水晶波長板

The transformation from linearly to circularly polarized light（or vice versa）, which occurs when the angle between the plane of linear polarization and the crystalline optic axis is exactly to elliptical（or vice versa）.
Applications; The combination of a polarizer and a quarter-wave plate is called an Isolator. Isolators are used to prevent feedback from interferometers into lasers, with the resulting troublesome mode-pulling and detuning of the lasers. Quarter-wave plates also find application in electro-optic modulators for laser beams.

The transformation from linearly to circularly polarized light（or vice versa）, which occurs when the angle between the plane of linear polarization and the crystalline optic axis is exacitly to elliptical（or vice versa）.
Applications; The combination of a polarizer and a quarter-wave plate is called an Isolator. Isolators are used to prevent feedback from interferometers into lasers, with the resulting troblesome mode-pulling snd detuning of the lasers. Quarter-wave plates also find application in electro-optic modulators for laser beams.

Zero Order Waveplates consist of two multiple order waveplates with the optic axes aligned orthogonally. The thickness difference of the two plates cancels out the integral part of the phase shift. These can be cemented for low power applications, or optically contacted or airspaced for high power applications.
Zero Order Waveplates have a broader bandwidth, useful for tunable lasers, and they are also less temperature sensitive than multiple order plates.