准分子激光（英文：Excimer laser）是一种紫外气态激光，处于激发态的稀有气体和另一种气体（稀有气体或卤素）结合的混合气体形成的分子，向其基态跃迁时发射所产生的激光，称为准分子激光。

准分子激光属于低能量激光，无热效应，是方向性强、波长纯度高、输出功率大的脉冲激光，光子能量波长范围为157－353纳米，寿命为几十纳秒，属于紫外光。最常见的波长有157 nm、193 nm、248 nm、308 nm、351-353 nm。

An excimer laser, sometimes more correctly called an exciplex laser, is a form of ultraviolet laser which is commonly used in the production of microelectronic devices, semiconductor based integrated circuits or “chips”, eye surgery, and micromachining.