Laser diode power supply

[Douxleurre]

Hello,


I work on a project in which I need to use powerful laser diodes in a lens pick-up unit of dvd graver. (I use wavelength-adapted safety glasses)

I have already made a power supply which worked fine for the following laser diodes (ordered alone) : ML101J29 & ML101U29-25 at around 110mA. Only, after around 60 seconds the irradiance decreases, as the diode heats up I suppose.

I did order 4 lens pick-up unit from Xbox 360 's dvd gravers (named HOP 141X). I was unable to find any datasheet for the red laser diodes in these lens pick-up unit and failed to make any of them work with my power supply unit.
I may have burned them all one by one by trying a wrong pinout however it seems unlikely to me as the powerful diodes with which I have first tested the power supply have seen many wrong pinout without significant damage.


Here is the schematic of my power supply, I believe a fixed-current source, with R1 = 8 Ohm (can be adjusted) and 9V as Vin (not 12V).


To pursue my project, I could replace the problematic laser diode in the lens pick-up unit by the laser diodes I bought separately and succeeded to supply power to, however, I expect heat evacuation issues. Before getting stuck I prefer to know if I did anything wrong.


To sum up, my questions are :
- I can't supply power to the red laser diodes in the HOP 141X lens pick-up units despite having a supply that should work on them. Does anyone has any tips/clues on this please?
- There are no fans in lens pick-up units, how is the heat generated by the laser diode evacuated? Only by conduction through lens pick-up unit?

Sincerely yours,

Douxleurre


Some details : the PCB on which the red laser diode is mounted has TS-2 written on it, and on the grey casing of the red laser diode can be found in black the inscription "1OTGO"
If that may help, here is how the HOP141X looks like and its red laser diode :

 

[Harald Kapp]

failed to make any of them work

I found an info that these units should have an ESD protection jumper/solder bridge. This needs to be removed before use.

 

[Douxleurre]

I found an info that these units should have an ESD protection jumper/solder bridge. This needs to be removed before use.

Hello, thank you very much I would not have thought of this I didn't know its existence yet... May you quote your source please? It could only help me to understand better how to remove this properly.

 

[Harald Kapp]

I'm afraid my source is in German. It was a quick Google search. Unfortunately there was no information on that page where exactly that jumper sits .

 

[bertus]

Hello,

On the page that @Harald Kapp showed, there is a picture of the ESD bridge:

Bertus

 

[Harald Kapp]

Nice find!

 

[Douxleurre]

Thank you very much ! I ended up cutting with my dremel the PCB on which the red laser diode was mounted and I did find a correct pinout lighting the laser diode when my previous solder couldn't. However, the red light was very weak. I end up having far better results with my mitsubishi diodes, despite having them heat up.

I still have a question thus. You may have guessed with my low level in electronics that it's not my speciality. Hence, I am curious to know how this ESD bridge protects some sensitive components from static electricity discharges. I have found no convincing explanation anywhere, may someone teach me (and the former readers of this topic ^^ ) how this specific solder/jumper works?

 

[Harald Kapp]

despite having them heat up.

Mount them on a heat sink.

I am curious to know how this ESD bridge protects some sensitive components from static electricity discharges.

Simply by creating a short circuit across the sensitive pins. Thus any ESD has no chance to enter the sensitive device. You simply remove the solder from these pins so they are no longer connected. No need for a Dremel or the like.

 

[Douxleurre]

Mount them on a heat sink.


Simply by creating a short circuit across the sensitive pins. Thus any ESD has no chance to enter the sensitive device. You simply remove the solder from these pins so they are no longer connected. No need for a Dremel or the like.

I have heat sinks and fans, however if I do so I cannot mount the diode within the casing inside of the lens pick-up unit and end up loosing a lot of intensity due to the inherent diffraction cone of the laser diode's beam. As far as the intensity fluctuation stay stable enough over a fistful of seconds I can work with this for the following of my project.


I guess that the short-circuit cannot be placed anywhere across the sensitive pins, or the device can't receive any power. A quick chematic may help clarify your explanation, a schematic with the high voltage source, the sensitive pins, and the jumper.

Meanwhile, here is the pinout I figured out for the red laser diodes within the HOP141X lens pick-up units, if that may help a future reader :

 

[Harald Kapp]

I guess that the short-circuit cannot be placed anywhere across the sensitive pins, or the device can't receive any power.

That is why you have to remove the short circuit before putting the laser into operation.

 

[Douxleurre]

That is why you have to remove the short circuit before putting the laser into operation.

Oh, I may understand better right now : Does it mean that on the original mounted final product this jumper is always unsoldered? Is it only soldered during transport between factories? Thus it just dumbly shorts all sensitive components alltogether but has to be removed (thus removing the ESD protection at the same time) for having the device to be functional?


If so I perfectly understand and need no schematic at all ^^. As I told you I was not familiar with the concept yet and thought notably that it would be a more tough concept to have a ESD protection while the system being active.

 

[Harald Kapp]

Is it only soldered during transport between factories?

Exactly.