Linking transducer transfer function with multi-pulse excitation photoacoustic response

Transducer-matched multipulse excitation for signal-to-noise ratio improvement in diode laser-based photoacoustic systems

“…Additionally, it is important to note that the twin resonance structure of the transfer functions of the C-type transducers translates well in the multipulse excitation response results in agreement with our previous observations. 24 Summarizing the results presented in Figs. 4-6, the TM-MPE is providing the 1.2 to 1.8 fold increase in the maximum registered amplitude, dependent on the transducer and particular arrangement used.…”

“…The oscillations of A n max jdp in the region III are due to the transducer transfer function. 24 Fig. 4 with roman numbers and illustrated with a typical signal for each of them.…”

“…Thus, inclusion of the phase transfer function into the analysis might be necessary to explain this behavior. 24,27 Based on good overall agreement between the measured double-pulse responses 25 and multipulse responses and the linear addition model (Fig. 5), we can use the maximum amplitude of the modeled response to obtain a lower estimate of the impact of the transducer resonance effects on the registered photoacoustic amplitude.…”

“…22 It is nonlinearly dependent on the interpulse delay time and in the limit of small t R it might cover the transducer resonance. On the other hand, in the absence of the resonant effects, the signals of individual pulses U sp ðtÞ arriving at the transducer with various interpulse delay times shall add linearly 16,17,23,24 E Q -T A R G E T ; t e m p : i n t r a l i n k -; e 0 0 1 ; 3 2 6 ; 4 5 2…”

“…Two illumination configurations are built as follows: (A) 905 nm DL (Laser Components), with driver LDP-V50-100V3 and CU PLCS-21, coupled into 600-μm core MMF, providing 1.2-μJ pulses of 12-ns length 25 and (B) custom-build laser diode bar 652 nm (Ferdinand-Braun Institute), with beam transformation optics (BTS series, LIMO), supplied with LDP-V-240-100 and PLCS-20, coupled into 550-μm core MMF, providing 1.1-μJ pulses of 31-ns length. 23,24 DL drivers (LDP-V*) and CUs (PLCS*) are from PicoLAS.…”