| Popis: |
The APART/PADE stray radiation analysis program uses paraxial image theory to transfer radiation through lenses or to reflect it from mirror surfaces. However, this theory is inadequate in analyzing systems having specular nonimaging surfaces for the rejection of aperture heat loads. This paper describes two methods by which the capabilities of APART/ PADE can be extended by means of real-ray-based algorithms. The first method is to use ray tracing to calculate geometrical configuration factors (GCFs) when nonimaging specular reflections are involved. The GCFs can then be appended to the files used in Program 3 of APART/PADE. This approach can be easily extended by ray-splitting techniques to include the effects of surface scatter from the specular baffles. The second method is to use ray tracing to define a synthetic BRDF for a complex reflective baffle. The synthetic BRDF can be input to APART/PADE in the form of a lookup table, and it can accurately model the distribution of radiation emerging from the baffles. An example of this method is the analysis of an off-axis rejection test in which light from the radiation source is reflected from the baffle into the test chamber and thereby significantly increases the chamber background radiation. |
