Late Edit:
I took a closer look at the original lens in the G301 laser and it is a plano-convex, not curved on the back side as I first thought and its diameter is closer to 6.4-6.5mm but anything from 5.6 to 6mm should fit well enough too.
I removed the expander lens and crystal from one of my weak G301 532nm lasers to measure the pure IR coming out of its diode and it was over 200mw. With the lens holder tube back on (the plastic lens in place) the IR power was measured at about 50mw because the raw beam-width of the IR diode is too wide, most of the power is then spread out inside the side walls of the tube and not exiting it. Putting the lens cap back on and even with the reduced output I could focus the IR to a point and burn things with it, but only if a few inches from the object, the focus did not have enough range to make a fine burning spot if over a foot away, judging by the fuzzyness of the dim red dot I could see. Even so, it is collimated enough to be a danger 100 or more feet away, keep that in mind and that even if the output of a IR or any laser diode isn't collimated, it can still blind you, the lens in your eye becomes the collimator. More than one person has been harmed by thinking the raw output of a laser diode isn't a problem, it is, as the lens in your eye will focus the energy just like a regular lens.
Later update: I removed the plastic collimation lens from the end of the tube and threaded in a S1 (close to G2) lens into the opposite end of the same tube nearest the laser diode and was able to focus all of the power, minus losses, into one very small rectangle spot with very crisp edges, so it was focused well, just needs beam shaping to turn it into a dot, if that is what you want. The power output after collimation was measured at 225 mw using this method.
I tried to focus the 532nm this way prior to the removal of the plastic expander lens glued on to the crystal assembly but it wouldn't work, the focal length of the S1 was too short to be used with this lasers expander lens. I then removed the expander lens and tried to collimate the green without it but this didn't work. Apparently, the green output of the crystal is such a tiny dot it is too small of a percentage of the 5.6mm lens I had up against it, because of this there wasn't much lensing action and I couldn't do anything with it as far as focus without some expansion first, that taught me a lot.
532nm module from G301 laser:
Exploded view of module with original parts:
Original lens on the end of the tube, expander lens and crystal all removed, S1 lens threaded into bottom of tube to turn the unit into a 200mw output IR burning laser. There are no other optics in the tube now, except the one I added:
Reassemble without all of the other parts by just adding a S1 or G2 lens (Aixiz lens will work too) and focus the tube by screwing it back down into the module to the right depth. Now you have something more dangerous, be damn careful with it, better yet, don't do this unless you are an experienced laser tech. IR lasers are far more dangerous than visible light lasers because you have no chance of a blink response, this will blind you before you even know you are hit in the eye. Personally, a small burning laser like this is very boring to me and probably should be disassembled to prevent someone from accidentally harming themselves with it. I really only did this because I destroyed my G301 laser by removing parts from it to show you what is inside and to take a power measurement of the IR diode, otherwise I wouldn't do this to a perfectly good laser, weak or not. Something interesting to me is that the plastic lens which was glued to the crystal assembly (the active or curved part of it) is nearly the same diameter as the crystal. This taught me that an expander lens must be close to the diameter of the beam to work well. Taking this apart and experimenting was a great way to start understanding the device, well worth it for me.
This thread drifted away from blue-ray, my apologies, I should have started another thread for this. Still, you could do this same mod with a 401 445nm laser using one of these Aixiz type lenses to replace the plastic lens and it ought to work fine, if it has the same kind of tube to hold the lens, or modified to be able to use it. Only thing is, the cost of one of these lenses might exceed the cost of the laser.
but for the price, still good. Just that they are not stable, after a few minutes many can drop to 20 or less mw if starting out that low. If I had a more massive heatsinking for the modules, I am sure they would not heat up so fast and would then be far more stable.
