Knowledge Base
Other Items of Interest
- No related articles at this time
- "Saccadic Lens Instability Increases with Accommodative Stimulus in Presbyopes," ARVO 2009 Poster Presentation
- "Software and Codes for Analysis of Concentrating Solar Power Technologies," Sandia Report
- "The Advanced Human Eye Model (AHEM): A Personal Binocular Eye Modeling System Inclusive of Refraction, Diffraction, and Scatter," Journal of Refractive Surgery
- "Optimization using rational Bézier control points and weighting factors," Proc. SPIE
- "Stray light test station for measuring point source transmission and thermal background of visible and infrared sensors," Proc. SPIE
"How Many Rays Do I Need to trace? Applying the Rose Model to Computer Analysis of Illumination Systems," BRO White Paper
Article Type: White Papers
Updated: Jan 03, 2005
Author(s): Gary L. Peterson
Abstract
"Illumination systems are analyzed by tracing large numbers of rays through computer models of lamps, reflectors, lightpipes, and diffusers. Surface or volume emitters are modeled as sources of rays that have random starting locations and directions. Many millions of rays are traced from the emitters, through the system, to a collecting plane. The irradiance is calculated by dividing the collecting plane into rectangular pixels and adding up the power of all rays in each pixel. The irradiance is then equal to the power in each pixel divided by the pixel area.
This is where the trouble begins. While actual systems produce a smoothly varying irradiance, the computer simulation superimposes a grainy or noisy background. This obscures features of interest and makes it difficult to evaluate the uniformity. The best solution to this problem is to trace more rays. But how many rays are enough? Because tracing millions of rays is time consuming, we want to estimate how many rays are really needed. This estimate is provided by the Rose model. ..."
Copyright 2005, Breault Research Organization, Inc (BRO). This paper is made available with permission of BRO. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.