High temperature is one of the most important parameters in the fields of scientific research and industrial production. At
present, thermocouple, thermo resistive and radiance thermometer are already technologically mature which can be
adopted to measure the general temperature, but when it comes to the transient high temperature that changes pretty
quickly in wretched conditions, those traditional pyrometers can not meet the requirements any more. In this paper, we
designed a transient optical high temperature measurement system. First, design of the temperature measurement probe.
The system took blackbody cavity sensor together with optical fiber to receive the measured signal, here, the integrated
emissivity model of the blackbody cavity was established and the optimum structure parameters were confirmed.
Secondly, design of the entire temperature measurement system. A contact-noncontact measurement method was
applied, which is to make the blackbody cavity and the measured high-temperature source contact, the fiber probe and
the blackbody cavity noncontact, as a result, the error caused by contact measurement is overcame and the precision is
guaranteed at the same time. In addition, a fiber grating was introduced as the wavelength filter device which can realize
the dynamic filter of narrow-band signals and reduce the impact of background light. Thirdly, signal processing. In this
part, we applied labVIEW software and wavelet analysis method. All of the signal acquisition and processing were
realized in the labVIEW environment. Through calling matlab in labVIEW, the signals from optical fiber detector were
wavelet denoised and decomposed, thus the temperature information was extracted, and the temperature value was
obtained. On basis of wavelet transformation, the paper adopted the 4dB wavelet with horizontal scale of 5 to realize the
feature extraction and noise removal, parts of the signals before and after the wavelet noise removal were given and
analyzed. Finally, the experimental result shows: the resolution is 1°C,the measurement range is 500~2000°C and the
dynamic response time is 5s.In view of possessing a high precision and resolution, resisting high temperature and
corrosion, and being able to realize the continuous measurement of the dynamic temperature, this transient optical fiber
high temperature measurement system can be applied widely in the continuous temperature measurement of molten steel
and heating furnace kiln temperature measurement and so many other fields of engineering technology.
A novel interrogating fiber grating array based on optical frequency domain reflectometry (OFDR) and wavelength division multiplexing (WDM) techniques was reported, and address inquiry of different measurement optical fiber was realized. Fundamental principle of OFDR has been analyzed and the space resolution and measurement range of this system were calculated theoretically. The calculated system's spatial resolution was 2.5m, and measurement range was 2000m. Thanks to the minimum resolution within meter range, frequency fluctuation due to trivial vibration in the environment won't cause error in the course of interrogating. Experiment studies on 3×3 fiber grating array were carried out. Experimental results confirm that with sufficiently large power of the light source, the novel fiber grating sensing array has attractive potential to interrogate and modulate several hundreds of fiber gratings in that it makes full use of optical frequency and wavelength information, and can be well applied to the distributed stress detection of two- or three- dimensional large structures
Fiber Bragg grating under transverse force to a small grating section was studied by numerical simulation and experimentation. A numerical simulation based on the transfer matrix method was used to calculate the consequent changes in reflected spectrum. The reflected spectra of the FBG subjected to the transverse force split in two main peaks, and the split point shifted linearity and periodically versus the applied force. The split point shifted in the bandwidth with the period of 11.06N, and the sensitivity of the split point wavelength shift versus the applied force was the ratio of bandwidth to the period. Experimental consequents show good agreement with simulation analysis.