Laser Scanning Calibration Plate for Solid-Imaging Alignment

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Solution Overview

Problem

Existing solid-imaging devices face challenges in efficiently and cost-effectively aligning radiation sources with image planes for precise three-dimensional object formation, particularly due to complex and tedious calibration processes.

Innovation Solution

A method involving a calibration plate with a periodic array of fiducial marks that scatter actinic light, allowing for iterative position measurements to establish a calibrated relationship between mirror angular positions and build plane coordinates, using a detector to receive scattered light and perform intelligent pattern-matching searches, which is immune to thermal environmental variables and can be completed quickly without moving the solid-imaging system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional alignment methods are used to align the radiation source and image plane, then the calibration can be performed, but the process becomes complex and tedious

Engineering Contradiction:
Improvealignment precisionVSAvoidcalibration process complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces a calibration plate with fiducial marks as an intermediary object between the radiation source and image plane. This calibration plate serves as a mediator that simplifies the alignment process by providing easily detectable reference points, thereby reducing the complexity of the calibration procedure while maintaining alignment precision

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent uses a digital model or map of the calibration plate that contains precise coordinate information of the fiducial marks. This digital copy allows the system to compare actual detected positions with expected positions, enabling automated calibration without complex manual alignment procedures

Inventive Principle:
Principle #26Copying

2Measurement precision

If traditional calibration methods are used, then alignment can be achieved, but the calibration process takes a long time

Engineering Contradiction:
Improvecalibration accuracyVSAvoidcalibration time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The calibration system performs self-calibration by automatically detecting the fiducial marks on the calibration plate and computing the transformation parameters between the radiation source coordinate system and the image plane coordinate system. This automated self-service approach eliminates the need for time-consuming manual calibration while maintaining high accuracy

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces manual mechanical alignment procedures with an optical detection system that uses the laser radiation source itself to detect the fiducial marks. This substitution of mechanical operations with optical detection and computational processing significantly reduces calibration time while preserving accuracy

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 method provides fast, accurate, and precise calibration, reducing the time required for calibration to less than an hour and minimizing the impact of laser power variations, while being relatively low-cost and capable of modeling system errors effectively.

Implementation Method 1

a periodic array of fiducial marks, which are formed in or on the non-scattering surface and which scatter actinic light

Methodology Applied
Scientific EffectLight scattering: Scattering

Data Source

PatentEP2185344B1Automatic geometric calibration using laser scanning reflectometry
Publication Date: 2018.06.13 3D SYSTEMS INC
  • EP2185344B1 patent drawingFigure 1
  • EP2185344B1 patent drawingFigure 2
  • EP2185344B1 patent drawingFigure 3

AI summary

Systems and methods for calibrating a solid-imaging system (10) are disclosed. A calibration plate (110) having a non-scattering surface (140) with a plurality (150) of light-scattering fiducial marks (156) in a periodic array is disposed in the solid-imaging system. The actinic laser beam (26) is scanned over the fiducial marks, and the scattered light (26S) is detected by a detector (130) residing above the calibration plate. A computer control system (30) is configured to control the steering of the light beam and to process the detector signals (SD) so as to measure actual center positions (xA, yA) of the fiducial marks and perform an interpolation that establishes a calibrated relationship between the angular positions of the mirrors and (x,y) locations at the build plane (23). The calibrated relationship is then used to steer the laser beam in forming a three-dimensional object (50).