Big reflectors

Was browsing the hardware store today, and came across this:



Then I thought the reflector looked pretty nice and might be of use, so I got it and took it apart:





The reflector is made of metal, and the front lens is glass (55W halogen I think? I couldn't test it since I don't have a car, cig-adaptor powered..)

But tested it with a 1W HD, and it sucked really bad. It's going back to the store. Would have been nice if it worked, imagine a 6.5 inch turbo head... /ubbthreads/images/graemlins/icon23.gif

-YC

Come here big mamma! /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif Got a X waiting for you /ubbthreads/images/graemlins/grin.gif Seriously... doesn't look parabolic enough for Luxeons.

Size matters? It all depends on reflector and emitter geometry. In the following diagram, the blue and red reflectors both share the same focal point. The dark red area of the red reflector actually reflects the same amount of light as the blue reflector. (It's interesting to note that the other portion of the red reflector only makes a small contribution relative to its volume.)

Unfortunately, things aren't so simple when you realize that the emitter is not a point source. The issue is not how well the reflector is able to "capture" emitted light, but how well it is able to collimate it. As the reflector gets smaller relative to the emitter (and by this I mean the actual part that emits light), it's ability to collimate light is progressively less because the emitter less approximates a point source.

Said another way, given a particular emitter, a larger reflector will be able to effectively collimate its output more than a smaller reflector.