Telescopes

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8

Millimeter wave horns

~2cm

Slide 81

Millimeter wave receiver electronics

Intermediate frequency (IF) plate

Slide 82

Millimeter wave electronics

Local oscillator

Slide 83

Submillimeter receivers

Submillimeter

300GHz-1000GHz

1mm-0.3mm

Slide 84

Submillimeter receiver

230 GHz mixer block

CSO, Mauna Kea

Slide 85

Submillimeter receiver

CSO, Mauna Kea

Slide 86

Submillimeter receivers

All of the receivers shown are called COHERENT detectors.

COHERENT detectors preserve the phase information and spectral information is retained.

Another type of receiver is called INCOHERENT detector.

INCOHERENT detectors respond only to the total power of the signal.

Slide 87

Submillimeter receivers

A type of INCOHERENT detector is called a bolometer.

A bolometer is a device that changes its electrical resistivity in response to heating by illuminating radiation.

Bolometers may be made of cooled semiconductors coated with an appropriate absorber for the wavelength which is to be observed.

Slide 88

Submillimeter receivers

SCUBA The Submillimeter Common-User Bolometer Array

JCMT, Mauna Kea

Slide 89

Submillimeter receivers

SCUBA The Submillimeter Common-User Bolometer Array

JCMT, Mauna Kea

Slide 90

Parts of a radio telescope

Antenna

Collects the radiation

Focuses the radiation on the receiver horn

Receiver

Horn

Amplifies the signal

Converts the radio-frequency signal to signals (current/voltage) we can record and analyze

Steering gear

Moves the telescope as it tracks the observed object

Slide 91

Steering gear

There are 2 styles of steering gear:

Altitude-azimuth mount

Equatorial mount

Slide 92

Altitude azimuth mount

Antenna

Receiver

Altitude track

Azimuth axis

VLA Very Large Array