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RED laser from DVD-RW




The Lightning Stalker

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Those will work okay. They are probably made of brass. More power can be squeezed from a copper
module. DTR is about the cheapest place to pick those up.
 

elian

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Hello everybody...take the chance to ask question: I have a laser diode chip (300x200x100um) on silicon 5mW, max 30mA. I need to drive this LD and I cannot use any feedback photodiode. Any suggestions? I can buy or design one...same for me. Thansk a lot
 

The Lightning Stalker

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Okay, first wow how did you measure something so small? Second, you can use something like this:

 
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elian

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Hi, thanks a lot.
I have in on silicon submount. I glue it on PCB and then i can measure. Since I can have MCU I was thinking to use PIC16 for PWM signal and the NU501 to regulate the current in the LD. Could you comment on it?thansk a lot
 

The Lightning Stalker

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You're welcoem. I've never used the NU501 before, but after reviewing the datasheet, it looks like it
should be doable. Just include the capacitor across the diode as above to help control overshoot. So
say you use the 1B30, you would attach the PWM from the PIC to the Vdd pin on the NU501 as
outlined in the datasheet. I would also recommend testing this with a few signal diodes in series, such
as the 1N4148 in place of the laser diode and an oscilloscope. You're trying to match the voltage drop of
your laser diode. Put a 1Ω 1% carbon or film (non-inductive!) resistor in series with the diodes and the
oscilliscope probe across the resistor. You will then get 1mV for every mA. Watch that the output never
goes above 30mA under any circumstances and you should be golden globes.

This all sounds like a lot of fun. I wish I had a few of those bare silicon wafers here to play
around with. Let us know how it all turns out.
 




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