Acousto-Optic Deflector Laser Writing System Angular Dispersion Compensation
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Solution Overview
Problem
Current two-photon-polymerization laser direct writing systems based on acousto-optic deflectors face challenges with high-speed and high-precision machining of three-dimensional micro-nano structures due to angular dispersion and astigmatism issues, which limit scanning speed and laser focus quality.
Innovation Solution
A two-photon-polymerization laser direct writing system that includes an ultrafast laser device, beam expander, scanning field center and edge angular dispersion compensators, and an astigmatism compensator, utilizing a two-dimensional acousto-optic deflector to achieve precompensation and compensation for angular dispersion and astigmatism, ensuring consistent laser focus and high-speed scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a two-dimensional acousto-optic deflector is used to increase scanning frequency, then scanning speed is improved, but angular dispersion and astigmatism increase, degrading laser focus quality
Solution Approach 1:
The patent introduces a pre-compensation module that performs preliminary compensation for angular dispersion before the light passes through the acousto-optic deflector. This preliminary action counteracts the harmful effects before they occur, allowing high-speed scanning while maintaining laser focus quality.
Solution Approach 2:
The patent uses an angular dispersion compensator as an intermediary component between the laser source and the acousto-optic deflector. This intermediary device specifically addresses the angular dispersion issue by introducing equal and opposite dispersion, thereby neutralizing the harmful effect while allowing the deflector to function at high speeds.
2Productivity
If scanning frequency is increased to improve machining speed, then productivity is improved, but angular dispersion compensation becomes more difficult to maintain
Solution Approach 1:
The patent divides the compensation system into separate functional modules: a pre-compensation module for angular dispersion compensation before the deflector, and a post-compensation module for additional adjustments after the deflector. This segmentation allows each module to be optimized independently, making the overall system more manageable even at high scanning frequencies.
Solution Approach 2:
The patent employs dynamic adjustment mechanisms where the compensation parameters can be modified in real-time based on the scanning frequency and conditions. This dynamic approach allows the system to adapt to varying operational requirements, maintaining effective compensation across different productivity levels without requiring complete system redesign.
3Productivity
If high-speed scanning is implemented, then machining efficiency is improved, but astigmatism increases, affecting feature size consistency
Solution Approach 1:
The patent introduces an astigmatism compensator as a specialized intermediary component that addresses astigmatism specifically. This compensator works in conjunction with the angular dispersion compensator to handle the distinct optical aberrations introduced during high-speed scanning, ensuring consistent feature sizes across the entire scanning field.
Solution Approach 2:
The patent utilizes parameter changes in the compensation system, adjusting optical parameters such as focal lengths and dispersion values dynamically to counteract astigmatism. By modifying these parameters in response to scanning conditions, the system maintains feature size consistency even at high machining efficiencies.
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
The system enables high-speed laser scanning at 50,000 lines/s, improving machining efficiency by 500 times or more, allowing for high-precision and high-speed fabrication of three-dimensional micro-nano structures, with consistent feature sizes reaching diffraction limits.
Implementation Method 1
The diffractive deflection scanners, including a liquid crystal spatial light modulator, a digital micro mirror array and the acousto-optic deflector, deflect a light beam by modulating a wavefront of light
Implementation Method 2
The two-photon absorption effect is a third-order nonlinear effect, the intensity of the two-photon absorption effect is in direct proportion to the square of light intensity
Implementation Method 3
The two-photon polymerization effect refer to an effect that when the light-sensitive material is irradiated by a tightly focused ultrafast laser, the powerful two-photon absorption effect near a tight-focusing focus results in a large number of free radicals, which polymerizes into chains and forms microstructures
Implementation Method 4
the accuracy of microstructure machining beyond diffraction limit is realized, a machinable horizontal feature size can be below 200 nm
Data Source
AI summary
A two-photon-polymerization laser direct writing system based on an acousto-optic deflector is provided, which includes an ultrafast laser device, a beam expander, a scanning field center angular dispersion compensator, a two-dimensional acousto-optic deflector, a scanning field edge angular dispersion compensator, an astigmatism compensator and a focusing objective lens, the ultrafast laser device is configured to emit an ultrafast laser; the scanning field center angular dispersion compensator is configured to conduct precompensation on an angular dispersion at a center of a scanning field; the two-dimensional acousto-optic deflector is configured to deflect the ultrafast laser on the angular dispersion at the center of the scanning field; the scanning field edge angular dispersion compensator is configured to compensate for an angular dispersion at an edge of the scanning field; the astigmatism compensator is configured to compensate for astigmatism; the focusing objective lens is configured to conduct tight-focusing on the ultrafast laser.