profile measured at ambient, so no temperature correction has been applied. NOT "OCLI Astronomy M" [4.72, 11.7%].
NOT W04711-4 [4.71, 12.8%] mentioned in Hora thesis.
|E||8.8 (10%)||Unambigously "OCLI Astronomy O". Both 77K and Ambient curves available. Extrapolation to 5K suggests a -2.96% shift in wavelength from the Ambient curve. Here, we take the 77K curve and multiply wavelength by 0.992393 and transmission by 1.017211. Both the filter and CaF2 blocker are included in the curve.||X_OCLI_O_8.8_5K.dat|
|F||9.8 (10%)||Unambigously "OCLI Astronomy P" [9.80, 9.7%]. Both 77K and Amb curves are available. Extrapolation to 5K suggests a -2.67% shift in wavelength to the Ambient curve. Here, we take the 77K curve and multiply wavelength by 0.993165 and transmission by 0.997469. The OCLI W-09529 [9.57, 44.0%] can be safely excluded as a match. Both the filter and BaF2 blocker are included in the curve.||X_OCLI_P_9.8_5K.dat|
|G||10.3 (10%)||Unambigously "OCLI Astronomy Q" [10.29, 9.8%]. Both 77K and Amb curves are available. Extrapolation to 5K suggests a -2.47% shift in wavelength to the Ambient curve. For a 5K curve, we take the 77K curve and multiply wavelength by 0.993745 and transmission by 1.017211.||X_OCLI_Q_10.3_5K.dat|
10.6W = 10.6N = W10773-8 (8.08-13.08; "-8" = silicon substrate)
[defined in WH email 4/12/1995].
W10773-8 was bought by L. Deutsch from OCLI 3/94 [10.746, 47.15% @ Ambient] Note that a W10575-9 [10.58, 45.8%] exists, which is similar. I can find only a transmission profile measured at ambient, so no temperature correction has been applied.
|I||11.7 (10%)||"OCLI Astronomy R" [11.70, 9.5%, 77K] is clearly the correct filter. Both the filter and BaF2 blocker are included in the curve. The Ambient and 77K curves suggest a correction of -2.71% to the Ambient wavelength scale to correct for 5K. Here, we multiply the wavelength of the 77K curve by 0.993067 and the transmission by 1.040762.||X_OCLI_R_11.7_5K.dat|
|J||12.5 (10%)||Unambigously "OCLI Astronomy S" [12.49, 9.3%]. Both 77K and Amb curves are available. Extrapolation to 5K suggests a -2.64% shift in wavelength to the Ambient curve. For 5K curve, we take 77K curve and multiply wavelength by 0.993276 and transmission by 1.011623. Both the filter and BaF2 blocker are included in the curve.||X_OCLI_S_12.5_5K.dat|
|M||18.0 QS (10%)||"Q short" - explicitly called "QS" in the MIRAC menu, with the widest bandwidth among the OCLI Q-band filters. Only ambient curve is given -- no temperature correction is given. [17.504, 10.62%]||X_QS_Amb.dat|
|N||18.5 M18 (7.0%)||Unambigously the Michelle M185B7 filter, 25K [18.29, 8.3%] and 300K [17.97, 11.1%] curves available. I've adopted the 25K curve.||X_M185B7_25K.dat|
|P||20.9 M20 (16.6-25.2)||Unambigously the Michelle M209B42 filter. 25K [20.68, 37.4%], 77K, 160K, 235K, and 300K [19.84, 43.2%] curves are available. The 25K curve is adopted here.||X_M209B42_25K.dat|
|Q||24.5 M24 (7.8%)||Unambigously the Michelle M245B5 filter. 25K [24.56, 7.9%] and 290K [24.85, 7.8%] filter curves are available. The 25K curve is adopted here.||X_M245B5_25K.dat|
|Notes||Input Data||Corrected Data (T=5K)|
|D||7.9Me (4%)||"ME" [7.69, 4.2%, Amb] is from an ORT/JPL/UA invoice from 6/1994. **Need to find out if wavelength can be corrected for temp.**||
|K||17.4 Q0 (2.6%)||Two Q0 curves exist, one gives [16.89, 2.5%], the other [16.84, 2.6%]. The first peaks at 48% transmission, the other at 43%. Both claim to be Amb measurements, so its unclear which is the best to use. Otherwise they appear identical.||
|L||17.8 Q1 (2.6%)||Only one Amb Q1 curve available [17.33, 2.7%].||
|O||20.6 Q3 (6.8%)||Amb Q3 curve available [20.01, 6.8%]. There is also something called Q3' [20.46, 6.8%] (see Hoffmann email dated 4/12/1995). The correct Q3 curve is ascertained by correcting the central wavelengths to LHe temps: Q3 becomes [20.59, 6.8%] and Q3' becomes [21.05, 6.8%]. Q3' is definitely the incorrect filter.||