First Laser Build Questions

[MHerzfeld]

Spectacular, thanks for the information. I used the DMM because the resolution of the current meter on the PS is on 10mA, I wanted a little more control than that. Hopefully I won't need to use it anymore as I should have a prototype of my driver circuit assembled today as well. (Which is a good thing because while my supervisor thought the laser was super cool, he didn't seem all that thrilled with me testing it at work even though it was Sat morning when no one was here ). 100 hours isn't too terrible and I though I could modify my driver circuit to include a PWM driver that seems a little more complicated than necessary. What is the difference in life on the CW for the 445 builds? As that was the end goal of this experiment I don't want to end up replacing the diodes every 10 hours of operation if I can help it... Also, I've been hearing good things about the USB LaserBee meter, do you have any experience with it? Is it worth the cash? Thank you again for all your help.

 

[Morgan]

10mA isn't too bad a resolution as long as you maintain restraint and don't push too hard. To preserve the LPC-826 diodes you have I would still keep to the 400s until you have a little more experience, (and there is more definitive testing done), and I don't mean to sound condescending. Even at that level and a way below you need to have bought some goggles. Do you have some? Plenty of info on LPF if you haven't.

Along with your prototype driver you will be best to set it up with a dummy test load, (search on this. There is some about these in the link in my sig but there is lots more info available).

PWM is one way to gain some control of brightness but as to length of life, it's difficult to say except the obvious - set a maximum, and anything below CW will prolong the life! Pulsed operation, (look up TTL in relation to laser diode drivers), is a way some display lasers control the mixing of colours but for the purist and professional display guys, this is considered primitive. For a 445 handheld? I really wouldn't worry about too much care as these seem to be the most robust diodes we have! Seriously, anything below 1.6A in and it'll last just fine. The caveat to that is that they haven't been around long enough to get any proper lifetime data but no matter how long it lasts, you'll be happy. 10 hours is probably selling them well short.

LaserBee power meters? They're just rubbish! (Just kidding Jerry, you know I love my LB1!!! ) I have a LaserBee 1 and when cashola permits will happily purchase an upgrade. They are a great little meter. For the price and support you get it's a steal. A much loved piece of kit that's highly thought of here. I would certainly recommend one. Seeing numbers representing an actual output is invaluable in determining health, trouble shooting, data collection, lens comparisons... The list goes on. Go to Jerry, tell him I sent you. You won't be disappointed.

Have more safe fun and remember to post some pics of your builds, set up, or queries. We love to see how others do it!

M

 

[Kmor2004]

This is a little late but I missed it, also Eudaimonium I like your idea of using light but frequent hammer strikes, my thing is I'm afraid the vibrations MAY damage the very fine wires, so my suggestion in place of a vice is (if your using an aixiz module) place the diode in the up housing of the aixiz module, then using the flat side of the bottom housing place it on the diode to apply force to fit it in, now just pressing with your hands is gonna hurt, so IF you have a C or D sized mag-lite use the battery cap with the spring removed and place it on top of the housing then just lay your weight into it it may take a few applications but you won't have to worry about vibrations.

 

[Eudaimonium]

The diodes are very tough and vibrations will not damage the fine wire connections inside.

Imagine that diode riding on the sled inside a DVD burner, changing directions several times a second searching for data.

Pressfitting with your bare hands.. hmm. Well, if it's a diode into an Aixiz housing (which is electroplated nickel over brass part) you need several hundred kilograms of force. The best you might be able to do is fit it halfway to get it secured in place somewhat.

If you really don't have any other way except bare hands, then I'd suggest using a very sharp knife and do some circular cuts along the 5.6mm hole for the diode inside the Aixiz module. It will scrape out some of electroplated nickel and possibly ease the job a bit.

However, maybe the best is to see if a friend or a neighbour has a vice in their garage and ask to use it. It's the best pressfitting method, because your diode will be alligned to the center as much as it can be (better than hammer or hands), and it'll go in evenly and at once (minimum diode damage).

 

[MHerzfeld]

I used a vice to press the diodes into place, never had a issue with that. Im having some problems with the focus however, I'd read that you need to focus the laser "at infinity" to get a decently collimated beam. I've tried to do that, however I cant get anything to burn unless I focus directly on the position where the item is. Focusing beyond the object doesnt seem to work, is this normal or am I doing something wrong. I'm using the lens that came with the aixiz case.

 

[Eudaimonium]

Focusing the laser beam to infinity, in our case, means the beam is ideally 5 mm wide all the way into infinity, that is - retains it's aperture exit diameter.

To burn something with it, you need to focus it to a small pinpoint. When laser is focused to infinity however, there is no pinpoint because the beam is wide all path long.

So yes, what you are getting is normal.

 

[gif]

....and what happened next???

this thread was full of great info, i was looking forward for MHerzfeld to start his actual main build and the end result from all this.