detection methods
DESCRIPTION
Detection Methods. Coherent ↔ Incoherent Photon Detection ↔ Bolometric Photon Counting ↔ Integrating. Radio Telescopes. Typical Designs Heterodyne Receivers. Jansky’s First Radio Telescope 1933. Grote Reber: 1937 Radio Telescope. The Arecibo Radio Telescope. Heterodyne Receivers. - PowerPoint PPT PresentationTRANSCRIPT
Detection Methods
• Coherent ↔ Incoherent• Photon Detection ↔ Bolometric• Photon Counting ↔ Integrating
Radio Telescopes
• Typical Designs• Heterodyne Receivers
Jansky’s First Radio Telescope
1933
Grote Reber: 1937 Radio Telescope
The Arecibo Radio Telescope
Heterodyne Receivers
• Mix signal and local oscillator• Mixed signal contains
“intermediate frequency”f_signal – f_local but also the sum of the frequencies
Heterodyne Signal Detection
MM and Sub-MM Telescopes
• Use both coherent and incoherent detection
• Heterodyne receivers for emission-lines• Mostly bolometers for continuum
Millimeter Valley on Mauna Kea
NGC 6334
SMA Receivers
Bolometers
• Absorb and thermalize photons• Measure temperature change• Balance between heating and cooling
results in long time constants• Typically used in chopped operation
Transition Edge Sensors: Extreme sensitivity to small temperature changes allows to build very sensitive bolometer arrays
Photocathods
• The photoelectric effect• Quantum nature of light• Photomultipliers, channel plates …
Photocathod Devices
• Cathods• Photomultiplier• Image intensifiers• Microchannel plates
Physics of Semiconductors
Basic Quantum PhysicsSolids
SemiconductorsPN Junctions
Semiconductors
• Conduction in semiconductors• Doping
PN Junctions
• Formation of pn junction• Rectifying properties• Charge separating properties
Electronics
• PN junctions and photodiodes• Field Effect transistors• Logic devices• Analog switches• Operational amplifiers• A practical example
Field Effect Transistor
• Junction FET (JFET)• Metal-Oxide-Semiconductor FET
(MOSFET)• CMOS circuits (Complementary Oxide
Semiconductor)
Fabrication of Integrated Circuits
• Doping• Depositing metal• Growing oxides (as isolators)• All controlled by photoresist masking
HAWAII-2: Photolithographically Abut 4 CMOS Reticles to Produce Each 20482 ROIC
Twelve 20482 ROICs per 8” Wafer
20482 Readout Provides Low Read Noise for Visible and MWIR
Canon 16mm x 14 mmGCA 20mm x 20 mm
ASML 22mm x 27.4 mmReticle-Stitching: 2048x2048 ROIC
Submicron Stepper Options
3-D Barrier to Prevent Glow from Reaching the Detector
Metal 1
Metal 2
Metal 3
Poly 1
Analog Capacitor
Low
-Noi
se C
MO
S M
ultip
lexe
r
p-type
n+
HgCdTeDetector
IndiumInterconnect
Overglass
CMOS (LOCOS)