In this paper, a novel photoacoustic (PA) sensing probe design consisting of single optical fiber is reported. The same optical fiber is used for light delivery, which also serves as an acoustic delay line to relay the PA signal. As the key feature of the design, the ultrasound transducer is made optically-transparent to allow excitation light to pass through. This probe design provides three major benefits, including miniaturization, co-registered optical excitation and acoustic detection, and clear separation of PA signal from interference signals. Testing results show that PA probe provides good sensitivity and high linearity.
In this paper, we report a new photoacoustic sensing probe design consisting of two optical fibers. One optical fiber is used for delivering the excitation light pulses. The other one serves as an acoustic delay line to relay the generated PA signal from the target to an outside ultrasound transducer. With the addition of suitable time delay, the original PA signal can be easily separated from the interference signals. To demonstrate this new design, a prototype probe was designed, fabricated and tested. The PA sensing performance was characterized with different concentration of black dye solutions. The testing results show that the PA sensing probe can provide good sensitivity and can maintain high linearity over a wide range of concentrations.
This paper reports the development of a new charge amplification approach for photoacoustic tomography (PAT) based on parallel acoustic delay line (PADL) arrays. By using a PADL array to create different time delays, multiple-channel PA signals can be received simultaneously with a single-element transducer followed by single-channel DAQ electronics for image reconstruction. Unlike the conventional voltage amplifiers whose output voltage drops with increasing transducer capacitance, both theoretical analysis and experimental results have shown that the charge amplification can provide almost constant transducer-amplifier gain, which is not affected by the transducer capacitance. Therefore, it allows the use of a large single-element transducer to interface many PADLs without sacrificing the SNR of each channel. This opens the possibility of using large PADL arrays to achieve PAT with a wide field of view and high lateral resolution.