In an image storing apparatus, files are enabled to be certainly copied without overlapping by the fairly simple operation. Glass windows are then placed in the openings, and are each fused to the metal plate by heat in a manner so that each window projects outwardly on each side of the plate. The method includes receiving a plurality of input signals at a first rate from at least one source, transmitting the input signals to a reference object, and transforming the input signal to a known temporal reference. A Bragg grating is located at the bending portion of the optical fiber.