I just started working with my first laser diode -- an LPC-815 650nm I bought which was pulled from a 20x DVD burner. Unfortunately, I fried it. It looks more like a red LED with an excessive voltage drop and the ability to handle quite a bit of current now.
The driver is an LM317 used as a current regulator. During the course of experimenting I tried running the LD at 100mA and 190mA. Even at 100mA, I would get smoke off a piece of electric tape placed at the focal point. Shortly after adjusting upward to 190mA, the laser stopped working. I don't recall if this happened while I had the power on or during some bout of re-wiring.
While I did have the LD powered for a number of minutes, at 100mA, the aixiz module it was mounted in was barely warm. Almost imperceptible. My impression is that at this low current, I'd be fine with a long duty cycle of several minutes. After all, I see folks recommend about 400mA on this LD for long life and builds were people often go 500mA plus with heat sinking.
So, my question is, did I kill this LD because of too much current or is some other failure mode more likely? Perhaps a voltage spike through the LD as I was rewiring? I'm measuring current by connecting my DMM in series with the high side of the LD. I may have done a disconnect and reconnect just before noticing the LD failure. Perhaps this had something to do with it? Any thoughts?
The driver is an LM317 used as a current regulator. During the course of experimenting I tried running the LD at 100mA and 190mA. Even at 100mA, I would get smoke off a piece of electric tape placed at the focal point. Shortly after adjusting upward to 190mA, the laser stopped working. I don't recall if this happened while I had the power on or during some bout of re-wiring.
While I did have the LD powered for a number of minutes, at 100mA, the aixiz module it was mounted in was barely warm. Almost imperceptible. My impression is that at this low current, I'd be fine with a long duty cycle of several minutes. After all, I see folks recommend about 400mA on this LD for long life and builds were people often go 500mA plus with heat sinking.
So, my question is, did I kill this LD because of too much current or is some other failure mode more likely? Perhaps a voltage spike through the LD as I was rewiring? I'm measuring current by connecting my DMM in series with the high side of the LD. I may have done a disconnect and reconnect just before noticing the LD failure. Perhaps this had something to do with it? Any thoughts?