Some info about this IR diode?

[Mato92]

Hi all! I found this diode on ebay, the title says: "2000mw 808nm laser diode C-mount with fast Axis Lens"...but there is only some c-mount diode on the picture...does anyone know what is the "fast Axis Lens" (I think it is supposed to be Aixiz)??
Also, operating current and voltage are 2.2V and 2.8A...Is there some schematic for a driver?

Here is a link:
2000mw 808nm laser diode C-mount with fast Axis Lens - eBay (item 140367561065 end time Jan-13-10 05:15:51 PST)

 

[diachi]

Hi all! I found this diode on ebay, the title says: "2000mw 808nm laser diode C-mount with fast Axis Lens"...but there is only some c-mount diode on the picture...does anyone know what is the "fast Axis Lens" (I think it is supposed to be Aixiz)??
Also, operating current and voltage are 2.2V and 2.8A...Is there some schematic for a driver?

Here is a link:
2000mw 808nm laser diode C-mount with fast Axis Lens - eBay (item 140367561065 end time Jan-13-10 05:15:51 PST)

A fast axis lens "collimates" the laser diodes output on the fast axis (most divergent axis). It looks like a tiny little bit of glass fiber attached to the front of the die. After the lens both axes should be closer to the same divergence.

 

[Mato92]

Thanks for answer. So this makes a light from the diode into a tight beam, but there will still be a little divergence?
And where can I buy some housing with lens for C-Mounts?
I would also really like some good schematic of a driver...I found nothing

 

[Cyparagon]

The C in fac is for correction, not collimation. It brings the divergence of the fast axis in line with that of the slow axis, but it is not collimated. If only the fast axis was collimated, that would mean you would also need a slow axis collimating lens.

 

[Mato92]

So...what do I have to do to focus this thing properly?

 

[billg519]

These are multimode diodes, I have purchased several of these exact diodes from this vendor. These do not collimate anywhere near as easily as a single emitter, single mode diode like an LPC. You can however collimate to a burning point a few inches in front of the laser. I have a pair of 2W handheld burners that use an aixiz lens to focus to a burning point a few inches from the laser. If you want a beam of some sort, be prepared to experiment with cylinder, aspheric, and plano-convex lenses. As far as I know, there is no aixiz style housing for c-mount diodes. You will need access to machine tools (metal lathe at minimum) and the training to use them. These are not a simple or beginner project. You will have to create a driver that works off 1 x 18650 and can deliver 2.8A to the diode. I used 2 x 1400mA regulator disks from DX. Finally, for a class IV laser such as this, goggles (good ones!) are absolutely mandatory. If you don't have the goggles, don't go any further at this. Powerful IR is dangerous and unforgiving.

 

[diachi]

The C in fac is for correction, not collimation. It brings the divergence of the fast axis in line with that of the slow axis, but it is not collimated. If only the fast axis was collimated, that would mean you would also need a slow axis collimating lens.

Thanks for explaining that more accurately ... I meant correction when I said "collimates" ... couldn't think of the right word .

Cheers!

 

[Mato92]

billg519: Thanks for answer, you helped me ...so, I think I will buy some good Anti-IR goggles first, and I will start building a laser after that...I don't need any complex battery powered driver, I would be also very happy with a lab-style laser, which also means the housing for a diode doesn't have to be very compact. I would not use it outdoors anyway...I don't have access to a lathe, but I have access to a drill press (and I am also trianed to work with it safely), so I think I could just make a hole in aluminum block for a screw to mount the diode, and a big hole in second block for some simple lens, and bolt them together.

