What is the length of coherence in physics?

In optics, a branch of light physics and its properties, the length of coherence (CL) is the maximum distance that a beam of light or other electromagnetic phenomenon can travel while maintaining a specified degree of time coherence. Time coherence refers to the shape of a sinus wave and the ability to predict where the wave will be at a specific moment in time. If the light is coherent, it remains in the phase with itself. As a result, some texts also refer to the time of coherence, which is the length of coherence divided by the speed of light. Although the term "length of coherence" is primarily used in optics, many optics concepts have been generalized to any situation involving the spread of waves such as radio waves, sound waves and compression waves.

one of the significant appliedThe look of the coherence length is holography, recording and recreation of three -dimensional images. Holography works by capturing the interaction between two laser beams - a reference beam and an object beam. The length of the coherence of the laser used is the maximum difference in the path that can be allowed between the beams, so it serves as the limit of the depth of the hologram that can be seen. For a normal five-perch helium neon laser, this CL is limited to about 6-8 inches (15.2-20.3 cm).

Additional application length of coherence is in telecommunications, message transmission through an electromagnetic signal. Here the CL is the maximum distance that the message can be sent without being handed over. For radio -waves, length can be approximated by distributing light speed through this medium by signal bandwidth. This range can reduce interference, dispersion and diffraction. For optical communication, the CL is directly proportional to the square of the central wavelength of the source and inversely proportional to the refractive index of the medium used and the spectral signal width.