Microlens Array Laser Homogenization With Air-Gap Focal Plane
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Solution Overview
Problem
Existing laser light homogenization devices face issues such as high energy density leading to component destruction, macro-inhomogeneity in intensity profiles, and lack of adjustability, particularly when handling high-energy laser radiation.
Innovation Solution
A non-monolithic design with an optical wedge positioned behind the second microlens array, where the focal plane is located in an air gap, and microlenses have varying focal lengths and diameters to reduce energy density and micro/macro-inhomogeneities, allowing for adjustable optical path compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the microlenses are ordered by increasing diameter and focal length from first to last, then the device structure is simplified, but macro-inhomogeneity occurs in the intensity profile causing uneven workpiece machining
Solution Approach 1:
The patent applies parameter changes by reversing the ordering of microlens parameters (diameter and focal length) from the conventional increasing sequence to a decreasing sequence. This inversion of the parameter gradient resolves the macro-inhomogeneity issue while preserving the simplified manufacturing structure, achieving both ease of manufacture and intensity profile uniformity.
2Device complexity
If the focal plane is located on or in the glass substrate of the second microlens array, then the optical path is compact, but high energy density causes destruction of the coating or glass substrate
Solution Approach 1:
The patent applies segmentation by dividing the optical path into distinct spatial zones: the focal plane is positioned in an air gap between the second microlens array and the optical wedge, separating the high-energy focal region from the optical components. This spatial segmentation prevents energy concentration on the microlens coating or substrate, eliminating the destruction risk while maintaining a compact overall structure.
3Ease of manufacture
If the device has a monolithic structure, then the manufacturing is simplified, but subsequent adjustment of the distance between microlens arrays is not permitted
Solution Approach 1:
The patent applies dynamics by making the distance between the first and second microlens arrays adjustable rather than fixed. This dynamic design allows the homogenized field length to be fine-tuned for different applications, providing adaptability while maintaining a relatively simple overall device structure through modular construction.
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
Prevents optical component damage and effectively reduces inhomogeneities, enabling high-power laser applications with adjustable intensity profiles and improved workpiece surface quality.
Implementation Method 1
a first microlens array (3) having a plurality of microlenses (30.1-30.n) arranged side by side in a first direction (x-direction), a second microlens array (4) having a plurality of microlenses (40.1-40.n) arranged side by side in the first direction (x-direction)
Implementation Method 2
the focal lengths of the microlenses arranged side by side in the first direction (x-direction) vary starting from the first microlens (30.1) to the nth microlens (30.n)
Data Source
AI summary
The invention relates to a device (1.1-1.m) for homogenizing laser light (2.1-2.m), comprising a first microlens array (3) comprising a plurality of microlenses (30.1-30.n) arranged side by side in a first direction and a second microlens array (4) comprising a plurality of microlenses (40.1-40.n) arranged side by side in the first direction; wherein the second microlens array (4) is arranged in the beam propagation direction of the laser light (2.1-2.m) from the first microlens array (3) and the plane (41) of the lens vertices of the second microlens array (4) is inclined at an angle |α| to the plane (31) of the lens vertices of the first microlens array (3), and wherein the microlens arrays (3, 4) are formed such that the focal lengths of the microlenses (30.1-30.n, 40.1-40.n) arranged side by side in the first direction change starting from the first microlens (30.1, 40.1) up to the nth microlens (30n, 40n), wherein an optical wedge (5) is arranged behind the second microlens array (4) in the beam propagation direction and the focal lengths of the microlenses (30.1-30.n, 40.1-40.n) of the microlens arrays (3, 4) are selected such that a focal plane (6) of the device (1.1-1.m) lies in an air gap (7) between the second microlens array (4) and the optical wedge (5).