Long Range Barcode Scanning via Coherent Light Conversion
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Solution Overview
Problem
Current barcode scanning technologies require close proximity to the scanner, leading to inefficiencies and inaccuracies due to laser speckle interference, especially in manufacturing environments where long-range scanning is necessary for quality control and inventory management.
Innovation Solution
A method using a coherent light source to illuminate indicia, distinguishing between coherent light reflection and non-coherent emission, allowing an imaging device to resolve patterns at long distances by converting coherent light to non-coherent light, thereby overcoming laser speckle issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a laser beam is used for close proximity scanning, then the fine focus can overcome high intensity of ambient light, but laser speckle disrupts the ability to discriminate the contrast of returned light
Solution Approach 1:
The patent introduces a spatial light modulator as an intermediary component between the laser source and the target. This modulator diffuses the coherent laser light into a structured illumination pattern that reduces laser speckle while maintaining the ability to overcome ambient light. The spatial light modulator acts as a mediator that transforms the problematic coherent light into a useful illumination pattern.
Solution Approach 2:
The patent changes the spatial and temporal parameters of the laser illumination by using a spatial light modulator to create time-varying illumination patterns. This parameter transformation allows the system to maintain high illumination intensity while reducing the coherence effects that cause speckle, thereby improving contrast discrimination.
2Measurement precision
If traditional close proximity scanning is used, then accurate scanning can be achieved, but additional steps are required to move indicia into close proximity to the scanner
Solution Approach 1:
The patent extends the scanning capability from close proximity (one-dimensional limitation) to long range (adding a distance dimension). By using structured coherent light illumination combined with speckle reduction techniques, the system achieves accurate scanning at extended distances, eliminating the need to move indicia close to the scanner and thereby improving manufacturing efficiency.
3Length of stationary object
If long range scanning is attempted with coherent light, then scanning distance is increased, but laser speckle generates a blurred response that is inherently inaccurate
Solution Approach 1:
The spatial light modulator serves as an intermediary that processes the coherent light before it reaches the long-range target. By introducing this intermediate processing stage, the system maintains coherent light's long-range propagation capability while eliminating the speckle blur that would otherwise occur at distance.
Solution Approach 2:
The patent employs time-varying illumination patterns created by the spatial light modulator, using periodic modulation of the coherent light. This temporal variation allows the system to capture multiple frames and process them to eliminate speckle blur, maintaining accuracy at long ranges.
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
Enables accurate scanning of barcodes and QR markers at significantly greater distances than traditional scanners, improving manufacturing efficiency and reducing the risk of errors in aerospace and automotive assembly by providing clear contrast between reflective and emissive features.
Implementation Method 1
The first feature includes reflection of coherent light
Implementation Method 2
The second feature includes emittance of non-coherent light
Implementation Method 3
An imaging device capable of distinguishing coherent light from non-coherent light is provided
Data Source
AI summary
A method of optically scanning indicia on an object includes providing a coherent light source for illuminating the object with coherent light. The object is marked with indicia including a first feature and a second feature, with the first feature including reflection of coherent light and said second feature including emittance of non-coherent light when illuminated. An imaging device is capable of distinguishing coherent light from non-coherent light. The indicia are illuminated with coherent light generated by the coherent light source causing the indicia to reflect coherent light and emit non-coherent light. The coherent light is distinguished from the non-coherent light emitted from the indicia by a controller for identifying a pattern of one of said first feature and said second feature.