Dissertation > Excellent graduate degree dissertation topics show

An Experimental Study on Photon Counting Based Lock-In Detection System for Diffuse Light

Author: WangZhiChao
Tutor: ZhaoHuiJuan
School: Tianjin University
Course: Biomedical Engineering
Keywords: Multi-wavelength continuous wave diffuse light detection photon counting lock-in detection FPGA
CLC: R318.51
Type: Master's thesis
Year: 2012
Downloads: 9
Quote: 0
Read: Download Dissertation

Abstract


Continuous Wave Diffuse Optical Imaging (CW DOI) can achieve organ level detection of human information and has the advantages of non-invasive, non-ionize, high time resolution and continuous dynamic function. CW DOI need the measurement of the surface distribution of the output photon flow inspired by more than one driving source, which means that source coding is necessary. The most currently used source coding in DOI is time-division multiplexing (TDM) technology, which utilizes the optical switch to switch light into optical fiber of different locations. However, in case of large amounts of the source locations, the measurement time will become too long to capture the dynamic changes in real-time. In this paper, a frequency division multiplexing source coding technology is developed to reduce the measurement time and to improve the time resolution.The Implemented system is comprised of two laser diode sources, a wavelength division multiplexer, a photon counting detector, FPGA based digital lock-in detection circuit, communication and digital-to-analog convert hardware as well as host computer based Labview program. However, when applied to practical diffuse light measurement experiment, several problems had been found concerning the accuracy and stability of the system performance, such as a relatively high dark noise, poor signal to noise ratio, slow data transfer rate, etc.For each of the above-mentioned problems, this paper made an analysis, proposed a solution as well as carried out a verification experiment. To deal with the dark noise and signal-to-noise-rate issue, the effect of parameter configuration on system performance had been studied. To cope with the gross errors emerging in measurements, impedance matching was adopted between the photon detector and FPGA I/O pin; besides, the input pulse to FPGA was preprocessed before it was used as trigger signal. For data transfer rate issue, the square root calculation was transplanted from host computer into FPGA so as to reduce the amount of data needed to transfer.Finally, experiments have been carried out to verify performance parameters the improved system can achieve. Results have shown that the measured value was consistent with the actual light intensity, with the maximum relative error of 7.32%; besides, the measurements of each channel within 16~30mm range of source-detector distance consistent with analytical results, with the maximum relative error of 17%.

Related Dissertations

  1. Research on Electromagnetic Acoustic Transducer Detection System Based on FPGA,TH878.2
  2. Study on Drive and Control System of Five-Phase PMSM Based on FPGA,TM341
  3. Development of LXI Arbitrary Waveform Generator,TM935
  4. Design of Digital Predistorter for RF Power Amplifier Based on FPGA,TN722.75
  5. Synchronization and Channel Estimation Algorithm in Bursted OFDM System and Its Implementation on FPGA,TN919.3
  6. Performance Analysis of Anti-Multipath Capability in DSSS System and Study on the Compensation Methods,TN914.42
  7. Optimizing and Realising Research on Vedio Compression in TV Guidance System,TN919.81
  8. Research and Hardware Simulation of Multiuser Spread Spectrum Code Acquisition Based on FPGA,TN914.42
  9. Research on Basic Algorithms of Digital Image Processing and Implementation with FPGA,TP391.41
  10. Research of High Speed Image Pre-processing System Based on FPGA,TP391.41
  11. Design of High-Speed Digital Image Acquisition and Interface Based on FPGA,TP274.2
  12. Development of Inductance Sensor Data Acquisition System Based on FPGA,TP274.2
  13. Development of Serial Bus Analyzer Based on Nios,TP274
  14. Development of PMC High-speed Data Transmission Board Design Based on FPGA-RocketIO_X,TP274.2
  15. Development of Pxibus High Performance Digital I/O Module,TP274
  16. Development of LXI Counter,TP274
  17. A High-Speed and Real-Time Data Acquisition System Based on FPGA,TP274.2
  18. Design of GPS Information Receiving System Based on Nios Ⅱ,TN967.1
  19. Temperature and pressure explosives temperature field memory test technology,TQ560.7
  20. Erbium-doped fiber amplifier pump laser drive source research applications,TN248
  21. Remote FPGA system design and implementation of security upgrades,TP309

CLC: > Medicine, health > Basic Medical > Medical science in general > Biomedical Engineering > Other branches of biomedical engineering > Light,laser biomedical
© 2012 www.DissertationTopic.Net  Mobile