The laser beam enter a beam expander after the laser beam is generated in the laser resonator. The most common type of beam expander is derived from the Galilean telescope which usually has one negative input lens and one positive output lens. The input lens presents a virtual beam focus at the output. For low expansion ratios(1.3-20´) the Galilean telescope is most often employed due to its simplicity, small package size and low cost.
Schematic Diagram of Beam expander
The lens 1 focuses the laser beam from the laser generator on the front focus plane and the new beam waist w¢0 and pergence angle q¢ can be represented as
From above equations, we can conclude that the beam expansion ratio and the collimation ratio for a Gaussian beam depend not only on the specifications of the beam expander, but also on the laser beam parameters as well as the positions of the optical lenses.
The function of a beam expander is to reduce the laser beam angle and thus make the focused beam diameter smaller.
We can provide all types of beam expanders such as fixed beam expanders and variable beam expanders (zoom beam expanders) at various laser wavelengths such as 1064nm, 432nm, 355nm, 266nm, 10.6um, 980nm and 1550nm etc.For more information, please click here.