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05-22-2009, 02:53 PM #33
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ElektroFreak
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Quote:
 Originally Posted by steve001 That's darn close to what I said. With typical beams diameters of hand held lasers a beam diameter of 10mm is close to what you'll have using a 10x expander. And a reduction of divergence about 0.12 mrd. That will put more light into a given area when compared to a 3 or 2x expander. Using commonly available lenses with focal lengths of -6mm and 60 for a 10x expander and -6mm and 18 for a 3x expander one can see that the Rayleigh length (RL) is greater with the 10x expander. 10x expander 0.12 mrd RL 83337.648 mm or 273.41748 feet 10mm exit beam dia 3x expander 0.40mrd RL 7500.348 mm or 24.607441 feet 3mm Exit beam dia. So what this means is this. The RL is the length over which the beam will expand the square root of 2 or 1.4 times it's initial diameter. After that distance the beam expands in a linear fashion. The 10 x expander will out perform a 3x expander once past the rayleigh length of the 3x expander
I see what you're saying here. Thanks for laying it out in mathematical terms..

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05-23-2009, 04:39 AM #34
 Class 2M Laser Join Date: Sep 2007 Posts: 761 Rep Power: 52
f22warzone
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Lol u think 10x is cool.... I have the 30x Beam expander for my Rpl 450 and man it is a 30cm dot for almost ever : ) my rpl had a .8mrad to being with so i ended up with .026 mrad divergence : )

lol how u liking your rpl?

05-23-2009, 01:19 PM #35
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steve001
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Quote:
 Originally Posted by ElektroFreak I see what you're saying here. Thanks for laying it out in mathematical terms..
Here's something more if you include another -6 focal length lens in your beam expander so that your expander resembles this )])] [) you'll have . Rayleigh Length
a 20x expander
beam diameter 2cm or 0.78 inches
Rayleigh Length of 333337.651 or 1093.62 feet
A divergence of 0.06mrd

Placing some space say 0.5cm between the two -6 lenses will
will increase the RL to 361694.876mm or 1186.662979
while only marginally increasing beam diameter from 20cm to 20.833 cm or 0.82 inches
The reason you'd do this is to keep the expander's dimensions as short as possible but perform like a two lens Keplerian system using a longer focal length positive lens.

Last edited by steve001; 03-17-2010 at 09:36 PM.

03-16-2010, 08:28 PM #36
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cmak
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Re: 35 mile laser shoot

a well deserved

holy crap that was an amazing read... although I must admit that it did get a little beyond my understanding at times

I live in a mountainous, minimally light-polluted town near LA that would be pretty great for testing, however I don't know too many laser enthusiasts around there (okay, none.)

I'd be more than happy to test something like this, though!

peace & thanks
-cmak
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03-16-2010, 11:04 PM #37
 Class 1 Laser Join Date: Mar 2010 Location: 5°47'33''S 35°12'09''W Posts: 58 Rep Power: 7
Heleno
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Re: 35 mile laser shoot

Quote:
 Originally Posted by cmak I live in a mountainous, minimally light-polluted town near LA that would be pretty great for testing, however I don't know too many laser enthusiasts around there (okay, none.) -cmak
[OFF TOPIC]
Hey - u know... i live in sunny Natal, the south america's closest spot to africa (check world map) and although i don't live in a city in the mountains i do feel like you sometimes...
but i gotta tell u... hehehe your statement, as quoted above, does really sound like unabomber!
[/OFF TOPIC]

but there is also another point:
so correct -me if i am right:
it means to get sparse photons as reflection from the moon surface (to see a dot in moon surface) i would need a "pen-pointer" around 5GW?
humm....

[OFF TOPIC- Rematch!!]
wow! if Dr. Brown had DPSS diodes, he could be writing his name on the moon with the help of lightining strikes, instead of building cursed useless timemachines
[/OFF TOPIC- Rematch!]

03-17-2010, 01:06 AM #38
 Class 2M Laser Join Date: Jan 2010 Location: my comfy padded cell *one eye wanders* Posts: 727 Rep Power: 17
cmak
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Re: 35 mile laser shoot

peace & thanks
-cmak
__________________
685nm MS-V4 (in progress)
<638nm MS-V4 (in progress)
589nm JL PL-E Pro >100mW (soon)
561nm (someday)
532nm Sky HL "300mW" (in progress)
<515nm Sky HL "30mW" (in progress)
>460nm Sky HL "100mW" (in progress)
>405nm FP 12X, heavy on the trit (soon)
Many JL PL-E Pros next (put me down for the first powerful 589s &473s in that sweet host)
WFTM (someday)

03-17-2010, 01:27 AM #39
 Class 1 Laser Join Date: Mar 2010 Location: 5°47'33''S 35°12'09''W Posts: 58 Rep Power: 7
Heleno
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Re: 35 mile laser shoot

@-cmak

hehehe. it was just a joke. pls don't be upset ok?
the thing is: u said u were living in the mountains, in a small-not-full-of-lights city... using high tecnology, potentialy hazardous equipment: it sounded like the unabomber, i bit like him... so it reminded me - no offenses intended!
btw -gee i'm so offtopic today... -
did you notice that this guy still lives!? wow! i thought that he was dead!

Ok!
/Offtopic! i'm affraid one of the moderators would hear my posts reported! from now on i'll stick it to the topic...

03-17-2010, 01:31 AM #40
 Class 2M Laser Join Date: Jan 2010 Location: my comfy padded cell *one eye wanders* Posts: 727 Rep Power: 17
cmak
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Re: 35 mile laser shoot

okay then tiger

peace & thanks
-cmak
__________________
685nm MS-V4 (in progress)
<638nm MS-V4 (in progress)
589nm JL PL-E Pro >100mW (soon)
561nm (someday)
532nm Sky HL "300mW" (in progress)
<515nm Sky HL "30mW" (in progress)
>460nm Sky HL "100mW" (in progress)
>405nm FP 12X, heavy on the trit (soon)
Many JL PL-E Pros next (put me down for the first powerful 589s &473s in that sweet host)
WFTM (someday)

03-17-2010, 11:27 PM #41
 Class 3R Laser Join Date: Mar 2009 Location: Samadhi Posts: 2,073 Rep Power: 142
Ash
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Re: 35 mile laser shoot

okay....
So, no pics of the 35-mile beam.
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