Compact Beam Homogenizer Using Nested Optical Path
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Solution Overview
Problem
The existing laser annealing techniques face challenges in achieving a compact optical system for homogenizing the energy distribution of a beam spot on an irradiation surface, particularly for larger glass substrates, leading to increased space occupation and reduced productivity due to the extended size of the optical system.
Innovation Solution
A compact beam homogenizer is developed using an array lens with shortened optical path length, categorized into three modes, employing a combination of cylindrical lens arrays and fly-eye lenses to reduce the distance between lenses and achieve homogeneous energy distribution in both short-side and long-side directions, thereby forming a rectangular beam spot efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a conventional optical system is used to homogenize energy distribution, then the beam spot can be shaped into a linear shape, but the optical system becomes large and occupies excessive space
Solution Approach 1:
The patent employs a nested optical structure where a condensing lens is positioned within the focal length distance from the cylindrical lens array, creating a compact nested arrangement. This nesting allows the condensing lens to be integrated into the existing optical path without requiring additional space, thereby achieving linear beam shaping while minimizing the optical system footprint.
Solution Approach 2:
The patent utilizes the focal length dimension by positioning the condensing lens at a specific distance (equal to or less than the focal length) from the cylindrical lens array. This dimensional approach allows the system to achieve linear beam shaping in the optical path while keeping the physical footprint compact by exploiting the optical dimension rather than extending the mechanical structure.
2Manufacturing precision
If the distance between lenses is increased to improve beam homogenization, then energy distribution can be homogenized, but the optical path length increases and the system becomes less compact
Solution Approach 1:
The patent changes the critical parameter of lens spacing by setting the distance between the condensing lens and the cylindrical lens array to be equal to or less than the focal length of the condensing lens. This parameter optimization allows the system to achieve effective beam homogenization while minimizing the optical path length, thereby resolving the contradiction between homogeneity and compactness.
Solution Approach 2:
The condensing lens performs preliminary condensing action on the beam before it reaches the cylindrical lens array. By pre-condensing the beam within the focal length distance, the system achieves effective energy distribution homogenization without requiring extended optical paths, thus maintaining compactness while ensuring manufacturing precision.
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 compact beam homogenizer effectively reduces the size of the optical system, allowing for more compact laser irradiation apparatuses with improved productivity by maintaining homogeneous energy distribution across larger substrate sizes.
Implementation Method 1
employing cylindrical or fly-eye lens arrays with controlled principal points to reduce the distance between lenses
Implementation Method 2
employing cylindrical or fly-eye lens arrays with controlled principal points to reduce the distance between lenses
Implementation Method 3
The compact beam homogenizer effectively forms a rectangular beam with homogeneous energy distribution
Data Source
AI summary
The present invention provides a beam homogenizer for homogenizing energy distribution by making the distance between lenses small to shorten the optical path length with the use of an array lens of an optical path shortened type, and a laser irradiation apparatus using the beam homogenizer. The beam homogenizer is equipped with a front side array lens of an optical path shortened type whose second principal point is positioned ahead on a beam incidence side, a back side array lens of an optical path shortened type whose first principal point is positioned behind on a beam emission side, and a condensing lens, wherein the distance between the second principal point of the front side array lens and the first principal point of the back side array lens is equal to the focal length of the back side array lens.