Laser dot module (cheap ones bad focus) - any experience / advice?

I buy this cheap RED laser diode module to help me test my 405NM without the safety gear. It does not create a dot at short distances, more like a pill shape (which is probably what the diode itself looks like). I focus the brass and it seems to also be emitting red light from all over the place. I'm trying to test within a 6" space, so this light is probably not important for people making cat-laser chasers or other cheap toys. My project is to etch PCB usning the 405nm diode. I have a few designs I am testing, on x & y stages and rotating mirrors.

So I ordered (2) more types. I am waiting for them to deliver, but probably do not expect much different:


I figured I would ask here, see if anyone has experience little red laser modules. If you have used anything else, is there another type of module or focusing housing I can buy that I can afford - WITHOUT talking about fibre optic hubble telescope laser-stations for thousands of dollars.

Do you have some more info DocStein, like where you bought it, and when? I have quite some experience with laser modules, and they are very hard to focus. Maybe it's possible to return it?

Mikeb1970:
Do you have some more info DocStein, like where you bought it, and when? I have quite some experience with laser modules, and they are very hard to focus. Maybe it's possible to return it?

They are basic newbie laser modules, found on eBay and all over everywhere else. I did not buy from authentic expert laser supply place. I believe they are the inside gut modules found in all the pet/toy laser pointers sold all over the place. I did not expect any kind of precision, but when I found the light bleeding out the sides and the pill shape form, it's too difficult for me to focus onto my rotating mirror without the contaminating light also bouncing off the other metal surfaces inside the fixture.

I have bought quite allot of laser from Ebay as well, and most of the times I didn't have a problem. Just be very firm and open a case, demand a refund, because fixing it will be very hard to do. I have complained a few times, and most of the time I just got a refund, they didn't even want their laser back. Should somebody want their laser back, then just sent it back, keep a record for the costs you have made for this, and most people don't know this, but most have an insurance with paypal to get these costs refunded. It beats spending hours to try to get the lasers in focus.

Have you tried using the laser out of an old dvd/cd player?

I not tried parting out out laser from cd rom player. I did not know they were visible. I need to do that anyway, I think that whole little stepper rail could be useful for a focusing jig as well.

Doc,

What is the optical power output of your 405nm (lowercase, not NM) module, and what driver are you planning to use? If you lower the drive current to just above the lasing threshold, you will get a much lower optical power output (safer to observe target, not direct out of the module, and you still need to watch out for blue light syndrome affects, limit observation time and watch for ghosting).

To substitute a 'red dot' for testing/calibration, you will probably need to replace the 405nm setup with a low power red LASER diode(10mW or less, any higher and you should use laser goggles), in a press fit module with a collimating lense, and a suitable current limiting driver (easy to make with a LM317 in current limiting configuration).

lots of help and sources available on Laserpointerforum.com

123Splat:
Doc,

What is the optical power output of your 405nm (lowercase, not NM) module, and what driver are you planning to use? If you lower the drive current to just above the lasing threshold, you will get a much lower optical power output (safer to observe target, not direct out of the module, and you still need to watch out for blue light syndrome affects, limit observation time and watch for ghosting).

That is a good question. When I bought the 405nm laser diode over 6 months ago from the cheapest vendor on eBay, I just wanted to see what it could do. After I saw that it could burn black spay paint off a copper sheet, then I knew exactly what I wanted to do with it. There are no certifications or paperwork, I have just a diode in a square black housing, with a fan on the back and the board the came with it.

The cheap kit looks like this:

There are lots of eBay listings for the same kit, and they claim 20mw, 100mw, 200mw - is anyone's guess. I think they are blue-ray laser diodes ? I read alot of threads people use them until they burn out, and then just replace like a consumable. They are probably over-driven, or maybe the heat sink is too small. Nobody wants to make a huge liquid cooled thing with nitrogen, for a $10.00 diode to swap out.

123Splat:
To substitute a 'red dot' for testing/calibration, you will probably need to replace the 405nm setup with a low power red LASER diode(10mW or less, any higher and you should use laser goggles), in a press fit module with a collimating lense, and a suitable current limiting driver (easy to make with a LM317 in current limiting configuration).

lots of help and sources available on Laserpointerforum.com

Ok thanks for the help. I will check out the laserPointerForum, and try to find some of those colum lenses.

For the red diode driver, I just have a 100-ohm 1/4watt resistor, through a 2n2222 transistor. I will need to do my homework for the 405nm diode, since obviously speed is an issue, and charging capacitors with any delay to activating that beam could set off the timing to the spinning mirrors.

Semiconductor diode lasers require a lens to produce a tight collimated beam since the optical cavity is very short and flat.

Well, I figured out I have to either coat the insides of these cheap things with paint, or spend hours on a lathe making my own housings, that do not have shiney reflective insides.

I spent too many hours getting confused by the 100 different types and sizes of housings I could choose from to buy. I do need to sort this out for the 405nm diode. It looks like I need to be able to replace the diode itself when it burns out.