I made this aluminium bit on the lathe/mill today. It holds a blue laser-module from dealextreme. The brass barrel measured about 11.81 to 11.84 mm in diameter so I first drilled a 10mm hole, then opened it up slowly on the lathe until the module just fit the hole. There is an M3 set-screw to hold the laser module in place. Four long M2.5 screws clamp the aluminium part into contact with a peltier-element and the copper heatsink. A thermistor for temperature measurement and feedback control will be glued to the aluminium part as close as possible to the peltier.
Temperature control of the laser diode should provide for rough tuning of the laser wavelength. We want the wavelength to be about 405.2 nm, to be used for photoionization of Strontium.
Aside: A few years ago I tried to order some of these 405nm laser-pointers to the university. It was impossibly difficult because the shipments were stopped by the customs. Negotiations with the radiation-safety authorities did not help. It's simply forbidden to import non CE-approved laser-pointers - it doesn't matter if you are a researcher or work at a research institution. The story is completely different for laser modules (this is exactly the same product as the laser-pointer, but without the pen-like shape and the battery holder). Apparently these are classified just as "diodes" or "electronic components" and there are no problems getting them through customs.