Search results
Results From The WOW.Com Content Network
The Gaussian function has a 1/e 2 diameter (2w as used in the text) about 1.7 times the FWHM.. At a position z along the beam (measured from the focus), the spot size parameter w is given by a hyperbolic relation: [1] = + (), where [1] = is called the Rayleigh range as further discussed below, and is the refractive index of the medium.
In optics, the complex beam parameter is a complex number that specifies the properties of a Gaussian beam at a particular point z along the axis of the beam. It is usually denoted by q . It can be calculated from the beam's vacuum wavelength λ 0 , the radius of curvature R of the phase front , the index of refraction n ( n =1 for air), and ...
Multiple prism beam expander using r prisms M is the total beam magnification given by M = k 1 k 2 k 3 ···k r, where k is defined in the previous entry and B is the total optical propagation distance [clarification needed] of the multiple prism expander. [5]
In laser science, the parameter M 2, also known as the beam propagation ratio or beam quality factor is a measure of laser beam quality. It represents the degree of variation of a beam from an ideal Gaussian beam. [1] It is calculated from the ratio of the beam parameter product (BPP) of the beam to that of a Gaussian beam with the same wavelength.
For a Gaussian beam, no simple upper integration limits exist because it theoretically extends to infinity. At r >> R, a Gaussian beam and a top-hat beam of the same R and S 0 have comparable convolution results. Therefore, r ≤ r max − R can be used approximately for Gaussian beams as well.
The factor is now called beam propagation ratio (M 2), and it is closely related to the beam parameter product. While the M 2 factor does not give detail on the spatial characteristics of the beam, it does indicate how close it is to being a fundamental-mode Gaussian beam.
The beam quality of a laser beam is characterized by how well its propagation matches an ideal Gaussian beam at the same wavelength. The beam quality factor M squared (M 2) is found by measuring the size of the beam at its waist, and its divergence far from the waist, and taking the product of the two, known as the beam parameter product.
If the beam is distributed in phase space with a Gaussian distribution, the emittance of the beam may be specified in terms of the root mean square value of and the fraction of the beam to be included in the emittance. The equation for the emittance of a Gaussian beam is: [1]: 83