Complex sentence: A laser guide star is an artificial star image created for use in astronomical adaptive optics systems, which are employed in large telescopes in order to correct atmospheric distortion of light (called "astronomical seeing").
Split into simpler sentences: A laser guide star is an artificial star image created for use in astronomical adaptive optics systems, which are employed in large telescopes. Adaptive optics (AO) systems require a wavefront reference source in order to correct atmospheric distortion of light (called "astronomical seeing").