Polarization converter for unpolarized light

摘要

A polarization converter for unpolarized light. The polarization converter comprises a prism, a wedge, a set of lens arrays, a first reflecting plane, and a second reflecting plane. The wedge comprises a tilt plane. The tilt plane is coated with multi-layer polarization dichronic thin film. The set of lens arrays comprises a light distributor and a light integrator. The tilt plane of the wedge is glued on the first reflecting plane. A second reflecting plane is the unglued plane of the wedge. When a light beam is incident towards the incident plane, the first reflecting plane splits and polarizes the light beam into a first type polarized and a second type polarized lights. Through the multi-layer polarization dichronic thin film, about 99% of the first type polarized light is reflected, and about 99% of the second type polarized light is transmitted and incident on the second reflecting plane. By adjusting the critical angle between the second reflecting plane and the air, almost all the second type polarized light is reflected. The second type polarized light is then traveling through a half-wave plate and converted to a first type polarized light. A good uniformity and a high efficiency are obtained on the projection screen by the disposition of a light distributor lens array in front of the incident plane and a light integrator lens array on the emerging plane of the prism.