Rainbow generator??

[The Heretic]

There is something primal, natural and very soothing to me about the colors that come from a prism and white light. I have a simple three sided prism that I often put in a window to get that rainbow.

Unfortunately I am very sunshine challenged here in the Pacific NorthWet, and I would like to buy something that would generate a rainbow anytime with the flip of a switch. There used to be a company that made these, but when I tried to order one from Edmund Scientific they said they were "back ordered". Then they dropped them from their catalog. I can't find anything like it anywhere else.

I have toyed with building one as a product to sell, but I would like to use a low power LED as the light source. The problem is that LEDs, as I understand them, don't put our "whole" white light - they generate a narrow spectrum of light which would not generate a rainbow. I do have a halogen 12V bulb I suppose I could use, but I am not sure what spectrum a halogen bulb generates.

Does anybody know of any inexpensive (under $50) commercial products out there along this line?

Any suggestions on making my own? I want the light source to consume very little power and heat (for safety), yet it obviously must be close to a whole spectrum white light source to generate a rainbow.

Thanks.

 

[Silverlily]

I'm not sure if they're full spectrum or not, but what about the florescent lights designed to grow plants?

 

[The Heretic]

I'm not sure if they're full spectrum or not, but what about the florescent lights designed to grow plants?

Some claim to be full spectrum, but I believe a property of just about any florescent light source is that the spectrum can be rather narrow. I am not sure though - I was hoping there would be somebody here that knew the answers.

I've not had any luck holding my prism near a florescent light source - a bright halogen (like from a torchiere) does work a little. I have seen physics experiments done with a slide projector - they are very bright, but they also consume a lot of power, are very hot, are generally noisy (a fan is needed to keep them cool) and they are rather expensive.

 

[Byron In Exile]

Fluorescent lights contain gases that emit specific frequencies, so you'd get bars and not a rainbow. Halogen is incandescent, but weighted towards red. You might be able to get some kind of filter to even it out.

Here are some examples of different sources:

(tungsten = halogen)

It might be too inefficient, with so little blue in the output spectrum to start with. A large projection might be difficult. On the other hand you could always move to Spokane. Things rust less quickly there, too.

 

[Byron In Exile]

Some claim to be full spectrum, but I believe a property of just about any florescent light source is that the spectrum can be rather narrow. I am not sure though

They only simulate a full spectrum to the imperfect human-eye/brain system. Actually, their output spectra are full of holes. You need to use an incandescent source.

I have seen physics experiments done with a slide projector - they are very bright, but they also consume a lot of power, are very hot, are generally noisy (a fan is needed to keep them cool) and they are rather expensive.

That will be your problem: getting rid of the heat. Because there's so little output in the high-frequency range, to get a useful amount you need to have very high output energy, and then waste the yellow, red, and infrared -- and the infrared needs heat sinks and fans. I imagine you're talking about a big projection? For something small, you might be able to get a reasonably flat spectrum by filtering white LEDs.

 

[Soblue]

Maybe this?

http://www.innovations.com.au/cda/product/sku/0,1568,742-14,00.html

or this?

http://www.hippygift.com/hidrainmoodl.html

 

[Shiner]

maybe the you could use the same type of bulb they use in light box's to treat people who have SAD (seasonal adjusted disorder).

Not sure about this but it might be worth a try