Types of Fiber Collimator

The output from an optical fiber can be collimated with a simple collimation lens placed at a fixed distance from the end of the fiber; a distance equal to the focal length. For ease of use, fiber collimators that are mounted to the fiber are often preferred.  These come in two types:

Fiber collimators designed to attach permanently to a fiber.These collimators are both compact and affordable, and a good solution for use with bare fibers.

Fiber collimators with mechanical interfaces that attach to a fiber connector. These can be designed to connect with whichever fiber connector you use; FC/PC, FC/APC and SMA are two popular options. These types of collimators are more expensive, but also more flexible as they can be easily attached or removed from a setup. Fiber collimators may include different types of lenses, including gradient-index (GRIN) lenses, singlet or doublet lenses. When you have a fiber with small mode radius and large beam divergent, you may need to use an aspheric lens to minimize aberrations. 

A fiber collimator may be adjustable, with screws for controlling beam directional and working distance, or fixed. It may be polarization maintaining. The exact fiber collimator you need will depend on the specifications of your application and the wavelength of light you need to have collimated as well as on collimated beam size.

A fiber optic collimator designed for a large collimated beam will be longer and larger than one designed for a small beam. Collimators to be used in high power laser applications must also be optimized for the high power levels and heat present in such situations.