Linear Optical Reader Alignment Using Collimated MicroLED Beam
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Solution Overview
Problem
Linear optical information readers face challenges in achieving a thin, well-defined line of light comparable to laser systems without speckle noise, while also requiring compact dimensions and precise alignment, especially with non-coherent light sources which have less stringent production precision requirements.
Innovation Solution
The design incorporates a collimator and beam shaper to emit a collimated beam with a thin line of light, ensuring the optical receiving and illumination axes are coplanar, using a compact optical group with few lenses and a microLED source to achieve a line thickness of less than 15 mm and divergence comparable to laser systems, while minimizing aberrations and misalignment issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a laser source is used to produce a thin line of light, then the line definition is improved, but speckle noise increases
Solution Approach 1:
The patent changes the fundamental parameter of light coherence by using non-coherent light sources (LEDs) instead of coherent laser sources. This parameter change maintains the ability to produce a thin, well-defined line of light while eliminating the speckle noise characteristic of laser illumination, as non-coherent light does not exhibit the interference patterns that cause speckle.
2Object-generated harmful factors
If non-coherent light sources are used, then speckle noise is reduced, but alignment precision requirements increase
Solution Approach 1:
The patent introduces an intermediary alignment system consisting of alignment marks and detection optics. These intermediaries facilitate the alignment process by providing visual or optical references that guide the positioning of the illumination device relative to the receiving device, thereby managing the increased alignment precision requirements imposed by using non-coherent light sources.
3Volume of moving object
If the optical system is made compact, then the device size is reduced, but alignment tolerance decreases
Solution Approach 1:
The patent implements self-alignment features where the optical components are designed to automatically align or guide each other during assembly. Alignment marks are integrated into the component structures themselves, and the optical design inherently promotes proper positioning, thereby reducing the impact of tight alignment tolerances in compact configurations.
4Measurement precision
If a thin line of light is produced, then reading accuracy is improved, but the optical system complexity increases
Solution Approach 1:
The patent segments the optical system into distinct functional modules: an illumination device with specific optical elements for line generation, a receiving device with linear sensor array, and separate alignment systems. This segmentation allows each module to be optimized independently for producing a thin line of light while managing overall system complexity through modular design and standardized interfaces.
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 allows for a compact, efficient linear reader that produces a thin, well-defined line of light with reduced speckle noise, effectively addressing alignment and noise challenges, and ensuring all photo-sensitive elements are adequately illuminated, enhancing reading depth and accuracy.
Implementation Method 1
a collimator suitable for emitting a collimated beam of light at its output, the cross-section of which in a plane substantially perpendicular to the direction of propagation has a major dimension and a minor dimension, with divergence in the minor dimension of less than 1.5° of half-amplitude
Implementation Method 2
a beam shaper suitable for emitting a shaped collimated beam at its output the cross-section of which in a plane substantially perpendicular to the direction of propagation has a major dimension and a minor dimension and is suitable for making said major dimension substantially parallel to said major dimension of said field of view
Implementation Method 3
an illumination device that includes at least one source of non-coherent light
Data Source
AI summary
The present invention relates to an active alignment method of a receiving device (2, 2′) including a sensor (4) and of a illumination device (6, 6′) including at least one light source (18, 8′) suitable for emitting a beam of light, including: —Assembling said receiving device (2, 2′); —Stably fixing said receiving device (2, 2′) on a chassis (30); —Actively aligning an optical group (11, 11′) of said illumination device (6, 6′) with respect to said light source (18, 18′); —Fixedly connecting said optical group (11, 11′) of said illumination device to said light source (18, 18′); —Actively aligning said illumination device (6, 6′) with respect to said receiving device (2, 2′); and —Stably fixing said illumination device (6, 6′) to said chassis (30).