Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

LPF Donation via Stripe | LPF Donation - Other Methods

Links below open in new window

ArcticMyst Security by Avery

Seeking highest power output 780-850nm pulse laser diode available

Joined
Jan 29, 2014
Messages
12,031
Points
113
Seeking the highest power output affordable 780-850nm pulse laser diode available and this is all I have found:

SPL LL85 Hybrid Pulsed Laser Diode with Integrated Driver Stage 850nm 14 w OSRAM | eBay

I have been unable to find this diode at what I consider a reasonable price, all I can find are listed at over 50 dollars each on ebay which I can't pull the trigger on yet because that price just seems too high and I want several of them.

Unfortunately, the Osram SPL LL85 is a discontinued device and I cannot yet find any relatively high power 850nm pulse diodes made by any other manufacturer anywhere, just old stock for this specific device on ebay. While the replacement for the SPL LL85 laser diode made by Osram which operate at 905nm are much less expensive and have more power output, I prefer 850nm due to the low atmospheric absorption at that wavelength compared to 905nm which is very high, at least for the distances I am wanting to use it for. My project is not for a laser range finder, but a beacon and need the shorter wavelength of 850nm.

Here is a link to a jpeg graph showing the atmospheric transmittance and absorbance of a band of near-IR wavelengths. The highest power pulse diodes with the shortest wavelength I can find in an area of low absorbance are close to 800nm, thus the reason I am interested in the Osram 850nm pulse laser diode which has the highest peak pulsed power at the shortest wavelength in an area of low absorbance:

transmittance.jpg


I want to use as high a power pulse diode as I can find at the shortest possible wavelength in the near IR spectrum, 850nm appears to be the only choice as I am not finding pulse diodes with output ratings over 10 watts at 780nm. Can anyone here point me at something better than the above ebay listing, or at least at a better price?
 
Last edited:





Joined
Sep 20, 2013
Messages
17,252
Points
113
Banggood.com sells a 850nm LD in a TO-18 case with a cover and window for $19.95. It is rated at 1000 mW CW, but they don't give a manufacturer part number. Don't know if this qualifies for what you are doing, but it might be worth a look. :)
 
Joined
Mar 10, 2013
Messages
2,918
Points
113
depends how much you want to spend. Coherent makes some damn big diode bars, but they're hardly cheap. If you run something in pulses, you can often push it far higher than what you could run it CW. and 1W of most any IR in a laser format is gonna travel a hell of a long way regardless of absorbance. what exactly do you want to do? :undecided:
 
Joined
Jan 29, 2014
Messages
12,031
Points
113
Communicate via pulsed laser beam with minimum atmospheric absorption

Joaquin%20Phoenix%20in%20Aluminum%20Hat.jpg


I found these on ebay: Imported OSRAM SPL LL90 3 SPL LL90 3 Laser Diode 70 w 905nm | eBay - They can't be carrier modulated because they are pulse, but groupings of pulses could certainly be made to pass data. This is just for play, but of course that's what we do here on this forum, talk about our laser toys :p

I would sure like to find someone who has taken a photograph or video one of these high power short pulse lasers at a distance to see how well they can be picked up with a camera, but it appears I'm going to have to be the one to do that and post here later. Although high power, with the extremely brief duration of the pulses, I'm guessing a CCD camera wouldn't pick them up well but hoping bright flashes can be viewed with a camera miles away. I've done a lot of searching the web looking for a photo someone has posted showing that, but the only one I could find is this, but off to the side of the beam output:

84831.jpg


Time of Flight Laser Project - Page 3 - Parallax Forums

I have a few surplus Coherent 808nm diode bars but they aren't pulse diodes, I've tried talking to Banggood about their IR diodes asking if they would ship in anti-static bags or something and they won't answer my questions directly, I saw a post where someone had bought some laser diodes from them but they were shipped in normal baggies, some of them dead, so I don't want to order from them, they weren't high power pulse diodes anyway.

To use 850 or 905nm:

I've been considering buying a few of these high power 14 watt pulsed 850nm diodes on ebay and stacking them, then using a cylindrical PCX lens to produce a combined line output and seeing if that might be visible via camera from many miles away. Although 905nm atmospheric absorption isn't so bad for a couple of miles, I'm wondering if at 10 miles it becomes significant and due to that perhaps I should stay at the lower 850nm wavelength. However, I can only find pulse diodes up to 14 watts at 850nm, where I can get 70 watts at 905nm. Decisions, decisions... Although the pulses are high peak power, the average power is very small, a very few milliwatts.

Wish I had paid more attention to math in school, I'd like to crunch some numbers to see how much using a cylinder lens to produce a line reduces the power delivered at different distances, due to spreading of the line as it travels forward. No online calculators for that! That's going to loose a lot of power if I do that, but there is one aspect of using a cylinder lens which has my attention, if you use a large enough one as a collimator, I believe the line has very low divergence in the opposite plane, due to the beam expanding so much before being collimated into a thin line.
 
Last edited:
Joined
Sep 20, 2013
Messages
17,252
Points
113
Sorry that Ganggood link was of no use. It was the only thing i could find at that time that might work for you. I don't have the answers about the camera and what duration you must use to get a good photo. Might find something else you can use, but I wouldn't hold my breath.
 
