Abstract: Periodic motions are analyzed by generation of real time moire fringe images. A line grating mounted on the object (1) surface is photographed using a rigidly supported camera (4) from an oblique angle to the plane of the grating. A negative transparency of the line grating is placed within the camera (4) supported by a glass plate and, with the shutter open, the transparency is first registered with the instant image of the stationary line grating then skewed to produce mismatch fringes. A TV camera (6) monitors the subsequent interaction between the skewed negative and the instant image of the line grating on the moving object (1) as seen on the glass plate at the camera image plane and this interaction is displayed on a TV monitor (10). The image is characterized by the presence of a secondary fringe phenomena indicative of object displacements.

Abstract: A signal-conditioning circuit for use in conjunction with transducers measuring simultaneously steady state and fluctuating parameters, e.g. pressure. The circuit comprises low-pass filtering means, preferably comprising an active filter, for removing the AC component of the transducer output signal representing the fluctuating component of the measured parameter, to produce a DC output signal representing the steady state component of the measured parameter; and subtracting means for subtracting the DC component from the transducer output signal to produce an AC output signal representing the fluctuating component of the measured parameter. The circuit is thus capable of producing simultaneous outputs representing separately the steady state, fluctuating, and combined components of the transducer output signal, with the introduction of little or no phase error.