FDML Wavelength Swept Laser for High-Speed Fluid Strain Measurement
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Solution Overview
Problem
Existing optical sensor interrogation systems using wavelength swept lasers face limitations in achieving high-speed, real-time measurement of strain in fluids due to mismatched round-trip time and wavelength tunable cycle time, resulting in low precision and speed constraints.
Innovation Solution
An optical sensor interrogation system is designed with a light source unit that includes an amplifier, delaying unit, tunable filter, and output coupler to match the round-trip time of light with the wavelength tunable cycle time, utilizing a Fourier domain mode locking (FDML) wavelength swept laser to enable precise measurement of fluid strain at speeds of several tens kHz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If wavelength tunable speed is increased to achieve high-speed measurement, then measurement speed is improved, but regular optical gain acquisition response time cannot conform to wavelength tunable time, causing speed to remain at few kHz or below
Solution Approach 1:
The patent applies dynamics by making the optical gain acquisition process adaptive to the wavelength tuning speed. The system dynamically adjusts the gain acquisition timing and duration based on the actual wavelength tunable cycle time, allowing the resonator to maintain synchronization even at high tuning speeds of several tens of kHz. This resolves the contradiction by enabling the system to operate at higher speeds while maintaining reliable optical gain acquisition through dynamic adaptation rather than fixed response time.
2Measurement precision
If round-trip time of light is not matched with wavelength tunable cycle time, then system complexity is reduced, but measurement precision and speed are limited
Solution Approach 1:
The patent applies parameter changes by adjusting the round-trip time of light in the resonator to match the wavelength tunable cycle time. This is achieved by changing physical parameters such as the resonator length or adding optical delay elements, thereby synchronizing the light round-trip duration with the wavelength scanning period. This synchronization enables high-speed, high-precision strain measurement by ensuring that the optical gain acquisition occurs at the optimal moment in the wavelength tuning cycle, resolving the contradiction between measurement precision and system 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
This configuration allows for precise measurement and real-time analysis of fluid strain at high speeds, overcoming previous speed limitations and improving measurement precision.
Implementation Method 1
an amplifier which provides optical gain in the resonator
Implementation Method 2
a tunable filter which periodically scans a wavelength of light in the resonator and tunes the wavelength of light
Implementation Method 3
an output coupler which outputs and feeds back light having the tuned wavelength in a predetermined ratio and continuously oscillates light
Implementation Method 4
a delaying unit which delays the round-trip time of light provided from the amplifier
Data Source
AI summary
Provided is an optical sensor interrogation system. The optical sensor interrogation system includes: a light source unit which matches round-trip time of light and wavelength tunable cycle time of light in a resonator and emits light; a sensing unit which receives an optical signal in which a center wavelength periodically tunes, from the light source unit and tunes the center wavelength of the optical signal according to physical changes applied from the outside; and a signal processing unit which receives the optical signal reflected from the sensing unit, detects data, and images the data. In particular, the light source unit includes a delaying unit which delays the round-trip time of light and a tunable filter which tunes the wavelength of light so as to match the round-trip time of light with the wavelength tunable cycle time of light. Accordingly, a Fourier domain mode locking (FDML) wavelength swept laser, which operates at speed of several tens kHz or above, is used as a light source so that strain of a fluid, which changes in a short time interval of 0.1 msec or below, is precisely measured and thus a real-time analysis may be performed at high speed.