Various configurations of optical flow sensors exist. Rayleigh scattering is an important component of the scattering of optical signals in optical fibers. Guidance can be mechanical, optical, or electromagnetic. A further application is in the characterization of particles by optical scattering measurements. This causes many interesting electrical, magnetic, optical, and mechanical properties. OSNR is measured with an optical spectrum analyzer. These innovations ushered in the era of optical fiber telecommunication. Others wear contact lenses for functional or optical reasons. The deformation can be measured using mechanical, optical or capacitive techniques. In phase conjugating mirrors based on stimulated Brillouin scattering optical vortices excite acoustical vortices. Both optical and electronic satellite data were used. The SCSI standards define commands, protocols, electrical, optical and logical interfaces. This deviation reduces the quality of images produced by optical systems. Rings were studied by analyzing results of radio, ultraviolet and optical occultations. It is a form of optical aberration.