What is the best lens for focusing or collimating the output from a can-type laser diode?

Laser Diode Modules are the simplest commercial packaging for laser diodes. They consist of the actual diode, a photodiode for monitoring output, and the can that holds them. Unfortunately, there is no single “best” lens to focus or collimate their output. Lasers diodes pose special challenges because their outputs are irregularly shaped (elliptical rather than circular) and vary widely amongst the on the market. It is difficult to compensate for these factors with a single lens and therefore the best lens will depend on the specifications of one’s laser diode (e.g. the beam divergence in each axis) as well as the desired beam characteristics (e.g. desired spot size and distance). In many cases, the desired results can only be obtained with multiple elements. Luckily, if the main concern is beam quality without the need for a custom multiple-element solution, Edmund Optics® offers many Laser Diode Modules and other packaged diode lasers that come with the diode and integrated optics to maximize the quality of the beam.