Lidar Gas-Density Sensing With Single-Source Frequency Modulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing lidar devices require two light sources to calculate gas density, which increases complexity and cost.
Innovation Solution
A lidar device utilizing a single light source with frequency modulation to generate two laser beams with different frequencies, one within and one outside the absorption wavelength band of the target gas, allowing density calculation without additional light sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two light sources are used to calculate gas density, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines the functions of two separate light sources into a single light source by using frequency modulation. The single light source generates two different frequencies (f1 and f2) through modulation, where f1 corresponds to the absorption wavelength band of the target gas and f2 corresponds to a non-absorption wavelength band. This merging approach maintains the measurement precision advantage of having two light sources while reducing device complexity by using only one physical light source component.
Solution Approach 2:
The patent applies dynamic frequency modulation to the single light source to generate two distinct frequencies dynamically over time. The frequency modulation allows the light source to switch between f1 and f2, enabling differential absorption measurements without requiring two static light sources. This dynamic approach resolves the contradiction by maintaining measurement capability while simplifying hardware configuration.
2Measurement precision
If two light sources are used to calculate gas density, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges the functionality of two expensive light sources into a single light source with frequency modulation capability. This reduces manufacturing costs by eliminating the need to purchase, install, and maintain two separate light source systems while preserving the differential absorption measurement technique that ensures high measurement precision for gas density calculations.
3Device complexity
If frequency modulation is applied to generate two laser beams, then device complexity is reduced, but frequency control difficulty increases
Solution Approach 1:
The patent employs feedback mechanisms in the frequency modulation system to maintain precise control over the two generated frequencies (f1 and f2). By using feedback to monitor and adjust the modulation parameters, the system ensures that f1 remains within the absorption wavelength band and f2 remains within the non-absorption wavelength band, thereby managing frequency control difficulty while maintaining device simplicity.
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 gas density calculation with reduced hardware complexity and cost by using a single light source, while maintaining accuracy and functionality.
Implementation Method 1
a light source 11 that outputs a laser beam, a frequency output unit 12 that outputs a first frequency or a second frequency different from the first frequency to an optical transmission unit
Implementation Method 2
an optical transmission unit 14 that generates a first laser beam by modulating an optical frequency of the laser beam output from the light source by the first frequency, generates a second laser beam by modulating an optical frequency of the laser beam output from the light source by the second frequency
Implementation Method 3
an optical receiving unit 15 that receives first scattered light that is the first laser beam after being emitted by the optical transmission unit and then scattered by a scatterer floating in the space or second scattered light that is the second laser beam after being scattered by the scatterer, and detects interference light between the first scattered light or the second scattered light and the reference light
Implementation Method 4
a first light source that oscillates a first laser beam having a wavelength included in an absorption wavelength band of an observation target gas and a second light source that oscillates a second laser beam having a wavelength not included in the absorption wavelength band
Data Source
Figure 1
Figure 2~4
Figure 5~6
AI summary
A lidar device (1) that radiates a first laser beam having a wavelength included in an absorption wavelength band of an observation target gas and a second laser beam having a lower absorption rate by the gas than that of the first laser beam to a space where the gas is present is configured. The lidar device (1) includes: a light source (11) to output a laser beam; a frequency output unit (12) to output a first frequency or a second frequency different from the first frequency; a reference light output unit (13) to output the laser beam output from the light source (11) as reference light; an optical transmission unit (14) to generate the first laser beam by modulating an optical frequency of the laser beam output from the light source (11) by the first frequency, generate the second laser beam by modulating the optical frequency of the laser beam output from the light source (11) by the second frequency, and radiate each of the first laser beam and the second laser beam to the space; and an optical receiving unit (15) to receive, as scattered light, the first laser beam radiated by the optical transmission unit (14) and then scattered by a scatterer floating in the space or the second laser beam radiated by the optical transmission unit (14) and then scattered by the scatterer, and detect interference light between the scattered light and the reference light.