Proper method for focusing high power lasers?

[thestug]

What is the proper method for focusing a high power laser?

I recently finished up my first 445nm 1W build. However, I'm not entirely sure how to focus it for the least divergence. I assume the best way to go about it is to simply adjust it a little, turn it on, check divergence, turn it off, adjust, check, etc... This is probably a total noob question. I just don't want to be sticking my hand near the aperture while the laser is on and causing damage to my eyes with diffuse reflection.

Also, how do I know when I've got it as good as I can possibly adjust it?

 

[Alaskan]

For myself, I just wait until dark and point strait up into the sky (if no airplanes present) and adjust the focus until I see the beam as thin as possible for as far as you can see it go.

You could also point the laser at a wall far away and adjust the focus until the spot is a small as possible.

 

[thestug]

Right, it would make sense that you could simply point the laser skyward and adjust it until the laser is narrowest at it's furthest visible point. However, I have to assume that adjustments are made with glasses on and that the glasses will need to be removed to see the beam in order to check proper focusing? In other words is it safe to adjust the small adjuster and risk getting your fingers in the beam without glasses?

 

[alessnilsen]

Hello! :yh:

I recently finished up my first 445nm 1W build. However, I'm not entirely sure how to focus it for the least divergence. I assume the best way to go about it is to simply adjust it a little, turn it on, check divergence, turn it off, adjust, check, etc...

I finished my too, and I used the same method that you said, and I got a good result (this took some hours). I put my laser into a window pointing to a wall, as far as possible.

Right, it would make sense that you could simply point the laser skyward and adjust it until the laser is narrowest at it's furthest visible point. However, I have to assume that adjustments are made with glasses on and that the glasses will need to be removed to see the beam in order to check proper focusing? In other words is it safe to adjust the small adjuster and risk getting your fingers in the beam without glasses?

I think this will not be accurate, unless if you could look to the spot using binoculars (only when pointing to far objects), because the distance and your eyes can trick your mind.

Always turn off your laser while adjusting the lens, a 1W laser can burn your finger quickly! When done, turn it on again!

 

[ChaosLord]

Right, it would make sense that you could simply point the laser skyward and adjust it until the laser is narrowest at it's furthest visible point. However, I have to assume that adjustments are made with glasses on and that the glasses will need to be removed to see the beam in order to check proper focusing? In other words is it safe to adjust the small adjuster and risk getting your fingers in the beam without glasses?

You don't necessarily have to take off the goggles, just use the dot as a guide. It it is far enough away, just adjust until the spot is as small as possible. The beam diameter is harder to judge than spot size.

As for focusing the laser while on, get a focus adapter and replace the focus ring. This lets you focus without worrying about burning your finger.

 

[thestug]

Thanks, guys.

Where do I find a focus adapter that will fit a C6 host?

 

[Alaskan]

Not sure how you are going to build the laser using a flashlight host, it depends on whether you are using an Aixiz module or some other method of building the laser. If using one of those, here's a video which might be helpful. This laser isn't using one of those modules, instead a cheap or maybe not so cheap 532nm module but the assembly is the same.

Where to buy the aluminum heat sink: http://www.survivallaser.com/Unanodized_Aluminum_Heat_Sink/p556088_2478981.aspx

When using a Aixiz module like that, the lens is built into it (if purchased with it, or added) and you just twist on the lens ring, left or right to focus.

Here's a kit: http://www.diy-lasers.com/product.php?id_product=168

 

[steve001]

What is the proper method for focusing a high power laser?

I recently finished up my first 445nm 1W build. However, I'm not entirely sure how to focus it for the least divergence. I assume the best way to go about it is to simply adjust it a little, turn it on, check divergence, turn it off, adjust, check, etc... This is probably a total noob question. I just don't want to be sticking my hand near the aperture while the laser is on and causing damage to my eyes with diffuse reflection.

Also, how do I know when I've got it as good as I can possibly adjust it?

Find a distant surface at least 100 feet away. That will almost certainly ensure your beam will be beyond the Rayleigh Length. Make adjustments until the spot size is smallest.

 

[Pi R Squared]

I always focus my lasers with the power on, however having burned myself once I won't come in direct contact with the beam of a class 4 laser, so I don't like those tiny standard focus rings, I always use an extended focus ring, so far I have been using the ones sold by Survival Laser but there are others you can get too. Also depending on power and distance you may or may not need glasses when focusing, you can tell if the dot is too bright to look at.

Alan