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Low Power IR Laser

BigDawg

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Hi,

I want to build a low powered IR laser to make a laser sight. I already have a Crimson Trace IR laser sight, but those are $150 and I think I can build one cheaper. I already put together nice LED flashlights for prices far less than Surefire and the like.

Specifically I want to build something in the 0.1 to 0.7mw range (yes, the decimal points are in the right place) with a 12x30mm module. This will replace a green laser module I removed from a laser sight.

I would like a 0.3 to 1.0 mrad beam angle (basically 1-3" dot at 100 yards).

My module looks like this: https://www.amazon.com/532MD-10-Gre...6181&sr=1-1&keywords=green+laser+diode+spring

I have potentially specified these:
Housing: https://www.ebay.com/itm/2pc-12x30m...e=STRK:MEBIDX:IT&_trksid=p2055119.m1438.l2649

Driver: https://www.ebay.com/itm/808nm-1mw-...e=STRK:MEBIDX:IT&_trksid=p2055119.m1438.l2649

Diode: https://www.ebay.com/itm/5-Pieces-8...122432?hash=item2a599d8740:g:XvMAAOSwdvpWEArI

My question is: How do I get a low output laser? That diode is 300mw and is the lowest power I could find. Will I be able to adjust the potentiometer on the driver for that low of an output? Am I barking up the wrong tree or pretty close? Thanks for any help.
 

paul1598419

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Why would you ever want a 0.1 to 0.7 mW IR laser? First off, I don't believe one exists as there is literally no use for one and the threshold of all diodes are far higher than that. I don't think it would be visible at 100 yards either. Your first post here would be put to better use if you did an introduction and told the community a little about yourself. You are unlikely to get much help going about it this way.
 
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Alaskan

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Introducing yourself to the group first in the welcome thread is kind of a go, no-go for a lot of members before you would get their assistance.
 

lasersbee

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Introducing yourself to the group first in the welcome thread is kind of a go, no-go for a lot of members before you would get their assistance.
Yeah... once he's introduced himself in the
Welcome section... I'll be more willing to take
the time to respond...

Jerry
 

BigDawg

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Sorry, I apologize for that. I will start a thread in the welcome forum before resuming this topic.
 

Alaskan

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i found some low power 5 mw laser diodes on ebay fairly easily too.
 

lasersbee

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Says 2 units available...

At any rate, there's other options out there.
Yup... that's what it says now...
At the time of my post the listing
had been ended due to no stock...

BTW...at 100ma of electrical current
I highly doubt it will only output 1mW
of IR.

@ Alaskan... there are many ways to
get the IR output power that he wants.


Jerry
 
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Alaskan

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i don't know where threshold is for a 5 mw diode, i was considering other suggestions too, lots of ways to loose power :)
 

BigDawg

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I believe the 980nm diodes are very close to the edge of the spectral sensitivity range of the camera sensors I'm using. Maybe they would work at high power. That is an idea I can experiment with after I find something in the 8-900nm range.

The power requirement is driven by my use, which is for digital night vision (using cameras for flying drones/quadcopters at night and FPV goggles). These cameras are responsive to visible light, but it's much more fun to use infrared "light" from an IR LED flashlight. I have built 850nm and 940nm flashlights. The 850nm is significantly more efficient in illumination for the camera than the 940nm.

The problem with getting into higher power is that when the laser dot shows up, the light is so bright that illuminates all around the dot as well. This causes the dot to appear very large. NV users call this "bloom". Companies like Las-tac and Steiner have 0.1mW and 0.2mW IR lasers that work great for ranges 100 yards and less. Some folks actually use optical neutral density filters to reduce the power output of the 0.2mW laser.

I have a 0.7mW IR laser and it is too bright until about 200 yards.

I tried searching on here and using the google site search, but I really only found where one other guy was attempting to construct an IR laser sight and he didn't report back with any of his findings. I suspect his lasers were way overpowered and potentially ruined his Gen 3 night vision. I will post up a how to thread with pictures once I find success.
 

Alaskan

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You could probably just use a neutral density filter to bring the output level down using a 5 mw laser diode. Maybe find something like this so you can select the amount of attenuation you need: https://www.ebay.com/itm/8pcs-Gradu...ter-Set-for-Cokin-P-Series-LF291/371813658056 - maybe a small disk can be cut out? You might even be able to make a dial-in variable filter out of it to turn up or down the output by cutting it in the right place, then turn the disk to get a darker area for lower power throughput.
 
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Cyparagon

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ND filter? That's ridiculous. Just use any 20-cent polarization film. Then you have variable output by rotating the film in front of the laser.
 




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