Variable Angle Illumination for High-Speed Machine Vision
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Solution Overview
Problem
Existing precision machine vision inspection systems face limitations in inspection throughput due to the relatively low optical energy output of LED lighting systems, which requires longer image exposure times and slower workpiece motion, and mechanical lighting systems that cannot adjust the angle of incidence quickly enough to support high-speed imaging.
Innovation Solution
A fast variable angle of incidence illumination configuration using a combination of a high-intensity light source, such as a halogen lamp, and a beam steering arrangement with movable elements and controllable actuators to rapidly adjust the angle and range of illumination, allowing for narrow or broad angles of incidence, enabling rapid reconfiguration between imaging positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If LED lighting systems are used with low optical energy output, then the system can be compact and long-lasting, but the image exposure time must be extended and workpiece motion must be slowed, limiting inspection throughput
Solution Approach 1:
The patent replaces LED lighting systems with a halogen lamp and optical fiber cable system. The halogen lamp provides high-intensity optical energy that can be transmitted through optical fiber cables to the illumination positions, eliminating the need for LEDs and enabling fast image exposure times while maintaining high productivity
Solution Approach 2:
The patent employs movable reflector mirrors that can be selectively positioned along the optical axis to adjust the angle of incidence dynamically. This dynamic adjustment capability allows the system to adapt to different imaging positions and workpiece features, supporting high-speed inspection through rapid reconfiguration
2Adaptability or versatility
If mechanical lighting systems with movable reflector mirrors are used to adjust angle of incidence, then the angle can be changed, but the adjustment takes tens or hundreds of milliseconds, limiting inspection throughput
Solution Approach 1:
The patent pre-positions multiple reflector mirrors at different locations along the optical axis, each configured for a specific angle of incidence. The system selects and activates the appropriate pre-positioned mirror based on the required illumination angle, eliminating the need for time-consuming mechanical adjustment during operation
Solution Approach 2:
The illumination system is divided into multiple independent optical paths, each with its own reflector mirror positioned at a specific location and angled to provide a particular angle of incidence. This segmentation allows the system to switch between different illumination angles by activating different optical paths without mechanical movement
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 configuration enables faster adjustment of illumination angles and intensities, supporting high-speed imaging and increasing inspection throughput by allowing for very short image exposure times and rapid reconfiguration between imaging positions, thus enhancing the capability to freeze high-speed motion effectively.
Implementation Method 1
a beam steering arrangement configured to receive the light beam along the first optical path portion and steer the light beam along a second optical path portion
Implementation Method 2
The Fresnel-like diffuser refracts and directs LED light beams onto the surface of a workpiece at various angles of incidence
Implementation Method 3
a beam deflecting arrangement that receives the light beam along the second optical path portion and deflects the light beam along a third optical path portion to illuminate a field of view of the objective lens
Implementation Method 4
The Fresnel-like diffuser includes a plurality of annular, prism-shaped projections which differ in shape depending upon the desired angle of incidence
Data Source
AI summary
A fast variable angle of incidence illumination configuration for a machine vision inspection system, including: a light source that directs a beam along a first optical path portion; a beam steering arrangement that receives the beam and steers it along a second optical path portion; and a beam deflecting arrangement including a plurality of surface portions arranged at respective angles of incidence to receive the beam and deflect it along a third optical path portion to a field of view. The beam steering arrangement includes different surfaces that provide either narrow or wide divergence of the beam toward the deflecting arrangement. The illumination configuration allows for fast adjustment of not only the illumination angle of incidence but also the range of angles (narrow or wide) about the nominal angle. The illumination configuration is particularly suitable for use with light provided by a high-intensity remote light source.