Cycloidal Diffractive Waveplate Beam Steering for Broad Field of Regard
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Solution Overview
Problem
Existing optical beam steering systems, such as Risley prisms and diffractive beam deflectors, face issues with weight, volume scaling, efficiency dependence on angle of incidence, polarization effects, and beam cross-section changes, which are impractical for large aperture applications, especially in aerodynamic enclosures.
Innovation Solution
A beam steering system utilizing a single cycloidal diffractive waveplate (CDW) with reflective or transmissive optics, allowing high-efficiency beam deflection over a broad range of angles without significant weight or volume increase, maintaining beam cross-section integrity, and accommodating various polarizations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If Risley prisms are used for beam steering, then beam deflection is achieved, but weight and volume increase as the cube of aperture dimension
Solution Approach 1:
The patent replaces the mechanical refractive prism system with a diffractive optical element that uses diffraction rather than refraction to achieve beam deflection. This substitution fundamentally changes the physical mechanism from bulk material refraction to surface-level diffraction, enabling large aperture beam steering without the cubic weight scaling of traditional prisms
Solution Approach 2:
The patent changes the operational parameters by using diffraction grating equations rather than Snell's law for refraction. The beam deflection angle is controlled by the grating period and diffraction order rather than prism apex angles and refractive indices, allowing for lighter weight components while maintaining steering capability
2Area of stationary object
If larger aperture prisms are used, then beam steering coverage increases, but weight increases by a factor of eight for doubled aperture diameter
Solution Approach 1:
The patent replaces bulk refractive prisms with thin diffractive optical elements that achieve the same beam steering function through diffraction. This allows large aperture areas to be achieved without the corresponding cubic increase in weight, as the diffractive element is a surface structure rather than a volumetric component
Solution Approach 2:
The patent employs thin diffractive optical films or gratings that can provide large aperture areas with minimal thickness and weight. These thin film structures achieve beam deflection through surface relief or phase modulation rather than bulk refraction, eliminating the weight-aperture scaling problem
3Weight of moving object
If diffractive beam deflectors are used, then weight is reduced, but diffraction efficiency varies with angle of incidence
Solution Approach 1:
The patent employs dynamic control of the diffractive element's orientation or configuration to maintain optimal diffraction efficiency across varying angles of incidence. By actively adjusting the element's state in response to changing incident angles, the system maintains high efficiency throughout the operational range
Solution Approach 2:
The patent modifies the diffraction grating parameters such as period, depth, or profile to optimize efficiency for specific angular ranges. By tailoring these parameters to the application's angular requirements, the system achieves high diffraction efficiency while maintaining the weight advantages of diffractive elements
4Adaptability or versatility
If beam deflection angle increases, then field of regard expands, but beam cross-section becomes elliptical
Solution Approach 1:
The patent introduces asymmetric optical elements or configurations that compensate for the symmetric distortion caused by large-angle beam deflection. By using asymmetric prism pairs or tilted diffractive elements, the system counteracts the elliptical distortion and maintains a more circular beam cross-section across the field of regard
Solution Approach 2:
The patent addresses the cross-section distortion by introducing control in an additional dimension through the use of tilted or rotated optical elements. This dimensional approach allows for compensation of the beam shape distortion by manipulating the beam in both horizontal and vertical planes simultaneously
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 system achieves lightweight, high-efficiency beam steering with minimal cross-section distortion across large deflection angles, suitable for aerodynamic enclosures, and compatible with diverse electromagnetic radiation spectra.
Implementation Method 1
A beam steering system utilizes a single cycloidal diffractive waveplate (CDW) with reflective or transmissive optics, allowing high-efficiency beam deflection over a broad range of angles
Implementation Method 2
A beam steering system utilizing a single cycloidal diffractive waveplate (CDW) with reflective or transmissive optics
Data Source
AI summary
Opto-mechanical assemblies, systems, devices and methods for pointing laser and other optical beam, and for directing the field of view of sensors are disclosed. The assemblies include means for rotating a cycloidal diffractive waveplate optic around a predetermined axis, and a reflective or transmissive optic that turns a diffracted optical beam onto a direction perpendicular to the rotation axis of the cycloidal diffractive waveplate, enabling a wide field of regard.