Provided are a crucible which prevents polycrystal formation to easily allow growth of optical part material single crystals, and a single crystal growth method employing the crucible. Using fuzzy technology, the membership of the image points ant their colors in color categories is determined by way of membership functions and a gray value GW is allocated to each image point depending on the thus determined color category. A pump is disposed at the outlet of the submersible tank to evacuate water from the submersible tank in a surrounding body of water. Since only minimal displacement inputs to such a FBW flight control system is required, the travel of the pedals are exceeding compact, such that pilot workload is significantly reduced through the reduction in the frequency and magnitude of aircraft control inputs. External communication with the MAC device andor the host interface is enabled after the first period is up.