Optical Imaging Techniques

The purpose of this chapter is to discuss optical imaging from the point of view of dynamic range, resolution and information capacity. Although photographic film has no proper place in a book on optoelectronic devices, we shall begin with a discussion of the properties of film in order to establish the basic principles of optical imaging. This is followed by a brief discussion of holography, an exciting new method of recording three-dimensional images. The remainder of the chapter deals with a new solid state imaging device, the charge coupled device (CCD) area image sensor. The resolution, dynamic range and information capacity of this device is considered in comparison with that of photographic film. The author concludes that although the density of sensing elements of the CCD area image sensor is low, its information capacity is reasonably high — because of the large dynamic range of silicon photodetectors — and that the problem is finding a method of encoding the optical image that can utilise this information capacity.