A Picosecond Optoelectronic Cross Correlator using
a Gain Modulated Avalanche Photodiode for Measuring the Impulse
Response of Tissue
David Kirkby, Ph.D.
Ph.D. Supervisor: Prof. David T. Delpy
David Kirkby completed his Ph.D.thesis in April 1999. His research
project involved the following:
- Designing an optoeletronic cross correlator, which was able
to measure the optical response of tissue to a 2 picosecond,
800 nm pulse of light. This used a combination of optical components
(avalanche photodiodes, fibers, lasers, etc.) and radio frequency
electronic components (step recovery diode, phase shifter, GaAs
RF switch, bias-tee, filters, amplifiers, etc.). A block diagram
of the system may be found here.
- Developing a parallel Monte Carlo model to model light transport
in tissue. This model can run on many computer types in parallel,
and has been used in parallel using Sun workstations running
Unix and PCs running DOS.
- Developing a tissue phantom so the optical properties could
be changed easily.
- Making measurements of the impulse response of the phantom
with the cross correlator.
- Developing several fitting algorithms to determine the optical
properties of tissue from actual measurements with the cross
- Comparing the various fitting algorithms for speed and accuracy.
The Ph.D. thesis is available on-line as a series of PDF files.
The total size is 3.14 Mb. Note: please click on "Reload"
if viewing in Netscape after the files are downloaded, otherwise
you just see a blank page.
to the BORL website.
Page updated: December 12, 2000