I will hopefully be able to make some progress in the new year, and get a physical prototype built up. I've been iterating through various options for building the laser head with only access to hacksaw, cordless drill and online 3D-printing and laser cutting services (I know some would suggest signing up to open access workshop, but it is just not cost justifiable).

Figure: updated holder block

The most recent iteration makes use of a brass TO-38 laser diode tubular housing, which then allows a fitting piece to couple the collimating lens and bellows tube to the housing. The plan is then to cast a heat sink block using copper powder/fillings and epoxy to couple the brass housing to the TEC module. This avoids the need for custom machining or printing of an aluminium heat sink.

The focusing stepper has also been moved so that it no longer clashes with the trigger laser beam (red).

Figure: Cut-away view showing new internal layout

Figure: TO-38 diode holder off ebay (rough dimensions, needs to be measured)

Looking forward I know that for the current design I am going to have issues with signal propagation and loss of integrity for the high speed switching of the laser, amongst other things.

However at this stage the whole system needs to be run to allow an accurate evaluation of which areas need the most attention, to measure the actual behaviour of the printing chemicals. Which will give a guide to power, pulse duration based on physical data, and allow a comparison with the theoretical calculations. And once I have the hardware, then it is easier to upgrade and test the control electronics.