- Sep 29, 2011
Ok if I'm testing a 3W 445nm laser on a LPM that is only rated to 2W using a 50/50 beam splitter will I still get an accurate reading? (give or take the absorption by the splitter)
EXACTLY..... I concur 100%....:gj:Okay, the first thing you need to know is EXACTLY what your optics are doing to your beam. In other words......You absolutely cannot assume that your 50/50 BS is actually 50/50. There are VERY FEW beam splitters that are flat across any real range of wavelengths (and they are VERY expensive).
There are also a whole host of other factors involved with anything you put between your laser and your power meter. The best advice I can give you is to leave the beam path clear, OR, if you have to attenuate the beam power (as you indicated here), then you need to use a KNOWN and MEASURED element in your beam path (whether it be a ND filter, beamsplitter, or other optic).
If you have a lower powered laser at the same wavelength as your 3W unit (one within the range of your meter), then you can measure the attenuation of any optic you want to use between your laser and your power meter.
Then, you can apply that loss factor to your measurement of the 3W laser.
This is a handy way of "extending" the range of a power meter. As long as you know the real attenuation of a given optic at your wavelength, you can use it to measure power levels beyond your meter's range.
But, you need to be aware that you are also introducing errors into your measurements here. (nothing comes for free) It all depends on just how accurate you need to be......
AND you also need some standard to begin with. Meaning...some MEASURED standard on which to base your comparisons.
But for the moment, I need to go. I'm sipping my favorite bourbon, and watching my girlfriend undress in front of me, so .......you know ....i gotta go...
I had the same question.I'm sorry, can I ask the simple question here?
- Who sold you a "3W" 445?
Unless you bought one of those knife-edge rigs (that are really two lasers combined into one beam) made by a clever member here in the forum, I would question anyone who marketed a "3W" 445.