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Large-range and high-precision autofocus method based on an annular DOE for a laser direct writing system
Optics Express
|March 18, 2022
Summary
A novel autofocus method using an annular diffractive optical element (DOE) achieves high precision for laser direct writing. This technique offers a large detection range and stability, crucial for microfabrication systems.
Area of Science:
- Optics
- Precision Engineering
- Laser Technology
Background:
- Laser direct writing systems require precise focusing for microfabrication.
- Existing autofocus methods may lack the required range or precision for complex applications.
Purpose of the Study:
- To develop a large-range, high-precision autofocus method for laser direct writing.
- To enable simultaneous determination of defocus direction and amount.
Main Methods:
- Utilized an annular diffractive optical element (DOE) in a laser direct writing system.
- Analyzed the shape of the return spot to extract focusing information.
Main Results:
- Achieved a linear detection range of at least 76 µm.
- Demonstrated a sensitivity and detection accuracy of 100 nm.
- Maintained noise fluctuation below 50 nm.
Conclusions:
- The proposed autofocus method offers significant advantages in detection range, precision, and stability.
- This method is suitable for various wafer-scale complex microstructure preparation systems.
