A first polarizer and a second polarizer have respective absorption axes extending approximately perpendicularly to each other, and a first retardation plate and a third retardation plate have respective slow axes extending approximately perpendicularly to each other. The sleeve includes at least one, and possibly a pair of, lengthwise removed strip section so as to expose a corresponding lengthwise surface of the metal ribbon. For example, the method can comprise mixing the solid material with the grinding aid, and using a grinding media such as steel balls to grind the solids.