Laser Cutter Build Night: Laser Driver Circuit

Tonight, I built the driver circuit I will be using to drive my burning laser and tested it, on a breadboard.  I used a practice laser diode from a dollar store laser pointer to test it out.  Eventually, I will move the entire circuit to be directly soldered together or put it on some protoboard stuff, once I verify that it works with my real laser diode.  I am waiting to order my Aixiz laser housing before I will solder and test the diode.  I used this schematic (sans reverse voltage diode) for my driver:
My LM317 voltage regulator was a free sample from some online company, but all the other parts were salvaged from junk electronics.  I left out the 1N4001 diode (which I believe is to protect against reverse voltage) because I don't intend to connect the power backwards.  Ever.

The Aizis laser module is necessary to cool and protect the fragile open can diode.  Even the tiny dollar store diode got fairly hot during use - imagine what a burning laser would do without heatsinking!  I took some pictures of my practice diode running off of the driver circuit:
My next objectives will be:
  • hook up some more transistor circuitry so that I can control this circuit with my Raspberry Pi
  • buy an Aixiz laser module
  • look into backlash on Y axis
  • possibly figure out alternative power supply to 9V battery