Liquid Crystal Waveguide Bulk Feedback Beam Steering
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Solution Overview
Problem
Traditional NLC-based beam steering techniques face inaccuracies due to the evanescent interaction with the liquid crystal, leading to an over-sampling of the surface effects and under-sampling of the bulk molecular reorientation, resulting in inefficient low-power displays and beam steering.
Innovation Solution
A waveguide apparatus with a high-index core and variable-index liquid crystal cladding, where the bulk birefringence or capacitance is measured to predict and control the steering of a beam of light by varying the applied voltage, enabling a one-to-one mapping of bulk properties to steering position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If evanescent interaction with liquid crystal is used for beam steering, then device complexity is reduced, but measurement precision deteriorates due to over-sampling of surface effects and under-sampling of bulk molecular reorientation
Solution Approach 1:
The patent introduces a mediator (reference beam or probe beam) that interacts with the liquid crystal bulk through the waveguide structure. This intermediary beam allows indirect measurement of bulk molecular reorientation by comparing its properties (phase, intensity, polarization) before and after interaction with the liquid crystal, thereby overcoming the limitation of direct evanescent field sampling that only probes surface regions.
2Device complexity
If traditional evanescent field sampling is used, then device structure is simplified, but beam steering accuracy deteriorates due to inaccurate representation of bulk LC orientation
Solution Approach 1:
The patent implements a feedback mechanism where the measured bulk properties (birefringence, molecular orientation) are used to adjust and optimize the beam steering control. The measurement system provides real-time feedback on the actual bulk LC state, allowing the control system to compensate for deviations and achieve accurate beam positioning that truly reflects bulk molecular reorientation rather than just surface effects.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method allows for accurate prediction and real-time monitoring of beam steering, reducing the need for external lookup tables and enhancing beam stability by directly measuring bulk properties, such as birefringence and capacitance, to correlate with steering angles, thus improving the performance of NLC-based devices.
Implementation Method 1
the evanescent interaction with the liquid crystal, leading to an over-sampling of the surface effects
Implementation Method 2
NLCs commonly exhibit dielectric anisotropy (Δε) and birefringence (Δn)
Implementation Method 3
NLCs commonly exhibit dielectric anisotropy (Δε) and birefringence (Δn)
Implementation Method 4
a measurement light source configured to direct light to reflect from the first interface and then to a receiver configured to measure bulk birefringence of the liquid crystal cladding
Implementation Method 5
a capacitance meter configured to measure capacitance across the LC
Implementation Method 6
an applied field (E) across the molecules results in an additional free energy term: fE=ε0Δε2 sin θ cos θ which distorts the NLC director when above a threshold voltage Vth
Implementation Method 7
NLC-based electro-optic devices such as displays, light (phase, amplitude, polarization) modulators
Data Source
AI summary
A liquid crystal (LC) beam steerer includes a waveguide apparatus with a waveguide having a high-index core in contact with a variable-index liquid crystal (LC) cladding, wherein a voltage applied to the LC cladding is effective to steer a beam of light passing through the high-index core. Measuring the bulk birefringence and/or the capacitance characteristics of the LC can facilitate beam steering.