Prealigned Optics

With prealigned optics means that the focal point of each individual unit is aligned to a defined position called the Design Focal Point (DFL). This makes it easy to work with the Optoskand external optics.

The Effective Focal Length (EFL) is related to the imaging properties of the lens and is what we normally call the focal length of the lens.

The Design Focal Length (DFL) of the focusing unit is related to the working distance of the focusing unit. The Design Focal Length is chosen close to the Effective Focal Length and defines the distance from our mechanical interface to the focal spot position of a parallel incoming beam. The optics is prealigned, which means that variations due to tolerance in Effective Focal Length and/or Back Focal Length will be adjusted for.

The Back Focal Length (BFL) is the distance from the exit side of a lens on the optical axis to the focal point assuming a parallel incoming beam. This distance is not used in the description of the focusing optics, but defines the position of the lens seat within the holder.

The lens above is a doublet lens (it consists of two lens elements).
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Prealigned optics make it easy to get into focus.