An optical apparatus for producing chromatic dispersion. The method produces contact holes with a relatively uniform CD from top to bottom, i. Such fluoroelastomers may be vulcanized with polyhydroxy curatives. A single hit to the logical register is selected among the group of register mappers. The connective portion is used to connect the impeller to the shaft and preferably comprises a nonthreaded, tapered bore extending through the impeller. A method for determining correctness of program code in the memory module includes making a value stored in at least one specific address match a first rule; providing a inspection instruction; and determining whether the value stored in at least one specific address matches the first rule or not according to the inspection instruction.