Efficient polarization converter for projection displays

Abstract

In the waveguiding limit, a twisted nematic liquid crystal cell behaves as an achromatic polarization rotator. We propose and demonstrate the application of such a polarization rotator to convert unpolarized light into linearly polarized light with almost 100% efficiency. This polarization converter has a 2:1 aspect ratio, which is close to the 16:9 ratio for modern televisions. It can be used therefore in a projection display with polarization-dependent light valves such as a liquid crystal light valve. Both transmittive and reflective light valves can be used. The temperature dependence of the achromatic polarization rotator is also studied.

Extremely broadband and wide‐angle retardation films

“…It will be seen that this is not a severe constraint on PIF design. The transfer function C(ω) of an N component PIF system is given by 6 (2) where τ d = d∆n/c, ∆n is the dispersive birefringence of the retardation plate, d is the film thickness, and c is the velocity of the light in vacuum. Since ω = 2πc/λ, thus…”

“…1 In projection systems, QWP and HWP are used in polarization conversion optics and in skew-ray compensation. 2,3 In all applications, the HWP and QWP should be constant in the entire visible spectrum (400-700 nm). However, conventional HWP and QWP using uniaxial retardation films have strong wavelength dependence.…”

Engineering liquid crystals for optimal uses in optical communication systems

“…This property has been extensively used to make twisted nematics wavelength insensitive, which is crucial for colour display applications [21] (dw30 mm is required in the visible range). Achromatic polarization rotators have been proposed following this principle [114]. A rapid calculation shows that the wave-guiding limit is difficult to reach with a TN liquid crystal with a reasonable thickness and Mauguin minima are generally considered [3], with a penalty in the achromatic range.…”

P‐73: Broadband Quarter Wave Plate by Coating Technique

“…Retardation films such as QWP and HWP have many applications such as in polarization manipulation, phase compensation, viewing angle enhancement and dispersion compensation [1]. In projection system, QWP and HWP are used in polarization conversion optics and in skew ray compensation [2,3]. As well in OLED display system, the contrast ratio, which is the transmittance ratio of bright state and dark state, is strongly depends on how "dark" it is.…”