Building Earth Observation Cameras

111Optomechanical Scanners

ground makes equal distance to the scanner. This can be achieved by conical

scanning in which the scanned strip is annular (Figure 5.8). This method of

scanning has been carried out in Multispectral Scanner S192 own on board

Skylab and in the Along Track Scanning Radiometer carried in the ERS1/2

satellites.

Across track

Scan angle deg

–40 –30 –20 –10

0

1

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2

10 20 30 40

Normalized IGFOV

Across track

Flat Earth

along track

Spherical Earth

along track

βh

βhSecθ

βhSec

2

θ

β

θ

h

Satellite altitude 800km

(a)

(b)

FIGURE 5.7

(a) Effect of scan geometry on ground resolution for an optomechanical scanner. h, satellite

hei ...