### Expanding a Collimated Beam' Diameter Reduces Beam Divergence

Beam Divergence A laser beam' diameter is always smallest at its waist. Away from the waist, the beam diameter increases due to the effects of diffraction, and this rate of increase is the beam' angular divergence. Far from the beam waist, the divergence angle is approximately constant (Figure 2). An estimate of this divergence angle (θ) in ...