Laser Line Module With SLM-Controlled Line Length
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Solution Overview
Problem
Existing laser-line triangulation devices are unable to vary the length of the projected laser line independently from the working distance, which limits their effectiveness in measuring small objects and reduces data quality and resolution.
Innovation Solution
A laser line module incorporating a spatial light modulator, such as a liquid crystal device, is used to selectively block radiation, allowing control over the laser line length without changing the working distance, utilizing a micro-lens array and polarizing filter to adjust divergence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the working distance is reduced to achieve a shorter laser line, then the laser line length decreases, but the working distance becomes too short for measuring distant objects
Solution Approach 1:
The laser beam is segmented into multiple parallel sub-beams by the diffractive optical element, creating a line structure. This allows independent control of line length through SLM masking without affecting the overall working distance, as each sub-beam maintains the original beam's propagation characteristics.
Solution Approach 2:
The invention controls laser line length in the lateral dimension (perpendicular to beam propagation) using SLM phase modulation and masking, independent of the longitudinal dimension (working distance). This dimensional separation allows line length and working distance to be controlled independently.
2Quantity of substance
If the laser line length is reduced to capture only regions of interest, then data volume decreases, but the field of view becomes too limited
Solution Approach 1:
The SLM provides dynamic, programmable control over the laser line length, allowing the system to adapt the line extent to match the specific measurement requirements. Different line lengths can be selected electronically without mechanical adjustments, optimizing the balance between data volume and field of view for each measurement task.
3Area of stationary object
If a longer laser line is used to increase the measurement area, then the field of view increases, but the data volume and processing requirements increase
Solution Approach 1:
The measurement area is segmented into multiple scans with optimized line lengths. Rather than using one long line that captures excessive data, the system uses multiple shorter lines that collectively cover the required area, reducing redundant data capture in each frame.
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 variable laser line lengths for improved data capture efficiency, reduced data volume, and enhanced resolution by allowing selective control over the laser line length, reducing unwanted data and reflections.
Implementation Method 1
the SLM selectively blocking certain parts of the emitted radiation, thereby allowing control over the divergence of the radiation and, thus, the laser line length
Implementation Method 2
a micro-lens array (MLA) 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 MLA at the respective point
Implementation Method 3
the SLM is an LCD element and comprises a polarizing filter, wherein the LCD element comprises a layer of liquid-crystal molecules
Data Source
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Figure 3a~3b
Figure 4a~4b
AI summary
The invention pertains to a laser line module (1) 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 (11) configured to emit radiation in the form of a laser beam; a beam-shaping optical arrangement; a micro-lens array (15) 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 (17) that is provided between the beam-shaping optical arrangement and the micro-lens array (15), wherein the laser diode (11) and the beam-shaping optical arrangement are arranged and configured to guide the radiation along an optical axis of the laser line module (1) onto the spatial light modulator (17), and the spatial light modulator (17) comprises a multitude of elements, each element being controllable to adopt a first state or a second state, wherein each element is configured, while adopting the first state, to let the radiation pass to the micro-lens array (15) and, while adopting the second state, to prevent that the radiation passes to the micro-lens array (15). The invention also pertains to a laser-line triangulation device comprising such a laser line module.