Etendue maintaining polarization switching system and related methods

A projection system comprising:

• an etendue maintaining polarization switching system including:
• a laser illumination system configured to provide polarized light along a first light path;
• a pivoted reflective element disposed in the first light path, the pivoted reflective element actuable to controllably and alternatively direct the polarized light in the first light path, without changing its polarization, along at least a second light path and a third light path;
• a reflective retarding system disposed in the third light path configured to change the polarized light into light having a different polarization and to reflect the light having the different polarization along the third light path;
• and
• a polarization combining device configured to combine light from the second light path with the light having the different polarization from the reflective retarding system in the third light path into a single light beam exhibiting a same or substantially a same etendue as the first light path;
• optics supporting the etendue maintaining polarization switching system;
• and
• a projection assembly.

A polarization switching system comprising:

• a laser illumination system configured to provide polarized light along a first light path;
• a pivoted reflective element disposed in the first light path, the pivoted reflective element actuable to controllably and alternatively direct the polarized light in the first light path, without changing its polarization, along at least a second light path and a third light path;
• a rotation device and a driving device collectively configured to pivot the pivoted reflective element, the driving device being configured to provide the rotation device a driving signal, wherein the driving signal includes a switching signal configured to cause the rotation device to pivot the pivoted reflective element between a first angular position that directs the polarized light along the second light path and a second angular position that directs the polarized light along the third light path, and wherein the driving signal also includes a noise signal configured to superimpose small angular shifts on the angular position of the pivoted reflective element, and wherein frequency characteristics of the noise signal are such that the human eye will average out variations in any resulting speckle patterns;
• a reflective retarding system disposed in the third light path configured to change the polarized light into light having a different polarization and to reflect the light having the different polarization along the third light path;
• and
• a polarization combining device configured to combine light from the second light path with the light having the different polarization from the reflective retarding system in the third light path into a single light beam exhibiting a same or substantially a same etendue as the first light path.