Overview of Design Process
This tutorial will use the Revolved reflector tool. This and the other design tools are premised on the idea that the final desired candela distribution is the result of a reflector that aims the right amount of light toward each angle within the distribution. Therefore, the problem that needs to be solved is determining the portion of the reflector that is aimed toward each angle in the distribution. The Parametric Optical Design Tools facilitate the design process by creating optics comprised of multiple sections, with each section aimed at an angle within the limits of the distribution. Each reflector section is then linked to a weighting factor that determines the size of the section, the size being defined as some fraction of the total area allocated for the reflector.
The process begins by first specifying some general parameters about the optic, including:
1. The construction plane in which the 2D profile of the design will be created
2. The lamp position within the construction plane
3. The start location of the reflector profile (either end can be used as the start location)
4. The total angular extent of the reflector (this is generally an estimate at the beginning of the process)
5. The angular limits of the designed beam pattern
Given this general information, Photopia will create a 3D optic comprised of multiple sections, each aimed at different angles within the desired beam limits. The number of sections (or the angular steps between the aiming angle for each section) is defined by the user. Different candela distributions are created by changing the weighting factor (and thus the size) of each reflector section. If a particular angle has too low of a candela value, then we can increase the amount of reflector aimed toward that angle. If an angle has too high of a candela value, then do the opposite. The final determination of the weighting factor distribution is reached by trial and error.