Laser beam width evaluation method based on moment invariance

Abstract

The invention discloses a laser beam width evaluation method based on moment invariance, and belongs to the field of optical measuring. According to the laser beam width evaluation method based on the moment invariance, background correction, binaryzation and median filtering processing are carried out on a collected light beam image at first to obtain a filtering image, then a zone marking is carried out on the filtering image to find an actual measurement light spot area, the center of mass and secondary moment of an actual measurement light spot are calculated, the calculated result is substituted into a formula acquired based on a moment invariance principle, and a long axis and a short axis of the light spot are calculated, namely the beam width; and finally the actual measurement light spot is framed by a rectangle adaptable to the calculated result and is displayed. The laser beam width evaluation method based on the moment invariance can not only calculate a laser spot of a regular shape, such as a round and an oval, but also calculate a laser spot of an irregular shape. Besides, the calculated result is not changed due to translation and rotation of the light spot, and reflects the inherent character of a laser beam.

Description

technical field [0001] The invention belongs to the field of optical metrology, and mainly relates to a laser airspace parameter measurement algorithm, in particular to an evaluation method for the beam width of a laser beam. Background technique [0002] In recent years, laser technology has developed by leaps and bounds, and has been widely used in many fields such as industry, medical treatment, national defense, information science, and biotechnology. Beam quality is an important technical indicator for judging the comprehensive performance of laser systems. Accurate measurement of laser beam quality can provide accurate and reliable experimental data for laser output, so that lasers can be used in various fields more safely, reliably and effectively. With the development of laser technology, laser beam quality measurement technology is also in continuous development. [0003] Laser beam quality mainly includes spatial parameters such as laser beam width, spatial intens...

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Problems solved by technology

[0010] In practical applications, the laser spot is not a rotationally symmetrical figure that strictly obeys the Gaussian distribution. For example, the laser spot used in the laser fuze is composed of three laser beams superimposed, and its shape is similar to a long strip of pods. There are also laser spots presents some irregular shapes, such as figure 1 Shown, then use 1 / e 2 The definition method cannot be calculated, and the second-order moment definition method has limitations. This limitation is manifested in that for a non-rotationally symmetrical spot with a certain light intensity distribution, the defined beam width in the x and y directions will vary with the spot size. The rotation changes, that is, for the same spot, when the spot rotates in the plane, the calculated beam width will change greatly, figure 2 and image 3 This change is visualized

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