Light Beam Receiver Interference Suppression
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Solution Overview
Problem
Conventional light beam receivers on construction sites are prone to interference from sources like fluorescent lamps, flash lamps, and electric welding, leading to false measurement readings due to insufficient suppression of interfering light flashes, especially when dealing with strongly expanded laser beams.
Innovation Solution
A light beam receiver design incorporating a separate photoelectric interference signal detector with an optical low-pass filter, allowing it to be insensitive to laser light and effectively detect interfering light flashes, while a microcontroller correlates the signals to discard false readings, and the detector can be mounted anywhere, including areas typically hit by the laser beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an additional photo detector is mounted above or below the detector line to detect interference signals, then interference signal detection capability is improved, but device dimensions are overly enlarged
Solution Approach 1:
The interference signal detector is integrated within the housing of the light beam receiver, nested alongside the detector line rather than mounted separately above or below it. This nesting approach allows the additional detector to be incorporated without significantly increasing the overall device volume, resolving the contradiction between improved interference detection capability and device compactness
Solution Approach 2:
The interference signal detector serves multiple functions: it detects interference signals from flash lamps and welding apparatus, while also being positioned to potentially detect laser beams for validation purposes. This multi-functionality justifies its inclusion without requiring additional separate components that would enlarge the device
2Measurement precision
If an additional detector is mounted at a larger distance from the detector line to avoid mistaking laser beams for interference, then false detection of laser beams is reduced, but device complexity and electronic processing requirements increase
Solution Approach 1:
An optical filter is introduced as an intermediary element in front of the interference signal detector. This filter selectively transmits wavelengths characteristic of interference sources (flash lamps, welding apparatus) while blocking or attenuating laser wavelengths. This allows the detector to distinguish interference from laser beams through optical filtering rather than complex electronic processing or spatial separation
Solution Approach 2:
The optical filter changes the spectral parameter of the light reaching the detector, allowing the same detector to respond differently to different light sources based on their wavelength characteristics. This simplifies the system by using optical parameter filtering rather than complex electronic discrimination
3Object-affected harmful factors
If a simple optical filter is used to suppress interfering light flashes, then suppression of light flashes is improved, but suppression of strongly expanded laser beams at the edge of elevation measuring range becomes insufficient
Solution Approach 1:
The detection function is segmented into two separate detectors: the detector line for primary laser beam detection and the interference signal detector for interference detection. Each detector can be optimized with appropriate filtering for its specific function, allowing the system to maintain both suppression of light flashes and accurate detection of expanded laser beams at the edge of the measuring range
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 effectively suppresses interfering light flashes, preventing false measurement readings and allowing accurate detection of laser beams, even at the edge of the elevation measuring range, without the need for complex electronic processing or enlarged device dimensions.
Implementation Method 1
A light beam receiver design incorporating a separate photoelectric interference signal detector with an optical low-pass filter
Implementation Method 2
a photodiode with an optical low-pass filter, allowing it to be insensitive to laser light and effectively detect interfering light flashes
Data Source
AI summary
An improved laser light beam receiver rejects unwanted pulses of optical energy, such as strobe lights or other flashes of light, that can occur on a jobsite. The receiver analyzes a light beam reception by using a photosensitive light beam detector arrangement and a separate photoelectric detector serving as an interference signal detector. This additional detector is not easily able to detect the light beams needed in normal operation. On the other hand, the additional detector does detect mostly all interfering light flashes—caused by flash lamps and other similar devices—whose threshold limit is either at the same level or below that of the light beam detector arrangement. An evaluating circuit such as a microcontroller correlates the time of reception of the light beam detector arrangement and the interference signal detector in order to discard the result if the times of reception correspond to a major extent.