Optical train

An optical train, also called an optical assembly, is an arrangement of optical components (lenses, mirrors) to guide a line of sight and/or a laser beam. For example, the position and angle of lenses may be adjusted to guide a laser through the path required. Instruments like microscopes, telescopes and DSLRs all have optical trains that guide the incoming light towards a detector or the eye of an observer.

An optical train showing the arrangement and angle of lenses and mirrors to guide the laser