Raytracing Surface Roughness, Global Optimization and more

On April 4th Photon Engineering released version 11.40 of their FRED Optical Engineering Software.

This new version includes the following main additions along with dozens of minor improvements.

Geometric Surface Roughness:
For many years, FRED has supported surface and volume scatter functions where ray power is assigned according to scatter function (BSDF). However a single incident ray can generate thousands of scatter rays (except in Monte Carlo raytracing) and Scatter is overridden by TIR which means that it can be inconvenient to setup the model.

This new Surface roughness model works by modifying the ray direction after the surface intersection according to a probability function (which may or may not be derived from a scatter function). It is a geometric calculation so surfaces are essentially raytraced, it has a one-to-one mapping (i.e. single ray incident => single ray exits) and can properly handle TIR on a rough surface.

Traditional Raytracing Scatter   Raytracing Surface Roughness

Optimization upgrades:
FRED Optimum's optimization feature has been dramatically improved.

  • More selectable optimization variables.
  • More selectable merit function aberrations including
  • X and Y RMS spot size
  • X, Y and RMS ray direction spread
  • Peak-to-valley irradiance or illuminance
  • X, Y and RMS irradiance or illuminance
  • X, Y and RMS color chromaticity variation
  • X and Y encircled color chromaticity variation
  • Aberattion targets can now be non-zero.
  • Optimization results are stored with the Document and restored at any time.
  • New optimization algorithms
  • Simplex with multiple restarts (pseudo-global)
  • Simplex with simulated Annealing (pseudo-global)

Raytracing Optimization Results

Multi-parameter Sensitivity Analysis:
FRED Optimum now includes a tolerancing feature which determines the sensitivity of a merit function on each variable. The user can select the threshold value.

Super-Gaussians Superposition surfaces:
This new surface type allows the user to define a single surface that is created from a superposition of multiple decentered and rotated Gaussians.

Super-Gaussian Surface

example image