Stereolithography Printer Light Intensity Calibration
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Solution Overview
Problem
3D printing technologies face challenges due to imperfections in light projection intensity, leading to variations in object build quality, as real-world constraints affect the consistency of light energy used in additive-manufacturing processes.
Innovation Solution
The development of an intensity map that accounts for variations in light projection intensity by calibrating cross-sectional images of a 3D model, using regression analysis based on calibration measures, to ensure consistent object building.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If light projection is used to cure resin in stereolithography printing, then additive manufacturing capability is achieved, but variations in light intensity cause non-uniform curing and build quality issues
Solution Approach 1:
The system performs preliminary calibration by printing a calibration object with known geometric features, measuring its actual dimensions, and calculating correction factors before producing the final object. This preliminary action characterizes the light intensity variations and creates a compensation map that is applied during subsequent printing operations, resolving the intensity non-uniformity issue while maintaining additive manufacturing capability
Solution Approach 2:
The system changes the exposure parameters dynamically based on spatial location by applying correction factors derived from calibration measurements. Each region of the build area receives adjusted exposure energy proportional to the measured light intensity variations, transforming the uniform exposure approach into a spatially-adaptive exposure strategy that compensates for optical imperfections
2Loss of time
If calibration measures are taken at discrete locations, then measurement time is reduced, but interpolation to full resolution requires additional computational processing
Solution Approach 1:
The calibration process divides the build area into a discrete grid of measurement locations, taking measurements at specific points rather than continuously across the entire area. This segmentation reduces the number of measurements required while maintaining sufficient characterization of light intensity variations through systematic sampling of the build volume
Solution Approach 2:
The system creates a digital model (intensity map) that copies and represents the physical light intensity distribution based on discrete measurements. This digital copy is then processed computationally to generate correction factors for all pixels, avoiding the need for physical measurements at every single pixel location while preserving the essential characteristics of the light field
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 compensates for light projection variations, reducing artifacts and achieving more uniform object builds by adjusting light exposure accordingly, thereby enhancing the quality of 3D printed objects.
Implementation Method 1
Photopolymer-based 3D printers that use bottom-up illumination can project light upwards through an optically transparent window into a vat of photo-reactive resin to cure at least a portion of the resin
Data Source
AI summary
Techniques and systems for 3D printing with machines having imperfect light projection are described. A technique includes receiving an intensity map comprising a plurality of pixel values, wherein the pixel values of the intensity map represent variations in intensity of light projection of an additive-manufacturing apparatus; receiving cross-sectional images of a three dimensional (3D) model of an object, each cross-sectional image comprising a plurality of pixel values, each pixel value of each cross-sectional image having an X-location and a Y-location; for each cross-sectional image of the 3D model, applying pixel values of the intensity map to corresponding pixel values of the cross-sectional image of the 3D model, to make one of a plurality of additive-manufacturing images that are calibrated to account for the variations in intensity of the light projection; and providing the additive-manufacturing images to the additive-manufacturing apparatus to build the object.