850nm Laser pointer

[texynz]

Newbie to this, so been trying to learn by lurking in the forums, and using the search, yet no more informed so sorry for the noob newbie question.

Basically what I want find is a 850nm or equivalent non visible laser pointer that I can produce a dot no larger than 10mm at a distance of 10m.

I will be using a camera which will use a pass filter to detect this dot.

I have a tried a few 3-4mW 850nm lasers, with and without lens, but unable to produce anything that i can project like you do with a equivalent "red" laser pointer at the same power.

What am i doing wrong, or is there something obvious I am missing?

Thanks

 

[Alien Laser]

Welcome to LPF

 

[BowtieGuy]

Welcome to LPF, texynz! :yh:

Did you try using the "custon search" bar at the bottom of the page, there is an abundance of laser related info. to be found there.

Try this link to see if that's what you're interested in: Jetlasers IR lasers, 780nm to 1064nm.

PS - Adding your general location to your profile would help us help you in finding what you're looking for.

 

[texynz]

Thank guys. From the reading I have done on the forums, the IR wavelength I need is going to difficult to project for a few reasons:

1) As the wavelength increases the divergence/mRad increases and thus to get a relatively small dot at the other end is difficult without beam expanders etc

2) I actually need more power than an equivalent visible light laser due to the divergence.

What I am trying to achieve I believe is possible, as similar technology is being used in the likes of products like "Lasershot" and military TESS equipment. TESS specifically have engaugement distances of upto 1km, but they have less of a requirement for a directed pin point small dot

 

[paul1598419]

I have found the 1 watt 808nm diodes to remain fairly well collimated and not diverge too badly. I use a three element lens with the one I built. I have a CMOS camera for focusing the spot, but it is still visible as a dark red dot that I can see without the aid of cameras.

 

[texynz]

paul1598419. Its pretty much the setup I am trying to create. I have opt for 850nm as it was easier to source a pass filter for the detection camera I am using. I have written an program that will view the camera scene and identify a bright spot within its FOV. The only light I want passing through is the IR spot/dot projected on the wall. I have also tried with the 780nm with varying success.

Could you share your tripple lense setup? In terms of physical size how big is your setup.

Thanks

 

[WizardG]

https://sites.google.com/site/dtrlpf/home/glass-lenses

No reason your setup should need to be any bigger than a pen style pointer.

 

[Cyparagon]

What am i doing wrong, or is there something obvious I am missing?

All you've given us is "I have a tried a few 3-4mW 850nm lasers, with and without lens". It is not possible to diagnose anything you're doing wrong with such an ambiguous story.

Where did you buy them? At what distance were they tested? What driver, if any? What power source? What lens? Give us something to work with.

 

[Skittles]

https://www.ebay.com/itm/Powerful-Focusable-850nm-IR-Infra-Red-Laser-Pointer-LED-Torch-Flashlight/222615863734?epid=2187564702&hash=item33d4f081b6:g:6-wAAOSwetRZlVBQ

^ It is pretty easy to find 850nm pointers on ebay, they are usually in $40 - $70 range, if below $40 don't trust it, just ask the seller what the real power and divergence are.
And (you probably already know this) make sure the seller has at least 99% positive feedback.

Good luck

 

[texynz]

Thank you everyone. There is defiantly alot of products off the shelf in 850nm that i can purchase, but the issue is that they dont fit the application I want.

I have yet to buy a "pen" type pointer like the one linked above, but have bought a few "modules" like:

https://www.aliexpress.com/store/pr...0nm-Laser-Dot-Module/1629343_32279668833.html

These were bought just to see what they can actually do. There is next to no technical specs about them, and as for the "adjustable focus" although it does focus the beam, the light doesnt even project more than a few cm, and nothing that my camera can pickup anyway.

I will buy a pen type next, but would rather make an educated decision on the product rather than pick the cheapest on the list.

Cheers

 

[texynz]

Oh other reason why I havent gone for pen type, is that I want it to fit inside a tube which is only approx 14mm diameter so those modules work out perfect if they worked. If the pen type worked, i would have to gut it out to fit inside the tube I am using.