how to lower laser's mW accurately?

[bobobob121]

what would be the best way to accurately reduce laser power without modification of laser itself? The reason i ask of this is because i need to have three different colored lasers "which i already have" but i need them at the same power level. I personally was thinking of a beam splitter of some sort.....can anyone help me with this. "i have a laser power meter"

 

[lasersbee]

The easiest way is to reduce the input voltage to you laser driver...  
assuming we are talking about Laser Diodes....

 

[bobobob121]

yes i knew that. But what would be the easiest way without adjusting the driver

 

[lasersbee]

That is the easiest way...IMHO
Unless you want to start adding optical filters... but that is not as precise..

Or maybe some other member has a better idea.... :-?

 

[bobobob121]

how much they go for?

 

[ElektroFreak]

Optical filters can be found relatively inexpensively from several different suppliers. I get them from http://myworld.ebay.com/omegabob2/, personally. You just need to pay attention to the transmission curves for each type of filter and select one that meets your needs.

If you're unwilling to mess with your driver, then filtering is the only other option.

 

[bobobob121]

thanks. what would u say i would need to lower the output to around 50mW from a 200mW laser

 

[ElektroFreak]

The transmission charts are in % of light transmitted through the filter at a given wavelength. 50mW is 25% of 200, so you'll need a filter that transmits 25% of light at the frequency of your laser.

 

[bobobob121]

alright..sounds good. thanks man

 

[randomlugia]

A cube beamsplitter from Novalasers would work. Using two would get 200mW down to 50mW. And if you get bored, you can even use them to combine the colors of your lasers!