Miniature particle image velocimetry system with LED in-line illumination

For two decades, there has been active research to enhance the performance of particle image velocimetry (PIV) systems. However, the resulting systems are rather costly, cumbersome and delicate. In this paper, we address the design and some first experimental results of a PIV system belonging to the opposite paradigm. The miniature PIV or MPIV system features relatively modest performance. For example, our MPIV prototype has a field of view of 6 mm x 5 mm and can measure about 50 velocity vectors for liquid flows slower than I m s(-1). However, it is considerably smaller (our MPIV could be held in circle divide40 mm x 120 mm), cheaper (our MPIV total cost is less than $500), easy to handle and less hazardous (accidental exposure of the eyes to the strobe light). Potential applications include industrial velocity sensors. The proposed MPIV system uses a one-chip-only CMOS camera with digital output. Only two other chips are needed, one for a buffer memory and one for an interfacing logic that controls the system. Images are transferred to a personal computer via its standard parallel port. No extra hardware is required (in particular, no frame grabber board is needed). In the MPIV prototype presented in this paper, a ring of 12 super-bright LEDs in line with the optical axis is used as a strobe light in a forward-scatter configuration. Experimental results are presented and discussed.