A hardware development for optical tomography system using switch mode fan beam projection

• Published in: Sensors and actuators. A. Physical. Vol. 120; no. 1; pp. 277 - 290
• Main Authors: Rahim, R. Abdul, Chan, K.S., Pang, J.F., Leong, L.C.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 29-04-2005
• Subjects: Beams (radiation); Clocks; Conditioning; Hardware; Optical sensors; Optical tomography; Projection; Switches; Tomography; Optical tomography
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/j.sna.2004.11.038

This research used 16 pairs of optical sensors. The working principle is based on the switch and measure principle in electrical capacitance tomography (ECT), and fan beam shape projection from light emitters. The fast setting time of optical sensors and wide coverage of optical beam become the is implemented in a tomography system. In general, the system can be divided to three subsystems; they are projection, sensor signal conditioning and data acquisition. In the projection subsystem, a 4.8
kHz clock has been used to drive the LEDs, as a result, 300 complete projections obtained in a second. In the signal conditioning subsystem, a current to voltage converter has been used with each photodiode output, the signals are filtered and amplified before interfacing with the data acquisition system. In the data acquisition system, a computer based data acquisition system has been utilized. The modulated clocks from the projection sub-system are used to control the operation of data acquisition. This paper will discuss the detail of hardware development and shows the result obtained from the designed hardware system.