Ray Tracing

•E.L. O’Neill, Introduction to Statistical Optics, Dover (1992),

•E. Collett, Polarized Light, Dekker (1992),

•Shurcliff and Ballard, Polarized Light, van Nostrand (1964),

•Kliger, Lewis, and Randall, Polarized Light in Optics and Spectroscopy, Academic Press (1990)).

Detect Ray Starting in Bodies

There are occasions when using TracePro where rays are emitted from within an object or multiple layers of embedded objects. Checking Detect Ray Starting in Bodies will cause TracePro to correctly determine the properties associated with the starting point of a ray. Leaving this box unchecked will allow a faster raytrace.

Random Seed

TracePro uses pseudorandom numbers for a variety of tasks, for example, for setting the directions of scattered rays or the starting locations for a random grid or surface source. Whenever a random number is needed, a random number generator is used to obtain the random number. The random number generator requires a seed, or initial value, to get it started generating a sequence of pseudorandom numbers. If the seed is the same for two successive simulations, the same sequence of random numbers is generated. Because such a sequence can be an advantage or a drawback, TracePro lets you set that seed value. Most users never need to change this value.

Wavelengths

As of TracePro 5.0, wavelengths are specified for each source where source data is entered. The Wavelengths tab only serves as a reminder to users of previous releases of TracePro to enter wavelengths with source data.

Thresholds

The Thresholds tab of the Raytrace Options dialog box, as shown in Figure 5.21, controls the flux threshold and the intercept limits. Thresholds control the raytrace by providing limits on how long TracePro follows a ray. The most commonly used limit is the flux threshold. Rays started by TracePro from a source are traced and split until the flux carried by a ray component is below the threshold. At that point, that branch of the ray tree is terminated.

5.38	TracePro 5.0 User’s Manual