Laser Pulse Burst Superposition Through Fundamental-Mode Waveguides
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Solution Overview
Problem
Existing methods for generating laser pulses in burst mode face challenges in achieving precise superposition of partial beams during material processing due to beam position, divergence, or angular errors, leading to non-uniform energy distribution and reduced processing quality.
Innovation Solution
A device and method utilizing an optical waveguide, such as a hollow core fiber, to guide laser radiation in a fundamental mode, ensuring precise superposition of partial beams by attenuating higher modes, and using coupling and decoupling optics to maintain beam alignment and direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If free beam propagation with volume-optical structure is used for pulse superposition, then pulse bursts with short temporal distance can be generated, but beam position deviations and non-uniform energy distribution occur due to smallest deviations in beam position, divergence or angular errors
Solution Approach 1:
An optical waveguide is introduced as an intermediary component between the beam splitting and superposition processes. The waveguide confines and guides the laser beams through its core, ensuring precise spatial overlap at the output end regardless of minor deviations in the input beam paths. This mediator structure eliminates the sensitivity to beam position and angular errors that plagues free-space propagation methods.
Solution Approach 2:
The invention changes the propagation parameter from free-space propagation to guided propagation within an optical waveguide. This parameter change transforms the system from one sensitive to beam alignment errors to one that maintains stable beam superposition through the waveguide's confining structure, while still achieving the desired pulse bursting effect through differential path lengths.
2Adaptability or versatility
If multiple mutually synchronized but different lasers are used for processing by means of temporally offset laser pulses, then tailored adjustment of interaction dynamics is possible, but position deviations of partial beams occur due to possibly long interaction distances and high aspect ratios
Solution Approach 1:
Multiple laser beams from different lasers are merged within a single optical waveguide structure. The waveguide combines the beams spatially and temporally, ensuring they emerge with precise alignment and superposition. This merging approach maintains the versatility of using different lasers while eliminating the position deviation problems associated with long interaction distances in free-space propagation.
Solution Approach 2:
The optical waveguide serves as a mediator that receives beams from multiple different lasers, guides them through controlled paths with different lengths, and outputs them with precise spatial and temporal synchronization. This intermediary structure enables the use of multiple laser types while ensuring accurate beam superposition at the workpiece.
3Power
If high average power laser pulses are used for material processing, then processing efficiency increases, but damaging effects on the workpiece increase due to excessive heat input
Solution Approach 1:
The invention implements periodic pulse bursting patterns where groups of high-power pulses are delivered in bursts separated by longer intervals. This periodic action allows the material to cool down between bursts, preventing excessive heat accumulation and damage, while still delivering high average power for efficient processing. The pulse train within each burst provides high peak power for effective material interaction.
Solution Approach 2:
The pulse bursts deliver energy in predetermined patterns with controlled timing and spacing. By pre-planning the burst structure with appropriate inter-pulse and inter-burst intervals, the system optimizes heat input to achieve effective processing while preventing damaging heat accumulation. The preliminary design of the burst pattern ensures both high power delivery and thermal management.
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
Ensures high-quality laser pulse generation with uniform energy distribution across the workpiece, enhancing processing quality and efficiency by maintaining beam alignment and reducing heat input.
Implementation Method 1
an optical waveguide, wherein the coupling optics couples the laser radiation superimposed in the output beam path into the optical waveguide at the input side thereof, and wherein the optical waveguide guides the laser radiation primarily in a fundamental mode
Data Source
AI summary
The invention relates to a device for generating a sequence of laser pulses consisting of pulse bursts. The object of the invention is to provide a possibility of generating laser pulses for material processing in the burst mode at a high quality based on the principle of beam combination. To that end, the invention proposes a device, comprising:at least one laser (1, 14, 15) which generates pulsed laser radiation in the form of a sequence of temporally equidistant individual pulses,a combination element (4) which superimposes the laser radiation supplied to the combination element (4) via at least two spatially separate input beam paths of different length, into pulse bursts in an output beam path (9),a coupling optics (10) arranged in the output beam path (9),an optical waveguide (11), wherein the coupling optics (10) couples the laser radiation superimposed in the output beam path (9) into the optical waveguide (11) at the input side thereof, and wherein the optical waveguide (11) guides the laser radiation primarily in a fundamental mode, anda decoupling optics (12) which couples out the laser radiation from the optical waveguide (11) at the output side thereof. Furthermore, the invention relates to a corresponding method.