A four dimensional data set of the cardiac cycle of a zebrafish embryo was acquired using postacquisition synchronization of real time photoacoustic b-scans. Utilizing an off-axis photoacoustic microscopy (OA-PAM) setup, we have expanded upon our previous work with OA-PAM to develop a system that can sustain 100 kHz line rates while demodulating the bipolar photoacoustic signal in real-time. Real-time processing was accomplished by quadrature demodulation on a Field Programmable Gate Array (FPGA) in line with the signal digitizer. Simulated data acquisition verified the system is capable of real-time processing up to a line rate of 1 MHz. Galvanometer-scanning of the excitation laser inside the focus of the ultrasonic transducer enables real data acquisition of a 200 by 200 by 200 pixel, volumetric data set across a 2 millimeter field of view at a rate of 2.5 Hz.
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http://dx.doi.org/10.1364/BOE.4.001451 | DOI Listing |
Micromachines (Basel)
November 2024
Key Laboratory of Antennas and Microwave Technology, Xidian University, Xi'an 710071, China.
A new type of fully polarimetric retrodirective array (RDA) using a PON-type structure is proposed in this paper. The fully polarimetric property is the result of the proposed phase conjugation circuits, which perform phase conjugation processing on the x, y, and z polarization electric field components of the incident wave when combined with a tri-polarized antenna array. It enables the retrodirective array to receive and retransmit an arbitrary polarized incident wave.
View Article and Find Full Text PDFThe Shack-Hartmann wavefront sensor (SHWS) is known for its high accuracy and robust wavefront sensing capabilities. However, conventional compact SHWS confronts limitations in measuring field-of-view to meet emerging applications' increasing demands. Here, we propose a high-density lens transfer function retrieval (HDLTR)-based SHWS to expand its field-of-view.
View Article and Find Full Text PDFRev Sci Instrum
November 2024
Tianjin Key Laboratory of Intelligent Control of Electrical Equipment, TianGong University, TianJin 300387, China.
Multifrequency electrical impedance tomography (MFEIT) has shown great application prospects in the field of biomedical imaging. To realize high-precision multifrequency electrical impedance information acquisition, a high-precision MFEIT system with undersampling combined with a fast digital demodulation algorithm is proposed. The system is integrated with 16 electrodes, and semi-parallel acquisition is used.
View Article and Find Full Text PDFWe report a characterization of the spatial resolution of terahertz (THz) apertureless near-field imaging of metal lines deeply buried beneath a silicon dioxide layer. We find a good resolution for edge contrast, even in the case where the capping layer is considerably thicker than the tip radius. We find that contrast and resolution depend on demodulation frequency, thickness of the capping layer, and radius of the tip.
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