Stress birefringence compensation in polarizing beamsplitters and systems using same

An optical system, comprising:

• a first polarizing beamsplitter (PBS) having a reflective polarizing layer disposed between first and second covers, the first cover being formed of a material having a stress optic coefficient greater than 0.1×10−6 mm2 N−1;
• a first reflecting image-forming device facing a first surface of the first cover so that light passes through the first cover from the reflective polarizing layer of the first PBS to the first reflecting image-forming device and is reflected from the reflecting image-forming device through the first cover to the reflective polarizing layer of the first PBS, the light being subject to stress birefringence in the first cover and to residual birefringence in the reflecting image-forming device;
• and
• a first quarter-wave retarding element disposed to retard the light passing between the first surface of the first cover and the reflecting image-forming device.