Laser Line Module With SLM-Controlled Line Length at Fixed Distance
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Solution Overview
Problem
Existing laser-line triangulation devices cannot vary the length of the projected laser line independently from the working distance, which limits their effectiveness in measuring small objects and affects data quality and resolution.
Innovation Solution
A laser line module with a spatial light modulator (SLM), such as an LCD, is integrated to control the divergence of the laser line by selectively blocking radiation, allowing independent adjustment of the laser line length without changing the working distance, using a micro-lens array and polarizing filters to manage radiation passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the laser line length is reduced to measure small objects or specific features, then the data volume captured by the sensor is reduced and measuring ratio is improved, but the working distance must be changed which limits flexibility
Solution Approach 1:
The patent applies the dynamics principle by making the laser line length adjustable through a spatial light modulator (SLM) that can dynamically change the divergence of the laser beam. This allows the laser line length to be varied independently from the working distance, enabling the system to adapt to different measurement scenarios without physically moving components. The SLM divides the laser beam into multiple sub-beams with different divergences, which can be selectively activated to achieve different line lengths while maintaining a constant working distance.
2Loss of time
If the laser line length is reduced to capture only regions of interest, then data processing efficiency is improved, but the device complexity increases due to additional optical components
Solution Approach 1:
The patent applies the segmentation principle by dividing the laser beam into multiple sub-beams using a spatial light modulator (SLM). Each sub-beam corresponds to a specific region of interest on the object surface. By selectively activating only the sub-beams needed for measurement, the system reduces the data volume captured by the sensor, thereby decreasing data processing time. The SLM segments the optical aperture into multiple zones, each with its own divergence angle, allowing precise control over which areas are illuminated and measured.
3Measurement precision
If a spatial light modulator and micro-lens array are added to control laser divergence, then laser line length control is improved, but the manufacturing cost and production complexity increase
Solution Approach 1:
The patent applies the mechanics substitution principle by replacing traditional mechanical methods of controlling laser line length (such as moving the laser source or sensor) with an optical-based solution using a spatial light modulator (SLM). The SLM uses liquid crystal technology to modulate the phase and amplitude of the laser beam, creating different divergence angles without any moving parts. This substitution of mechanical control with optical control improves measurement precision while reducing mechanical complexity in the optical path.
4Measurement precision
If the laser line length is reduced to improve lateral resolution, then pixel sampling quality is improved, but the working distance adjustment capability is lost
Solution Approach 1:
The patent applies the parameter changes principle by independently controlling the laser line length parameter through the spatial light modulator (SLM) without changing the working distance parameter. The SLM modifies the divergence angle of the laser beam, which directly affects the laser line length and consequently the lateral resolution. By decoupling these two parameters, the system can optimize lateral resolution for specific feature measurement while maintaining a constant working distance, thereby preserving adaptability for different measurement scenarios.
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 flexible laser line length adjustment, reducing data volume, improving measurement resolution, and enhancing data quality by minimizing unwanted reflections, while maintaining a constant working distance.
Implementation Method 1
each point on the surface having a distance from an average height of the height profile and providing a divergence for radiation passing through the MLA at the respective point, which divergence depends on the relative height of the respective point
Implementation Method 2
the radiation has a first polarisation and the SLM is an LCD element and comprises a polarizing filter, wherein the LCD element comprises a layer of liquid-crystal molecules
Data Source
AI summary
A laser line module for projecting a laser line onto a surface of a distant target object, the projected laser line having a laser line length, the laser line module comprising: a laser diode configured to emit radiation in the form of a laser beam; a beam-shaping optical arrangement; a micro-lens array comprising a multitude of microlenses and having a surface with a height profile, each point on the surface having a distance from an average height of the height profile and providing a divergence for radiation passing through the micro-lens array at the respective point, which divergence depends on the relative height of the respective point; and a spatial light modulator that is provided between the beam-shaping optical arrangement and the micro-lens array.