CNI linearity issues.

[aXit]

Hey guys.

Just got my meter up and running, using a coherent 210, and decided to do a linearity graph on my CNI MGL-III-400. , It's not calibrated yet, but I know it's pretty close, and the graph just shows it referenced to the detected full power. When I'd connected it up to a pot and twisted it around, I'd noticed the obvious bumps and power drops at two points. The graphs ended up showing this:



Red was at startup, green was about half an hour after.

Is this a major flaw? Something that I can fix? Or is it normal?

Thanks guys.

[dave]

Thats pretty typical on most Chinese lasers from all manufacturers. Some are worse than others.

Once you are scanning, the dip wont be a issue at all.

[aXit]

Is it that the dip actually goes away when modulating? Or just that you won't notice it.

Thanks.

[MechEng3]

Don't you just love DPSS technology? Thermal issues with SHG crystal...normal...for most like Dave said. Not to worry...direct 523nm diodes are being evaluated in China. You would hate to see the actual bumps with a photo diode and fast modulation.....did someone say picket fence?

[aXit]

Picket fence as in my power response? :P

The diode current is constant across the range of modulation, that isn't a problem.

I probed around the psu a bit today, trying to find anything to do with photofeedback. Not much luck.

Anything I can do in terms of TEC adjustment, or max diode current, do get the gradient a little bit less... well, less looking like a mountain range? I can easily sacrifice some power for my planned projector setup.

Thanks again.

[dave]

I wouldnt worry too much TBH.. Maybe it would be a bigger issue if you have a pair of these lasers, and are trying to get matched yellows and cyans, etc