The T81-20X Laser Beam Expander provides a low cost means of focusing and shaping laser beams with a high degree of accuracy. This Galilean 20X beam expanders incorporate the highly regarded Tropel optical designs with improved adjustability and mounting. They are ideal for applications in which a small spot must be formed at some distance from the laser, or where the collimation range must be extended for illumination, or for alignment of distant objects. Wavefront distortion of less than λ/4 guarantees a minimum focused spot size even at long ranges. The lenses are antireflection coated with magnesium fluoride optimized for 632.8 nm, yielding transmission of over 95%. The T81-20X has an expansion ratios of 20x and a means for continuous focus change. As the power increases, the beam divergence decreases proportionately, providing a greater collimation range. These beam expanders can be conveniently attached to most HeNe lasers with the 1-32 accessory thread and are equipped with precision beam centering adjustments to compensate for slight decentrations of the entering laser beam.