Research and Realization of the Minimized Far-Field Spot Size of Laser Weapons Variable-Focus Emission System

Abstract

The sufficient irradiation power density is an important prerequisite for laser weapons to cause effective damage to targets. It is necessary to evaluate and optimize the irradiation spot size in order to satisfy the requirements under the situation of the limited laser output power. Based on the model of Cassegrain co-axial variable-focus emission system and the transmission theory of Gaussian beam, the general rule between the spot size at the target position and the parameters of the emission system is calculated. Meanwhile, the typical emission system is simulated and analyzed with MATLAB software. The results show that the spot size is not the minimum value when the laser beam is focused on the target. Instead, when the laser beam is focused on a certain position before the target, the spot size diverging to the target is the minimum value. Based on this, the formula for the defocusing amount is derived. The results reflect that the defocusing amount is inversely proportional to the target position, proportional to the square of the focal length of the main mirror, and it is independent of parameters of emission laser beam. The research has the important practice significance for the quick adjustment of the emission system and the realization of the minimum irradiation spot size and the destruction of the target.

Keywords

• |laser weapon|gaussian beam|variable-focus system|defocusing amount|spot size