Achromatic waveplates are generally composed of two types of birefringent crystal materials, commonly quartz and magnesium fluoride materials. The relative displacement delayed over a wide wavelength range is balanced and cancelled out by two materials, and each crystal surface is coated with an efficient broadband anti reflection film to ensure excellent transmission wavefront quality. The flat response of the achromatic waveplate is particularly suitable for tunable lasers, multi laser line systems, and other broadband sources. The design of the air gap enables the achromatic wave plate to have a higher damage threshold and can be used in high-power application scenarios.