The method and system operate to calibrate a transmission laser of the dense wavelength division multiplexer and to lock the laser to a selected transmission wavelength. Subsequently, a trim piece is attached along the side wall through the use of a second mechanical fastening element which is threadably connected to the first fastening element. As a result, if the number of colors used in image data is large, it can be judged that the image data is of a natural picture. The electric circuit comprises at least two contacts between the bowl unit and the driving block. A light emitter is affixed to the first surface of the substrate in an area not covered by either of the at least one first electrically conductive layer or the at least one second electrically conductive layer.