Optical Time Domain Reflectometer (OTDR) is a precision optoelectronic instrument that utilizes the backscatter of light caused by Rayleigh scattering and Fresnel reflection during the transmission of light in fiber optic cables. It is widely used in the maintenance and construction of fiber optic cable lines and can be used to measure the length of fiber optic cables, transmission attenuation, carbon monoxide testing, connector attenuation, and fault location and other parameters.
The OTDR test is performed by receiving the reflected information at the OTDR port. As the light pulse travels through the fiber optic cable, it scatters and reflects due to the nature of the fiber optic cable, connectors, splices, bends or other similar events, and a portion of the scattered and reflected light returns to the OTDR. The useful information from the return signal is measured by the OTDR detector and is represented as a time or curve fragment at different positions within the fiber optic cable. The distance can be calculated by determining the time it takes for the return signal to reach the OTDR and knowing the speed of light in the glass material.
The method of testing is to receive the light signal on the same side where the pulse is injected because the injected signal is scattered and reflected back by media with different refractive indexes. The intensity of the reflected light signal is measured and is a function of time, which can be converted into the length of the fiber optic cable.
The OTDR uses Rayleigh scattering and Fresnel reflection to characterize the properties of fiber optic cables. Rayleigh scattering is caused by the random scattering of light signals along the fiber optic cable. The OTDR measures a portion of the backscatter light that is reflected back to the OTDR port, indicating the degree of attenuation caused by the fiber optic cable. The resulting trajectory is a downward curve, which indicates that the backscatter power decreases continuously due to signal loss after a certain distance of transmission. After the parameters of the fiber optic cable are given, the power of Rayleigh scattering can be indicated, and if the wavelength is known, it is proportional to the pulse width of the signal: the longer the pulse width, the stronger the backscatter power. The power of Rayleigh scattering is also related to the wavelength of the transmitted signal, with shorter wavelengths resulting in higher power.
+86-21-5445 1260
