A catalytic converter for purifying exhaust gas discharged from an automotive internal combustion engine. This propagating far field pattern is focused by a lens to obtain a flattop intensity at the focal plane. The bandwidth utilization rate of optical networks can be obviously increased when transmitting fine granularity services in accordance with the embodiments of the present invention; furthermore, the storage space of each node through which the LSP passes is saved and the recovery performance of fine granularity services is guaranteed. The ultra-sound sensor measures the position, quality and size of the emulsion band.