Science Project

Im very new to this forum and i plan to choose lasers as my science project subject. I want to show what color burns the best. i know to use safety clases:san:. I plan on using a 200mw blue laser, red laser, and green laser. For the red laser i plan on purchasing this: $47.53 Focusable Red Beam Laser Pointer Pen Flashlight 200mW - BudgetGadgets.com

For the Green i plan on building it like in this video:

http://www.youtube.com/watch?v=Y7JavGjcb0Y

The blue laser i am not completely sure of, This is why im coming to the forum. What im asking is what is the cheapest blue laser that is 200 mw. I should be capable of building it (with very very detailed instructions ) but i am able to buy it. Whichever is recommended.

Any other ideas that are better than my original thoughts will be greatly appreciated.

One other thing, a violet-blue laser would be fine :yh:

Actually, all laser colors at the same power with the same lens burns the same.
Even not seen colors like 808nm infrared.
Anyway, Focusable 200mW 405nm Burns Match + Money Detector Blue-Violet/Royal Purple Laser Pen (2*CR2)

It's a violet, they are the only ones that come in thease powers and in this price.

Have a blast!

Gofilord said:

Actually, all laser colors at the same power with the same lens burns the same.
Even not seen colors like 808nm infrared.
Anyway, Focusable 200mW 405nm Burns Match + Money Detector Blue-Violet/Royal Purple Laser Pen (2*CR2)

It's a violet, they are the only ones that come in thease powers and in this price.

Have a blast!

Click to expand...

while this statement is true^^^. in real world practicality it is not. The most common material we burn/ignite seem to absorb violet then blue better.

i have never been burned by a red, nor have i ever seen a red burn through white paper.

michael.

^That is something worth checking^

Chip is right, the extent to which something can be burned by a particular wavelength of laser light is dependent on how well that material absorbs that wavelength of laser energy. A cheaper alternative to you above mentioned experiment would be to only have ONE wavelength of laser light and vary the target material. Doing this, you could compare which materials are burned best by that particular wavelength and compare that data with literature values for the peak absorbancy of varying materials. And you might save $$$ too.

Did you know that the color of an object depends on what wavelengths that material absorbs and what wavelengths it reflects?

You ever notice how nothing has that same weird violet color of 405nm?

I second Ibu's suggestion.
By using only one wavelength of laser with the different color media you could plot the temperature variations and calculate joules of energy and all kinds of other of that "science" stuff. That should make your teacher happy.
Besides, there are many variables concerning the "burning" power of a laser.
To make it a valid science project you would need to calibrate all the different lasers to the same power level before you could even start your "burning" demonstrations. If you spend some time reading here you will find out quickly that just because a seller claims that the unit will do 200mw of output that actually getting it is a far different thing.
And even if you do get them all matched up/calibrated for your demonstration, EVERY set of eyes in the audience NEEDS eye protection too ! For ALL of the different wavelengths that you decide to be using. That will quickly total up to big buck$ !$!$!$!$!

Stick with just one laser for your demo burn. Maybe get a couple of <5mw versions of the other colors to show the concept(s) or to use in static displays of the concepts.
For safety, a demonstration area behind a tinted window coupled with the distance away from the demo might be safe enough for the viewers as long as you keep the power level of the laser to just enough to do the burning. Make sure to promote not staring at the point of contact as well.
SAFETY for everyone involved is your first priority. Nobody watching should need to worry about a blindspot or loss of color in their vision. That is YOUR responsibility.

Be safe and have fun.

EDIT - Or you can use a video camera & TV to show the project while keeping the whole thing behind a safe "wall". Then nobody but you needs the protective eyewear. But you might want to include some for your instructor too.