Laser Beam Deflection Control Using Lissajous Mirror Scanning
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Solution Overview
Problem
Laser-based additive manufacturing processes face challenges with rapid prototyping due to mechanical inertia and acceleration/deceleration issues in laser scanner mirrors, requiring numerous process parameters and inefficient irradiation strategies, which affect performance and precision.
Innovation Solution
A control device using orthogonally rotatable vertical mirrors secured on shafts, excited to continuous vibrations with synchronized frequencies and phase differences, creating a Lissajous curve for precise and reproducible laser beam deflection in the irradiation field, allowing for position-dependent activation/deactivation of the laser.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If rapid mechanical movement of mirrors is used for laser beam deflection, then processing speed is improved, but mechanical inertia and acceleration/deceleration problems worsen
Solution Approach 1:
The patent applies mechanical vibration by continuously oscillating the mirrors at specific frequencies (e.g., 10 kHz) to generate Lissajous curves. This vibration-based approach replaces rapid start-stop mechanical movements, eliminating inertia and acceleration/deceleration issues while maintaining high processing speed through continuous motion.
Solution Approach 2:
The patent implements periodic action by using continuous sinusoidal oscillations of the mirrors at defined frequencies. The mirrors perform repetitive cyclic movements along orthogonal axes, creating predictable Lissajous patterns that enable high-speed processing without mechanical shock or instability.
2Manufacturing precision
If numerous process parameters are provided for individual point movement, then positioning precision is improved, but device complexity and computing effort worsen
Solution Approach 1:
The patent changes the control parameters from individual point coordinates to global oscillation frequencies and phase relationships. Instead of specifying millions of individual point positions, the system defines a small set of parameters (frequencies, amplitudes, phases) that automatically generate the complete irradiation pattern through mathematical Lissajous curves, dramatically reducing complexity.
Solution Approach 2:
The patent replaces the mechanical control system (which requires detailed path planning and coordinate specifications) with an optical/mathematical system based on superimposed sinusoidal oscillations. The complex multi-axis mirror movements are controlled by simple frequency and phase parameters, substituting mechanical complexity with mathematical elegance.
3Productivity
If multiple laser units are used for simultaneous irradiation, then processing efficiency is improved, but device complexity and cost worsen
Solution Approach 1:
The patent makes a single laser unit multi-functional by using continuous mirror oscillations to direct the beam along complex Lissajous curves that visit multiple irradiation points in sequence. The single laser performs the work of multiple lasers by rapidly repositioning itself through the oscillating mirror system, eliminating the need for additional laser units.
Solution Approach 2:
The patent introduces dynamic mirror oscillations to enable a single static laser source to achieve effects previously requiring multiple dynamic laser units. The continuous motion of mirrors creates time-varying beam paths that cover multiple locations, transforming a static single-point laser into a dynamic multi-point irradiation system.
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 approach simplifies the dynamics of mirror movements, reduces costs, enhances stability and predictability, and enables efficient, precise irradiation of complex geometries with reduced computing effort, allowing for continuous and iterative processing of irradiation points.
Implementation Method 1
at least one first and one second orthogonally rotatable vertical mirror, via which the laser beam can be reflected, for guiding the laser beam to the irradiation field
Data Source
AI summary
A method and a control device for deflection of a laser beam for laser-based additive manufacturing processes includes first and second orthogonally rotatable mirrors designed to reflect the laser beam and guide the laser beam to an irradiation field. The first mirror and the second mirror are secured on respective first and second shafts, with the first mirror performing a continuous first vibration with a first frequency, and the second mirror performing a continuous second vibration with a second frequency different from the first frequency and/or with a phase difference with respect to the first vibration. Each of the two shafts has a known position such that the first vibration is synchronous with the second vibration. The laser is activated/deactivated upon reaching/leaving an irradiation point. The generated vibrations of the mirrors describe a continuous Lissajous curve.