Below that diode: The faint red glow of 808nm love
The thicker pair of wires on the transformer are the output - not mains. I found this out by tripping the circuit breaker a couple times. It's so nice having a house!
Plugging this thing in caused a spark in the mains connection, which failed after a few seconds making me fear the worst for the laser. Turns out my soldering iron is not hot enough to bond to the heavy steel connectors so I hit them with a hammer to make them touch the cables. Works great.
This is the first circuit I've built where the fan really is necessary. The far transistor on the power supply tends to heat up and lose current without the fan.
This nice diode has a TEC right in the case, so I am just running that series with the diode from the driver circuit.