Fiber Laser Doppler Velocimeter for Multi-Axis Velocity Measurement
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Solution Overview
Problem
Conventional laser Doppler velocimeters face challenges in measuring air speed due to the need for large, bulky, and fragile laser sources, and limitations in using fiber optics for remote configurations, particularly with stimulated Brillouin scattering, as well as the inability to perform multi-dimensional velocity measurements without moving parts.
Innovation Solution
The development of a lightweight, compact laser Doppler velocimeter using erbium-doped glass fiber amplifiers and optical fibers for generating and guiding laser energy, allowing for simultaneous multi-axis velocity measurements with n transceivers, each carrying a continuous wave or pulsed beam from a common seed laser, and power amplification within transceiver modules to avoid nonlinear fiber effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional laser sources are used in LDV, then sufficient laser power is achieved, but the device becomes large, bulky, and fragile
Solution Approach 1:
The patent replaces conventional mechanical laser sources with fiber optic-based laser systems, where laser energy is transmitted through flexible optical fibers rather than requiring rigid mechanical mounting of large laser components. This substitution enables high power output while dramatically reducing device weight and eliminating fragility issues associated with traditional laser sources
Solution Approach 2:
The patent changes the physical state and delivery mechanism of laser energy by using fiber optic transmission. Instead of generating and directing laser beams through mechanical optical components, the system uses fiber optics to guide laser energy, fundamentally changing how laser power is delivered and enabling compact, lightweight device design
2Adaptability or versatility
If fiber optics are used for remote configurations, then device flexibility is improved, but stimulated Brillouin scattering limits performance
Solution Approach 1:
The patent applies partial action by using fiber optics only for the specific function of delivering laser energy to remote transceiver locations, while accepting the Brillouin scattering limitation and designing the system to operate within acceptable performance bounds. The fiber optic links are used strategically where their flexibility benefits outweigh the power transmission limitations
Solution Approach 2:
The patent uses fiber optics as an intermediary medium to transmit laser energy from centralized laser sources to distributed transceiver units. The fiber optic cables serve as flexible conduits that enable remote positioning of measurement points while managing the inherent power loss and scattering effects through proper system design
3Device complexity
If a single laser source is used, then device simplicity is maintained, but multi-dimensional velocity measurements require moving parts
Solution Approach 1:
The patent segments the laser system into multiple independent transceiver units, each with its own laser source and measurement beam. This segmentation allows simultaneous multi-dimensional velocity measurements without requiring moving parts, as each transceiver independently measures velocity along its specific axis. The modular architecture maintains relative simplicity while enabling comprehensive 3D velocity measurement
Solution Approach 2:
The patent creates universal transceiver modules that can be positioned and oriented in different spatial configurations to measure velocity components along different axes. Each transceiver unit is multi-functional, capable of serving various measurement geometries without requiring mechanical reconfiguration, thus eliminating moving parts while maintaining measurement versatility
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 solution enables accurate, eye-safe, and durable multi-dimensional velocity measurements without moving parts, suitable for various applications, including wind and object velocity determination, while compensating for platform motion, and is scalable for high energy operation.
Implementation Method 1
an active lasing medium, such as e.g., an erbium-doped glass fiber amplifier for generating and amplifying a beam of coherent optical energy
Implementation Method 2
an optical system coupled to the beam for directing the beam a predetermined distance to a scatterer of radiant energy
Implementation Method 3
the scatterer reflects the beam back to the receiver so that a frequency shift is generated
Implementation Method 4
for determining the velocity of the scatterer from the frequency shift generated
Data Source
AI summary
A laser Doppler velocimeter is formed using a fiber laser as the lasing medium. Within the velocimeter, all optical signals, transmitted and received, are conveyed by optical fibers. An amplifier amplifies a source laser, which is then transmitted to one or more transceivers. The one or more transceivers, each projecting along a different axis, and each with a single optical fiber input/output interface act as both the transmission device to focus the radiation at a target region, and as the receiving system for collecting reflected radiation. The transceivers each include an amplifier to further amplify the radiation received from the laser source. The one or more transceivers transmit radiation simultaneously to the target region, and may be located remotely from the laser source. The portion of the reflected radiation collected by the receiving system is analyzed to determine the Doppler shift caused by targets at the focal point of the one or more transceivers.