homemade laser spectrometer.

[lasersbee]

The only thing you need to do is make sure your diffraction grating has got a small enough number of lines.  I went with 500 lines per mm.
http://cgi.ebay.com/Laser-Diffracti...1QQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247

[highlight]The smaller the number the more spacing there will be between the lines or spectrum.[/highlight]  So obviously, if you want to determine the small shift in wavelength in a bluray for example, you want to move it further away from the grating than I have, and a small number of lines per mm on the grating.  I think 500 is the smallest you can go.

Hey Ken...
                I just noticed this Thread... and I had purchased those same plastic Diffraction gratings
as well... (1000 lines/mm and 500 lines/mm)

I Don't know if mine are mis-printed/identified... but I when I shine a Red laser through them...

the 1000 lines/mm grating has the beam dots farther apart than the 500 lines/mm grating... by 2X...
Did I use them wrongly... :-? :-?

Jerry

 

[Kenom]

Nope you did that right I think.

 

[lasersbee]

So... if we use a 13,500 lines per inch diffraction grating... it would be even
better... b/c the dots would be even farther apart and we could reduce the
distance from the diffraction grating to the dot display area...

I think that sounds about right.... :-?

Jerry