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How do I make my beam...well, less bad?

TheDudeMakesLasers

TheDudeMakesLasers

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So I just finished my first build (hooray). Successfully with no broken diodes and I'm now the proud owner of a pen style PHR 805 build. Problem is my beam and dot is less than desirable.

I fiddled around a bit with the lens and got it to focus. It even focuses beyond the best point so I know it's at least within the proper range for the lens. Problem is it doesn't seem to really get to a nice tight dot, more like a circle (almost looks like a target dot with a ring around a dot). I took it outside and it has terrible divergence. Won't light a match, won't cut electrical tape, and I don't have balloons. I'd love to know what I can do (or could have done) to make a better, cleaner beam with better divergence.
 





TheDudeMakesLasers

TheDudeMakesLasers

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I'm pretty sure the lens is in the right way because flipped around it won't even focus to a point at all...it makes it a large like a spotlight
 
Jaseth

Jaseth

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It's the 405nm wavelength. Since it is on the verge of being UV, it is hardly visible to most people. Shorter wavelengths also have a higher amount of Rayleigh scattering and make more substances fluoresce, ultimately resulting in a beam which appears to be wide and fuzzy.

Try putting on your goggles, turning your laser on, focusing down to the smallest possible point and placing it somewhere secure where it will not move. Then walk towards the dot and see if it looks small and focussed when you get closer. If it does, there is no problem with your diode or lens.
 
TheDudeMakesLasers

TheDudeMakesLasers

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So that would explain any fuzziness in the dot and whatnot, but what about divergence. How do you improve the divergence on your builds? Would I just buy a "nicer" lens? Does quality of the lens alone improve the quality of the beam? If so could anyone suggest a good lens for a 405 build?
 
billg519

billg519

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A lens upgrade depends on whats in there now. If you have an acrylic lens, you could try a 3 element glass lens, or go for power and get a 405 G-1 lens. You can get these from DTR. 405nm does look funny when you view the spot on a wall. There are quite often fluorescence effects as well as the hard to see beam spot itself. I find that I have to walk across the room to check focus. If you can fog the room, this helps greatly, the beam becomes very visible.
 
S

steve001

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TheDudeMakesLasers said:
but what about divergence. How do you improve the divergence on your builds? Would I just buy a "nicer" lens? Does quality of the lens alone improve the quality of the beam? If so could anyone suggest a good lens for a 405 build?
Click to expand...

Many off the shelf AR coated singlet lenses. If a longer focal length pcx lens will fit that's what you'd want. lots of technical information is available on the site or in their free catolog.
Edmund Optics singlet lenses.
Online Catalog of Precision Optical Components | Edmund Optics



405nm Laser-Line Coated Plano-Convex (PCX) Lenses | Edmund Optics

VIS 0° Coated Plano-Convex (PCX) Lenses | Edmund Optics

How many lenses are you using right now ?
 
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Grix

Grix

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TheDudeMakesLasers said:
So that would explain any fuzziness in the dot and whatnot, but what about divergence. How do you improve the divergence on your builds? Would I just buy a "nicer" lens? Does quality of the lens alone improve the quality of the beam? If so could anyone suggest a good lens for a 405 build?
Click to expand...

Did you try the experiment Jaseth suggested? It may look like your laser has a large divergence while really it does not. 405nm dots don't just look fuzzy, they also look enormous from a distance while in reality they are tiny. Same goes for the beam.
 
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TheDudeMakesLasers

TheDudeMakesLasers

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Grix said:
Did you try the experiment Jaseth suggested? It may look like your laser has a large divergence while really it does not. 405nm dots don't just look fuzzy, they also look enormous from a distance while in reality they are tiny. Same goes for the beam.
Click to expand...

No I haven't tried this yet mainly because I'm retarded and don't have glasses yet. In fact if anyone know of cheap effective ones for 405, or 405, 445, 532 multi would be nice as well, I'd love to know.

I've only used my laser in very small amounts because I don't have glasses yet. If I take it outdoors and shine it at something 50 feet away it looks pretty huge though. In the dark I can also see the beam and I can see the divergence of it. I guess the only way I can improve this with my current lens is to get the glasses and try focusing it as precisely as I can?

btw I'm using just a standard acrylic aixiz lens
 
Grix

Grix

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TheDudeMakesLasers said:
I've only used my laser in very small amounts because I don't have glasses yet. If I take it outdoors and shine it at something 50 feet away it looks pretty huge though. In the dark I can also see the beam and I can see the divergence of it. I guess the only way I can improve this with my current lens is to get the glasses and try focusing it as precisely as I can?

btw I'm using just a standard acrylic aixiz lens
Click to expand...

As said it doesn't really matter how large the beam and dot looks, you simply cannot accurately judge the properties of 405nm.

You don't really need glasses to do the experiment. Just try to focus the laser as best you can, then lay it down pointing to a wall like 20 meters away, then just approach the dot and be amazed at the tricks your eyes play at you.
 
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TheDudeMakesLasers

TheDudeMakesLasers

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Grix said:
As said it doesn't really matter how large the beam and dot looks, you simply cannot accurately judge the properties of 405nm.

You don't really need glasses to do the experiment. Just try to focus the laser as best you can, then lay it down pointing to a wall like 20 meters away, then just approach the dot and be amazed at the tricks your eyes play at you.
Click to expand...

Now that is interesting. As I approach the dot, the "ring" around the dot shrinks. I guess that ring I was seeing is basically an illusion created by the 405 wavelength...love it.

Now my issue is burning power. I was of the understanding that 405 is the best visible wavelength for burning power per mW. I was also under the impression that 100+ mW of 405 is enough to light a match...PHR 805 at 110 ma should be putting that out right? I can't light a match, I can't cut electrical tape, and I popped a balloon with a black sharpie dot on it but it took way way too long. My old 30mW greenie pops balloons instantly with fresh batteries. What did I do wrong here?
 
TheDudeMakesLasers

TheDudeMakesLasers

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Sorry to answer my own question but I figured this out and want to pass this information on to any other newbies out there who might not understand the simplicity of this...Lasers focused to infinity are NOT lasers focused to burn something 1 foot in front of the laser...I fiddle around with the focus and focused it to a point close by (making it essentially a flashlight at 50 feet...2-3 inch dot). Decided to try popping my red balloon first without a black dot on it and bam...instant poppage. My next step is to try a match though I don't have one on hand.
 
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