Radio Telescopes Typical Designs Heterodyne Receivers
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Janskys First Radio Telescope 1933
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Grote Reber: 1937 Radio Telescope
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The Arecibo Radio Telescope
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Heterodyne Receivers Mix signal and local oscillator Mixed
signal contains intermediate frequency f_signal f_local but also
the sum of the frequencies
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Heterodyne Signal Detection
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MM and Sub-MM Telescopes Use both coherent and incoherent
detection Heterodyne receivers for emission-lines Mostly bolometers
for continuum
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Millimeter Valley on Mauna Kea
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NGC 6334
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SMA Receivers
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Bolometers Absorb and thermalize photons Measure temperature
change Balance between heating and cooling results in long time
constants Typically used in chopped operation
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Transition Edge Sensors: Extreme sensitivity to small
temperature changes allows to build very sensitive bolometer
arrays
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Photocathods The photoelectric effect Quantum nature of light
Photomultipliers, channel plates
Electronics PN junctions and photodiodes Field Effect
transistors Logic devices Analog switches Operational amplifiers A
practical example
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Field Effect Transistor Junction FET (JFET)
Metal-Oxide-Semiconductor FET (MOSFET) CMOS circuits (Complementary
Oxide Semiconductor)
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Fabrication of Integrated Circuits Doping Depositing metal
Growing oxides (as isolators) All controlled by photoresist
masking
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HAWAII-2: Photolithographically Abut 4 CMOS Reticles to Produce
Each 2048 2 ROIC Twelve 2048 2 ROICs per 8 Wafer 2048 2 Readout
Provides Low Read Noise for Visible and MWIR
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3-D Barrier to Prevent Glow from Reaching the Detector