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INTERFEROMETER MICROSCOPE

MAKER: KIRK-NORLAND

APRIL 1989

SIGNED: 'NORLAND PRODUCTS, 695 JOYCE KILMER AVE.,NEW BRUNSWICK, NJ 08902, MODEL 25100, INPUT VOLTS 7.5 AMPS 0.3, SERIAL NO. 2134, MANUFACTURED April 1989'

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Interferometer Microscope

DESCRIPTION:

The Interferometer Microscope is basically in the same format as the metallurgical microscope, except that the light source is a monochromatic red light and the stage surface has attached to it a fitting for holding a reference flat horizontally with the fiber oriented vertically held in a grooved fitting. There is one eyepiece, and two objectives. The eyepiece is a 20X wide field type. The two objectives are a X and a X. The microscope came standard with a 40X objective, 10X and 20X objectives were additional options. Also included is an AC power supply and an extension for the fitting to hold the fiber. The red LED is turned on and off via a square pushbutton on the right side of the micrscope.

FROM THE KIRK DATA SHEETS: Ideal for checking cleaver performance. A unique, small, portable interferometer for checking the cleaved ends of optical fibres. It is based on a commercially available microscope with illumination provided by a red LED. Battery or mains versions are available. An interference pattern is formed by the wedge-shaped air gap between the fibre end face and a reference flat. By counting the number of fringes, the end angle can be deduced (71 /2 fringes across a 125gm diameter fibre is equivalent to one degree). The fibre is held perpendicular to the reference flat by a glass capillary which is itself a sliding fit into an accurately machined block. Using different capillaries, any size of fibre can be examined.The shape and distribution of the fringes also gives data on the topography of the end face and consequently valuable information on the state of the blade of the cleaving tool.

The author is eternally greatful to Dr Yuval Goren for providing this instrument to me for my collection so it may be added to this web site.

PRINICIPALS OF INTERFERENCE MICROSCOPY:
Interferometry of fiberoptic fibers takes advantage of two paths of light waves which are uneven with respect to phase shift. One set of light waves is reflected off the reference flat, while the second passes through the flat and is reflected back. The interaction of the two different sets of light waves leads to a barred pattern which reveals, depending on the number of bars ('fringes'), a difference in flatness of one surface, the reference flat, from the subject being studied, in this case the cut end of the fiber.

HISTORY OF THE INTERFEROMETER FIBER MICROSCOPE

The principal of light wave interference dates back to Young's experiments in the early 1800's and led to acceptance of the wave theory of light. The principals of interferometry eventually became important in astronomy, microscopy, and other fields.

When the use of fiberoptics started to develop, a method for inspecting the cleavage of a cut fiberoptic fiber was needed. This started with principals used in the optical system found in this microscope, but evolved into a much more complex computerized instrument now used in the 21st century.

Fiberoptic bundles were first used in endoscopy instruments starting in the 1950's. Fiberoptic endoscopy did not become commonplace until the last quarter of the twentieth century.

The first use of fiberoptics to transmit data rather than simply allow a flexible optical path for imaging, was accomplished in the 1960's. It was gradually incorporated into various devices, but it was not until the early 21st century that commercial data transmission using optical fibers became a practical use. Fiberoptic cable is now not only capable of faster data transmission, but at a faster bandwidth and with much less signal loss than with traditional wire. It has also become less expensive to make fiberoptics than copper wire.