1.Introduction of the Product
      Based on the principle of optical frequency domain reflection (OFDR), the high-precision distributed optical fiber strain/temperature sensor is built on frequency domain analysis as a back reflection measurement technology. Compared with the previous generation of OPTICAL TIME DOMAIN REFLECTOMETER (OTDR), OFDR can accurately locate the analysis points to the level of μm and simultaneously analyze the reflection spectral information of any location in the link. Therefore, the moment OFDR emerged, it brought significant changes to traditional industry testing technology;
 
2.Application Fields
      About structural health monitoring, especially superficial or internal strain monitoring on such large devices as aircrafts, ships and buildings, etc., traditionally lots of strain-gage sensors were attached to different positions, which brought about complexity of wiring and signal addressing, with only point strain information obtained, and electromagnetic interference resisted almost in vain; after the emergence of OFDR technology, you can just lay out one single optical fiber, and continuous strain or temperature detection can be completed for hundreds of meters test range, and the sensitivity to space positions is less than 1 mm; meanwhile, regarding the strain measurement precision, it is as excellent as strain-gage sensors; In the testing of optical devices, OFDR technology can accurately locate the loss point and circuit break in the optical link, and can complete the test of the spectral transfer function of the loss point, which made it an important equipment for the pre-delivery testing of optical devices. In security monitoring applications, OFDR technology has higher sensitivity, more accurate intrusion perception, and far higher positioning accuracy than Brillouin Optical time-domain reflection (BOTDR) technology, granting itself with great technical advantages.

3.Measurement System
      OFDR system is comprised of demodulator and computer/embedded system. The demodulator is of a 300mm*250mm*135mm dimension, bearing the optical sensing circuit, optical-electrical conversion circuit and wavelength calibration module inside. The demodulator is connected by cable to the computer/embedded system to display distributed strain measurements on the computer's software or to process strain information in the embedded system.
      When OFDR system carries out distributed measurement, the measuring optical fiber is installed on the surface of the measured structure. By transmitting light to the fiber and retrieving the returning light, the demodulator can acquire the strain and temperature information at various positions along the fiber, which is resistant to electromagnetic interference and highly adaptable to harsh environments.
      The OFDR system is not only applicable to the monitoring of distributed strain and temperature, but also to the detection of abnormal loss points in optical device testing,  location of the circuit break in the link test, as well as border monitoring in the security field and so on.