Free-Form Lens Illumination System for Edge Light Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional illumination systems for image processing, especially in industrial applications, suffer from edge light fall-off, leading to measurement inaccuracies and reduced signal-to-noise ratio in three-dimensional image sensors due to non-uniform light distribution.
Innovation Solution
A lighting system employing a free-form lens in the condenser arrangement to increase light intensity towards the edge regions of the object field, compensating for edge light drops without active control elements, ensuring a more uniform light distribution and reducing central reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional lenses are used in the illumination system, then the system structure is simple, but edge light fall-off occurs causing non-uniform illumination
Solution Approach 1:
The free-form lens is designed with spatially varying optical properties to provide different light redirection functions for different regions of the light source. The lens surface geometry is specifically tailored to redirect light from the outer peripheral regions toward the optical axis more strongly than from central regions, creating locally optimized illumination that compensates for edge light fall-off when combined with the imaging lens.
Solution Approach 2:
The free-form lens breaks the rotational symmetry typical of conventional lenses by implementing an asymmetric surface profile. This asymmetric design allows differential light redirection angles for different radial positions, enabling the lens to compensate for the specific asymmetric light fall-off pattern that occurs in the imaging system's edge and corner regions.
2Measurement precision
If conventional lenses are used in the imaging system, then manufacturing is easier, but measurement precision decreases due to edge light drop
Solution Approach 1:
The free-form lens is designed with specific geometric parameters (surface curvature, thickness distribution, radial and tangential profiles) that are optimized to compensate for the imaging system's edge light fall-off characteristics. By carefully controlling these geometric parameters during manufacturing, the lens achieves the required light redistribution function while maintaining compatibility with standard manufacturing processes for plastic optical lenses.
3Measurement precision
If uniform light distribution is achieved in the object field, then signal-to-noise ratio improves, but light intensity in central area increases causing central reflections
Solution Approach 1:
The free-form lens creates a non-uniform light intensity distribution in the object field that is specifically tailored to the imaging system's requirements. By providing stronger illumination to edge and corner regions while maintaining moderate central illumination, the lens achieves uniform effective signal strength across the image sensor without over-illuminating the central area, thus avoiding central reflections on shiny surfaces.
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
The solution provides a fail-safe, uniform illumination system that effectively compensates for edge light drops, enhancing measurement accuracy and reducing light intensity variations across the image sensor, particularly in safety-relevant applications.
Implementation Method 1
a free-form lens (16) facing the light source (12) and further condenser optics (18) arranged behind the free-form lens (16) in the direction of propagation of the light emitted by the light source (12)
Data Source
Figure 1
Figure 2~3
AI summary
The present invention relates to an illumination system for illuminating an object field, in particular for illuminating a scene, comprising a light source and a condenser arrangement for focusing the light emitted by the light source. The condenser arrangement includes a free-form lens designed to illuminate the object field such that the light intensity increases towards the edges of the object field. The invention further relates to an imaging system with such an illumination system.