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M 2 is useful because it reflects how well a collimated laser beam can be focused to a small spot, or how well a divergent laser source can be collimated. It is a better guide to beam quality than Gaussian appearance because there are many cases in which a beam can look Gaussian, yet have an M 2 value far from unity. [1]
When a Gaussian laser beam is focused, the focused spot diameter is defined by d 00 = 4 λ f π D 00 {\displaystyle d_{00}={4\lambda f \over \pi D_{00}}} , (3) where d 00 is the ideal focused spot diameter, f is the focal length of the focusing lens, and D 00 is the input beam waist and is placed one focal length from the lens as shown in the ...
For example, a helium-neon laser (633 nm) with 1 mm beam diameter would focus to a 317 μm spot with a 500 mm lens. A laser beam profiler with a 5.6 μm pixel size would adequately sample the spot at 56 locations.
The most widely used numerical laser diffraction results are: The median volume-weighted diameter, or D 50. Derived from the cumulative curve, it represents the particle diameter separating the upper 50 % of the data from the lower 50 %. The D 10 and D 90 values, also derived from the cumulative curve.
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 θ = Θ / 2 {\displaystyle \theta =\Theta /2} is close to the minimum possible value, which is given by [ 2 ]
Traditionally, SNR is defined to be the ratio of the average signal value to the standard deviation of the signal : [2] [3] = when the signal is an optical intensity, or as the square of this value if the signal and noise are viewed as amplitudes (field quantities).
Laser linewidth from high-power high-gain pulsed laser oscillators, comprising line narrowing optics, is a function of the geometrical and dispersive features of the laser cavity. [29] To a first approximation the laser linewidth, in an optimized cavity, is directly proportional to the beam divergence of the emission multiplied by the inverse ...
Gaussian beam width () as a function of the axial distance .: beam waist; : confocal parameter; : Rayleigh length; : total angular spread In optics and especially laser science, the Rayleigh length or Rayleigh range, , is the distance along the propagation direction of a beam from the waist to the place where the area of the cross section is doubled. [1]