Multi-Frequency Laser Range Finder Anti-Jamming
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Solution Overview
Problem
Laser range finders face challenges in accuracy and reliability due to interference from environmental conditions like rain, fog, and dust, which can result in false returns and inaccurate measurements, and are vulnerable to jamming and false reflections.
Innovation Solution
A resilient multi-frequency laser range finder system utilizing a plurality of modulated seed lasers, a wideband laser fiber amplifier, and advanced detection and processing techniques to provide robust and accurate range measurements, including adaptive optics and mode hopping calculations, to stabilize and correct for environmental interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single frequency laser is used for range finding, then the device complexity is reduced, but the reliability decreases due to vulnerability to jamming and false returns
Solution Approach 1:
The laser system is segmented into multiple independent frequency sources (seed lasers at different wavelengths: 1550nm, 1650nm, 1900nm, 2100nm). Each frequency acts as an independent channel for range finding, allowing the system to select valid returns based on frequency consistency while rejecting jamming signals that cannot replicate all frequencies simultaneously.
Solution Approach 2:
The system changes the frequency parameter of the laser by using multiple discrete wavelengths. This parameter diversity creates a signature that legitimate target reflections must match across all frequencies, while jamming signals typically affect only specific frequencies, enabling discrimination between valid and invalid returns.
2Measurement precision
If visible light is used for range finding, then the illumination intensity is sufficient, but the measurement precision deteriorates in rain, fog or dust conditions due to scattering and false returns
Solution Approach 1:
The system transitions from spatial dimension analysis alone to adding frequency dimension analysis. By measuring range consistency across multiple frequencies, the system creates an additional verification dimension that distinguishes true target returns (which maintain consistent range across frequencies) from scattering artifacts (which do not).
Solution Approach 2:
The system uses feedback by comparing range measurements across multiple frequencies. When the calculated range from different frequency channels agrees within a threshold, the return is validated. This cross-frequency feedback mechanism filters out false returns from environmental scattering that would produce inconsistent range values across frequencies.
3Reliability
If pulse modulation is used to avoid jamming, then the reliability improves, but the device complexity increases due to additional modulation components
Solution Approach 1:
Instead of temporal modulation, the system changes the frequency parameter dimension. Multiple optical frequencies serve the same anti-jamming function as pulse modulation would, but implemented more directly through wavelength diversity rather than temporal encoding, reducing the complexity of modulation electronics while achieving similar reliability benefits.
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 system achieves robust and accurate range measurements by utilizing multiple frequencies and advanced signal processing, enhancing data security and reliability in adverse conditions, and providing improved resistance to false returns and jamming.
Implementation Method 1
Light from the seed lasers is provided to a wideband laser fiber amplifier
Implementation Method 2
The remainder is transmitted to a target through a collimating lens
Implementation Method 3
Reflections from the target are received by a telescope
Implementation Method 4
A portion of amplified laser light is directed to a first detector. A major portion of the returned light is provided to a second detector
Implementation Method 5
Processor analyzes the time delay between the transmitted light and the reflected light to provide a range output
Data Source
AI summary
A range finder includes a plurality of modulated seed lasers providing light at different wavelengths. Light from the seed lasers is provided to a wideband laser fiber amplifier. A portion of amplified laser light is directed to a first detector. The remainder is transmitted to a target through a collimating lens. Reflections from the target are received by a telescope. A major portion of the returned light is provided to a second detector. A minor portion is provided as feedback to the wideband laser fiber amplifier for stabilization. Outputs from the first and second detector are provided to a processor. Processor analyzes the time delay between the transmitted light and the reflected light to provide a range output. Other embodiments could use adaptive optics and mode hopping range calculations.