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Grinlens shows the use of gradient-index materals to make a focusing element for a CD player. In this design, the gradient coefficients are used as variables. In an alternate approach, the gradient is predetermined and the curvatures are varied. Gradient-index technology has been applied to several diverse application areas. One of the common ones is in consumer optics, where small gradient lenses or arrays of gradient lenses are used in CD-ROMS and copiers. The lens shown here was designed by Nishi and Tayuma at Nippon Sheet Glass (NSG), manufacturer of gradient lenses known by the trademark Selfoc. In connection with Selfoc lenses, it is worth noting that although NSG makes the paraxial data for their lenses available to the public, the actual data describing the real index distributions has not been published. The data for the index distributions used in this lens do not necessarily coincide with that for commercial Selfoc lenses. The lens is included here to show an example of how it can be entered into OSLO, as well as to assess the general performance level that might be expected from a GRIN lens of this type. In the drawing shown below, the block on the right is an optical disc. In analyzing this system, please recall that since the standard paraxial trace does not handle gradient index materials, you must use the * pxc and * pxt commands to obtain paraxial data.