808 nm Diode from a Green Laser Pointer

 While fitting a heatsink to the outside of a green laser pointer I broke the cyanoacrylate glue holding the driver board to the brass housing. I did not think this was a problem. I was quite wrong. A laser diode is very fragile inside. I thought I only had to be careful with heat and static shock. Here are some photos of the inside of a dead 808nm laser diode.

This is the diode at 10x.

 



This is the laser diode chip. It is about .020 inch square! It sits on the front edge of the end of the can. I did not find it with my naked eye. I thought the laser diode was lost until I looked at 60x.

 



This is the photo diode at 60x.

 

 

This is the laser diode at 60x from the front. The two lines are for alignment and are about .025 inch apart.

 



Here is a picture of the Laser Diode and the pin it used to conect to. The wire hanging on the pin was soldered to the laser diode. If you look closely the blob of solder is still on the end of the wire.

 



Here is the photodiode. Notice the wire soldered to the corner. The ring is the strain relief for the pin. The pin was pulled out of the diode.

 



I could not see the wire on the pin with my naked eye but with a little help it is still there!

 



 

This is a strand of hair to show the scale involved.



Can this be repaired?

Here is Chris Luebner's method. I don't think I will try. Without a 60x stereo microscope the method he describes would be very difficult.

 

 

Looks like the bonding wires got yanked off the diode, set it up so the diode is facing a cm or so from some white paper and tie the can to the positive side of 2 d cells hooked up in series.

Then add a 2 ohm resistor in serieswith the negative side of the battery and gently touch the top of the diode (with the gentleness and steadyness of a neruosurgeon) with the free reistor lead to see if it still lases.

You should see a dim red elipse if it still is alive, be sure you are more than a foot away when you view it and do not do so for very long. Technically it is defused to an eye safe value after a mere couple inches when shone on paper, but it's still VERY very bright and you will ge a nasty headache because your eyes still _FEEL_ it as if you are looking at a 1/2 watt argon laser.

If you have an IR sensitive camera or night vision scope handy you can use that to view it, be sure that you have the pinhole attenuator for the NV scope or it will die.

If the diode is still good you may try a soldering pin (Yes, really smd tips are much too big! Wire wrap a brass pin to a 15W temp controlled soldering pen tip.) with indium tin solder. To re-attach a wire try to move the bonding wires using a cactus needle to the diode, or if they are too far gone a tiny piece of wire like a single strand from a cheap bad headphone wire works well. Never use any other solder but indium/tin on the pin, and never let it get very hot and allways pre-heat your part on a hotplate before soldering it or it will fail to bond if you don't.

If all else fails I do have some fiber coupled 1-2W laser pump diodes that i'll sell ya for 125.00 each. The c-mount diode inside has a circulaser lens that makes the beam round and would be ideal for pumping a dpss crystal.

hope this helps, Chris

 

A. Roithner from http://www.roithner.mcb.at/ indentified it as a Sony 500 mw diode part number #SLD322V which he stocks for $116.00. Looking at the data sheet I think he is wrong.

Here is the datasheet:

http://www.roithner.de/All_Datasheets/Laserdiodes%20%231/SLD322V.pdf

Z-bolt has the complete laser pointer BTG-1 for $139 (today 9/16/2) at:

http://z-bolt.com/generic27.html

 

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Copyright 2002 Colin Kaminski