368
P. Liu
With the application of narrow linewidth single-mode solid-state lasers in
laser Doppler, argon-ion gas lasers have been eliminated. LDA laser emission
optical systems such as DopplerLite and FlowExplorer DPSS have been developed. The new DPSS laser not only provides an unregulated integrated LDA
transmitter probe, but also a reliable fiber optic transmitter probe. Among
them, the integrated LDA transmitting probe has a built-in device such as
a laser and a Bragg unit, and the adjustable components such as the fiber
coupler are eliminated, thereby greatly reducing the adjustment difficulty
and directly using without any optical coupling adjustment. However, the
disadvantage is that due to the built-in laser, the temperature and humidity
requirements and vibration requirements of the probe are relatively high.
Due to the photoelectric integration, the probe cannot be dustproof and
moistureproof. Fiber optic probes based on DPSS lasers inherit all the advantages of traditional fiber laser Doppler. The watertight probe has no strict
requirements on the cleanliness of the use environment, can withstand certain
vibrations, has high adaptability to the temperature and humidity of the
environment, and can even be configured with the internal gas purging
system of the probe. The disadvantage is that when the ambient temperature
and humidity change greatly, it is necessary to periodically check the fiber
coupling condition to prevent the fiber coupling efficiency from decreasing.
The latest laser Doppler signal processor, whether in the time benchmark,
the highest data rate, the highest processing Doppler frequency, bandwidth,
transit time, and other core indicators, or memory, sampling bits, and other
auxiliary indicators, has been greatly improved. There are significant optimizations in power management, cooling, and stability, and almost all aspects
that can affect the final data quality are improved. It not only provides
laser power adjustment, signal optimization, and other functions, but also
achieves data quality monitoring through real-time signal oscilloscope function, through the vector graphics and a variety of combined 3D graphics to
obtain intuitive data display results. In addition, a special coordinate frame
system is set up to ensure stability and accuracy during the movement. For
single-point measurement systems (as shown in Fig. 5.27), measurement time
can be significantly reduced and data quality can be improved.
P. Liu
With the application of narrow linewidth single-mode solid-state lasers in
laser Doppler, argon-ion gas lasers have been eliminated. LDA laser emission
optical systems such as DopplerLite and FlowExplorer DPSS have been developed. The new DPSS laser not only provides an unregulated integrated LDA
transmitter probe, but also a reliable fiber optic transmitter probe. Among
them, the integrated LDA transmitting probe has a built-in device such as
a laser and a Bragg unit, and the adjustable components such as the fiber
coupler are eliminated, thereby greatly reducing the adjustment difficulty
and directly using without any optical coupling adjustment. However, the
disadvantage is that due to the built-in laser, the temperature and humidity
requirements and vibration requirements of the probe are relatively high.
Due to the photoelectric integration, the probe cannot be dustproof and
moistureproof. Fiber optic probes based on DPSS lasers inherit all the advantages of traditional fiber laser Doppler. The watertight probe has no strict
requirements on the cleanliness of the use environment, can withstand certain
vibrations, has high adaptability to the temperature and humidity of the
environment, and can even be configured with the internal gas purging
system of the probe. The disadvantage is that when the ambient temperature
and humidity change greatly, it is necessary to periodically check the fiber
coupling condition to prevent the fiber coupling efficiency from decreasing.
The latest laser Doppler signal processor, whether in the time benchmark,
the highest data rate, the highest processing Doppler frequency, bandwidth,
transit time, and other core indicators, or memory, sampling bits, and other
auxiliary indicators, has been greatly improved. There are significant optimizations in power management, cooling, and stability, and almost all aspects
that can affect the final data quality are improved. It not only provides
laser power adjustment, signal optimization, and other functions, but also
achieves data quality monitoring through real-time signal oscilloscope function, through the vector graphics and a variety of combined 3D graphics to
obtain intuitive data display results. In addition, a special coordinate frame
system is set up to ensure stability and accuracy during the movement. For
single-point measurement systems (as shown in Fig. 5.27), measurement time
can be significantly reduced and data quality can be improved.