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Please school me on long range lasers.

rdyno

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Hi all I am new here and have been looking for info on long range lasers.

I have been unsuccessful so far, I want to know how to make a beam go for say 30km and have a small point. I have learned that this is quite a feat but what collimators would I need and what power?
 

sinner

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You will need something like this infront of a very powerful laser.. what's the budget ?

 

rdyno

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I would not want to spend to much, but I have looked at some gear and I would expect the setup I want will be in the $2000-3000 range but I would only want to spend $1000.
 

corey5188

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500mw green lasers can be had for $400-$600 and are remarkable quality (from the right source of course).
 

Things

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Yeah, you're going to need a beam expander to have any chance at 30km, along with quite a high powered laser so it isn't completely scattered by particles in the air by the time it gets there.

What is this for?
 

rdyno

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Astronomy yea I know I don't need the range as such but want to see what I can do. I have emailed the supplier of the 0.01 mrad extender for a price.

I also want to sight ground objects for alignment again I don't really need the range as such, but don't we all want more than we need?

My original goal was to put a beam on the moon for fun but I have realised that this feat would cost upwards of 100k easily probably up to millions.

For a one million km range I have done rough math on it I would need something like 0.00001 mrad starting with a 5-10mm beam of 0.1 mrad. Power would only need to be able to break through the atmosphere after that atmospheric interference would cease to hamper the beam of light. So if I used a lab laser of 50w with a beam of 5-10mm and a 0.1 mrad I could collimate the beam I theorised using a telescope to get the mrad to the specs I need, but 30km is sufficient for now.
 
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Teslanium

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I have been unsuccessful so far, I want to know how to make a beam go for say 30km and have a small point. I have learned that this is quite a feat but what collimators would I need and what power?
Most lasers are set up so that the beam 'waist' (point of minimum divergence) occurs at or near the output window. The larger the beam diameter at the waist, the smaller the dot will be at a given distance for a given divergence value.

To get the smallest spot at the greatest distance you may have to expand the beam to a relatively large diameter and focus it so that a new minimum-diameter 'waist' occurs at the target distance.

T.
 

steve001

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Astronomy yea I know I don't need the range as such but want to see what I can do. I have emailed the supplier of the 0.01 mrad extender for a price.

I also want to sight ground objects for alignment again I don't really need the range as such, but don't we all want more than we need?

My original goal was to put a beam on the moon for fun but I have realised that this feat would cost upwards of 100k easily probably up to millions.

For a one million km range I have done rough math on it I would need something like 0.00001 mrad starting with a 5-10mm beam of 0.1 mrad. Power would only need to be able to break through the atmosphere after that atmospheric interference would cease to hamper the beam of light. So if I used a lab laser of 50w with a beam of 5-10mm and a 0.1 mrad I could collimate the beam I theorised using a telescope to get the mrad to the specs I need, but 30km is sufficient for now.
You seem like you know what you are doing. Play around with this app.
gausian beam rev 2.0.xls
 

Teslanium

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^ Apparently...YES. :D

rdyno, about what size spot are you looking to achieve at (X) km?

Very likely the smaller the spot desired at distance, the larger the diameter of collimated beam required, and with correspondingly larger optics.

T.
 
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drspastic

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i bounced microwaves off the moon with a oven magnetron and a dish. ham radio is fun! the dish is a bit like a beam spreader, microwaves are a lot more forgiving than light. plus you get 800 watts to play with. try something like the catadioptric mirror lens, you can ebay a russian one for 50 bucks. spread the beam first to fully cover the input mirror so you dont highlight the mirrors inaccuracies. i have one in my camera junk cupboard i might try tomorrow. but yeah get a few hundred watts first, and warn the aviation authorities, maybe shoot mtv down by accident.
 

drspastic

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what will you be viewing your 'dot' through? thats gona be a huge telescope
 




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