Sorry if I spelled something wrong, I had to use a dictionary

 

[billg519]

Yes, your block idea will work. This will give you a test mount to try out diodes and various optics. One thing to remember about a c-mount is that it is a diode whose die is open to the air. You must take precautions to ensure that no contaminants from burning can get on the output facet of the die. Dust is also an enemy. Try to seal up somehow after the diode and lens are affixed to your mount. You don't want anything harming the output facet. I killed one of these diodes a couple of years ago by letting some smoke from a burn waft over my diode on its' test heatsink, the result was a damaged output facet and a reduction of power to 100mW. The diode subsequently died completely. I would have replied sooner but my ISP was down for a couple of days and I had no internet.

 

[Mato92]

Thanks for reply. I have decided to build a driver first. I tried to search, but I did not find anything useful for me...Is there some good schematic? As I said, it doesn't have to be powered by a battery. Also, what does "multimode" mean? What are "modes" of these diodes? And where can I get some good goggles? I found some shops, but I don't know if goggles they sell will protect my eyes properly.

 

[pseudonomen137]

If you're going to be doing a lot of projects like this, a good starter investment would be an adjustable power supply. You can normally find a cheapo 0-30V 0-5A one for just over $100. With that you could hook the diode up to the PSU and test it out at whatever current or voltage limit you want.

For a very basic circuit to run it you could always use some variant of the LM317 circuit we love here. The current demands of the diode are quite high, so you probably couldn't run it at full power from a 317 and you'd need to make sure you use the TO-3 LM317K with plenty of heatsinking. You could just take an LM317 circuit though and use a higher current regulator like the LM1084 (again with good heatsinking at that high a current). I'm sure there are much better ways of doing it too, but I'm not very experienced with electronics.

A simplistic way of looking at multi-mode in this context is that with a single-mode diode the cavity is so small from top to bottom that only the simplest, cleanest mode can be supported. Whereas when you increase power and cavity size, modes corresponding to more complicated ways of supporting an electric field can exist. There are far more rigorous explanations than that on google if you're interested. From a practical context though, this means your beam properties are going to suck compared to what you could get from a single-mode diode. Its common to see collimated multi-mode diodes have >3 mRads divergence and a beam diameter >3mm, and that's if you're lucky! You have a lot more power than you'd typically get with a single-mode, but its also hard to get that power at high intensity at distance because the beam's so damn big.

For goggles, I don't know how much good 808nm goggles go for now so I dunno if this is a decent price, but I have some new, quality Glendale OD3+ 804-1700nm goggles I could sell for $85+shipping. Keep in mind at 808nm this diode is going to appear very dim despite its high power, so you have to be extra-cautious with safety! (well, at least the light from the diode will be dim. If the diode itself appears dim it may already be too late to save your eyes! =P)

PS: Cool avatar picture, where'd you find it from?

 

[Mato92]

Thanks for reply. I am thinking about using my 18V 3A transformer, could it handle the diode? Also, it is not filtered, nor stabilised. If I make a good circuit, can I power the diode with this? Also, I would like to know how to make a high-power dummy diode. And is there LM317 that will not melt if I connect it to 3A (I think there will be a problem with setting of the current - even a small rotation of potenciometer will cause a huge difference in current)? How big capacitor I have to use in the circuit to power up smoothly?

PS: I found my avatar when I was searching something with Google

 

[geohal]

It would be better if you used a transformer closer to the 2.2v voltage that is required plus the drop-down voltage of the lm.I think you should go to lm138 it stands up to 5 amps and its drop-down voltage is about 1.5V .So a transformer of about 5 volts would save you a lot of temperature.The bigger the voltage difference the hotter the lm is going...

 

[Mato92]

geohal: That sounds good, I will try it

 

[billg519]

You can substitute an LM350 for the LM317. The LM350 allows up to 3A. Another choice is the LM338, which can go over 5A if well heatsinked. The problem can be one of getting the correct resistor, which for 2.8A is 0.45 ohm. One way is to use resistance wire, and cut the appropriate length. Many scrap electronics items have low value multi-watt resistors in them, like current sense resistors. I got a bunch of 0.47 ohm 5W resistors this way. The DX disk regulators are cheap, but if you don't have any, it takes a long time to get them.