Violet diverges more than red? Then why . .

[Greenhorn]

I've been working on some red and violet lasers for the last two days. I've heard that the violet lasers diverge more than the red ones. But in my experience, the violet ones have divergence specs just as good as the red. When I focus my PHR-803t just right, it hardly looks any bigger at 20 meters than it does at a few inches. It's a different shape, and there's a lot of noise around the spot (the noise could probably just be a dirty lens), but the spot is only a few millimeters larger.

My Wicked Lasers executive, however, spreads out to 3.5cm at 20 meters.

Anyway, why do people say that the violet lasers have poor divergence specs?

 

[daguin]

Re: Violet diverges more than red?  Then why . .

I've been working on some red and violet lasers for the last two days.  I've heard that the violet lasers diverge more than the red ones.  But in my experience, the violet ones have divergence specs just as good as the red.  When I focus my PHR-803t just right, it hardly looks any bigger at 20 meters than it does at a few inches.  It's a different shape, and there's a lot of noise around the spot (the noise could probably just be a dirty lens), but the spot is only a few millimeters larger.
My Wicked Lasers executive, however, spreads out to 3.5cm at 20 meters.  
Anyway, why do people say that the violet lasers have poor divergence specs?

I've never heard that, at least not about the violet laser's beam after optics.

Peace,
dave

 

[ixfd64]

Re: Violet diverges more than red?  Then why . .

Violet lasers are actually supposed to have better divergence than red ones. The divergence of a laser is proportional to its wavelength and inversely proportional to its beam size.

 

[Xplorer877]

Re: Violet diverges more than red?  Then why . .

Right so 405nm should have very good divergence when properly focused. My 220mW 650nm custom build laser has more noise than my 405nm build.

 

[Switch]

Re: Violet diverges more than red?  Then why . .

What everyone else said.Violet lasers have excelent divergence.The huge starting diameter also helps a lot.My phr build has the best divergence I have ever seen.

 

[styropyro]

Re: Violet diverges more than red?  Then why

Violet has .61 the divergence of red when focused properly, so this means you should have better divergence on your 803T build then the red one.

 

[FokoF]

Re: Violet diverges more than red?  Then why

I seem to have the same problem.... at 5m the spot is great after that the spot gets really big... Is there no better way to focus a 803t.... more like a real module? more correction optics???

 

[pseudolobster]

Re: Violet diverges more than red?  Then why

I seem to have the same problem.... at 5m the spot is great after that the spot gets really big... Is there no better way to focus a 803t.... more like a real module? more correction optics???

How is it not "real"? I consider my violet modules to be just as real as any others. They focus well too. Try putting a mirror on something far away, reflect it back and then focus it... It'll give you twice the distance and will allow you to see the dot close up... Violet lasers have just as good of divergence as any red diode laser, in fact because of their lower wavelength can be focused much better. They're just hard to see with human eyes.

 

[flogged]

Re: Violet diverges more than red?  Then why . .

In theory 405nm should diverge less then red (650nm). The shorter the wavelength the better the divergence and the tighter the focused spot size (hence a BR disc has more bits on it and a greater capacity).

However, certain 'real world' factors may lead to 405nm have poor divergence - the diode specs, and the optics.

Ideally you wanted optics and coatings tuned for 405nm.

I can say, based on my homemade builds, that I get comparable divergence between my red and violet lasers. This is using Meredith optics. Tightest divergence is my 405nm pointer based on an 811 diode running at 45mA - I get very good divergence on this one, even though the beam appears fat at night. Prolly something to do with the diode specs.