Converting a 532nm 50mw laser pointer to a 200mw 808nm Infrared laser

Curious to know how much IR power this laser was producing to pump the KTP crystal, I removed the expander lens and crystal from one of my weaker (50mw) ebay eight dollar 532nm type lasers http://www.ebay.com/itm/5Mile-Range...Visible-Beam-Mark-Direct-150-US-/141147727954 and measured close to 300mw of 808nm IR without the lens.




To collimate the IR into a burning laser beam, due to the need to have the lens much closer to the diode now, I had to remove the original plastic lens from the end of the tube and replaced it by threading in a S1 lens (any lens of this type will work if designed for a red laser, or even an uncoated G2 type of lens) into the opposite end of the same tube nearest the laser diode and was able to focus all of the power, minus the loss from the lens, into one very small rectangle spot with very crisp edges, so it was focused well. The power output after collimation was measured at 225 mw using this method. Also, I was able to focus the beam to what appeared to be at infinity this way but at the normally poor divergence of an IR laser, probably greater than 4 mRad for this one..

532nm module from laser:



Below; a photo of the original parts. The lens was on the end of the black tube, the beam expander and crystal assembly were deep inside the metal part of the laser module and had to be forced off with a small screw driver, they are glued together inside. The IR laser diode is not shown in these photos as it is deep inside the metal part of the module:



With the original ~6.5mm diameter lens on the end of the tube removed along with the expander lens and crystal from inside the module taken out and the S1 lens threaded into bottom of tube I have been able to convert the 532nm 50mw laser into a 200+ mw output IR burning laser. There are no other optics in the tube now, except the brass one I added, as shown below:



Diagram of a 532nm DPSS laser:



Driver board:

I purchased two 200mw green laser modules on eBay. One of the modules arrived with a defective diode, the other works great and it's very bright. High Quality 200mW 532nm Green Laser Diode Module Green Beam Lab Stage Lighting | eBay The defective diode can be easily removed from the module and I would like to replace it with a new one. Could you tell me if a 808nm 300mw diode will work in fixing the module?

RobR1976 said:

I purchased two 200mw green laser modules on eBay. One of the modules arrived with a defective diode, the other works great and it's very bright. High Quality 200mW 532nm Green Laser Diode Module Green Beam Lab Stage Lighting | eBay The defective diode can be easily removed from the module and I would like to replace it with a new one. Could you tell me if a 808nm 300mw diode will work in fixing the module?

Click to expand...

If you want to get 200mW output, 300mW pump input isn't enough. Maximum efficiency of DPSS in this case is 30% - that is best case, could very well be (and probably is!) lower.

Did you meter the output? A lot of these eBay modules are advertised as 200mW but never actually make 200mW of 532nm.

They are at best 20% efficient, some are as low as 10%, if you got a really good crystal pair maybe 30% but usually 15-20%.

So a 50mw 532 can have a 200mw to 500mw 808nm pump diode. Rip out the crystal mount and the double concave and screw back in the final focus lens and you have an 808nm laser, BE CAREFUL with 808nm!
p.s. 808 shows up better on web cams and security cams and cell phone cams, photography cameras have a built in ir filter.

Here's some for sale with a chart. LOOK AT THE CHART it varies with pump power, it's not linear. See how the crystals are 2 parts, the yvo4 turns 808 into 1064 and the ktp doubles 1064 into 532

Optical Crystal with Copper Holder for 808nm Laser Diode 200mW 500mW LD Pumped | eBay

Thanks for the great info! I don't have a LPM to test it with, I've been using another 532nm pointer that I purchased from a forum member 2 years ago to compare with the working module. I believe it was from Blord and it came with LPM chart showing it was metered at 124Mw. The ebay module is on the left in the pictures.

Here is another angle, ebay module is on the left.

