Help to focus 445nm M140

keyblade95 · Mar 7, 2016

Hi! I'm not able to focus my 445nm laser diode using G-2 glass lens. What can I do?
https://www.youtube.com/watch?v=a3C_P9ALgaY

Pi R Squared · Mar 7, 2016

This shouldn't be possible, your lens may be in backwards.

Alan

keyblade95 · Mar 9, 2016

I reversed the lens... now I got a pretty straight line with a brighter dot before the end... Pleaseee help!

diachi · Mar 9, 2016

keyblade95 said:
I reversed the lens... now I got a pretty straight line with a brighter dot before the end... Pleaseee help!

Some pictures would help if you could post some. Not sure about the M140 but a lot of the higher powered diodes DO have a rectangular/line shaped beam.

keyblade95 · Mar 9, 2016

I found out that g-2 lens was set at the wrong orientation! Thanks to this: G2 Lens Correct Focus Ring Orientation

RedCowboy · Mar 9, 2016

Take the silver thumb adjuster off and see if the lens will screw in further, the thumb adjuster may be stopping it from getting close enough to the diode.

keyblade95 · Mar 9, 2016

If I screw the lens in further, going on very near to the diode, I get a bigger and bigger circle.. I think the result above is the best I can reach

Isaac Clarke · Mar 10, 2016

yes G-2 give horible beam shape and not to mention it's a multimode diode.. if you got a line then that the best things will get..

DTR · Mar 10, 2016

It does depend. He put a link to Darkly Digital for the G-2 orientation so I am guessing there is a chance he is using it for engraving. If so then the G-2 will make a smaller spot than the three element lens since it is a short focal length lens and exits the aperture smaller but does diverge more over distance. The three element lens is a longer focal length so it exits with a larger beam but diverges a little less over distance. In the 30mm from the aperture to the work which is the most common distance I see the CNC guys recommending for use of these diodes in engraving the G-2 will make a smaller spot.

If this is not for engraving and you are looking at longer distances yes the three element lens will make a more pleasing spot. This thread give a pretty good comparison.
http://laserpointerforums.com/f65/there-something-wrong-my-beam-spot-59400.html

Pman · Mar 10, 2016

Sure seems like that is actually a 405nm and not a 445nm watching the video. Looks like a low powered module which makes the odds of it being a 445nm low unless it is a single mode which I highly doubt. Sure that lens isn't scratched up or has junk on it? What is the laser used for?

keyblade95 · Mar 10, 2016

My purpose is not to engraving. It's the M140 diode is 445nm for sure! And I have temporary underfed the diode (100mA) in this testing phase

Bionic-Badger · Mar 12, 2016

You'll have to just rotate the lens gradually so that the beam gets smaller. You'll eventually get it to a point where the beam is tightest, but with those G2 lenses you'll probably still see a lot of splash outside the main "dot." The dot itself will look somewhat rectangular. It's just how they look.

Alien Laser · Mar 12, 2016

could be the lens is lose or the lens is no good !!

Or the diode is no good !

keyblade95 · Mar 13, 2016

I don't know why my laser or lens aren't good... They aren't damaged or scratched :bowdown:

Lifetime17 · Mar 13, 2016

Hi,
Sure the lens is in backwards , lens closest the end of the barrel goes towards the diode.

Rich

keyblade95 · Mar 13, 2016

Lifetime17 said:
Hi,
Sure the lens is in backwards , lens closest the end of the barrel goes towards the diode.

Rich

Thanks Rich. As already said in the page I linked above, I set correctly the lens now.

Help to focus 445nm M140

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