The main elements of the lens cover include the lens, transducer, and the thin film. This subsystem is vital to the overall functionality of the LCS. Measuring the impedance response of the lens cover represents an important intermediate step between the piezo and the final LCS. This measurement is essential for understanding the variations in resonant frequency and impedance that occur once the piezo is adhered to the lens/film.

Figure 3-3 Lens Cover = Lens + Glue + Transducer + Thin Film

Figure 3-4 shows the impedance response of the lens cover. Two resonant frequencies are obtained within the 20kHz to 100kHz range. The mode at 65.8kHz has a much lower impedance of 226.7Ω, which can draw higher current for a given voltage compared to the mode at 29.9kHz, and therefore possibly a higher acceleration level to expel water. Note that the frequency of 65.8kHz is a few kHz away from the resonant frequency of the piezo alone. This deviation is reasonable, considering the significant alteration in boundary conditions that occurs once the piezo is adhered to a lens.

Figure 3-4 Impedance Response of Lens Cover