Building Earth Observation Cameras

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5

Optomechanical Scanners

5.1 Introduction

Civilian Earth observation started with the launch of TIROS-1, carrying an

electron beam imaging (TV camera) system. The need to cover larger spec-

tral regions soon led to the replacement of electron beam imagers with sys-

tems using discrete detectors. In this arrangement, radiance from the scene

is directed to the optics with the help of a mechanical scanner and, hence,

such systems are known as optomechanical scanners. Because of the mode

of scanning, they are also known as whiskbroom scanners.

5.2 Principle of Operation

Consider a collecting optics—say, a telescope—at whose prime focus along

the opt ...