Glass MEMS Scanner Mirror for Low-Heat Lissajous Laser Machining
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Solution Overview
Problem
Existing laser processing technologies face challenges with thermal management in MEMS scanners, leading to undesired heating, phase shifts, and reduced imaging quality due to the absorption of residual radiation by the mirror elements.
Innovation Solution
The use of a glass-based MEMS scanner with a highly reflective coating and a transmissive substrate material helps to avoid thermal heating by allowing residual radiation to pass through, while maintaining high reflectivity for efficient laser processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a reflective coating is applied to the mirror element to improve laser reflection efficiency, then the laser processing efficiency is improved, but thermal heating of the mirror element occurs due to absorption of residual radiation
Solution Approach 1:
The mirror element is designed with a reflective coating applied only to the specific region where laser radiation strikes, while other regions remain transparent. This allows the coated area to reflect laser energy efficiently for processing, while uncoated areas allow residual radiation to pass through, reducing thermal accumulation in the mirror substrate.
Solution Approach 2:
The mirror element combines a transparent substrate material (such as glass or transparent polymer) with a reflective coating layer. This composite structure enables simultaneous reflection of incident laser radiation by the coating and transmission of residual radiation through the transparent substrate, solving the thermal management problem while maintaining high reflection efficiency.
2Manufacturing precision
If the mirror element is made highly reflective to improve laser beam direction control, then the imaging quality is improved, but phase shifts occur due to thermal loading
Solution Approach 1:
By applying the reflective coating only to the necessary functional area of the mirror element, the design minimizes the amount of material that absorbs thermal energy. This localized approach maintains precise beam control where needed while reducing overall thermal loading that causes phase shifts and imaging degradation.
Solution Approach 2:
The transparent substrate acts as an intermediary between the reflective coating and the external environment. It allows residual radiation to pass through rather than being absorbed and converted to heat, thereby reducing thermal expansion and phase shifts that would otherwise degrade imaging quality and stability.
3Device complexity
If a traditional opaque mirror is used to deflect laser radiation, then the mirror structure is simple, but thermal management becomes problematic due to heat accumulation
Solution Approach 1:
The mirror element uses a composite structure combining a transparent substrate with a reflective coating. This maintains relative structural simplicity while fundamentally improving thermal management by allowing residual radiation to transmit through the transparent material rather than accumulating as heat in an opaque mirror.
Solution Approach 2:
The mirror substrate transitions from being opaque (traditional) to transparent (innovative), fundamentally changing its optical parameters. This parameter change allows residual laser radiation to pass through the substrate, transforming the thermal management approach from heat dissipation to heat avoidance, while maintaining the mechanical simplicity of a single-piece mirror structure.
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 enables high ablation rates with controlled thermal input, maintaining imaging quality and reducing the risk of thermal deformation in the scanner, thus achieving efficient and precise laser processing.
Implementation Method 1
The use of a glass-based MEMS scanner with a highly reflective coating
Implementation Method 2
a transmissive substrate material helps to avoid thermal heating by allowing residual radiation to pass through
Implementation Method 3
at least one mirror element can be deflected by means of electrostatic, electromagnetic, thermal and/or piezoelectric force exertion
Implementation Method 4
at least one mirror element can be deflected by means of electrostatic, electromagnetic, thermal and/or piezoelectric force exertion
Implementation Method 5
at least one mirror element can be deflected by means of electrostatic, electromagnetic, thermal and/or piezoelectric force exertion
Implementation Method 6
at least one mirror element can be deflected by means of electrostatic, electromagnetic, thermal and/or piezoelectric force exertion
Data Source
AI summary
A method for processing a workpiece includes directing laser radiation by a micro-electromechanical system (MEMS) scanner onto the workpiece along a processing line in a form of a Lissajous figure, which is variable or static during processing of the workpiece by the laser radiation. A power of the laser radiation is more than 20 W, a pulse length of the laser radiation is between 100 fs and 200 ns, a pulse repetition rate of the laser radiation is more than 200 kHz, a mirror aperture of the MEMS scanner is between 6 mm and 10 mm, a scan frequency of the laser radiation is between 5 kHz and 20 kHz, an angle of incidence of the laser radiation is less than 5° in deviation and a scan angle of the MEMS scanner is less than 2°.