A vortex induced vibration suppressor and method is disclosed. The MDD and hybrid detector overcome saturation problems observed in conventional hybrid detectors by providing a unique electron multiplier portion that avoids the path-length differences. In operation, a pulse signal is applied to a measurement point on the other side of the coupling capacitor, and the voltage generated at that point is detected. The frame is provided with slots for inserting the two faced portions and supporting holes for rotatably supporting the axle portions. A passkey image file corresponding to the passkey is generated. The image processing apparatus acquires a first area identification result by performing area identification processing on the generated binary image data and acquires a second area identification result by performing area identification processing on the generated edge image data.