In Figure 2.14 we showed a one-dimensional CCD array for measuring positions or lengths of objects. In general, we can use the same sensor to acquire two-dimensional images; we only have to scan the second dimension. There are two principal ways to do this:
Figure 2.18. Principle of a Line-Scan Camera
With this technology, one can easily generate images with a large number of pixels. For example, the sensor of the line-scan camera in Figure 2.18 has 2048 pixels, which means that it is a high-resolution type. Imagine further that the resolution in both directions should be the same, resulting in a total resolution of about 2048 x 4800 9.8 million pixels ”and that with a simple sensor of 2048 CCD cells .
The main application area for line-scan cameras is product inspection; in particular, products transported by a conveyor belt or rotating cylindrical objects are easy to scan. Figure 2.19 shows a line-scan sensor for those or similar applications.
Figure 2.19. Line-Scan Sensor Used in a Flat-Bed Scanner
CMOS Image Sensors
Introduction and Definitions
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