Phase-shifting Mirrors

Phase-shifting mirrors (Type MPC/MPS) are used to convert linearly polarized light into circularly polarized light. Circularly polarized light is used, for example, in laser cutting to achieve an axis-independent, uniform cut.

The circular polarization is achieved by a L/4 phase shift of the incident light. This occurs as a result of the coating on the mirrors, a coating which can be applied to both copper and silicon substrates. 

When inserting the mirrors into the beam path, it is important to note that the exiting, linearly polarized laser beam has to hit the phase-shifting mirror at an angle of 45° and must also be polarized at 45° to the deflection plane (see drawing).

Specifications:

• Tolerances: See copper/silicon mirrors
• Phase shift: 90° ± 6°
• Reflectivity: R > 98.8% (10.6 µm)

Water-cooled phase-shifting mirrors are also available.