Guiding light

Mention fiberoptics to most people today and they likely think first of optical communications and telecom applications, but that was not always the case.

Sep 1st, 2005

Mention fiberoptics to most people today and they likely think first of optical communications and telecom applications, but that was not always the case. The precursor to optical fiber was the light pipe, which was originally developed to guide light for illumination from one place to another. As early as the 1840s, Swiss physicist Daniel Collodon and French physicist Jacques Babinet showed that light could be guided by total internal reflection along jets of water for fountain displays, notes Jeff Hecht in his book, City of Light: The Story of Fiber Optics. By the late 1800s inventors had realized that bent quartz rods could carry light and in 1899 David D. Smith of Indianapolis was granted a U.S. patent (number 624,892) for a surgical lamp . . . [that is] wholly free from heat in the part that touches or enters the body. It is this ability to separate a light source from the area being lit that has driven ongoing development of optical fiber for delivering illumination. In machine vision for example, intense sources such as -halogen lamps are often required and fiber delivery of the light brings many significant benefits including sparing the target area from unnecessary heat and unwanted radiation content (see p. 72).

Of course, fiber isnt the only method of guiding light. Bulk optics are an integral aspect of optical systems and novel design and manufacturing approaches are improving overall system designs. Aspheric lenses, for -instance, can reduce the overall lens count in an optical system or improve -performance of a low -number lens, but their use has been limited by -fabrication -constraints. The new approaches combined with techniques like the magneto-rheological finishing featured on this months cover are changing the way aspheres are viewed and creating new design opportunities (see p. 68). Meanwhile at the forefront of photonics advances, a family of new concepts is extending optical resolution to subwavelength scales that are -unobtainable with classical optics and changing the way light is guided and collected on the nanoscale (see p. 86).

Stephen G. Anderson
Associate Publisher/Editor in Chief
stevega@pennwell.com

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