Laser Additive Manufacturing Diffractive Optical Element Intensity Control
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Solution Overview
Problem
Laser additive manufacturing with high energy density lasers often results in nonuniform temperature distributions within molten pools, leading to solidification cracking, voids, and residual stresses due to the Gaussian light intensity distribution of typical laser beams, and the top-hat type light intensity distribution does not fully address these issues, especially during continuous additive manufacturing.
Innovation Solution
A laser additive manufacturing apparatus and method utilizing a diffractive optical element to convert the laser beam's light intensity distribution into a 'dog-ear' type, where the outer peripheral portion has higher intensity than the central portion, ensuring uniform heat accumulation and preventing plasma formation by supplying powder material to the irradiated area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a laser beam with Gaussian light intensity distribution is used for additive manufacturing, then high energy density can be achieved, but nonuniform temperature distribution occurs causing solidification cracking and poor deposition quality
Solution Approach 1:
The patent applies local quality by creating different light intensity characteristics in different regions of the laser beam. The diffractive optical element modifies the Gaussian distribution to produce a top-hat distribution with enhanced peripheral intensity, where the outer peripheral portion has higher light intensity than the central portion. This local intensity adjustment ensures uniform melting and temperature distribution across the irradiation region, preventing solidification cracking while maintaining high energy density for efficient material processing.
Solution Approach 2:
The patent changes the light intensity distribution parameter from Gaussian to top-hat type with inverted intensity profile. By using a diffractive optical element, the laser beam's intensity distribution is transformed so that the outer peripheral portion has higher intensity than the central portion. This parameter change resolves the contradiction by maintaining high overall energy density while achieving uniform local temperature distribution for high-quality deposition.
2Temperature
If a top-hat type light intensity distribution is used to achieve uniform temperature, then temperature uniformity improves, but continuous scanning causes excessive heat accumulation in the central portion
Solution Approach 1:
The patent applies local quality by inverting the traditional top-hat distribution concept. Instead of uniform intensity across the beam, the diffractive optical element creates a distribution where the outer peripheral portion has higher light intensity than the central portion. This local intensity reversal prevents heat accumulation in the central portion during continuous scanning, while the enhanced peripheral intensity ensures complete melting and uniform temperature distribution across the entire irradiation region.
3Productivity
If high energy density laser beam is used for efficient manufacturing, then productivity increases, but plasma is generated that blocks the laser beam and deteriorates deposition quality
Solution Approach 1:
The patent applies local quality by concentrating higher light intensity in the outer peripheral portion of the laser beam while maintaining lower intensity in the central portion. This spatial redistribution of energy density prevents excessive energy concentration that would otherwise generate plasma. The modified intensity profile enables use of high overall energy density for efficient manufacturing while the peripheral concentration specifically prevents plasma formation, maintaining beam quality and deposition uniformity.
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 enables high-quality, uniform depositions with reduced temperature differences and prevents plasma blockage, enhancing efficiency in continuous additive manufacturing processes.
Implementation Method 1
a diffractive optical element for converting a light intensity distribution of the laser beam
Data Source
AI summary
A laser additive manufacturing apparatus and a method thereof are provided. The apparatus includes an irradiation unit that irradiates an irradiation region with a laser beam having a light intensity distribution converted by a diffractive optical element, a head having a material supplying unit for supplying powder material to the irradiation region, and a movement mechanism which relatively moves the head and a workpiece. In the irradiation region, irradiation light forms a substantially circular spot having a light intensity distribution in which light intensity in an outer peripheral portion is higher than light intensity in a central portion, and the central portion has predetermined light intensity, and the material supplying unit supplies the powder material to the substantially circular spot.