445 focusing

[Robkaos]

Tips to focusing to infinity

 

[ARG]

Point laser at a wall a few feet away from you. Focus until dot is the smallest it will get.

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[Robkaos]

Focused and burnin but wondering is it better to focus on a farther distance rather than closer
r

 

[jimdt7]

Are you using a lens ?

Jim

 

[Robkaos]

Coated glass Aixiz replacement

 

[GAtkins]

Depends on where you want it to burn better.

Glenn

 

[Robkaos]

I would like about 10to 12 feet optimal

 

[GAtkins]

The laser will be most focused where the beam is skinniest when viewed from the side. Likewise, make the dot as small as you can at the distance you are at. In this case, focus the dot at 10 feet and adjust the focus to make the dot as small as you can.

Don't forget appropriate safety goggles. Enjoy!

Depending on the power and optics, 445nm's may not burn at 10 feet.

Glenn

 

[sesam]

I have a problem seeing the dot when using higher powered diodes, so I
found a small plastic sheet that lets the beam pass through, and it only reflects a tiny bit.
So I place this in the beams way and I can se exactly how big the beam is.

Then I adjust the focus so the beam becomes as narrow as possible.

You can also make small markers on the laser for different distances
so you can shift focuspoint easyer :shhh:

 

[Robkaos]

Th&t helpsthanks!!

 

[Inequality]

I have a problem seeing the dot when using higher powered diodes

I think a good pair of safety glasses takes care of that?

 

[sesam]

:yh: of course I use googles when looking at the beam-spot,
I guess I would be blind othervise cause 1.3W 445 is serious power.
The problem is that I see a large orange thing through my glasses, so it
looks like the beamspot is around 1Cm.
When using what I describe above I can see the real diameter of the beam.

I use this googles
ARG - Blu Ray, Argon, Blue, KTP from oemlasersystems.com

 

[BShanahan14rulz]

the "speckle" will get larger as the "dot" gets closer to its smallest point.

 

[Bigpapashooga]

I focus mine at 3ft but the diameter on the dot grows dramatically within a few inches. I would like to have a continuous small dot at long distances but cant seem to find the correct lens kit. Anyone on this thread know of any?

 

[DrSid]

It's impossible .. there will always be divergence. You can decrease it by increasing aperture size .. ie using bigger lens. But nothing can be made specifically for 445nm laser, AFAIK. I used photographic lens with some success - feed it with raw diode output, they go well with 445nm diode beam cone. But they have lots of elements, and are not coated specifically for 445nm .. so the losses are huge. Of course you can damage such lens, so don't try it with anything you plan to use on camera ..
Your best bet would be large glass single element plani-convex lens with focal distance about the same as it's diameter .. but I don't have any. You would use it with flat side toward the diode, to lower spherical aberration. 445nm coating would help even with single element, as every uncoated glass surface takes about 4% (depends on angle though).

 

[Bigpapashooga]

Ah alright, I just thought that it was strange that it grows so much within a few ft. Thanks ill have to expirement with what I can find.