Variable-Magnification Imaging Optics for Thermal Substrate Deformation
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Solution Overview
Problem
During laser processing of substrates, the high energy density laser beam causes the substrate to deform through heat expansion and contraction, leading to inaccuracies in the projected image on the substrate.
Innovation Solution
A laser processing unit is equipped with a line-beam forming optical system, an imaging optical system with a one-direction variable magnification optical unit consisting of a concave cylindrical lens and a convex cylindrical lens, and a scanning mechanism. The distance between the concave and convex cylindrical lenses is adjustable, allowing for changes in imaging magnification in at least one direction to correct for substrate deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high energy density laser beam is used for processing, then processing speed and efficiency are improved, but substrate deformation due to heat expansion and contraction increases
Solution Approach 1:
The imaging optical system pre-calculates and compensates for substrate deformation before laser processing occurs. By determining the deformation amount based on processing conditions and adjusting the imaging magnification in advance, the system counteracts the expected thermal expansion and contraction, maintaining image accuracy throughout the high-speed processing operation.
Solution Approach 2:
The system dynamically changes the imaging magnification parameter of the optical system to compensate for substrate deformation. By adjusting the magnification ratio in response to detected deformation amounts, the system maintains accurate image projection on the substrate despite thermal effects from high energy density laser processing.
2Device complexity
If the imaging magnification is fixed, then the optical system structure is simple, but it cannot correct for substrate expansion and contraction
Solution Approach 1:
The imaging optical system incorporates a variable magnification capability that allows dynamic adjustment during operation. The system can change the imaging magnification ratio based on detected substrate deformation, transforming a static optical system into a dynamic one that adapts to processing conditions while maintaining correction capability.
3Device complexity
If the distance between lenses is fixed, then the optical unit is compact and simple, but the imaging magnification cannot be adjusted
Solution Approach 1:
The system makes the lens spacing dynamic by enabling movement of at least one lens along the optical axis. This allows the distance between lenses to be adjusted based on processing conditions, providing magnification adjustment capability while maintaining a relatively compact structure when lenses are in their base positions.
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 adjustable one-direction variable magnification optical unit enables precise correction of the line-shaped image projected on the substrate, ensuring accurate pattern formation despite substrate expansion and contraction during laser processing.
Implementation Method 1
a one-direction variable magnification optical unit including a concave cylindrical lens (32A) and a convex cylindrical lens (32B) arranged along an optical axis (C) opposite to one another
Implementation Method 2
As a laser beam with high energy density irradiates a substrate, the substrate deforms by heat and expands and/or contracts during laser processing
Data Source
AI summary
A laser processing unit according to the present invention includes a line-beam forming optical system configured to form a line-shaped laser beam from a laser beam with luminous flux, an imaging optical system configured to form the line-shaped laser beam on an object to be processed via a mask, a one-direction variable magnification optical unit including a concave cylindrical lens and a convex cylindrical lens, and a scanning mechanism. The concave cylindrical lens and the convex cylindrical lens are arranged along an optical axis and opposite to one another. A distance between the concave cylindrical lens and the convex cylindrical lens is changeable in order to change an imaging magnification of the imaging optical system in at least one direction.