Divergence

[JerzyDevil]

How is divergence measured?

 

[Razako]

Read this
http://www.pseudonomen.com/lasers/calculators/mRadCalculator.html

 

[pseudonomen137]

Honestly, I don't know a single member of this forum who has the equipment to measure divergence. You can get a rough estimate of it though. Divergence is a measure of how much wider the laser's spot gets over distance, so if you can estimate the spot diameter (which is the diameter in which ~86% of laser power is enclosed) at close range, and far range (ideally 50m+) you can get an idea of your divergence.

 

[bobobob121]

so according to that calculator...my DX 20mW has a divergence of 0.54mRad?

 

[pseudonomen137]

so according to that calculator...my DX 20mW has a divergence of 0.54mRad?

Check your units. Let us know what you're measuring and how because there's definitely something wrong there.

 

[bobobob121]

im shooting the beam onto a piece of film strip to get rid of most of the static light. I recorded the beam to be 2mm at 1 foot and the beam to be 3mm at 7 feet. i measured it again at a larger distance and got these results... at 1 foot i get 2mm and at 17 i get 10. so the new divergence would be 1.64mRad. what kind of factors would change the divergence of the laser?

 

[styropyro]

im shooting the beam onto a piece of film strip to get rid of most of the static light. I recorded the beam to be 2mm at 1 foot and the beam to be 3mm at 7 feet. i measured it again at a larger distance and got these results... at 1 foot i get 2mm and at 17 i get 10. so the new divergence would be 1.64mRad. what kind of factors would change the divergence of the laser?

You are using too short of a distance is why, use a longer distance and see what the divergence is.

 

[Helioplasma]

[quote author=bobobob121 link=1213050389/0#3 date=1213062655]so according to that calculator...my DX 20mW has a divergence of 0.54mRad?

Check your units. Let us know what you're measuring and how because there's definitely something wrong there.[/quote]

Well I have had a pulsar which had a divergence of 0.084mRad ; unfortunately, it was defective (you know WL)
Also there is something when mesuring the beam spots diameter, when the outer region is at 20% (or something) of the center's brightness, it shouldn't be counted.

 

[Ace82]

What is the typical divergence for a diode dirrect aka 650nm lasers assuming it's focused for the cause? Isn't it like .85mRad?

 

[pseudonomen137]

Naaah, you guys aren't measuring far enough. The farther you measure, the closer the estimate you get. If you're measuring <25 feet, you might as well throw a dart at your calendar and proclaim that number your divergence.

50meters is your ideal MINIMUM distance to get any half-decent estimate.

And no, there is no rough divergence for any type or wavelength of laser. The divergence is dependent on your beam diameter. If you have a huge beam diameter, you can have a lower divergence and vice versa.

[quote author=pseudonomen137 link=1213050389/0#4 date=1213074194][quote author=bobobob121 link=1213050389/0#3 date=1213062655]so according to that calculator...my DX 20mW has a divergence of 0.54mRad?

Check your units. Let us know what you're measuring and how because there's definitely something wrong there.[/quote]


Well I have had a pulsar which had a divergence of 0.084mRad ; unfortunately, it was defective (you know WL)
Also there is something when mesuring the beam spots diameter, when the outer region is at 20% (or something) of the center's brightness, it shouldn't be counted.

[/quote]

 

[Helioplasma]

... I did it at 13,2 meters (about 39.6 feet I think) but my house isn't big enough and there is too many humps in my place to get a accurate mesurement. probably the highest range I could get is around 25 meters.
Now I mesured my (replaced) puslars divergence and is -- 0.94mRad with the same distance from aperture. It may seem more credible for you pseudo...

All right I'll retake the mesurements again when my sister comes.