A vane pump is composed of a casing having a cylindrical inner bore and a rotor disposed in the inner bore with an eccentric relation to the inner bore. The apparatus is characterized in that it further comprises a sensor device set up for recording a remaining pattern of the coloring agent on the carrier film after the heating of the carrier film and set up for generating a sensor signal on the basis of the recorded pattern. The ball valve includes in one embodiment a hydraulic piston, containment union, ported stem, containment cage and drag plunger, and is adapted to regulate the flow of fluid northward through the valve. The sleeve member is mounted on the core such that the core is disposed in the sleeve passage and the sleeve member exerts a radially compressive recovery force on the core. The microinterferometer further includes a lens formed on the substrate for focusing the second portion of the incident light to a predetermined local distance, and a photo-detector for receiving interference patterns produced from the first portion of the incident light reflected from the diffraction grating and the second portion of the incident light reflected from the object surface.