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A multi-point dynamic displacement probe was developed for measuring dynamic displacement and deformation. In this probe, a self-focusing micro-lens array (SMLA) replaces a microscope objective normally used in autofocus sensors, and an acousto-optic deflector (AOD) is used as a scanner to allow the collimated laser beam to scan the SMLA, namely, allow the focused spot to scan the sample surface. Due to the very high scanning speed of the AOD, the relative position of many points, and thus the dynamic deformation, can be measured in near real time. The method’s principles, accuracy, and error sources are described. © 1997 Society of Photo-Optical Instrumentation Engineers.

A time-sharing collimation (TSC) method is developed to measure the beating force of an insect. In this method, a rod with a square cross section is used as a sensor block to transform the force variation to tilt angle variation, and an acousto-optic deflector is used as a diffractive scanner to measure these angle variations in two directions. We first calibrate the force variation with respect to the tilt angle variation and find that the uncertainty in force measurement for the TSC system is 8.8×10−4N.We then apply the method to measure the dynamic angle variations and the beating force of a bumblebee. © 1997 Society of Photo-Optical Instrumentation Engineers.

A novel scanning fringe projection method is developed to simultaneously measure the variations in both position and shape of a swimming fish. This method combines the commonly used fringe pattern projection method and a laser scanning technique into one optical system. In this new system, one or more reference fringes are generated by an acousto-optic deflector, and laser triangulation is used to determine the order of the reference fringe. These reference fringes are then combined with the conventional fringe pattern, and the fringe order is determined from the reference fringes. The method enables us to simultaneously measure the position and shape of a moving object. We successfully apply the method to a swimming fish. © 1998 Society of Photo-Optical Instrumentation Engineers.

A multireference fringe-pattern projection (MRFP) method is developed for rapid measurement of the shape of an object that has spatially isolated surfaces. The method combines the commonly used fringe-pattern projection method and an acousto-optic deflector (AOD) scanner in one optical system. The AOD scanner generates reference fringes, whose positions can be conveniently adjusted to suit the respective object by changing the control signal to the AOD. We determined the accuracy of this MRFP method by measuring the displacement of a plastic plate and comparing the results with those obtained using a linear gauge. We find the relative accuracy to be 0.3. To demonstrate the capability of this method to measure objects that have isolated surfaces, we use it to measure a vertical translation stage. Finally, we use it to measure the variations in position and shape of a fish while it is swimming. Such variation measurements are useful for studying the fluid dynamics of a swimming fish. © 1997 Society of Photo-Optical Instrumentation Engineers.