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| imagerteleconnotes20170807 [2017/08/14 10:18] – hanany | imagerteleconnotes20170807 [2017/08/14 10:48] (current) – hanany | ||
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| __Action Items__ | __Action Items__ | ||
| + | * UMN to develop focal plane loading model including load from mirror(s) and cold stop as a function of temperature | ||
| + | * JPL to develop scaling of cooling cost depending on what mass we cool to which temperature | ||
| + | * Need input on feasibility and cost model of deployable shields | ||
| + | * Need input on cooling and trade-off with mass of stop and secondary mirror | ||
| + | * Roger to work on ASIC solutions to TDM, FDM | ||
| + | * discuss with Matt | ||
| + | * do wiring load trade-off between the two options | ||
| ====Telecon Notes==== | ====Telecon Notes==== | ||
| - | Optics | + | __Optics__ |
| * UMN reviews tradeoff study between open and cross Dragon. For fixed aperture and f# Open Dragone has 3/4 the DLFOV of the crossed system. Largely agrees with the result from the comparison shown a week before when they had different f#. | * UMN reviews tradeoff study between open and cross Dragon. For fixed aperture and f# Open Dragone has 3/4 the DLFOV of the crossed system. Largely agrees with the result from the comparison shown a week before when they had different f#. | ||
| * How large is the stop in the current Open Dragone design? | * How large is the stop in the current Open Dragone design? | ||
| Line 28: | Line 35: | ||
| * What are ' | * What are ' | ||
| + | __Focal Plane Technology__ | ||
| + | |||
| + | Roger and Jeff post their answers to the questions Shaul posed on last week on last week’s minutes page. | ||
| + | |||
| + | * Q1: what is the plan for detector technology for the high frequency bands of the imager? | ||
| + | * monochroic PSBs above 600 GHz because of Nb band gap. Not suitable for Nb-based antenna coupling. | ||
| + | * Q2: are the distribution of colors for pixels as described by the worksheet reasonable? | ||
| + | * Yes. 2-3 colors per pixel is OK. Perhaps could fit more bands in lower frequency bands. | ||
| + | * Q3: are the bandwidths assumed reasonable? | ||
| + | * Yes. Currently assuming 25% bandwidth | ||
| + | * Q4: what should we assume about beam sizes as a function of frequency, specifically for the high frequency bands? Is it reasonable to assume single mode coupling all the way to the highest frequencies? | ||
| + | * Yes. Single mode all the way to 900 GHz. “Technologies are there.” | ||
| + | |||
| + | * Roger points out that power consumption is poised to be an issue. He is looking to have a discussion with Matt. Charles (and Shaul) advocate assuming custom-made ASICs for which the power consumption could be significantly lower. How much lower? Need to check | ||
| + | * Roger says that with current technologies he projects 400 and 1.1 kW for 10,000 detectors for the TDM, FDM, respectively. | ||
| + | * Jamie says that for EPIC-IM a JPL engineer found ways to reduce the power consumption of the TDM by a factor of 3(?) even without ASICs. | ||
| + | |||
| - | Focal Plane Technology: | ||
| - | Roger and Jeff post their answers to the questions from last week on last week’s minutes page. | ||
| - | Below is a copy of the questions and some discussions people had today. | ||
| - | Q1: what is the plan for detector technology for the high frequency bands of the imager? | ||
| - | - > 600GHz for Galactic Science; conservative choice is SPT-type polarization-sensitive absorber | ||
| - | - Power consumption of read out is quite a large impactor considering the cost | ||
| - | - Different read out systems are discussed, e.g. TDM, FDM and ASICS | ||
| - | - 400 W or 1.1KW is probably too large | ||
| - | - ASICS has a factor of 10 cost saving in power | ||
| - | Q2: are the distribution of colors for pixels as described by the worksheet reasonable? | ||
| - | - 2-3 colors per pixel | ||
| - | - maybe fit more bands in lower frequency | ||
| - | - high frequency depends on f#, pixel size etc. | ||
| - | Q3: are the bandwidths assumed reasonable? | ||
| - | - 25% is reasonable | ||
| - | Q4: what should we assume about beam sizes as a function of frequency, specifically for the high frequency bands? Is it reasonable to assume single mode coupling all the way to the highest frequencies? | ||
| - | - “Technologies are there.” | ||