Modulating 532nm 5mW diode

[ParoXoN]

Hi,

So I'm on my way to my first (very hackish) monochrome projector build and the thing I thought I'd have the least trouble with is causing me the most pain. I've managed to interface the galvos and align everything to get what appears to be a nice, solid beam.

Unfortunately, I find myself unable to turn the laser on and off programatically.

I have two laser modules I can work with. One's a no-name one that I sourced from dealextreme.com (which seems to be broken, since it's drawing 500mA of current @ 3V to produce a reasonable output) and the other is scavenged from an Orion series laser pointer from laserglow.com. (Also 3V; current draw capped at 240mA by driver/regulator board.)

What I need to be able to do is modulate the laser using a 0-3.3V digital output from the microprocessor I'm working with. I'd thought a simple BJT switch would be sufficient but it looks like I was wrong

Any thoughts on a more advanced modulating scheme that would work?

Thanks in advance,

paro

[andy_con]

could you not replace the driver with one that has modulation, like a die4laser driver?

[ParoXoN]

I could potentially replace the driver board but I'm curious as to why the current setup isn't working. Those die4drives look simple enough to build... Might have to try that...

[badger1666]

i also use a die4drive on a green laser that simalar to your dealextream also from ebay
works well but these cheap lasers are not very good at analog modulation
so dont expect very good results they are designed for ttl mod
i use die4 drive in my main projector and they work very well when setup

[ParoXoN]

Hmm... Maybe it would help if I used a BJT that didn't current starve the laser >.< 100mA max collector current is insufficient.

Replaced with a TIP50 BJT; seems to work much better