A typical imaging sensor, such as a CCD or a CMOS chip in a commercial camcorder or other video-imaging system, uses a full two-dimensional detector array or focal plane array (FPA). Very much analogous to film, these FPAs record the entire image essentially at once. In the thermal infrared these FPAs are called staring, mosaic, or two-dimensional (2-D) detectors.

Infrared detectors are still quite costly and difficult to manufacture, and for this reason detector arrays which are much smaller in extent than a full two-dimensional array are often used with appropriate scanning to allow imaging coverage over the full desired two-dimensional field of view. If we use a small detector array, we can create a full two-dimensional field of view by following the steps outlined here and illustrated in Figure 12.6.

• Scan the field of view in the azimuth or horizontal direction over the full width of the field. This is the upper swath shown in Fig. 12.6.

• Then simultaneously increment the field down by the vertical extent of the array while reinitializing to the original azimuth position on the left.

• Now we scan again in azimuth.

• This procedure is repeated until we cover the full vertical or elevation field of view, after which the entire process is repeated again and again to create the full two-dimensional field of view.

Figure 12.6: Serial Scanning

This process is known as serial scanning. It requires two scan motions, one for the azimuth or horizontal scan...