Ring Light Illuminator with Anamorphic Beam Shaping
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Solution Overview
Problem
Ring illumination systems using LEDs face challenges in achieving maximum light intensity and homogeneous illumination due to the large divergence of light exiting optical fibers and inhomogeneous illumination fields, especially when light is directed at an oblique angle, which reduces the effective intensity on the surface being illuminated.
Innovation Solution
A ring light illuminator comprising a plurality of annularly arranged LEDs with a light collector and an anamorphic system that directs light efficiently onto the surface, compensating for the oblique angle by shaping the beam to maintain intensity and homogeneity, using a homogenizing rod for total internal reflection and an anamorphic system for beam shaping and focusing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light from LEDs is directed into the area of interest using conventional optical elements, then the area is illuminated, but the light intensity is reduced due to oblique angle incidence and large divergence
Solution Approach 1:
The optical system is divided into distinct functional modules: LED light sources, individual condensing lenses for each LED, a rod lens for homogenization, and beam shaping elements. Each module performs a specific function, allowing optimization of light intensity at each stage while managing overall system complexity through modular design.
Solution Approach 2:
A rod lens is introduced as an intermediary element between the condensing lenses and the final illumination area. This rod lens serves as a light integrator that homogenizes the light from multiple LEDs and redirects it to provide high-intensity illumination at normal incidence to the surface, effectively mediating between the divergent LED sources and the target area.
2Illumination intensity
If multiple LEDs are arranged in an annular configuration, then the area can be illuminated, but the illumination field becomes inhomogeneous
Solution Approach 1:
The rod lens acts as a light integrator that receives light from multiple annularly arranged LEDs and homogenizes it through total internal reflection. This intermediary element transforms the inhomogeneous light distribution from individual LEDs into a uniform illumination field, eliminating the need for precise alignment between multiple LEDs and the target area.
Solution Approach 2:
The rod lens is specifically designed to create homogeneous illumination through its light-integrating properties. By using total internal reflection within the rod, the light from multiple sources is mixed and redistributed uniformly across the exit face, ensuring homogeneous illumination in the area of interest regardless of the annular LED arrangement.
3Area of stationary object
If light is directed at an oblique angle to illuminate the area, then the field of view is expanded, but the effective light intensity on the surface is reduced
Solution Approach 1:
Instead of directing light at an oblique angle to expand the illuminated area, the system inverts the approach by using the rod lens to redirect light at normal incidence to the surface. This inversion maintains maximum light intensity while the annular arrangement of LEDs and beam shaping elements ensure the entire area of interest is uniformly illuminated.
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 ensures a well-defined and homogeneous illumination field with maximized light intensity on the surface, preventing reduction in intensity due to oblique angle incidence, thus enhancing the efficiency of machine vision and inspection processes.
Implementation Method 1
using a homogenizing rod for total internal reflection
Implementation Method 2
an anamorphic system for beam shaping and focusing
Data Source
AI summary
A ring light illuminator with annularly arranged light sources is disclosed. To each light source there corresponds a light collector, a homogenizing means for light from the light source, and an anamorphic system for imaging an output of the homogenizing means into an area to be illuminated. The anamorphic system compensates deformations of a cross-sectional area of a light beam in a surface to be illuminated due to an oblique angle of incidence of the light beam onto the surface. The homogenizing means in embodiments is a rod, into which light from the light collector is directed. The end of the rod opposite the light collector is imaged by the anamorphic system into the area to be illuminated on the surface. Also disclosed is a method for illumination.