DA (Divergence Adjustable) Fixed HeNe Beam Expanders offer high performance optical designs packaged in a precise opto-mechanical platform. Two full rotations of the focus knurl provide smooth movement for the optics in order to vary the output from collimated to the minimum focus distance of 1.2 meters. The precise focusing mechanism keeps optics from rotating, which helps maintain bore sight accuracy and a minimally aberrated focused beam. Focus lock secures position. The beam expanders are easily secured to both metric and English threaded mounts. Four tapped holes (two M6 on 25mm centers and two ¼-20 on 1" centers) are located near the middle of the assembly for mounting.