^^what they said. In my experience with the 808nm to 532nm I have found the ratio usually ranges from 4 to 1 up to 7 to 1
I have two metered 1100mW 532nm lasers that are about 4 years old and it is pretty amazing to think that there is an 808nm diode in their cranking out 4.5W to 7.7W

Both bump up to around 1125mW and then settle around 1065mW to 1080mW

got my fair share of experience of invisible laser before but (i ended up on the other side of the Spectrum). got hit in the eye with a UV laser before and apparently i gains perfect vision from that....

I found this 800mw diode on ebay 800mW 808nm 5 6mm High Power IR Laser Diode See Video US Seller | eBay would it make a good replacement choice?

Some use c-mounts but they usually have a FAC lens, the 5.6 808 diodes sometimes use a little lens depending on their emitter size and divergence, not just any diode will work right because they make the crystals as small as possible to save money.
A lot of 50mw and 100mw 532's I have salvaged use open can pump diodes, but they use a little collimation lens before the crystal.
So basically not any diode will work, but I have also seen crystals be forgiving but alignment is often very critical.


Some don't use the lens for the pump diode, so emitter size and divergence of the 808 pump need to match, or remove the glued double concave and glued crystal to take off the pump lens then you have to re glue the crystal and double concave, but alignment is critical.

The middle 2 pics you can remove the pump diode that the driver is attached to and remove the pump lens if you are using a different diode without removing the glued crystal, but going bigger may not work because of the physical crystal size.

If you are replacing the pump with what came out then make sure your crystal is not burnt.

For the price I usually buy a new one, but I have put them together from pieces before.

The last 2 pics are a 2nd module with no pump lens.
The second module has no 808 lens.
The double concave glues on section 2 and the crystal glues on section 1
But that open can pump has no lens

This is my diode and module assembly.

This is interesting to me. I want to find an 808nm illumination source - not for burning things, but for targetted transdermal irradiation.
I had been wondering if hacking a green laser pointer would be an inexpensive source, and had planned some FastTech purchases of 5mW, 100mW and 200mW 18650-based pointers, hoping I could get inside their heads and remove the vanadate assembly, focusing lenses and IR filter. Wide divergence would be my friend in this case.

I am wondering now if the 200mW would be too powerful (at possibly 1W @ 808nm).

Does anybody have an idea how much divergence I could count on? This would be used at close-close range/ barrel contact, if there was enough divergence at that point. If not, then in a jig to provide a minimum distance stand-off from skin.

Any input is welcome. Thanks

Dang... only 1 post in 5 years? I thought I had done more than just lurk since 2011, but I guess not.

mvisconte said:

This is interesting to me. I want to find an 808nm illumination source - not for burning things, but for targetted transdermal irradiation.
I had been wondering if hacking a green laser pointer would be an inexpensive source, and had planned some FastTech purchases of 5mW, 100mW and 200mW 18650-based pointers, hoping I could get inside their heads and remove the vanadate assembly, focusing lenses and IR filter. Wide divergence would be my friend in this case.

I am wondering now if the 200mW would be too powerful (at possibly 1W @ 808nm).

Does anybody have an idea how much divergence I could count on? This would be used at close-close range/ barrel contact, if there was enough divergence at that point. If not, then in a jig to provide a minimum distance stand-off from skin.

Any input is welcome. Thanks

Click to expand...

It's probably easier just to buy an 808nm laser directly, unless you already have a 532nm laser lying around that you don't mind destroying.

Anyway - not sure on divergence - with just the bare diode you can probably count on >10mRad - but you won't even feel 1W of 808nm unfocused on your skin if that's what you are worried about(Unless maybe you have dark skin, I'm on the pale side...). 18W of 808nm unfocused on my hand felt only slightly warm.

Could you give us some more detail about what you're trying to achieve?

mvisconte said:

Dang... only 1 post in 5 years? I thought I had done more than just lurk since 2011, but I guess not.

Click to expand...

:crackup::crackup::crackup:

I've got 4W of 808nm and it's meaningless unless you have a black surface.