Joined
Jan 29, 2014
Messages
12,031
Points
113
A few choices for pulse diodes at All-lie***press: Shop pulse laser diode online Gallery - Buy pulse laser diode for unbeatable low prices on AliExpress.com

There have been reports of problems buying from China sellers on that web site, even worse than ebay, but for these, I have no doubts their ratings are correct, hard to lie about components with part numbers, unless they switch them on you for something which looks the same, not very easy to do for these parts. So far, the SPL LL85 14W 850nm diode appears to be the highest output I can find for that portion of the spectrum which has a clear atmospheric window.
 
Joined
Sep 20, 2013
Messages
17,252
Points
113
With the plastic case, I wonder how you would focus it. It doesn't seem to lend itself well to using it as a focused pulse. But then, I'm not familiar at all with this case style.
 
Joined
Apr 26, 2010
Messages
4,175
Points
83
Whether the lasers will be visible is also determined by your camera.

Most cameras pick up IR, even with the camera setup for visible light. I've had some cameras pick it up at a magenta-ish color, while others see it as blue.

However. Are you trying to send rapid pulses and then have a photo-receptor ping for each pulse? Like sending binary over a long distance with a laser? Wireless fiber...

Or will this be a slower process and the person receiving the signal is expected to decipher the incoming message by hand?

Either way, without true night-vision, you will gain nothing from this. Though, with that said, you don't need this kind of light. IR illuminator lasers aren't nearly as powerful as what you're looking for.

A lousey night-vision camera setting will pick up a couple hundred mW in an IR beam. There was a video on LPF a long time ago with someone recording themselves shining an IR laser around their neighborhood onto roofs and into trees. Was fascinating to watch.

Get yourself a watt or two of 808nm, mount it in a well heatsinked module, collimate it, face it towards your second party, send message.
 
Last edited:
Joined
Jan 29, 2014
Messages
12,031
Points
113
I was wanting to send strings of pulses which could be decoded with a computer on the other end, would be too fast for anyone to count them with a camera. Another reason for wanting 850nm is because most cameras can detect that wavelength, I believe most can do 905nm too, but 850 is fairly certain, although the IR filter should be removed. I was going to build a hybrid of pulse diodes as well as CW 850nm diodes at 1.5 watts, all driven in parallel for a simple continuous or flashing output mode, just the pulse diodes for data mode. That way I figured I'd get the best of both worlds and Junktronix made a great deal with me on some 1.5 watt 850nm C-Mount laser diodes, 12 bucks each for a quantity of them. I found an ebay seller who will sell the 14W 850nm pulse diodes at 13.50 each, thinking of buying 25 of them and running them all in parallel but have not pulled the trigger on the purchase for those yet.

My big question now is if a CCD camera can register 30ns pulses, might be too fast, building something to detect the pulses, save them to a register and then decode them is another big project. But I'd be happy with just the CW function and ability to send pulses first, I might not invest the time or money into going the full route of decoding data as an IR link, but I do want to at least get this thing built as a IR flasher.
 
Last edited:
Joined
Sep 20, 2013
Messages
17,252
Points
113
I spent some time reading this and it looks like alignment is crucial. Also, the avalanche circuit to get the high powered pulse at a very narrow time frame is critical as well. This won't be a cake walk.
 
Joined
Jan 29, 2014
Messages
12,031
Points
113
I will take a look at ARG's sale, thanks. I found a design to drive the diode already, just need to build it. I spent a couple of years building digital TTL circuits, photo etching my own circuit boards, I look at this project as being something like I used to do in college.

Edit: Take a look at this web page, they have most of what I need to know already worked out:

http://forum.arduino.cc/index.php?topic=110549.0

I found a schematic for the laser diode circuit board online too, but on another forum page. With a low enough divergence lens setup I could probably use their detector circuits for a data link too. Just split this thing in half and use it as a link instead of for distance measuring. Although I want to try this with a camera to see if that works for me, if not perhaps their avalanche detector diode but not sure if will be sensitive enough for long distance.
 
Last edited:
Joined
Apr 26, 2010
Messages
4,175
Points
83
Your standard camera will not catch the ns pulses accurately. The shitter speeds of the camera will miss a lot of them at a time.

Much like how laser shows aren't picked up well.
 
Joined
Jan 29, 2014
Messages
12,031
Points
113
Yea, I was afraid of that. I've searched the web for a couple of hours and can't find video or photo's of the IR from these nanosecond pulsed diodes except that one out of focus photo from the side I posted earlier in the thread.

Edit: I'm back, I just found this video of a laser range finder pulsing off of a tree, although the camera is a night vision camera, from this I can see if you pulse a lot of pulses together, even if short pulses, the nigh vision camera will pick them up. I will order one of these diodes and see if it can pick up a string of pulses when aimed right at it from 50 feet away.

https://youtu.be/HtLYuisBKaM

 
Last edited:

diachi

0
Joined
Feb 22, 2008
Messages
9,700
Points
113
I'd opt for a photodiode (large surface area would be best) with a narrow pass filter in front of it, maybe throw in a telescope if you need it too. I agree with the others, I think you'll have a hard time with a camera assuming you want to achieve any relatively fast transmission rate.
 
Last edited:




Top