What is a Polarization Directed Flat Lens?
A Polarization Directed Flat Lens is a thin (0.45mm) flat window with a complex photo-aligned liquid crystal polymer (LCP) film deposited on the surface. By varying the geometrical phase shift spatially, the LCP achieves near perfect diffraction efficiency of the holographically recorded lens wavefront. Essentially, a Polarization Directed Flat lens is a thin film equivalent of a geometric optic with very little volume, yielding significant reductions in weight and thickness.
How does Polarization affect the performance?
The Polarization Directed Flat Lenses are sensitive to circular polarization. The lenses have the unique property that one circular polarization will focus or converge through the lens (positive focal length) and the orthogonal circular polarization will defocus or diverge (negative focal length).
- When the lens is oriented with the LCP surface facing the light source: Left-Hand Circular Polarization (LHCP) light will focus with the stated positive focal length of the lens. Right-Hand Circular Polarization (RHCP) light will diverge with the negative stated focal length of the lens.
- When the lens is oriented with the LCP surface away from the light source: RHCP light will focus with the stated positive focal length of the lens. LHCP light will diverge with the negative stated focal length of the lens.
Will the lens focus unpolarized light?
With unpolarized light, the Polarization Directed Flat Lens will act as a positive lens for 50% of the light (one of the circular polarizations) and it will act as a negative lens for the other 50% of the light (the orthogonal polarization).
What are the advantages of Polarization Directed Flat Lenses?
Polarization Directed Flat Lenses are a thin film equivalent of a geometric optic. Thus, they have significantly less volume than an equivalent spherical optic, yielding significant reduction in weight and thickness. The technology used to create them is also well suited to create gratings and other polarization optics, allowing for multiple optical technologies to be designed into a single optical component.