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Beam profile: A beam profile is the 2D intensity plot of a beam at a given location along the beam path. A Gaussian or flat-top profile is often desired. The beam profile indicates nuisance high-order spatial modes in a laser cavity as well as hot spots in the beam.
In optics, a tophat beam (also Flat-top [1] or top-hat beam) such as a laser beam or electron beam has a near-uniform fluence (energy density) within a circular disk. It is typically formed by refractive [ 2 ] or diffractive optical elements from a Gaussian beam .
The equations below assume a beam with a circular cross-section at all values of z; this can be seen by noting that a single transverse dimension, r, appears.Beams with elliptical cross-sections, or with waists at different positions in z for the two transverse dimensions (astigmatic beams) can also be described as Gaussian beams, but with distinct values of w 0 and of the z = 0 location for ...
The equation for the divergence of a pure Gaussian TEM 00 unfocused beam propagating through space is given by =, (1) where D 00 is the diameter of the beam waist, and λ is the wavelength. Higher mode beams often start with a larger beam waist, D 0, and/or have a faster divergence Θ 0. In this case Equation (1) becomes
A Gaussian beam has the lowest possible BPP, /, where is the wavelength of the light. [1] The ratio of the BPP of an actual beam to that of an ideal Gaussian beam at the same wavelength is denoted M 2 ("M squared"). This parameter is a wavelength-independent measure of beam quality.
The diameter of the multimode beam is then M times that of the embedded Gaussian beam everywhere, and the divergence is M times greater, but the wavefront curvature is the same. The multimode beam has M 2 times the beam area but 1/M 2 less beam intensity than the embedded beam. This holds true for any given optical system, and thus the minimum ...
A circular laser beam with uniform intensity across the circle (a flat-top beam) focused by a lens will form an Airy disk pattern at the focus. The size of the Airy disk determines the laser intensity at the focus.
If the phase profile on SLM is flat, the SLM works effectively as a mirror. If the phase has a helical profile, the resulting beam is a Laguerre-Gaussian (LG) beam with a well-defined OAM. In real applications, there is a non-negligible admixture in the reflected beam in the form of a Gaussian beam.