Liquid Crystal Light Deflection Device with Variable Pitch Diffraction
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Solution Overview
Problem
Existing light deflection devices, such as those using gimbal mirrors or liquid crystal prisms, are not suitable for applications requiring reduced size, weight, and low power consumption, and have complex manufacturing processes and control difficulties.
Innovation Solution
A light deflection device comprising a liquid crystal optical phase modulation element, a diffraction element with a periodic structure pitch that changes from the center to the outside, and a driving unit, which uses a liquid crystal diffraction element with an optically-anisotropic layer having a concentric circular alignment pattern to achieve a high deflection angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a gimbal mirror or galvanometer mirror is used for light deflection, then the deflection control is simple and direct, but the device size and weight increase
Solution Approach 1:
The patent replaces the mechanical mirror deflection system with an optical system consisting of a liquid crystal optical phase modulation element and a diffraction element. The liquid crystal element modulates the phase of incident light, and the diffraction element converts this phase modulation into angular deflection, eliminating the need for heavy mechanical moving parts while achieving the same light deflection function.
Solution Approach 2:
The patent changes the operating parameters by using variable pitch periodic structures in the diffraction element. The pitch varies from the center toward the outside, allowing different diffraction angles for different regions. This enables precise control of light deflection angles through parameter variation rather than mechanical movement, reducing device weight and complexity.
2Shape
If a liquid crystal prism with a prism-shaped liquid crystal layer is used, then the deflection angle can be extended, but the manufacturing process becomes complicated and control becomes difficult
Solution Approach 1:
The patent divides the optical system into two functional segments: a liquid crystal optical phase modulation element and a diffraction element with variable pitch periodic structure. This segmentation allows each component to have a simpler, more standardized manufacturing process compared to a complex prism-shaped liquid crystal layer, while collectively achieving extended deflection angles through the collaboration of both elements.
Solution Approach 2:
Instead of extending the deflection angle by changing the three-dimensional prism shape of the liquid crystal layer, the patent uses a two-dimensional variable pitch periodic structure in the diffraction element. The pitch varies in one dimension (from center to outside) to achieve angular extension, simplifying the manufacturing process by avoiding complex 3D prism fabrication while maintaining the deflection angle extension capability.
3Device complexity
If a wedge-shaped prism is used with liquid crystal, then the structure is simpler, but the device weight and size cannot be reduced sufficiently
Solution Approach 1:
The patent uses thin film structures for both the liquid crystal optical phase modulation element and the diffraction element with variable pitch periodic structure. These thin films replace the bulky wedge-shaped prism, maintaining structural simplicity while dramatically reducing device weight and size. The thin film diffraction element achieves the same optical function with minimal material mass.
4Reliability
If conventional light deflection devices are used, then the structure is established and reliable, but the power consumption is high
Solution Approach 1:
The patent replaces the high-power mechanical deflection systems (gimbal mirrors, galvanometer mirrors) with a low-power optical system using liquid crystal and diffraction elements. The liquid crystal element requires only electrical voltage to modulate light phase, and the diffraction element passively converts this modulation into deflection without requiring mechanical actuation, significantly reducing power consumption while maintaining reliable light deflection functionality.
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
The solution enables a compact, lightweight light deflection device with a high deflection angle, suitable for applications like free-space optical communication and laser radar, while simplifying the structure and control processes.
Implementation Method 1
a light deflection element that deflects incident light to be emitted; in which the light deflection element is a liquid crystal optical phase modulation element
Implementation Method 2
a diffraction element that is disposed on a light emission side of the light deflection element in which a periodic structure pitch gradually changes from a center of deflection from the light deflection element toward an outside
Implementation Method 3
the liquid crystal diffraction element includes an optically-anisotropic layer that is formed using a composition including a liquid crystal compound and has a liquid crystal alignment pattern in which a direction of an optical axis derived from the liquid crystal compound changes while continuously rotating
Implementation Method 4
the optically-anisotropic layer includes a liquid crystal compound that is twisted and aligned along a helical axis extending in a thickness direction
Data Source
AI summary
An object of the present invention is to provide a light deflection device having a simple structure suitable for reducing the size and weight where a deflection angle can be increased. The object can be achieved with a light deflection device including: a light deflection element that deflects incident light in one direct to be emitted; a driving unit that drives the light deflection element; and a diffraction element that is disposed on a light emission side of the light deflection element in which a periodic structure pitch gradually changes from a center of deflection from the light deflection element toward an outside.