Frequency Modulated Laser Range Finder Multi-Target Detection
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Solution Overview
Problem
Traditional time of flight laser range finders are limited to detecting only one object and measuring the distance to its leading edge, restricting their utility in applications requiring multiple target detection and more comprehensive distance measurements.
Innovation Solution
A frequency modulated laser range finder that projects a continuously modulated laser beam, uses beam splitters to combine reference and target beams coherently, and detects the difference frequency to calculate distances, enabling simultaneous measurement of multiple targets and providing depth, acceleration, and scattering cross-section information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional time of flight laser range finder detects only the first backscattering signal, then the device structure remains simple, but the capability to detect multiple targets is limited
Solution Approach 1:
The patent applies frequency modulation to the laser beam, changing the temporal parameter of the light signal. By modulating the frequency over time and analyzing the frequency spectrum of the returned signal, the system can distinguish multiple targets at different distances without adding complex hardware components, thus improving multi-target detection capability while maintaining relatively simple device structure
Solution Approach 2:
The patent transitions from detecting only the first backscattering signal (one-dimensional detection) to analyzing the frequency spectrum of the returned signal (adding spectral dimension). This dimensional change in signal processing enables the system to extract information about multiple targets with different time delays, effectively providing multi-target detection capability
2Loss of information
If traditional laser range finder measures only the leading edge distance, then the measurement process remains simple, but the information about target depth and structure is lost
Solution Approach 1:
The patent applies frequency modulation to the laser beam before transmission. This preliminary action imprints a time-varying frequency signature on the light that allows differentiation of signals returning at different times. By analyzing the frequency spectrum of the returned signal, the system can extract depth and structural information about the target, reducing information loss while keeping the measurement process relatively simple
Solution Approach 2:
The patent uses the frequency-modulated return signal as feedback to extract multiple pieces of information. By analyzing the frequency spectrum and time delays of different spectral components, the system can determine not only the leading edge distance but also depth and structural characteristics of the target, thereby reducing information loss through effective feedback analysis
3Productivity
If frequency modulated continuous wave is used, then multiple targets can be detected simultaneously, but the device complexity increases compared to pulsed laser systems
Solution Approach 1:
The patent uses continuous frequency-modulated laser beams instead of pulsed beams. This continuous action allows the system to continuously illuminate all targets in the measurement range and continuously receive reflected signals. By analyzing the frequency spectrum of the continuous return signal, multiple targets can be detected simultaneously without the need for complex pulsed timing control mechanisms, thus improving productivity while managing device complexity
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 accurate and simultaneous distance measurement to multiple targets, overcoming the limitations of traditional laser range finders by using frequency modulation to determine distances based on the difference frequency, enhancing the range finder's utility in various applications.
Implementation Method 1
the frequency of which is modulated at a known modulation rate
Implementation Method 2
the target beam and the reference beam are coherently combined, the coherently combined beams establishing a difference frequency
Implementation Method 3
a detector configured to measure the difference frequency and calculate the distance to the target object based on the measured difference frequency
Data Source
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AI summary
A laser range finder including a laser configured to project a laser beam onto a target object thereby causing a target beam to be reflected from the target object, wherein the laser beam has a frequency, and wherein the frequency is modulated at a known rate, a first beam splitter positioned to split a reference beam from the laser beam, a second beam splitter positioned to receive the target beam and the reference beam, wherein the target beam and the reference beam are coherently combined, the coherently combined beams establishing a difference frequency, and a detector configured to measure the difference frequency.