This calculator aims to address the following problem: given dimensions of a parabolic forward reflector* plus an emitter, predict the beam profile** generated. Parabolic reflectors are inherently much messier than convex lenses, so various approximations such as thin-lens equations fail to apply.
Input:
- Reflector diameter
- Reflector height (depth)
- Emitter diameter***
Output:
- Full angles of hotspot, corona, and spill
Optional:
- Input LES area and out-the-front lumens, output peak intensity (candela)
*Real-world reflectors may deviate from an ideal paraboloid due to manufacturing imprecision.
** Beam profile is simulated at a far distance, not 1m in front of white wall!
***For a square emitter, you get a side length and a diagonal, instead of a single diameter. The resulting beam will be square-ish, and you will need to simulate twice (with side length and with diagonal) to get the beam shape along the side length and diagonal directions.
This is technically a repost of earlier work (threads [1], [2]), but the original version appeared in a comment and has been revised many times since; for this reason, I feel that it merits a separate post for visibility/searchability.