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Departure from paraxial approximation for beam x. Error: due to previous message, calculation truncated at beam x
Article Type: Application Messages
Updated: Dec 21, 2005
Author(s): Breault Research Organization
Abstract
The complex paraxial optical invariant should be equal to zero, if the parabasal rays remain in a linear region about the base ray. As it sometimes happens for a variety of reasons, the parabasal rays begin to diverge and are no longer linear.
This message is printed during a FIELD calculation whenever the complex paraxial invariant exceeds a prescribed value (0.1 waves is the default). For 1 wave or larger the calculation will be terminated. You can extend the range of the violations allowed using the VIOLATION command, but this does not solve the initial problem.
Severity Level: Application Error
Category: Arithmetic
Applies to: All versions of ASAP
Solution
For steep curvatures or complex structures, use enough sub-beams so that the sampling frequency is high enough to be "locally quadratic" on that surface. If surface variations or structures become too small, and you cannot get enough sub-beams to sample adequately, you may need to switch over to the BPM method or look to Lumerical for a solution.
