# What would I need to make a spotlight with a CFL?



## Barbarin (Dec 6, 2004)

It is acvery technical question for optics experts out there. I have a couple 250 Watt CFL 6400ºK lamps, and would like to explore the possibility of making a spotlight with that.


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## Steelwolf (Dec 10, 2004)

To make a spot means that you need to focus the light to a point. Already not an easy job with light sources that start out as a point, even more difficult when you start out with a diffused source like a CFL.

You could possibly make a custom-tuned reflector where each point on the reflector is matched to the CFL tube such that the light emitted is reflected to a point. Not likely! /ubbthreads/images/graemlins/smile.gif

An idea I've been tossing around is to use optic fibres to bring the light to a small coherent emission point, then focus it with a lens. It might be possible to encase the CFL tube in a thick fibre, or else use a simple reflector to direct most of the light in one direction along the major axis. The optic fibre is lined up along the major axis to collect the light and bring it to a point. From there it can be focused with a simple lens.

Probably quite a lot of losses along the way though.


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## twentysixtwo (Dec 20, 2004)

*Re: What would I need to make a spotlight with a C*

Do a search on "Nonimaging optics"

I think you may be able to do what you want by using a lens to convert the light into a collinear set of beams, then collimate then with another reflector or a lens.

IMO it would be a lot of work.....


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## Lynx_Arc (Dec 20, 2004)

*Re: What would I need to make a spotlight with a C*

basically you have too much light coming from too big an area that needs to be refocused to a tight spot. It is a lot easier with a sharp line or dot with one or several dimensions fading to the point of infinitely small vs wide swaths of light coming from a cylindricular source. With a point or line filament you can use a parbola to focus easily but to focus a cylinder source is not easily done. One method would be an almost perfectly reflecting light pipe to slip over the tube like a perfect fiber optic with almost no loss. The idea being to bounce light multiple times until it reaches a more easily managed angle to be focused.


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