Glass Laser Machining With Interlaced Raster Scanning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional machining methods for glass materials, such as grinding and precision moulding, are limited in achieving complex shapes and high-quality surface finishes, especially for aspheric and freeform optics, and laser direct write techniques face challenges with thermal accumulation and surface roughness.
Innovation Solution
A direct write laser machining process using an interlaced raster scan pattern with ultrashort pulsed lasers, where scan lines are interlaced to reduce thermal accumulation and increase machining speed, and a subsequent polishing step with a CO2 laser to achieve smooth surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If traditional grinding methods are used to machine glass materials, then surface quality can be achieved, but complex aspheric and freeform shapes cannot be efficiently produced
Solution Approach 1:
The patent replaces traditional mechanical grinding methods with laser-based direct write machining. The laser beam directly ablates glass material to create complex aspheric and freeform optical shapes, eliminating the need for mechanical tool contact and enabling geometries that are impossible or extremely difficult to achieve with conventional grinding tools.
Solution Approach 2:
The patent utilizes controllable laser parameters (wavelength, pulse duration, power, scan speed) to efficiently machine complex optical shapes. By adjusting these parameters, the laser can directly write intricate aspheric and freeform surfaces with high precision and speed, achieving both shape complexity and manufacturing efficiency simultaneously.
2Productivity
If conventional laser direct write techniques are used to machine glass, then material removal can be achieved, but thermal accumulation causes surface roughness and limits machining quality
Solution Approach 1:
The patent employs periodic pulsed laser action with carefully controlled pulse duration and repetition rate. The pulsed regime allows thermal diffusion between pulses, preventing heat accumulation that would otherwise cause surface roughness. This periodic action maintains both high material removal rates and smooth surface quality by synchronizing pulse frequency with thermal relaxation time of the glass material.
Solution Approach 2:
The patent optimizes laser parameters including pulse width, repetition rate, and fluence to achieve clean ablation without thermal damage. By adjusting these parameters within specific ranges, the process removes material efficiently while maintaining surface integrity and preventing the thermal accumulation that leads to roughness.
3Productivity
If high power laser ablation is used to increase machining speed, then productivity improves, but thermal damage and melting occur reducing surface quality
Solution Approach 1:
The patent uses ultrashort pulse durations (femtosecond to picosecond range) combined with high peak power to achieve rapid material removal without thermal damage. The extremely short pulse width delivers energy faster than heat can diffuse into the surrounding material, enabling high machining speeds while maintaining pristine surface quality free from melting or thermal stress.
Solution Approach 2:
The patent employs high-repetition-rate pulsed laser operation where successive pulses are delivered in a periodic manner. This allows cumulative material removal at high speed while the periodic timing ensures adequate thermal relaxation between pulses, preventing heat accumulation and associated surface degradation.
4Manufacturing precision
If CO2 laser polishing is applied to reduce surface roughness, then surface quality improves, but additional process time is required
Solution Approach 1:
The patent combines the ablation and polishing functions into a single integrated laser process. By using ultrashort pulsed laser parameters optimized for both material removal and surface smoothing, the system achieves high-quality surfaces directly during the primary machining operation, eliminating or minimizing the need for separate polishing steps and reducing total process time.
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 process enhances machining depth and surface quality, achieving ablation depths of up to 1000 μm with surface roughness as low as 100 nm, overcoming thermal issues and providing efficient fabrication of optical elements without the need for tooling or mask writing.
Implementation Method 1
Laser direct write machining processes have now been developed. Direct write is the technique of machining, marking or texturing a material wherein the substrate is placed at the focal plane of a focused laser beam
Implementation Method 2
the laser, an acousto-optic modulator and a translation stage are controlled to ablate portions of a monolithic substrate in a shot by shot raster regime
Implementation Method 3
a subsequent polishing step with a CO2 laser to achieve smooth surfaces
Data Source
AI summary
A direct write laser based machining process wherein a laser beam is controlled to machine a glass material in an interlaced raster scan pattern. An embodiment of machining a glass substrate to form an optical element is described. An ultrashort pulsed laser is used for machining and smoothing fused silica, followed by CO2 laser polishing. High speed and high quality machining is possible using this approach, which allows efficient use of high laser repetition rates.