Search for a command to run...
This chapter discusses the origins of light scatter and the various scatter sources that are commonly observed, and it defines how scattered light is quantified. Except for the following brief overview, the book is largely restricted to the measurement and analysis of scatter caused by surface, bulk, and contaminant imperfections, as opposed to scatter from isolated particles and resonance effects, such as Raman scattering. Scatter from optically smooth components is treated as diffraction in many cases. For the special case of clean, optically smooth, reflective surfaces, there is a well-defined relationship between the scatter distribution pattern and surface roughness statistics, and scatter measurements can be analyzed to characterize the surface. In many cases, insight may be gained into possible improvements in surface-finish techniques. A simple example of this technique is given in this chapter and treated in more depth later. In later chapters it will be seen that, in some cases, discrete surface features can be identified as pits or particles from their scatter patterns, and estimates are made of their diameters from scatter measurements in the semiconductor industry.