In example implementations, an apparatus and method are provided. The apparatus includes a movable carriage, an energy source coupled to the movable carriage and a plurality of shutters coupled to the movable carriage. In one example, the plurality of shutters is coupled to the movable carriage along a length of the energy source. Each one of the plurality of shutters may be coupled to the movable carriage via respective coupling mechanism that provides a continuously variable movement of each one of the plurality of shutters.