IdealPhotonics' beam expander is an optical component that adjusts the divergence angle by changing the beam's cross-sectional area. Its core function is to compress the beam divergence angle (collimation) or enlarge/resize the spot size while maintaining wavefront quality. Based on its structure, it can be divided into two types: Galilean (without a real focus) and Keplerian (with a real focus), and is widely used in laser processing, optical measurement, and communication systems.By precisely controlling the ratio of beam diameter to divergence angle through lens groups (Galilean/Kepler type), it achieves a beam expansion ratio of 2×-20× while maintaining wavefront quality (distortion <λ/4), meeting the laser system's requirements for synergistic spot size and collimation.