The Glan laser consists of two birefringent crystals placed back-to-back with inclined surfaces facing each other. These two prisms have the same optical axis direction, parallel to the reflecting surface and perpendicular to the propagating beam. Due to the birefringence property of crystals, the refractive index of light waves propagating in the optical axis direction and perpendicular to the optical axis direction is different. The incident beam undergoes total internal reflection at the glass air interface at the prism junction: the reflected light includes all o-light and some e-light, while the transmitted light through the polarizer is highly linearly polarized e-light, which can be applied to scenes that require high-quality polarized beams. The air gap structure is used between two birefringent crystals instead of chemical bonding, which increases the damage threshold and allows a large amount of reflected light to exit from the side window of the housing, making it suitable for high-power lasers. For medium power applications, a Gran Taylor crystal polarizing prism can be used.