Fig. 1. Schematic of out-of-plane movement detection system

Fig. 2. Curve of zero-order Bessel function

Fig. 3. Schematic of DSSPI system

Fig. 4. Schematic of results of amplitude fluctuation method

Fig. 5. Cantilevered and slotted aluminum plate

Fig. 6. Fringe patterns of first 10 orders of out-of-plane vibration modes of specimen obtained by ESPI. (a)-(j) Complete plates; (A)-(J) slotted plates

Fig. 7. Mode patterns of bending vibration of complete plate. (a) 2nd order; (b) 3rd order; (c) 4th order

Fig. 8. Derivative fringe patterns along X direction of first 10 orders of out-of-plane modes of complete plate. (a)-(j) DSSPI; (A)-(J) FEM

Fig. 9. Derivative fringe patterns along Y direction of first 10 orders of out-of-plane modes of complete plate. (a)-(j) DSSPI; (A)-(J) FEM

Fig. 10. Derivative fringe patterns along X direction of first 10 orders of out-of-plane modes of cantilevered and slotted aluminum plate. (a)-(j) DSSPI; (A)-(J) FEM

Fig. 11. Derivative fringe patterns along Y direction of first 10 orders of out-of-plane modes of cantilevered and slotted aluminum plate. (a)-(j) DSSPI; (A)-(J) FEM