Compact Field Mapper for Flat-Top Beam Shaping at Distance
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Solution Overview
Problem
Existing laser field mapping systems face challenges in maintaining a desired intensity distribution and flat wavefront over a significant depth of focus, leading to rapid degradation of the intensity profile as the beam propagates, which is problematic for applications requiring small, precise spots at distances far from the optical system.
Innovation Solution
The optical system employs an intermediate optical field derived from the inverse Fourier transform of the desired intensity distribution, using a simple focusing lens to create the desired intensity and wavefront at a selected distance, thereby reducing system complexity and size while maintaining the intensity profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a single field mapping optic is used to create a divergent beam with desired intensity distribution, then the beam profile shaping is achieved, but the depth of focus is significantly reduced and the intensity distribution degrades quickly
Solution Approach 1:
The single field mapping optic is divided into two separate optical elements: a field mapping optic for intensity distribution shaping and a phase correcting optic for wavefront flattening. This segmentation allows each element to perform its specific function independently, resolving the contradiction between achieving desired intensity distribution and maintaining depth of focus.
Solution Approach 2:
A phase correcting optic is introduced as an intermediary element between the field mapping optic and the output beam. This intermediate element corrects the phase distortions introduced by the field mapping optic, enabling the beam to maintain both the desired intensity distribution and a flat wavefront over an extended depth of focus.
2Duration of action of moving object
If a phase correcting optic is added to flatten the wavefront, then the depth of focus is improved, but the system complexity increases
Solution Approach 1:
The field mapping optic and phase correcting optic are combined into a single integrated optical element with two surfaces. This merging reduces the number of separate components and interfaces, thereby reducing system complexity while maintaining the benefits of both intensity shaping and phase correction.
Solution Approach 2:
The integrated optical element performs multiple functions: it shapes the intensity distribution and corrects the phase simultaneously. This multi-functionality eliminates the need for separate dedicated components, reducing overall system complexity while achieving both objectives.
3Manufacturing precision
If an image relay system is used to deliver the beam to a process plane, then the spot size control is improved, but the system size and complexity increase
Solution Approach 1:
The complex image relay system is extracted and replaced by a simple focusing lens. The integrated optical element directly produces the desired intensity distribution and flat wavefront, eliminating the need for additional relay optics while maintaining spot size control precision.
Solution Approach 2:
The system uses parameter optimization in the design of the integrated optical element to achieve the desired spot size and intensity distribution directly at the process plane. By carefully designing the optical parameters of the integrated element, the system achieves precise spot control without requiring complex relay systems.
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 approach allows for the creation of compact optical systems that deliver a desired intensity distribution with a flat wavefront at a chosen process plane without the need for extensive image relay systems, enabling precise and efficient laser processing with reduced complexity and cost.
Implementation Method 1
The intermediate optical field is derived from the inverse Fourier transform of the second optical field
Implementation Method 2
beams with other intensity distributions may be propagated using diffraction-based calculations
Data Source
Figure 1~2
Figure 3~4
Figure 5a~6b
AI summary
A field mapping optical system and method for converting a light beam having a known spatially coherent first optical field to a second optical field with a required intensity distribution and flat wavefront at a desired distance from the system, by creating an intermediate optical field, between the first and second optical fields, the intermediate optical field being derived from the inverse Fourier transform of the second optical field. The optical system provides a compact and simplified field mapper.