clearify somethings about nd filters plz

[genocidex]

ok so i was looking at laserbee's lpm and was told i can use a nd filter to reduces the power of my laser to put it into the range of his meter which is awsome. but i have no clue what the hell they are so i did a wiki search since yahoo was throwing all sorts of stuff at me that i couldnt absorb also i did a ebay search to see how much they would cost.

things i think i got right:

-ND stands for natural density
-i saw some ND "X" filters and a chart the ND 4 will reduce the power of the laser by 4X as i think i understand from the wiki page?
-they are made for camera originally?

things im trying to ponder over
-are there special ones made for lasers or will the ones for cameras work?
-if not does any one know were i can get ones for lasers that an reduce the power of my laser by about 4-6x


thanks for any ones help and if there are some things i should know about these filters please throw in that info as well ;D

 

[lasersbee]

ND stands for "Neutral Density"... :

Buy the "Glass" ND Filters for testing...

Here is a link to some we have purchased in the past for another Laser project....

http://cgi.ebay.ca/37mm-Neutral-Den...ryZ67346QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

You would need to ask the Seller if indeed they were Glass ND filters...
(this is only a suggestion... )


Jerry

 

[Warske]

-are there special ones made for lasers or will the ones for cameras work?
-if not does any one know were i can get ones for lasers that an reduce the power of my laser by about 4-6x

The ones for cameras should work.  Since the filter you want will absorb most of the laser energy, if the beam is tightly focused on the filter you may burn it just like you would electrical tape, depending on your laser power.

As the wiki says, "An ideal neutral density filter reduces light of all wavelengths or colors equally"

Keep in mind that a camera filter may not be ideal, and it may not be accurate.  I tested an ND8 camera filter recently and it only attenuated the beam by a factor of 6.5 instead of 8.  

So you may need to use your power meter or a light meter to measure the actual attenuation at your actual laser wavelength before you trust its accuracy.

Keep in mind that other filters might also work for you to attenuate the beam.  Welders goggles, sun glasses, colored glass or plastic, crossed polarizers, colored water, etc.  If you are going to measure the attenuation anyway, you can probably use one of them instead.