laser diode

I need to drive a 650nm cheap 5mW laser diode. It seems to have a current limiting resistor in series, but the laser still got damaged. I powered it directly from an 18650 at 4V and it was working fine. I left it on for an hour or so, but it was in a 3D-printed shell that I had made to position...

I am looking for laser sensor to measure velocity of fast moving bullet/projectile traveling through barrel. I have a bullet of 5mm length and it would cut the laser for just 5- 20 microseconds. The sensor need to be fast enough to give trigger to oscilloscope with this kind of small intervals...

Good day! Can anybody identificate this red laser diode. It's used in chinise hematology blood analyser and I cannot find datasheet or characteristics of it. Markings: DU6H 2610. Voltage 2.3v, current 80mA.