ABSTRACT
Use of a laser beam is an obvious choice in many metrological applications. When the laser is oscillating in TEM00 mode, the beam has a Gaussian profile, and its spatial extent is very small. It is important to understand its propagation and manipulation by the lens or any other image-forming component. Since light is characterized by wave motion as well, we begin with the three-dimensional wave equation and search for a solution, which would resemble a laser beam. The wave equation is given by ∇ 2 u − 1 c 2 ∂ 2 u ∂ t 2 = 0
