Divergence measurements - question

Hahahahahaha! No offense meant deadal. I'd like a copy of yours as well. I'm fairly new to this laser stuff. Been messing with it for ooooh 5 months or so. I started off with a 15mw laser I purchased years ago and fried it not long ago. Soo, off I go in search of another laser and ran into CPF. Hence my new hobby was born. I met a lot of very knowledgable peps and have started my new adventure and I learn DAILY.

;D None takes from you Kenom... I was referring to Pseudo...

pseudonomen137 said:

Eh, sorry to be a jerk but that's not really what I meant.

Click to expand...

a little of his knowledge wouldn't go amiss....anyway sort of on topic of divergence, i took my 50 mW ebaser to a fayre the other night and i saw a huge shaft of green light light up the sky.... someone else had a green laser!! so i fired my one that i had on me into the sky and after having fun with the light show we were putting on for many people i went to find the guy.... when i got there i found out that he had a wicked laser. it was a 125 i think??? not sure bout around that output. anyway we fired them side by side and i barely noticed a difference in brightness and also the divergence of his laser was 4 or five times mine... is it normal for higher powered lasers to have higher divergence ?
anyway another point for my ebaser thats still going strong!

That's just really cool! Lose to hear that your 50mW is as bright as 125mW ;D

But to answer your question... Higher power lasers do not have more divergence. It is simply a matter of the alignment of the optics and the proper adjustment to the collimating lens. Labby style laser usually have much more power than pointers, and even better divergence.

--DDL

Here is a link to the Google Earth screenshot of the Toronto location.

Still don't seem to be able to post links.. (paste into browser URL window)

http://img529.imageshack.us/img529/7474/tozu3.jpg



Paul

***EDIT  fixed link***

Holy CRAP man ! THAT is a HUGE distance ! I would have to say that is most likely far enough !

Sweet lord! If I had something like that anywhere near me it'd be painted with lasers 24/7

--DDL

OK, I did this one again!

My target distance was 102m. The dot size was 73mm. -> .72mrad -> keeper

My swag on dot size on the tower from the post above was close.

now just don't mess with it - one drop or "I'll just open it up" may ruin it .
Leave well enough alone on this one...

Sorry to bump an old thread but there is some good advise in here ;D

Okay I would like to measure the divergence of my Nova Alpha 105 but I am having a hard time. Reading this thread I am not sure what I should measure and how.

As an example I think my beam size at the aperture is 0.98mm. Now don't laugh but I measured this with a digital micrometer and a set of clamps to hold everything steady. The beam can pass through the gap in the calipers without touching the sides. If I go below 0.98 I get a reflection off the side of the calipers where it starts to hit.

Now if I measure the dot size by shining the laser at a piece of black card from a few inches. 1) the paper starts to smoke : and 2) the light is so bright I am measuring around 2.5mm

I have not found a good place that I can get a known distance to test the large dot but when I do, do I measure the beam somehow or the dot on the surface?

If anyone can share some tips on how best to measure that would be great. Once I have the data I can use pseudonomen137's calculator to do the rest.
http://www.pseudonomen.com/lasers/calculators/mRadCalculator.html

Many thanks in advance

XG

You should be measuring in terms of feet...not inches. I tried to measure mine yesterday from 18 feet, but all I have to measure it with is a yellow measuring tape. Therefore the dot is much bigger then when I hold something black behind it. But you have calipers. So I would try from a good distance away like I did, and hold something black behind the beam that will absorb the light. It still might be a larger mrad than what the factory measured it at because it is hard to absorb the part of the beam that spreads out...much more so than a red dot.

In general, the farther you are away to measure the dot size, the more accurate you will be. This is due to the margin of error in your measurements playing a much smaller role in the calculation.

If your measurement margin of error is +/- 0.5mm and the measured dot size is 2mm, the potential is there for a 25% error for that figure alone.

If your measurement margin of error is the same but you measure a 70mm dot at 100m, the potential for error for that measurement drops to 0.7%. The same concept applies for the aperture beam diameter when the mrad calculation is done.

I did my measurement with a helper because I did not want to turn the laser on, sprint 100m, measure and then sprint back to turn the laser off to keep a reasonable duty cycle. HTH,

Paul

Made it back to Toronto this weekend and took a couple of beam pics.

One is of the laser on the stack and the other is on another stack that can been seen under rge "Dr" of "Coronation Dr" in the pic above.  Not too bad from a DX30 (running on a single 10440 Li-ion).  Click on the pic for a larger image.

The stack in the first pic is about 2500m away and the one in the second pic is about 1700m away. The stacks are about 5m diameter.