Stellar rotation can have a very rapid rate of rotation; on the order of a hundred rotations per second. Pulsars are rotating neutron stars that have a magnetic field. A narrow beam of electromagnetic radiation is emitted from the poles of rotating pulsars. If the beam sweeps past the direction of the Solar System then the pulsar will produce a periodic pulse that can be detected from the Earth. The energy radiated by the magnetic field gradually slows down the rotation rate, so that older pulsars can require as long as several seconds between each pulse. A black hole is an object
Beam divergence minimum beam diameter. The divergence of good-quality laser beams is modeled using the mathematics of Gaussian beams. Gaussian laser beams are said to be diffraction limited when their radial beam divergence formula_5 is close to the minimum possible value, which is given by where formula_7 is the laser wavelength and formula_8 is the radius of the beam at its narrowest point, which is called the "beam waist". This type of beam divergence is observed from optimized laser cavities. Information on the diffraction-limited divergence of a coherent beam is inherently given by the N-slit interferometric equation. Beam divergence In electromagnetics, especially