Quartz crystal is an excellent artificially grown crystal, grown by the hydrothermal method in an autoclave, with left-handed and right-handed forms. It has low stress birefringence and high refractive index uniformity, with a transmission range of 0.15–4 μm. Due to its piezoelectric properties, low thermal expansion coefficient, and excellent mechanical and optical characteristics, quartz crystal is widely used in retardation waveplates and small-angle beam splitting devices.