Vasilios Aris MorikisDan DeLahunta
Dr. Hyle Park, Ph.D.
Optical Coherence Tomography◦An Overview of OCT
System Setup◦Sample Arm◦Galvanometer
Project Overview◦Methodology◦Results◦Conclusions
High resolution sub-surface imaging Non-invasive
◦Not harmful to subject Potential in many fields
◦Ophthalmology (RNFL thickness, AMD)◦Dermatology (photoaging, BCC detection)◦Cardiology (assessment of vulnerable
plaques)◦Gastroenterology (Barrett’s esophagus)
Time delay between reflected light is measured to determine depth of the reflecting structure◦ Due to the short time delays between signals OCT must use an
interferometer to detect the reflected light. Interference fringes are formed when the sample and reference
arms are within a small range. A depth profile is formed by the detection of the interference
pattern between the reference and sample arm as the reference arm is scanned.
The intensity of the depth profile is encoded on a logarithmic scale.
A 2D cross section or even a 3D volume can made by scanning the beam across the sample.
Helped to construct the Sample Arm.
Built the box to power and control the Galvo
Video of the Galvo moving
Develop analysis/processing code in MATLAB
Objective: Mathematically focus raw data obtained from the 1310 nanometer system.◦Adjust the incident angle, focal length, and
the wavelength.◦Increase the signal to noise ratio (SNR) to
produce high resolution image.
Collimator
Diffraction Grating
Focusing Lens
Fast Line Scan Cameras
Polarized beamsplitter cube
Read the Image
Flip Matrix (if
necessary)
Zero Padding
FFTDisplay Image
Interpolate
Raw data obtained when the reference and sample arm are 600 microns apart.
Image taken of the mirror.
Pixel Number
Inte
nsi
ty
Completely unprocessed data. To create accurate image
point spread function should be narrow and high (ignore all the noise in the middle).
Creates a blurred black line when the actual image is formed.
Splits the matrix and adds many 0’s in Fourier space.
Doubles the size of the original graph.◦ Used to increase the point density to interpolate
more accurately.
Inte
nsi
ty
Inte
nsi
ty
Pixel Number Pixel Number
Used to find remap the data linearly in wave number (k) to improve the results of a subsequent FFT
Takes the Intensity vs. Pixel number graph and Intensity vs. k.
Fourier transform switches one complex valued function into another.◦Transforming k (wave number) into actual
space.
Side Camera Straight Camera
Incident Angle 49 degrees 51 degrees
Grating Spacing 1.0e-3/1145 1.0e-3/1145
Focal Length 92 millimeters 95 millimeters
Wavelength 1350 nanometers 1350 nanometers
Pixel Width 25 micrometers 25 micrometers
Now that the parameters are correct a much more focused image is created.◦Dark line at the top is thin and not blurry
Image obtained form the 1310 nanometer system before processing (left) and after processing (right).◦ Image width:100 microns◦ Image height: 500 microns
Very first image acquired with either system.
I would like to thank NSF and the UC Riverside BRITE program for funding, as well as the University of California, Riverside and NIH (R00 EB007241), and Dr. Hyle Park and the rest of the Park Research Group for their guidance.
Mr. Jun Wang for organizing and Dr. Victor Rodgers for directing the program.
