Optical Frequency Shift Beam Steering via Diffraction Grating
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Solution Overview
Problem
Conventional laser beam steering systems in LiDAR and remote sensing applications rely on moving parts, which are slow, prone to thermo-mechanical disruptions, and require complex coherent laser combinations or limited by liquid crystal damage thresholds, making them unsuitable for high-power and high-speed applications.
Innovation Solution
A non-mechanical beam steering system using optical-frequency shifting techniques with dispersive optical elements, such as diffraction gratings, and electro-optic phase modulators, allowing for precise and fast angular deflection of laser beams without moving parts or coherent emitter arrays, suitable for both low-power and high-power lasers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If moving parts (mirrors, actuators) are used for beam steering, then beam deflection can be achieved, but the system becomes slow and vulnerable to thermo-mechanical disruptions
Solution Approach 1:
The patent replaces mechanical beam steering systems (mirrors, galvanometers, piezoelectric actuators) with an optical-frequency shifting system using electro-optic modulators and dispersive optical elements. This substitution eliminates moving parts entirely, achieving both high-speed operation (limited only by electronic modulation bandwidth) and enhanced reliability (no mechanical wear or thermo-mechanical disruptions).
Solution Approach 2:
The system changes the optical frequency parameter of the laser beam using electro-optic modulation, then uses a dispersive optical element to convert frequency changes into angular deflection. This parameter-based control method achieves fast, precise beam steering without mechanical movement, resolving the contradiction between speed and reliability.
2Speed
If optical phase arrays with multiple coherently combined emitters are used, then beam steering can be achieved without moving parts, but the device complexity increases significantly
Solution Approach 1:
The patent extracts the beam steering function from complex multi-emitter optical phase arrays and implements it using a single laser source with frequency shifting. By removing the need for multiple coherent emitters and their associated phase control electronics, the system achieves fast beam steering with dramatically reduced device complexity.
Solution Approach 2:
The patent introduces an electro-optic modulator as an intermediary device that shifts the optical frequency of a single laser beam. This intermediary enables beam steering functionality without requiring complex multi-emitter arrays, simplifying the overall system while maintaining high-speed performance.
3Adaptability or versatility
If liquid crystal cells are used for beam steering, then non-mechanical steering is achieved, but the damage threshold power is significantly lower than passive optical components
Solution Approach 1:
The patent extracts the frequency shifting function from the liquid crystal cell and relocates it to an electro-optic modulator positioned before the high-power laser beam path. The liquid crystal cell is removed from the high-power beam path entirely, eliminating the damage threshold limitation while preserving non-mechanical beam steering capability through frequency-based control.
Solution Approach 2:
The electro-optic modulator serves as an intermediary that performs frequency shifting on low-power laser output before amplification. This placement ensures that the modulator operates on low-power signals (below its damage threshold) while the final high-power beam passes through only passive, high-damage-threshold optical components like diffraction gratings.
4Ease of operation
If frequency shifting is performed close to the laser output, then beam steering control is achieved, but the frequency-shifting component must tolerate high laser power
Solution Approach 1:
The patent performs frequency shifting as a preliminary action on the laser beam before it reaches high-power amplification stages. By placing the electro-optic modulator at the low-power output of the master oscillator, the system achieves precise beam steering control while the modulator is exposed only to low-power signals, well below its damage threshold.
Solution Approach 2:
The patent separates the frequency shifting operation from the high-power beam path by operating in a different power dimension. The electro-optic modulator works on low-power signals in the master oscillator output dimension, while the high-power amplified beam is steered using passive dispersive elements, thus avoiding power tolerance limitations.
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 solution provides high-speed, precise, and robust beam steering that decouples frequency shifting from laser power handling, enabling efficient operation in various laser systems and applications, including LiDAR, with improved ruggedness and performance over traditional methods.
Implementation Method 1
an optical phase modulator to impart a shift in the optical frequency of the beam from the laser
Implementation Method 2
a dispersive optical element to map the shift in the optical frequency to a corresponding angle with respect to the dispersive optical element
Data Source
AI summary
Methods and apparatus for optical beam steering including a laser to generate a beam having an optical frequency and an optical phase modulator (OPM) to impart a shift in the optical frequency of the beam from the laser. A dispersive optical element maps the shift in the optical frequency to a corresponding angle with respect to the dispersive optical element, which can comprise a diffraction grating.