Abstract: The present invention is a method for providing a disk of an optical tester. The disk comprises a transparent substrate that has a first surface and an opposite second surface. The disk also includes a coating on the first surface of the transparent substrate. An identical coating can be applied to the second surface of the transparent substrate. The coating can have multiple layers of thin films. The present invention provides a method to determine the required thickness of the coating to enhance the sensitivity of zero flying height measurement.

Abstract: The present invention is a method for providing a disk of an optical tester. The disk comprises a transparent substrate that has a first surface and an opposite second surface. The disk also includes a coating on the first surface of the transparent substrate. An identical coating can be applied to the second surface of the transparent substrate. The coating can have multiple layers of thin films. The present invention provides a method to determine the required thickness of the coating to enhance the sensitivity of zero flying height measurement.

Abstract: An apparatus that can measure a space between a first surface and a second surface. The apparatus may include a light source that can reflect a light beam from the first and second surfaces. A birefringent element may split the reflected light beam into an ordinary beam and an extraordinary beam. The ordinary and extraordinary beams are detected by a photodetector. The apparatus may include a controller that is coupled to the photodetector and which can compute the space from a phase value that is determined from data collected when the mechanism varies the phase between the ordinary and extraordinary beams, and a ratio between a first modulation amplitude detected from light reflected from the first and second surfaces and a second modulation amplitude detected from light reflected from the first surface when the second surface is not adjacent to the first surface. The ratio can also be used to compute the reflectance and index of refraction of the second surface.

Abstract: Optical fibers having novel refractive index profiles are disclosed. Optical fibers in accordance with the invention are especially useful for application in telecommunication applications such as networks. Processes for the preparation of optical fibers are also disclosed.

Abstract: Optical fibers having novel refractive index profiles are disclosed. Optical fibers in accordance with the invention are especially useful for application in telecommunication applications such as networks. Processes for the preparation of optical fibers are also disclosed.