frequency domain optical coherence tomography (fdoct) joon s kim imsure summer research fellow at...
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![Page 1: Frequency Domain Optical Coherence Tomography (FDOCT) Joon S Kim IMSURE Summer Research Fellow At Beckman Laser Institute University of California at Irvine](https://reader035.vdocument.in/reader035/viewer/2022062300/56649d185503460f949ee02e/html5/thumbnails/1.jpg)
Frequency Domain Optical Coherence Tomography
(FDOCT)Joon S Kim
IMSURE Summer Research Fellow At Beckman Laser Institute
University of California at IrvineIrvine, CA 92612
Email: [email protected]
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OCT
• Optical Coherence Tomography– New field of imaging technology that can
complement conventional imaging techniques – Based on interference of EM wave– Provide high spatial resolution cross-sectional
view of tissues without excision– Endless potential biomedical applications
• Non-invasive Diagnostics
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OCT vs. Conventional Imag. Tech
1 mm 1 cm 10 cm
Penetration depth (log)
1 m
10 m
100 m
1 mm
Resolution (log)
OCT
Confocalmicroscopy
Ultrasound
Standardclinical
Highfrequency
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Two kinds of OCT
• TDOCT– Time Domain OCT– Use of Scanning Mirror
• FDOCT– Fourier (Frequency) Domain OCT– Use of laser source over band of optical
frequency– Advantages over TDOCT
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My research experience with FDOCT are in 2 phases…
• First phase: – Understanding and Replicating FDOCT
experimental setting from scratch
• Second phase: – Learning the physical and mathematical
reasoning behind the magical DSP algorithm which extract images out of OCT data!
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Part 1• FDOCT experiment set upSwept source
Phase Modulator
Sample
Probe
Detector1
Detector2
2 x 2 CouplerGrating
Mirror
Collimator
Attenuator
Fiber Fabry-Perot
interferometer
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Current FDOCT System
• No human intervention required
• Everything controlled from execution module in host computer
• Host computer – houses NI-6112: A2D Conversion of OCT
data– performs digital signal processing– controls peripherals
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Scanning sample
• Surface of sample is divided into imaginary grid.
• Each block in grid: Pixel
• Scanning in X direction– Lateral scan
• Scanning in Z direction– A scan
Z
XY
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Scanning sample (cont.)
• 1600 samples / A-scan (pixel)
• 400 A-scan / Lateral scan
• Lateral scanning Frequency: 2 KHz
• A-scanning Frequency: 10 MHz– Limited by A2D converter (NI-6112)
• Pixel size: 10 micron
• Slow process => not applicable in Vivo
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With NI-5122
• Max. Sampling Frequency: 100 MS/sec
• A-scanning Frequency: 100 MHz– More time for DSP – Boost lateral scanning frequency to 20 KHz– One step closer to in Vivo application of
FDOCT