High quality collimator have dropped in price:
http://store.laserextreme.nl/catalog...products_id/75
Ex. With a opnext 150mW 642nm 5,6mm diode you get a 1,2mm x 2,2mm 0,6mRad beam.
<1% loss on complete collimation normally ~0,5%
The collimator is a brass cylinder
11mm diameter
Glass optical lens, tread for fine adjusting of the lens.
avaiable for red 640-660nm and blue 405-450nm