Divergence

How is divergence measured?

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

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.

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

bobobob121 said:

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

Click to expand...

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

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?

bobobob121 said:

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?

Click to expand...

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

pseudonomen137 said:

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

Click to expand...

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.

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

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.

Helioplasma said:

[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?

Click to expand...

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]

... 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.