Some embodiments include a valve positioned within a test tube to maintain a separation between components of liquid with different densities after centrifugation. The movable section and the lighting control section operate together such that the quantity of light per unit time of the diffused light guided to the objective illumination region is within a predetermined range. The function model verifying unit verifies a concurrent and parallel function model, to verify appropriateness of function module division and correctness of concurrence and parallelism. In one embodiment, the main bearings are lubricated by a portion of the process fluid so that the only fluid in the sealed spaces is the process fluid. An outer periphery of a plunger is adapted for slidable engagement with the interior surface of the gas cylinder, so as to form an operational chamber within the gas cylinder between the bottom portion thereof and the plunger. The antireflective coating is useful for providing a single-layer composite graded antireflective coating formed beneath a photoresist layer.