Variable Beam Expander Theory

The fixed magnification sliding lens beam expanders are offered with optics that have either narrowband or wideband ar coatings.

Variable beam expander theory.

Beam expanders thorlabs galilean type beam expanders which are available in both fixed and variable magnification options are offered for use in the uv visible near infrared and mid infrared spectral ranges. Techspec research grade variable beam expanders feature λ 4 transmitted wavefront galilean designs and high laser damage threshold ar coatings to ensure maximum transmittance while minimizing ghost reflections. By expanding a beam prior to focusing smaller focal spot sizes can be achieved. The beam expander contains a fixed lens at the front followed by two movable lenses.

Rotating focusing mechanisms such as threaded focusing tubes rotate the optical elements during translation. Thorlabs 0 5x to 2x galilean variable beam expanders reducers allow the user to easily adjust the beam diameter without altering the alignment of the optical setup. Beam expanders improve a beam s collimation. A beam expander with adjustable magnification.

Beam expanders have numerous uses. Where f 1 is the focal length of the positive lens and f 2 is the focal length of the negative lens. Our variable beam expanders allow separate magnification and divergence adjustment. Beam expanders also known as collimators or up collimators typically are used in systems with a long beam path to keep the beam collimated or to vary the focus spot size for a given focusing lens.

Techspec research grade variable beam expanders rvbx are ideal for high power laser applications where magnification changes may be required such as prototyping or r d. There are variable beam expanders zoom expanders i e devices where the magnification can be adjusted in a certain range e g. The magnification of a galilean beam expander is determined by the following equations. 2 optical track length f 1 f 2 optical track length f 1 f 2.

The mechanics used to focus a beam expander or change the magnification of a variable beam expander are typically classified into two different types. These variable magnification zoom beam expanders are designed for required wavelength and each type of our beam expanders has a divergence adjustability. A beam expander is a two or more element optical system that changes the beam s size and divergence characteristics. All optical elements of beam expanders are made of fused silica with high lidt coatings and provide stable and reliable performance even using them with high power lasers.

Various magnifications are available but it is important to ensure that the input and output beams clear the apertures. Those contain at least three lenses and some fine mechanics to adjust the position of at least one of them. Once the desired beam size and divergence is reached the position can be locked with two sets of screws. The zoom is adjusted by turning the magnification.