Laser Beam Expander with Adjustable Collimation

A laser beam expander has at least two negative lenses with adjustable collimation. The amount of required motion can be reduced by an order of magnitude over single negative lens approaches by splitting the input lens in two and adjusting the small remaining air gap between the lenses. The change in collimation may be accomplished by heating/cooling (i.e., thermal), mechanical motion (e.g., motors), electro-optical means (e.g., applying or reducing an electric current), any combination thereof, or any other suitable mechanism.