Atmospheric Cloud Height Measurement Using Interference Filter Stabilization
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Solution Overview
Problem
Existing methods for measuring atmospheric cloud height, humidity profiles, and temperature profiles using semiconductor pulse lasers face issues with signal-noise ratio due to wide wavelength range and instability, leading to unsatisfactory results and high costs associated with single-mode lasers.
Innovation Solution
The use of an interference filter in the optics to stabilize the optical power at the center frequency, allowing for a narrow measuring band and stabilization through simple mechanical means, enabling the use of economical multimode semiconductor lasers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a semiconductor pulse laser is used for cloud probing with wide wavelength range, then the laser can operate at high transmission power, but the signal-noise ratio becomes unsatisfactory due to wavelength instability and broad band
Solution Approach 1:
An interference filter is introduced as an intermediary component between the laser source and the atmosphere. The filter has a narrow transmission band that selectively transmits only a specific wavelength range while blocking other wavelengths. This mediator stabilizes the effective transmission wavelength despite laser heating and manufacturing tolerances, thereby improving the signal-noise ratio while allowing high transmission power operation
Solution Approach 2:
Instead of using the entire wide wavelength band of the laser, the interference filter creates a localized narrow transmission window at a specific wavelength. This local quality approach concentrates the transmission power into a narrow spectral band, improving the signal-noise ratio by eliminating interference from other wavelength regions while maintaining high overall transmission power
2Measurement precision
If a single mode laser is used to achieve narrow spectrum and stable wavelength, then the measurement precision improves, but the cost becomes extremely high
Solution Approach 1:
The interference filter serves as a cost-effective intermediary that provides wavelength selection and stabilization functionality. Instead of requiring an expensive single-mode laser, the system uses a relatively inexpensive multimode laser combined with a narrow-band interference filter to achieve the same spectral purity and wavelength stability, dramatically reducing system cost while maintaining measurement precision
Solution Approach 2:
The invention replaces an expensive single-mode laser source with a combination of a cheaper multimode laser and an interference filter. The multimode laser is a more economical and widely available component, and when combined with the filter, it achieves the required spectral characteristics at a fraction of the cost of a single-mode laser system
3Ease of manufacture
If the laser operates in multimode with line shaped radiating area, then the cost is reduced, but the optical power is spread over wide wavelength range causing instability
Solution Approach 1:
The interference filter acts as a spectral mediator that receives the wide wavelength output from the economical multimode laser and selectively transmits only a narrow wavelength band. This stabilizes the effective transmission wavelength despite the laser's multimode operation and heating effects, enabling cost-effective operation with wavelength stability previously achievable only with expensive single-mode lasers
Solution Approach 2:
The interference filter creates a localized narrow transmission band from the broad multimode laser spectrum. By concentrating the optical power into this narrow spectral window, the system achieves stable effective wavelength operation while using the inexpensive multimode laser source, resolving the contradiction between cost and wavelength stability
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 significantly improves the signal-noise ratio, allows for precise stabilization, and is suitable for various atmospheric measurement applications, reducing costs while maintaining performance across a wide wavelength range.
Implementation Method 1
The invention is based on using an interference filter in the optics, in order to stabilize the optical power transmitted to the centre frequency of the interference filter
Implementation Method 2
The invention is based on using an interference filter in the optics, in order to stabilize the optical power transmitted to the centre frequency of the interference filter
Data Source
Figure 1a~2
Figure 3
Figure 4~5
AI summary
The present publication discloses an atmospheric cloud height, humidity profile, or temperature measuring method and arrangement. In the method, pulsed laser signals (14) are transmitted through transmission optics (2, 3, 4, 5, 6) to the atmosphere and the signal (15) reflected or scattered back from there is detected. According to the invention, an interference filter (3) is used in the optics, in order to stabilize the transmitted optical power to the centre wavelength of the interference filter (3).