Laser Beam Machining Apparatus with Orthogonal Polarization Splitting
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Solution Overview
Problem
Existing laser beam machining apparatuses struggle to simultaneously form both circular and elliptical condensed beam spots, limiting the versatility of machining operations such as via hole formation and groove cutting in semiconductor wafers.
Innovation Solution
A laser beam machining apparatus is designed with a beam splitter that splits the laser beam into two orthogonal polarization paths, using a rotary half-wave plate, quarter-wave plates, and cylindrical lenses to create both circular and elliptical beam spots, allowing for simultaneous formation of these shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a condenser with cylindrical lenses is used to change the condensed beam spot shape, then the condensed beam spot shape can be changed into circle or ellipse, but the shape becomes close to a square due to aberration and cannot form a perfect circular via hole
Solution Approach 1:
The laser beam is divided into two separate beams with orthogonal polarizations using a beam splitter. Each beam is independently processed through separate optical paths, allowing independent control of their respective condensed spot shapes. This segmentation enables one beam to form a perfect circular spot while the other forms an elliptical spot, resolving the contradiction between shape adaptability and circular precision.
Solution Approach 2:
Different optical components are assigned to different optical paths to create locally optimized beam conditions. The first optical path uses components optimized for circular spot formation, while the second optical path uses components optimized for elliptical spot formation. This local quality approach allows each beam to achieve its desired spot shape without compromising the other.
2Adaptability or versatility
If a condenser based on cylindrical lenses is used, then the condensed beam spot shape is either a circle or an ellipse, but machining with elliptic and circular condensed beam spots cannot be carried out at the same time
Solution Approach 1:
The single laser beam is segmented into two beams with orthogonal polarizations that can be independently controlled. Each beam can be configured to produce either circular or elliptical condensed spots, and both beams operate simultaneously to perform different machining operations. This enables simultaneous machining with both circular and elliptical beam spots, resolving the contradiction between shape variety and productivity.
Solution Approach 2:
The dual optical path system provides multi-functionality by enabling the laser beam machining apparatus to perform both circular spot machining and elliptical spot machining simultaneously. The system can switch between different operating modes (circular only, elliptical only, or both simultaneously) making it universally applicable to various machining requirements without sacrificing productivity.
3Adaptability or versatility
If the laser beam is split into two orthogonal polarization paths with multiple optical components, then both circular and elliptical beam spots can be formed simultaneously, but the device complexity increases
Solution Approach 1:
The two optical paths are merged at the beam splitter, allowing both circular and elliptical beam spots to be formed from a single laser source. The orthogonal polarization beams are combined and directed to the same condenser, enabling simultaneous formation of both spot types without requiring separate laser systems. This merging approach achieves the desired versatility while managing device complexity.
Solution Approach 2:
The beam splitter acts as an intermediary that divides the single laser beam into two orthogonal polarization paths and later recombines them. The rotary half-wave plate serves as another intermediary to control the polarization state and enable switching between different beam configurations. These intermediary components facilitate the simultaneous formation of circular and elliptical spots while maintaining a relatively compact and manageable optical system.
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
Enables the formation of both perfect circular and elliptical beam spots, enhancing the versatility of machining operations by allowing for various machining techniques, including precise via hole formation and groove cutting.
Implementation Method 1
a beam splitter by which the laser beam oscillated by the laser beam oscillation means is split into a first laser beam having a first plane of polarization and a second laser beam having a second plane of polarization orthogonal to the first plane of polarization
Implementation Method 2
a first quarter-wave plate disposed between the beam splitter and the first reflecting mirror; a second quarter-wave plate disposed between the beam splitter and the second reflecting mirror; a rotary half-wave plate disposed between the laser beam oscillation means and the beam splitter
Implementation Method 3
a cylindrical lens disposed between the beam splitter and the second quarter-wave plate
Implementation Method 4
a condenser lens disposed in a first optical path for guiding the first laser beam split by the beam splitter
Implementation Method 5
a first reflecting mirror which is disposed in a second optical path for guiding the second laser beam split by the beam splitter and by which the second laser beam is returned to the beam splitter; a second reflecting mirror which is disposed in a third optical path for splitting thereinto the second laser beam returned to the beam splitter through the second optical path
Data Source
AI summary
A laser beam machining apparatus including a laser beam irradiation unit, the laser beam irradiation unit including: a laser beam oscillator for oscillating a laser beam; a beam splitter by which the laser beam oscillated by the laser beam oscillator is split into a first laser beam and a second laser beam; a rotary half-wave plate disposed between the laser beam oscillator and the beam splitter; a condenser lens disposed in a first optical path for guiding the first laser beam split by the beam splitter; a first reflecting mirror disposed in a second optical path for guiding the second laser beam split by the beam splitter; a first quarter-wave plate disposed between the beam splitter and the first reflecting mirror; a second reflecting mirror disposed in a third optical path for splitting thereinto the second laser beam returned to the beam splitter through the second optical path; a second quarter-wave plate disposed between the beam splitter and the second reflecting mirror; and a cylindrical lens disposed between the beam splitter and the second quarter-wave plate.