Coupon Reader Illumination Uniformity via Axicon Lens
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Solution Overview
Problem
Current coupon readers face challenges in providing uniform illumination over the surface of coupons, leading to non-uniform light intensity and potential shadows, which can confound analysis of assay results, especially in compact portable devices where a near-field macro imaging design is preferred.
Innovation Solution
A device with a digital camera and logic assembly that repeatedly takes images of the coupon after exposure, comparing them to a stored target indicator pattern representation to determine if they pass a similarity threshold, using a light diffusing assembly with a negative axicon lens to ensure even illumination, and providing a human perceptible indication of target substance detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a compact portable device design is used with near-field macro imaging, then device portability is improved, but illumination uniformity deteriorates due to hotspot problems and shadow formation
Solution Approach 1:
A light diffusing assembly is introduced as an intermediary component between the light source and the coupon. This assembly includes a diffuser element that scatters light rays to eliminate hotspots and create uniform illumination across the coupon surface, while also including a reflective element to redirect oblique light rays and prevent shadow formation in the near-field imaging configuration
Solution Approach 2:
The optical parameters of the illumination system are modified by changing the light ray distribution pattern. The light diffusing assembly transforms the concentrated light rays from the LED into a diffuse, uniformly distributed illumination pattern, altering the spatial distribution of light intensity to eliminate hotspots while maintaining compact device dimensions
2Loss of time
If repeated digital images are taken and compared to target pattern, then detection speed is improved, but analysis time increases due to multiple image comparisons
Solution Approach 1:
The target indicator pattern is pre-captured and stored in memory before actual coupon analysis. This preliminary action creates a reference standard that enables rapid comparison with subsequent coupon images, eliminating the need to perform complex pattern recognition algorithms during real-time analysis and thus speeding up detection while maintaining accuracy
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 solution allows for faster detection of indicator patterns, reduces the time required for analysis, and provides more accurate results by ensuring uniform illumination and minimizing the hotspot problem, even in compact devices, thereby improving the reliability of coupon reading.
Implementation Method 1
light from the light source is transformed by a negative axicon lens into a conical beam pattern
Implementation Method 2
A light diffusing assembly includes a negative axicon lens and a light source. The light from the light source is transformed by the negative axicon lens into a conical beam pattern, which is then incident on a coupon to be analyzed
Data Source
AI summary
When reading a coupon that displays a pattern when a target substance is detected, recognition of the target pattern can be hindered by nonuniform illumination of the coupon. In one aspect, methods and devices are disclosed for uniform illumination of a coupon using a negative axicon lens and a light diffusing assembly. In another separate aspect, methods are disclosed for mathematically compensating for nonuniform illumination of a coupon.