Rayleigh and Mie scattering are the most common elastic scattering. In a linear collision process energy of scattered photon is not changed. Raman and Brillouin scattering are the most common inelastic scattering. In a nonlinear collision process energy of scattered photon is changed due to occurrence of the phonon, vibrating or rotating molecule. Stokes and anti-Stokes signals occurre in Raman scattering. Stokes has 13,2 THz lower frequency than incident photon and anti-Stokes has higher frequency components. We describe two methods of distributed optical measurement. In the OTDR, high-power optical pulses are launched into a fiber, which is being inspected, or is used as a distributed sensor, the pulses are scattered back along with propagation in the fiber, and their intensity decays due to the fiber loss. The return signal is thus a declined curve displayed in an oscilloscope. The OFDR uses the frequency-modulated continuous wave (FMCW) ranging technique, referring to the radar technology. In the system, a cw optical carrier with a periodic linear frequency sweep is employed. We made an distributed optical sensor system that can measure increment of temperature in specific place of system, depending of resolution. Pulse width was 348 ns and resolution of system was 72 meters. Measurements of reflected signals can give us an information of temperature at specific place in system.