Beam of light most visible laser pointer

If you want to produce a clear beam of light outdoors during the day with a handheld laser (especially under the sun at noon) and the sky is gloomy, you should be able to see a clear beam of light with a 445nm laser above 3W or a 532nm laser with 0.8-1W. There are bright and dark bright spots found in the laser beam, no matter what color of light, as long as it is visible, this will appear (invisible lasers are also available, and they must be captured by CCD, etc.). Other friends have also explained the reason. That is, the laser is a coherent light source, and due to the superposition of the phases, the brightness changes.Visibility of the laser pointer beam The color of the Laser pointer is related to the environment in which it is used. The light beam is produced by reflecting particles in the air. A large number of particles can be seen from close observation of the light beam. For the daily environment, even if the air quality is good, it will be produced. In terms of visibility, the human eye is more sensitive to green, so the 532nm green laser only needs 100mW (0.1W) to produce a clear beam of light indoors during the day. The beam quality of a laser beam has multiple definitions, which are usually used to measure the degree to which the laser beam is focused under certain circumstances (for example, with a limited beam divergence angle). Commonly used methods to quantify beam quality include: — Beam parameter product (BPP), which is the product of the beam radius at the beam waist and the far-field beam divergence angle — M2 factor, defined as the beam parameter product and the diffraction-limited Gaussian beam with the same wavelength The ratio of BPP to M2 is the reciprocal of M2, which is very large when the beam quality is high.