Abstract
Pressure measurement technique for pulsed small pressure variation with duration range of several hundreds msec and the pressure range of several Pa on a flat wall induced by an approaching vortex ring was presented. The pressure variation causes deflection of a thin silicon nitride diaphragm with a thickness of 0.2μm and a size of 2 mm square. The deflection of the diaphragm was measured by optical interference method using a He/Ne laser. A sensitivity was optimized by selecting the internal stress of the diaphragm. This measurement technique was applied to a measurement of pressure variation on a flat wall induced by an approaching vortex ring.
