Line Beam Optics Using Reflective Focusing for Thermal Stability
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Solution Overview
Problem
Existing laser apparatuses face challenges in maintaining a consistent focal length during laser irradiation due to thermal expansion of focusing lenses, which can lead to defects in the irradiation process.
Innovation Solution
The apparatus includes a laser source, a telescope unit, a beam-transforming unit, a Fourier unit, a long-axis optical unit, and a short-axis optical unit with a concave reflective surface, which reduces the short-axis width of the line beam and maintains constant curvature in the X-axis direction, thereby minimizing thermal expansion effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a focusing lens is used to condense the line beam to reduce cross-sectional width, then the power per unit area of the laser beam is increased, but the focusing lens thermally expands and the focal length changes causing defects
Solution Approach 1:
The patent replaces the traditional refractive focusing lens with a reflective optical system consisting of a parabolic mirror and a planar mirror. This substitution eliminates the thermal expansion problems associated with refractive lenses by using reflection instead of refraction, thereby maintaining stable focal length while still achieving the desired beam condensation and power concentration.
Solution Approach 2:
The patent changes the optical path parameters by introducing a parabolic mirror with specific focal length characteristics and positioning it at a precise distance from the beam source. The planar mirror is positioned to reflect the beam at a controlled angle, creating a stable optical path that maintains consistent focal properties without thermal drift.
2Productivity
If the cross-sectional width of the line beam is reduced to increase power per unit area, then the efficiency of the laser irradiation process is improved, but thermal expansion of the focusing lens occurs
Solution Approach 1:
The patent replaces the thermal-prone refractive lens system with a reflective mirror system that does not suffer from thermal expansion. The parabolic mirror focuses the beam to achieve the required power density, while the reflective nature of mirrors eliminates the temperature-related focal length instability that plagues refractive lenses.
3Length of moving object
If a focusing lens is used to create a line beam with reduced cross-sectional width, then beam condensation with small focus is achieved, but the focal length of the focusing lens changes due to thermal expansion
Solution Approach 1:
The patent substitutes the unstable refractive focusing lens with a stable reflective parabolic mirror system. The parabolic geometry inherently provides stable focal properties, and the reflective mechanism avoids thermal expansion issues, ensuring consistent focal length while maintaining the desired reduced cross-sectional beam width.
Solution Approach 2:
The patent employs a parabolic mirror with a specifically designed curved surface geometry. This spherical/parabolic curvature is optimized to focus the line beam to the desired cross-sectional width while maintaining thermal stability, as the reflective curved surface does not undergo thermal expansion like refractive lens materials.
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 solution effectively prevents changes in the focal length of the focusing lens during laser irradiation, enhancing the reliability and consistency of the laser beam irradiation process.
Implementation Method 1
a short-axis optical unit configured to focus the dispersed light from the long-axis optical unit onto a reference plane, wherein the short-axis optical unit includes a concave reflective surface
Implementation Method 2
as a line beam passes through the focusing lens, the focusing lens may thermally expand, and a focal length of the focusing lens may change. This may cause a defect to be generated during a laser irradiation process. Therefore, there is a need in the art to reduce the thermal expansion of a lens
Data Source
AI summary
The present disclosure relates to an apparatus for forming a line beam. The apparatus includes a laser source, a telescope unit, a beam-transforming unit, a Fourier unit, a long-axis optical unit, and a short-axis optical unit. The laser source is configured to generate input light. The telescope unit is configured to magnify the input light in an X-axis direction perpendicular to an optical axis, which is a progression direction of the input light. The beam-transforming unit is configured to divide light incident from the telescope unit into a plurality of sub-columns. The Fourier unit is configured to uniformly mix the plurality of sub-columns. The long-axis optical unit is configured to uniformly disperse light mixed by the Fourier unit in the X-axis direction. The short-axis optical unit is configured to focus light passing through the long-axis optical unit onto a reference plane, wherein the short-axis optical unit includes a concave reflective surface, and a curvature of the reflective surface is maintained constant in the X-axis direction.