Building an IR laser - need advice

[spajta111]

I intend to build an infrared laser for special purposes.
i need it for night-vision binoculars, i need it to be just a dot up to 100 meters.
i already have a housing from regular red 650nm 20mW SunFire inre-202b laser.
I already took out the diode and the driver from the housing. and trued to put in an infrared laser diode from an cd drive, and it fits, BUT i cant focus the beam to be a dot.
On very close ( like 2 cm from the wall it is a dot ) but when i move it away the dot expands more and more. i didn't have much time experimenting with it because i used it without a driver and it burned out ( i used it with 2 AA battery's 3 V total directly ).

Now i need an advice how to build a small driver for it, and how to focus the beam to a dot. I was using the original lens from the laser housing, but i also have a lens that was in the cd drive ( it fits also ).

i will buy another cd drive and take out the infrared diode, and now i want to use it with a driver.
I know about the danger from infrared so a never looked at it with my eyes i looked it with my night-vision not directly but the reflection on the wall.

so please explain to me how the laser diode is to be focused and what type of cd drive should i buy?

 

[spajta111]

ok i have now a new ir diode i need the driver for it that will protect the diode, can this one work:

or this one:
https://www.youtube.com/watch?v=dsWbqP6z-X4&list=PL9873C518FFDA2832&index=3

please help

 

[Hemlock_Mike]

You have there the basic driver which we first used years ago
in the hobby. You will need to know the current required by the
LD and adjust the resistor to provide that current. I used a
50 Ohm pot from Radio Shack with low Ohm resistors to make
it adjustable. That will get you started.
HMike

 

[The Lightning Stalker]

It sounds like maybe the diode is not fully seated in the module or maybe the old diode was
longer and closer to the lens. You have to find a way to get the diode and lens closer
together. To get a good dot at 100m it should be a 3 element glass lens. For the driver, I
would recommend a 48-52X writer, but 2pcs TO18 5 6mm 100mW 780nm 785nm Infrared IR Laser Diode No PD Sony LD | eBay
may be cheaper unless you can get one for free. Set the current to 100-130mA.