Laser Beam Spot Shaping With Single Cylindrical Lens Alignment
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Solution Overview
Problem
Adjusting the spot shape of a laser beam on a workpiece in laser processing apparatuses is difficult due to the complexity of adjusting cylindrical lens pairs, leading to mechanical accuracy issues and increased apparatus size.
Innovation Solution
A laser processing apparatus with a chuck table, a laser beam irradiation unit that includes a condensing lens, an energy distribution correcting unit forming a perpendicular energy distribution, and an imaging lens group composed of multiple lenses, along with a single cylindrical lens to adjust energy density, allowing for easy adjustment of the spot shape without enlarging the apparatus size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a cylindrical lens pair is used to adjust spot shape, then the adjustment of energy density in X-axis direction is achieved, but the adjustment becomes difficult and time-consuming due to generatrix alignment requirements
Solution Approach 1:
The patent extracts the generatrix alignment requirement from the adjustment process by using a single cylindrical lens without the need for pair alignment. The cylindrical lens is positioned with its optical axis parallel to the X-axis, eliminating the complex generatrix matching that would be required with a lens pair, thus simplifying the adjustment process while maintaining spot shape control capability
Solution Approach 2:
The patent segments the adjustment functions by separating the X-axis energy density control (handled by the single cylindrical lens) from the Y-axis energy distribution (handled by the elliptical aperture). This functional segmentation allows each component to be adjusted independently without interfering with the other, improving ease of operation while maintaining manufacturing precision
2Ease of operation
If the number of cylindrical lenses is reduced from two to one, then the adjustment difficulty is reduced, but the movement distance of the cylindrical lens becomes long which makes it difficult to keep mechanical accuracy
Solution Approach 1:
The patent introduces an intermediary component - the elliptical aperture - that mediates the energy distribution control function. By placing the elliptical aperture at a specific position in the optical path, it pre-shapes the beam profile before it reaches the cylindrical lens, allowing the cylindrical lens to operate over a shorter range while achieving the desired spot shape adjustment without compromising mechanical accuracy
3Ease of operation
If the number of cylindrical lenses is reduced from two to one, then the adjustment process is simplified, but the apparatus size is enlarged due to increased movement distance
Solution Approach 1:
The elliptical aperture acts as an intermediary that modifies the beam profile upstream, allowing the single cylindrical lens to achieve the same spot shape control effect over a shorter travel distance. This reduces the space required for the lens movement mechanism, thereby preventing apparatus size enlargement while maintaining ease of adjustment
Solution Approach 2:
The elliptical aperture performs a preliminary action by pre-shaping the energy distribution before the light reaches the cylindrical lens. This preliminary modification reduces the adjustment range required for the cylindrical lens, compacting the overall optical system and preventing apparatus size enlargement
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 easy adjustment of the laser beam spot shape on the workpiece, reducing adjustment time and maintaining mechanical accuracy while minimizing apparatus size.
Implementation Method 1
a condensing lens that condenses the laser beam emitted from the laser oscillator
Implementation Method 2
one cylindrical lens that adjusts energy density in the X-axis direction regarding the laser beam
Implementation Method 3
an imaging lens group composed of two or more lenses that form an image of a beam shape of the laser beam for which the energy distribution has been corrected
Implementation Method 4
a laser beam irradiation unit that irradiates the workpiece held by the chuck table with a laser beam with a wavelength having absorbability with respect to the workpiece
Data Source
AI summary
A laser processing apparatus includes an energy distribution correcting unit that forms skirt parts of a Gaussian distribution of an energy distribution in a Y-axis direction regarding a laser beam emitted from a laser oscillator into a perpendicular distribution, an imaging lens group composed of two or more lenses that form an image of the beam shape of the laser beam for which the energy distribution has been corrected by the energy distribution correcting unit on the upper surface of the workpiece, and one cylindrical lens that adjusts the energy density in an X-axis direction regarding the laser beam for which the energy distribution has been corrected by the energy distribution correcting unit.