Visible-Light Alignment for Multi-Beam Light Barriers
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Solution Overview
Problem
Existing light barriers with multiple mirrors for redirecting light beams from emitters to receivers are difficult to align due to the small diameter and precise alignment requirements of laser beams, leading to misalignments and inefficiencies.
Innovation Solution
A light barrier system with optical alignment elements that emit incoherent visible light beams with a larger divergence than the operative light beams, allowing for easier alignment by ensuring the visible light beam covers a predetermined target area, which is retroreflective, ensuring the operative light beam hits the receiver even with minor misalignments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If laser pointers are used for alignment, then the alignment precision is improved, but the difficulty of aligning multiple beams simultaneously increases
Solution Approach 1:
The patent merges multiple alignment functions into a single optical element. Instead of using separate laser pointers for each emitter/receiver pair, a single alignment element emits a common alignment beam that serves all pairs simultaneously. This beam is divided into multiple sub-beams that can be adjusted independently to align with respective mirrors and target marks, thereby simplifying the alignment operation while maintaining precision.
2Measurement precision
If laser beams with small diameter are used, then the alignment precision is improved, but the robustness to misalignment decreases
Solution Approach 1:
The alignment beam is segmented into multiple sub-beams, each corresponding to a specific emitter/receiver pair. Each sub-beam can be independently adjusted to hit its respective target mark on the mirror or receiver. This segmentation allows the system to maintain high alignment precision for each individual beam while providing robustness through independent adjustability, so that misalignment of one beam does not affect others.
3Measurement precision
If multiple individual alignment beams are used for each emitter/receiver pair, then the alignment precision is improved, but the device complexity increases
Solution Approach 1:
A single alignment element performs multiple functions: it emits a common alignment beam that is divided into multiple sub-beams, each serving a specific emitter/receiver pair. This universal alignment element replaces what would otherwise require multiple separate alignment devices, thereby reducing device complexity while maintaining the precision benefits of individual beam alignment through the sub-beam division and independent adjustment capability.
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 system simplifies the alignment process, reduces misalignment issues, and enhances robustness to minor adjustments, while avoiding safety concerns associated with laser light and reducing costs by using LEDs instead of laser diodes.
Implementation Method 1
a first retroreflective element... arranged in a fixed spatial relation to the receiver such that the visible light beam emitted by the alignment element covers the retroreflective element, if the light beam emitted by the emitter impinges on the receiver
Implementation Method 2
The light barrier system comprises an emitter unit... and a receiver unit... An optical alignment element... configured to emit a beam of incoherent visible light... having a predetermined or fixed orientation with regard to a beam of light emitted by the emitter
Data Source
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AI summary
A light barrier system is provided, which comprises one or more pairs of an emitter of light (12), especially invisible light, and a corresponding receiver(50a, 50b, 50c), wherein in an operative state of the system a light beam emitted by the emitter of a pair is directed to the corresponding receiver of the pair and detected by this receiver and the system is configured to detect the interruption of the light beam from the emitter of a pair to the corresponding receiver. The emitter or emitters may be arranged in an emitter unit (1) and the corresponding receiver or receivers may be arranged in a receiver unit (5). At least one of the pairs is associated with an optical alignment element (14), which is arranged in a fixed spatial relation to the emitter(12) of the pair and configured to emit a beam of incoherent visible light having a predetermined orientation with regard to a beam of light emitted by the emitter of the pair(12), such that the visible light beam covers a predetermined target area if the light beam emitted by the emitter impinges on the corresponding receiver of the pair, wherein the beam of visible light emitted by the optical alignment element has a divergence less than or equal to the divergence of the light beam emitted by the emitter of invisible light. A method for aligning an emitter and a receiver in this light barrier system provides for placing one or more retroreflective elements (52a, 52b) on or in the vicinity of the receiver (50a, 50b, 50c) such that the beam of visible light emitted by the optical alignment element impinges on the retroreflective element or one or more of the retroreflective elements when the light beam emitted by the emitter impinges on the receiver of the respective pair, activating the optical alignment element to emit a beam of visible light and adjusting optical components of the system so that the visible beam emitted by the optical alignment element impinges on and is reflected by the retroreflective element or elements.