Fraunhofer diffraction integral

The total effect of the dS wavelets can be integrated across dE to get an expression for the far field or Fraunhofer diffraction pattern. The initial exponential term in (1.4) refers the wave to an origin at t = 0, but we are only... 

Particle sizing instruments can be categorized by the method qjplied to determine a size distribution. Integral optical methods like Fraunhofer Diffraction or Dynamic Light Scattering require extensive mathematics to extract the particle size distribution from samples. The general shape of this distribution is ordinarily assumed and a few parameters of this assumed distribution are adjusted to represent features of the data. Because of these restrictions, integral optical methods are not able to resolve all fine details of a particle size distribution. 

For a given C(x ), Equation 3 can be evaluated to produce a diffraction pattern appearing at the screen. The integral may be solved for any set of experimental conditions, but the problem is simplified significantly if the screen is placed at some large distance away from the electrode. This is a standard approximation in solving diffraction problems known as the Fraunhofer approximation,13 and can easily be realized experimentally. When this approximation is made, the expression for f-7 is simplified, and Equation 3 becomes... 

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