Laser Scanner Reference Target Stabilization
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Solution Overview
Problem
Conventional laser scanners face challenges in maintaining long-term stability and reliability due to environmental influences and installation tolerances, leading to deviations in reference measurements, especially in harsh industrial environments.
Innovation Solution
A laser scanner with a reference target designed as a trapezoidal prism featuring two reflective surfaces and a microlens array to widen the light beam, ensuring robustness and insensitivity to alignment and environmental changes, allowing for a stable reference measurement over a larger angular range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional reference target is used in a laser scanner, then the reference measurement can be performed, but the measurement stability deteriorates due to environmental influences and installation tolerances
Solution Approach 1:
The patent introduces a reference target with a specific geometric configuration (trapezoidal prism with reflective surfaces) that acts as an intermediary element. This reference target is designed to reflect the laser beam back to the receiver in a controlled manner, mediating between the laser scanner and the external environment. The geometric design ensures that the reference measurement is independent of installation tolerances and environmental factors like temperature and humidity.
Solution Approach 2:
The patent changes the geometric parameters of the reference target by designing it as a trapezoidal prism with specific reflective surface configurations. This geometric parameter change transforms the reference target from a conventional design to one that is insensitive to installation tolerances. The trapezoidal shape with reflective surfaces creates a beam path that is tolerant to angular deviations and environmental variations, thereby stabilizing the reference measurement.
2Illumination intensity
If the reference target is designed with high reflectivity to ensure strong reference signal, then the signal strength improves, but stray light increases and measurement precision deteriorates
Solution Approach 1:
The patent applies local quality by designing different surfaces of the reference target with different optical properties. The trapezoidal prism has specific reflective surfaces positioned to reflect the laser beam back to the receiver, while other surfaces are designed to minimize stray light. This localized optimization of optical properties ensures strong reference signal without excessive stray light, maintaining measurement precision.
Solution Approach 2:
The patent employs asymmetry by using a trapezoidal prism design rather than a symmetric conventional reference target. The asymmetric geometry creates a specific beam path that is tolerant to installation tolerances and environmental factors. The asymmetric shape allows the reference target to reflect the laser beam back to the receiver while minimizing stray light in other directions, thereby improving measurement precision.
3Area of stationary object
If a continuous angular range is used for reference target measurement, then the field of view increases, but the support structure and deflection unit create dead zones that limit the effective field of view
Solution Approach 1:
The patent extracts the reference target measurement function from the continuous scanning process. By designing the reference target as a separate, stationary element with specific reflective surfaces, the system can perform reference measurements independently of the deflection unit's position. This extraction allows the reference measurement to be performed without being constrained by the support structure and deflection unit arrangement, effectively eliminating dead zones.
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 enhances the robustness and stability of the reference measurement, reducing stray light and fluctuations, thereby ensuring reliable operation and miniaturization of the scanner while maintaining compliance with safety standards.
Implementation Method 1
a microlens array to widen the light beam
Implementation Method 2
two reflective surfaces... reflected back sequentially at the two reflective surfaces by total internal reflection
Implementation Method 3
the emitted light beam enters the reference target at a beam entry region of the front surface
Data Source
Figure 1~2b
Figure 3~4
Figure 5a~5b
AI summary
A laser scanner (10) is described, comprising a light transmitter (12) for emitting a light beam (16), a light receiver (26), a movable deflection unit (18) for scanning the monitoring area (20), an internal reference target (40) that reflects the emitted light beam (16) back within the laser scanner (10) to the light receiver (26) to generate a reference signal, and an evaluation unit (36) configured to detect objects based on the received signal and to verify the functionality of the laser scanner (10) based on the reference signal. A front surface (46, 48, 50) and/or at least one reflective surface (56, 58) of the reference target (40) is configured to widen a light beam (16, 60) reflected from the reference target (40).