Multi-wave EM-Acoustic Systems
In this chapter, several EM-Acoustic systems for biomedical sensing and imaging will be introduced.
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Multi-wave EM-Acoustic Systems
In this chapter, several EM-Acoustic systems for biomedical sensing and imaging will be introduced. In Sect. 4.1, a photoacoustic microscopy system is designed and implemented for 3D imaging, which has been proved on phantom study and will be used for ex vivo and in vivo experiments. In Sect. 4.2, a multi-channel microwaveacoustic imaging system is designed, together with a multi-channel photoacoustic receiver system including a linear-array ultrasound probe and multi-channel data acquisition card. In Sect. 4.3, a miniaturized photoacoustic receiver is designed, prototyped and demonstrated with dramatically reduced compact size in palm.
4.1
NTU Photoacoustic Microscopy System for 3D Imaging
In this section, a prototype of photoacoustic microscopy system is designed, developed and tested using phantom. The overview of the photoacoustic microscopy system will be introduced, followed by the detailed specifications, operation procedure, and an initial phantom experiment to prove the functionality of the system.
4.1.1
System Overview
The system diagram of the photoacoustic microscopy is shown in Fig. 4.1. It includes a computer to synchronize the whole system and perform the image reconstruction; a function generator to trigger the OPO laser firing and oscilloscope data recording; a 3D X/Y/Z motor system to scan the sample along with the water tank; and a set of optical components (ND filter, ConL: convex lens, FC: fibre coupler; MMF: multi-mode fibre) to guide the laser light to focus on the sample. © Springer Nature Singapore Pte Ltd. 2017 F. Gao, Multi-wave Electromagnetic-Acoustic Sensing and Imaging, Springer Theses, DOI 10.1007/978-981-10-3716-0_4
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4 Multi-wave EM-Acoustic Systems
ND filter
Func on generator
MMF
OPO Laser ConL
FC ConL
Oscilloscope ConL
Amplifier
X
X-axis driver Y-axis driver
Y Z
US Water tank
Z-axis driver
Sample
X-Y-Z step motor
Fig. 4.1 The system diagram of the photoacoustic microscopy system
With 2D raster scanning, a 3D image could be reconstructed after bandpass filtering and Hilbert transformation to extract the envelope of the PA signals. The custom-designed software is developed based on C++ programming language using Microsoft Visual Studio 2012. The GUI of the software is shown below (Fig. 4.2): The function of each part in the software is listed below: Communication: To connect the motor and function generator with PC through series port. Enable And Disable: To turn on/off the step motor; reset the system if alarm. Monitor: To show the current position of the scanner. Homing: To reset the motors moving to the homing positions. Motion Profile: To set the moving velocity; manually move the scanner for adjustment.
Fig. 4.2 The GUI of the photoacoustic microscopy system
4.1 NTU Photoacoustic Microscopy System for 3D Imaging
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Precise Motion: To move the scanner to accurate position precisely. Scan: To set the scan step size, delay time, starting and stopping positions; To start and stop scanning in 2D or 3D; To monitor the to
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