Laser Return-Beam Optics Layout for Compact Contamination Control
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Solution Overview
Problem
The existing laser processing apparatuses face challenges in reducing the size of the quarter-wave plate and preventing contamination due to its location closer to the processing target, which increases the apparatus size and susceptibility to splashes during processing.
Innovation Solution
The apparatus includes a polarization beam splitter and quarter-wave plate positioned between the laser beam source and optical scanning unit, allowing for improved detection efficiency and reduced quarter-wave plate size, while maintaining effective contamination prevention by not placing the quarter-wave plate directly in front of the processing target.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the quarter-wave plate is disposed between the fθ lens and the processing target to detect reflected light, then the detection efficiency of the return beam is improved, but the size of the quarter-wave plate must cover the entire processed surface which increases the apparatus size
Solution Approach 1:
The quarter-wave plate is extracted from its conventional position between the fθ lens and processing target, and relocated to the optical path between the polarization beam splitter and optical scanning unit. This extraction allows the quarter-wave plate to operate in a region where a smaller size suffices, while still achieving effective detection of the return beam through the polarization beam splitter's reflection characteristics.
2Measurement precision
If the quarter-wave plate is disposed between the fθ lens and the processing target, then the detection efficiency is improved, but the quarter-wave plate is exposed to splashes generated from the processing target causing contamination
Solution Approach 1:
The quarter-wave plate is extracted from the contamination-prone zone near the processing target and relocated to a cleaner region in the optical path. This spatial extraction eliminates direct exposure to splashes while preserving the detection function through the optical system's return beam path.
Solution Approach 2:
The optical scanning unit and polarization beam splitter act as intermediaries that allow the quarter-wave plate to detect the return beam without being directly exposed to the processing target. The return beam passes through these intermediary components to reach the quarter-wave plate, providing indirect detection while protecting the plate from contamination.
3Area of stationary object
If the quarter-wave plate size is increased to cover the entire processed surface, then the detection coverage is improved, but the overall apparatus size increases
Solution Approach 1:
The quarter-wave plate is extracted from the position requiring full processed surface coverage and relocated to a compact optical path configuration. This extraction enables adequate detection coverage through the optical system's beam path without requiring the quarter-wave plate to physically cover the entire processed surface area.
Solution Approach 2:
The detection coverage is achieved by utilizing the optical path's three-dimensional configuration rather than relying on the quarter-wave plate's two-dimensional surface coverage. The return beam's path through the optical scanning unit and polarization beam splitter enables effective detection with a smaller quarter-wave plate by exploiting the spatial arrangement of the optical components.
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 configuration enables a more compact apparatus design and reduces contamination risks, while enhancing detection efficiency and monitoring capabilities through the use of a control unit for processing state analysis.
Implementation Method 1
a polarization beam splitter disposed between the laser beam source and the optical scanning unit on an optical path of the laser beam
Implementation Method 2
a quarter-wave plate disposed between the polarization beam splitter and the optical scanning unit on the optical path
Implementation Method 3
an optical scanning unit configured to scan the processed surface with the laser beam by operating a dielectric mirror to adjust an incident angle of the laser beam
Data Source
AI summary
A laser processing apparatus according to an embodiment includes a laser beam source, a stage, an fθ lens, a galvano scanner that scans a processed surface of a processing target with a laser beam by operating a dielectric mirror to adjust an incident angle of the laser beam with respect to the fθ lens, a polarization beam splitter disposed between the laser beam source and the galvano scanner on an optical path of the laser beam, a quarter-wave plate disposed between the polarization beam splitter and the galvano scanner on the optical path, and a light detection unit that detects a return beam of the laser beam from the processed surface irradiated with the laser beam, the return beam passing through the fθ lens, the galvano scanner, the quarter-wave plate, and the polarization beam splitter in this order.