Laser Distance Meter Mode Hopping for Measurement Accuracy
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Solution Overview
Problem
Existing laser distance meters often fail to provide accurate measurements due to noise, interference, and coherence problems, particularly at long distances, as they may not adequately receive or reflect laser light of a single wavelength.
Innovation Solution
The laser distance meter induces controlled mode hopping to emit laser light of different wavelengths, increasing the likelihood that at least one wavelength will reach and be reflected by the object, and uses a drive circuit to vary the drive current over time to achieve this, allowing for accurate distance calculation based on multiple wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a laser emits only laser light of one wavelength, then the device complexity is reduced, but the measurement precision deteriorates due to noise, interference, and coherence problems
Solution Approach 1:
The patent applies parameter changes by inducing mode hopping in the laser to emit multiple wavelengths instead of a single wavelength. This changes the optical parameter (wavelength) to overcome noise, interference, and coherence problems that affect single-wavelength measurements, thereby improving measurement precision without significantly increasing device complexity
Solution Approach 2:
The patent employs periodic action by modulating the drive current to the laser in a periodic manner to induce controlled mode hopping. This causes the laser to periodically switch between different modes and wavelengths, allowing the system to collect multiple measurements at different wavelengths and improve overall measurement accuracy
2Ease of manufacture
If the laser distance meter uses a single laser, then the manufacturing cost is reduced, but the reliability of measurement deteriorates due to inadequate reception or reflection at single wavelength
Solution Approach 1:
The patent changes the wavelength parameter of a single laser through controlled mode hopping, enabling one laser to provide multiple wavelength measurements. This maintains the cost advantage of using a single laser while improving reliability by ensuring that at least one wavelength will be adequately received and reflected, overcoming environmental interference
3Measurement precision
If multiple lasers are used to emit different wavelengths, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent changes the operational parameter (wavelength) of a single laser by inducing mode hopping, replacing the need for multiple lasers. This achieves the measurement precision benefits of multi-wavelength operation while avoiding the complexity and cost of multiple laser sources, as the single laser dynamically switches between wavelengths through controlled parameter changes
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
This approach enhances the accuracy and reliability of distance measurements by averaging or discarding outlier readings from multiple wavelengths, reducing the impact of noise and interference, and enabling reliable detection even in challenging environmental conditions.
Implementation Method 1
mode hopping is induced in the laser in use so that the laser emits laser light of different wavelengths
Implementation Method 2
a laser for emitting laser light
Implementation Method 3
a photodetector for detecting laser light emitted by the laser and reflected by an object
Implementation Method 4
the drive circuit is arranged to vary the drive current to the laser over time to induce mode hopping such that the laser emits laser light of different wavelengths
Data Source
Figure 1
Figure 2~3
AI summary
A laser distance meter (10) for measuring a distance to an object (50) has at least one laser (20) for emitting laser light and a photodetector (24) for detecting laser light emitted by the or each laser (20) and reflected by the object (50). The laser distance meter (10) is arranged such that mode hopping is induced in the laser (20) so that the laser (20) emits laser light of different wavelengths. The laser distance meter (10) calculates the distance to the object (50) based on at least laser light of one of the different wavelengths reflected by the object (50) and detected by the photodetector (24).