Interfering Laser Beam Shaping for Aberration-Corrected Structuring
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Solution Overview
Problem
Existing methods for processing optical components using interfering laser radiation face challenges due to accumulated aberrations, which limit precision and flexibility in generating well-defined refractive index modifications, particularly in achieving desired periodic structures.
Innovation Solution
The method employs adaptive optical elements to correct aberrations and control the intensity and phase distribution of laser beams, allowing for precise compensation of deviations and flexible modulation of the period progression in the material, enabling high-quality modifications with lower laser power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high numerical aperture optics are used to generate a well-defined focus, then the intensity distribution and focus definition are improved, but accumulated aberration increases
Solution Approach 1:
A beam shaping element is introduced as an intermediary component in the laser beam path to modify the intensity distribution and compensate for aberrations. This mediator element allows the system to maintain high numerical aperture focusing while correcting the accumulated aberrations that would otherwise degrade the focal quality
Solution Approach 2:
The beam shaping element dynamically adjusts parameters such as intensity distribution, wavefront curvature, and beam profile to optimize the focal characteristics. By changing these parameters, the system maintains well-defined focus with high numerical aperture while compensating for aberration accumulation
2Reliability
If dynamic delay is used to maintain coherence, then coherence is preserved, but device complexity increases
Solution Approach 1:
The beam shaping element combines multiple functions including coherence maintenance, intensity distribution control, and aberration compensation into a single integrated component. By merging these functions, the system maintains coherence without requiring separate dynamic delay mechanisms, thereby reducing overall device complexity
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 allows for the generation of well-defined modifications with improved precision and flexibility, enabling the creation of desired optical functionalities with enhanced imaging quality and adjustable period progression.
Implementation Method 1
at least one adaptive optical element, in particular a deformable mirror or a spatial light modulator, modifies the phase and/or intensity profile across the cross-section of the respective partial beam
Implementation Method 2
the laser beam accumulates varying degrees of aberration along its path from its generation in a (nearly) perfectly collimated initial state to the target object
Implementation Method 3
These partial beams are then deflected and focused so that they superimpose and interfere within a processing zone in the object's material. The resulting interference pattern (hologram) is inscribed into the material by the laser pulses
Implementation Method 4
The high power of the laser pulses heats the component material locally, either up to or below the threshold at which a plasma is generated within the material by a single laser pulse
Data Source
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AI summary
The invention relates to a method and a device for machining an object (1) by means of interfering laser beams. The object of the invention is to ensure improved compensation of the aberrations accumulated over the beam path with methods/devices of this type, given that these aberrations are a significant disruptive factor in terms of precision when structuring the material. In addition, the influencing of the period progression, i.e. the spatial modulation of the periods of the modification generated in the material of the object (1), is to be improved. According to the invention, the laser radiation is generated as a collimated laser beam (3). The intensity distribution and/or the phase progression is influenced for the correction of aberrations over the cross-section of the laser beam (3). The laser beam (3) is divided into two sub-beams (6, 7). Finally, a deflection and focussing of the sub-beams (6, 7) occurs such that the sub-beams (6, 7) overlap in a machining zone (10) in the material of the object (1). Preferably, the deflection and focussing of the sub-beam (6, 7) occurs by means of an adaptive optic (11), which modifies the phase and/or intensity progression over the cross-section of at least one sub-beam (6, 7) and thereby adapts the intensity and/or period progression of a structure generated in the object (1) via the interfering sub-beams (6, 7). Furthermore, the deflection and focussing of the sub-beams (6, 7) preferably includes an aberration correction.