Laser Scanner Refractive Index Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Laser scanning devices face challenges in generating accurate scanning point clouds across various environments due to the influence of refractive indices, leading to issues such as redundant or uneven scanning points, especially in mediums like water, where the speed of the laser scanning device is reduced, and in air, where high deflection speeds can result in interference from ambient scattered light.
Innovation Solution
A laser scanning device with a processor-controlled pulse repetition rate and optical elements that adjust based on the refractive index of the surrounding medium, allowing for adaptive beam divergence and receiving field of view, as well as deflection speed control, to ensure accurate distance and direction calculations and optimal scanning performance across different mediums.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pulse repetition rate is increased to maximize the number of scanning points in air, then the productivity is improved, but the scanning points become redundant and uneven in water due to reduced travel speed
Solution Approach 1:
The pulse repetition rate is made dynamically adjustable based on the detected refractive index of the ambient medium. The processor automatically increases the pulse repetition rate when scanning in air (lower refractive index) to maximize point density, and decreases it when scanning in water (higher refractive index) to prevent redundant points and maintain uniform distribution, thus resolving the contradiction between productivity and manufacturing precision.
2Manufacturing precision
If the beam divergence is reduced to achieve small scanning points and high spatial resolution in water, then the manufacturing precision is improved, but the eye safety is compromised in air due to larger beam divergence requirements
Solution Approach 1:
The beam divergence parameter is dynamically changed based on the refractive index detection. In water (higher refractive index), the beam divergence is reduced to achieve tight focal spots and high spatial resolution. In air (lower refractive index), the beam divergence is increased to spread the laser energy over a larger area, reducing intensity and ensuring eye safety. This parameter adaptation resolves the contradiction between manufacturing precision and object-affected harmful factors.
3Productivity
If the deflection speed is increased to maintain uniform scanning patterns in air, then the productivity is improved, but the scanning points become redundant in water due to reduced device travel speed
Solution Approach 1:
The deflection speed is dynamically adjusted according to the ambient medium's refractive index. In air, the deflection speed is increased to maintain high productivity and uniform scanning patterns. In water, where device travel speed is reduced, the deflection speed is decreased proportionally to prevent redundant scanning points and maintain uniform point distribution. This dynamic adjustment resolves the contradiction between productivity and manufacturing precision.
4Reliability
If the receiving field of view is increased to improve signal-to-noise ratio in water, then the reliability is improved, but the measurement precision deteriorates in air due to interference from ambient scattered light
Solution Approach 1:
The receiving field of view parameter is dynamically changed based on refractive index detection. In water (higher refractive index), the receiving field of view is increased to collect more reflected laser energy and improve the signal-to-noise ratio, enhancing reliability. In air (lower refractive index), the receiving field of view is reduced to a narrow cone that excludes ambient scattered light, maintaining measurement precision. This parameter adaptation resolves the contradiction between reliability and measurement precision.
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 device generates universally correct scanning point clouds by accounting for refractive indices, preventing redundant or uneven scanning, and optimizing performance in both dense and thin mediums, ensuring high spatial resolution and signal-to-noise ratio, while maintaining eye safety and uniform scanning patterns.
Implementation Method 1
the refractive index n, which is proportional to the ratio of the vacuum speed of light c0 to the speed of light c in the medium
Implementation Method 2
the refractive index changes the direction of the sampled point as seen from the device and thus its position in the sample point cloud, due to the refractive index-dependent refraction angle of the laser beam when it passes from a device with internal refractive index n0 at the angle of incidence α0 into a medium with refractive index n at the angle of reflection α according to Snell's law of refraction
Data Source
Figure 1~4
Figure 2~3
AI summary
Device (1) for measuring an environment (2), comprising a housing (17), a transmitter (9) and receiver (12) for a laser beam (4), a deflection device (11) for the laser beam (4), a measuring device (16) for the deflection direction (α1,i) of the laser beam (4) and a processor (13) which measures distances (di) to sampling points (Pi) in directions (Ri) by time-of-flight measurements on the emitted and reflected laser beam (4) and creates a sampling point cloud (8) therefrom, wherein the housing (17) has a transmission window (18) for the laser beam (4), a sensor (21) is provided for determining the refractive index (n3) of a medium (M3) located outside the transmission window (18) and the processor (13) is configured to take into account the refractive index (n3) determined by the sensor (21) when measuring the distances (di) and directions (Ri) of the sampling points (Pi).