Patent ID: 6404491
Filing Date: 2002-06-11
Classification: G01N

Abstract:
An apparatus for applying electromagnetic radiation to a moving sheet of epoxy prepreg material to measure the extent of chemical cure of said moving sheet of epoxy prepreg material, said moving sheet of epoxy prepreg material having a top and bottom surface;said apparatus comprising: a feeder for feeding said moving sheet of epoxy prepreg material; a collector for collecting said moving sheet of epoxy prepreg material; an optical element, comprising a solid, cylindrical mechanically durable inner core roller having an exterior surface with a thin coating of transparent material secured thereon; said optical element having a top and a bottom and two conical ends, said thin coating of transparent material on said exterior surface of said inner core formed of a material selected from the group consisting of organic polymer or inorganic solids transmissive to said electromagnetic radiation, said electromagnetic radiation comprising the light wavelength ranges; said optical element disposed between said feeder and said collector; and said optical element being adapted for rolling on said top surface of said moving sheet of epoxy prepreg material at a speed; means for controlling the rotation speed of said optical element to synchronize said optical element speed with the speed of said moving sheet of epoxy prepreg material; a plurality of alignment roller wheels arranged in staggered position forward and laterally with respect to one another and applying pressure against said top of said optical element so that said optical element contacts said moving sheet of epoxy prepreg material, said alignment rollers formed from an elastomer selected from the group consisting of siloxane and polyphosphazine: a counterpressure roller contacting said bottom of said sheet of epoxy prepreg material so that there is the necessary physical contact between said sheet of epoxy prepreg material and said bottom of said optical element; a circular coupling prism attached adjacent each said conical end of said optical element; a source for directing said electromagnetic radiation into said thin coating of transparent material on said exterior surface of said inner core at an input location at an angle below that for total internal reflection so that said electromagnetic radiation internally reflects within said thin coating of transparent material and determines the refractive index of said material using a critical angle technique wherein said radiation exits from said thin coating of transparent material on said exterior surface of said inner core cylinder at an output location; a detector positioned to receive said electromagnetic radiation exiting said thin coating of transparent material on said exterior surface of said inner core, said radiation detected by said detector providing the degree of chemical and physical changes of said epoxy prepreg material.