Characteristics of Laser Atmospheric Transmission

Characteristics of Laser Atmospheric Transmission
1、 Atmospheric transmittance
The energy attenuation of laser atmospheric transmission is mainly caused by the absorption and scattering of molecules and aerosols. The degree of attenuation is directly related to the laser wavelength, atmospheric conditions, and transmission distance. Aerosol and cloud particles will significantly increase the degree of attenuation, and the beam cannot penetrate the barriers formed by rain, clouds, and fog. The atmospheric transmittance is used to characterize the energy changes of light beams passing through the atmosphere. The article provides calculation methods for transmittance under horizontal transmission and oblique impact scenarios. The atmospheric sol model constant in urban environments is usually taken as 3.132, and atmospheric visibility is a direct indicator of atmospheric transmittance.
2、 Spot size of laser to target
The diffraction effect during transmission can cause the beam to diverge, thereby changing the size and energy distribution of the target spot; In practical scenarios, the size of the light spot is also affected by factors such as atmospheric turbulence, carrier platform shaking, and errors in the observation and tracking system. Atmospheric turbulence can cause random changes in atmospheric refractive index, leading to beam refraction and diffraction, resulting in drift and diffusion of the light spot. The article provides a corresponding calculation method for the radius and area of the target light spot based on various influencing factors, among which the atmospheric refractive index structure constant model of the International Telecommunication Union ITU-R can be used to describe different turbulence intensities.
3、 Power density of laser to target
This indicator is the core element that determines whether laser weapons can destroy targets. Only when the target power density exceeds the damage threshold of the target material, can effective damage to the target be achieved. The article combines the laser system output power and the corresponding atmospheric transmittance in the scene to provide a calculation method for the target power density.
Finally, it should be noted that this content is a rough and simplified introduction to the laser atmospheric transmission characteristics that are close to actual combat. Nonlinear effects such as thermal blooming have not been included, and the actual engineering scenarios are more complex. In practical applications, relevant conditions can be flexibly set to simplify calculations, obtain qualitative or approximate quantitative results, and evaluate and guide practice accordingly.