Effect of the Photoconductive Layer on the Resolution of Opto-Acoustic Transducers
Resolution of opto-acoustic transducers (OAT’s) may be determined using linear systems theory. An OAT is treated as a linear spatial system. Each of its constituent layers is regarded as a subsystem characterized by a unique spatial transfer function. In a previous paper we have shown that the resolution of OATs is determined, to a very good approximation, by the transfer function of the piezoelectric layer alone. In this paper we show that the transfer function of the piezoelectric layer is affected by the presence of the photoconductive backing layer in such a way as to lower the resonant frequency of the OAT. We show also that the normalized resolution, the resolution measured in wavelengths at the operating frequency of the device, is affected if the OAT is operated off resonance. The normalized resolution increases for frequencies below the resonant frequency and decreases for frequencies above resonance.
KeywordsTransfer Function Resonant Frequency Spatial Frequency Piezoelectric Material Piezoelectric Layer
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