An optical scanning device is for scanning with a radiation beam a substantially circular track of an information layer. In undesirable cases the axial vibrations may lead to or exasperate the stick-slip problems of the logging tool. Disposed above the first mattress is a second mattress that has an air bladder construction. A first connector is monolithically formed with a longitudinal end portion of the base member to connect the at least one groove to one of the liquid container and the liquid ejection head. and exercises control so that, within the same parity group, idle seek is not executed by two or more drives 23, 23,. A water hose of a radiator and an exhaust pipe are arranged in the space.