There are a variety of applications where the positioning of an optical beam, or generally the steering of an optical beam, is used. For example, coupling laser light into a fiber optic is a fairly common practice when using fiber optics—e.g., coupling light into a fiber optic cable is a common practice in optics labs and in the fiber optic industry. Thus, a wide variety of environments (laboratory and otherwise) use lasers coupled into fiber optics, where this coupling is adjusted in such environments. In many of these applications, precise coupling is desired, but it is often difficult to achieve. For example, fiber optic coupling can be especially difficult when using a single-mode fiber, e.g., where the core of the fiber is less than about 10 microns in diameter, thus making the alignment of the light into the fiber an extremely sensitive undertaking, often needing less than a one-micron level of accuracy.
Fiber optic coupling may be achieved with an optical mount using a mechanical lead screw to adjust the position of a laser relative to a fiber optic cable. However, lead screws and similar mounts can lead to hysteresis and poor thermal performance in systems. Electronic actuators can be used with such screw drives and the like, but these devices and systems may still experience significant hysteresis.
There are also a variety of additional fiber coupling configurations, e.g., sold by most major optics vendors, but these can be quite costly, difficult to use, and can experience a great deal of hysteresis and poor thermal performance. In particular, there are several methods for fiber optic coupling that largely involve moving an optic mirror and/or lens to optimize laser power coupled into the fiber. However, because both the position and the angle of the laser into the fiber should be controlled, there is often a great deal of hysteresis using such complex setups.
In general, previous methods of fiber coupling can be grouped into two methods: (1) moving the beam relative to a fixed fiber optic, or (2) moving the fiber tip relative to the input light. As mentioned above, beam motion is most-often achieved using a pair of ‘steering’ mirrors that are mounted on tip/tilt mirror mounts. However, in such systems, the beam may be reflected multiple times, which can amplify angular errors from previous optical elements. The fiber tip may also or instead be moved relative to an input beam using, e.g., flexure mounts, translation stages, compressed springs, and so on. In such systems, the act of touching the alignment components may introduce a small change in position, which can lead to increased difficulty in achieving a precise and repeatable optical alignment. Thus, there remains a need for improved positioning of an optical beam, especially where precise positioning is desired.