Device principle of asymmetric green laser beam
The near field laser beam is the area near the waist (focus) of the beam. The far field refers to the beam section far from the beam waist, that is, the distance to the focus is much greater than the effective Rayleigh length. The far field intensity profile can give the green laser beam divergence Angle. If the green laser beam divergence Angle is required in the near field, only the wavefront can be measured. In practice, it is difficult to obtain the far-field beam directly, so we need to use a focusing lens to obtain the intensity cross section on the focal plane, so as to obtain a simplified version of the far-field pattern. Beam quality is an important index to measure the quality of beam.
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There is no accurate definition of green beam quality and no standard measurement method, which brings inconvenience to scientific research and application. The commonly used methods to evaluate beam quality include: original diffraction limit multi-factor, Sterhl ratio, peripheral energy ratio, M2 factor or its K factor (beam transmission factor). Different beam quality definitions have different application purposes and different focus of reflected beam quality. The quality of the beam shall be assessed according to the specific purpose of application. Beam quality is a qualitative evaluation of laser characteristics and plays an important role in Laser pointer design, manufacture, detection and application. It is of great significance to discuss how to improve the universality of beam quality factors, analyze the factors affecting beam quality and control them. Laser beam quality is an important technical index of laser, which is used to evaluate the characteristics of laser qualitatively. However, for a long time, there has been no precise definition of green laser beam quality, and no standard measurement method has been established, which brings inconvenience to scientific research and application. In 1988, AESiegman introduced a dimensionless quantized beam quality factor parameter that scientifically describes laser beam quality and was adopted in 1991 by the draft ISO/TC172/SC9/WG1 standard. The research and measurement of laser beam quality has become a hot topic in recent years.
2021-09-18 06:14:29
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