Improved Image Quality in AOOCT through System Characterization

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Improved Image Quality in AO-OCT through System Characterization Samelia O. Okpodu Vision Science and

Improved Image Quality in AO-OCT through System Characterization Samelia O. Okpodu Vision Science and Adanced Retinal Imaging Laboratory, Department of Ophthalmology & Vision Science, University of California, Davis Mentor: Dr. Julia W. Evans Faculty Advisor: Dr. John S. Werner Additional Collaborators: Dr. Robert J. Zawadzki, Steve Jones, Dr. Scot S. Olivier Home Institution: Norfolk State University 1

Outline n Background n Data n Importance n Proof of Principle n AO-OCT vs.

Outline n Background n Data n Importance n Proof of Principle n AO-OCT vs. OCT n Conclusion &Future Directions n My Research n Installation Process 2

Background-What is OCT? n n n Optical Coherence Tomography (OCT) In vivo imaging technique

Background-What is OCT? n n n Optical Coherence Tomography (OCT) In vivo imaging technique Diagnosis and monitoring treatment of human retinal diseases OCT permits us to see retinal layers http: //www. 99 main. com/~charlief/theeyebg. gif n OCT B-Scan. UCD 3

OCT vs. AO-OCT n Allows rapid acquisition of cross sectional retinal images. n Volumetric

OCT vs. AO-OCT n Allows rapid acquisition of cross sectional retinal images. n Volumetric reconstruction of retinal structures with micrometer axial resolution. AO-OCT n Improves lateral resolution. n 3 microns in all directions. AO-OCT Reconstruction. UCD 4

UCD AO-OCT System S-H WFS Far. Field CCD 5

UCD AO-OCT System S-H WFS Far. Field CCD 5

My Research n Installing a Far-Field Camera n Proof of principle testing (basic system

My Research n Installing a Far-Field Camera n Proof of principle testing (basic system testing) n Measured errors which affect OCT image quality ¨ Used wavefront measurements to simulate the PSF ¨ Used the far field camera to measure the PSF 6

Installation Process n Proper components ¨ Machine n Optical Constraints ¨ Far n Shop

Installation Process n Proper components ¨ Machine n Optical Constraints ¨ Far n Shop Field and WFS both require pupil planes Mechanical/ Space Constraints 7

Installation Process Pellicle Beamsplitters Pupil Plane Spherical Flat Mirror 26 cm Input Fiber Iris

Installation Process Pellicle Beamsplitters Pupil Plane Spherical Flat Mirror 26 cm Input Fiber Iris Pupil Plane • Proper space b/w CCD’s, to avoid beam clipping. • WFS & Far Field Lens require a pupil plane. • Far Field has to be located at the focal length of the lens. • Calibration mode used for proof of principle. lens Pupil Plane FS ) W cm H S x 14 4 (1 ld e i r. F D ) a F CC cm 14 x 4 (1 8

Types of Data WFS n n n Far Field Data n Side by Side

Types of Data WFS n n n Far Field Data n Side by Side comparisons n Proof of Principle 0. 12 D neg. Cylinder 9

Proof of Principle: Defocus n n n Trial Lens: 0. 12 D neg. defocus.

Proof of Principle: Defocus n n n Trial Lens: 0. 12 D neg. defocus. Amount of defocus and spot size are directly proportional. Change in spot size ¨ Measured ¨ Simulated 10

Proof of Principle: Aberrator n Plastic bag- simulates higher order aberrations n Qualitatively similar

Proof of Principle: Aberrator n Plastic bag- simulates higher order aberrations n Qualitatively similar n Would prefer quantitatively similar ¨ Improved by correlation or re -sampling 11

Conclusion & Future Directions n Far Field Camera is installed and working in calibration

Conclusion & Future Directions n Far Field Camera is installed and working in calibration mode. n Far Field data compares relatively well to the WFS data in calibration mode. n Understand Calibration Error n Investigate mitigation techniques to improve the performance of the AOOCT system. n Far Field Camera Software n Adjust optical design (ghost reflections) n Testing with model & human eye 12

Acknowledgements n Dr. John S. Werner, UCD Dr. Julia W. Evans, UCD, LLNL Dr.

Acknowledgements n Dr. John S. Werner, UCD Dr. Julia W. Evans, UCD, LLNL Dr. Robert J. Zawadzki, UCDMC Center for Adaptive Optics Dr. Patricia Mead, NSU Dr. Demetris Geddis, NSU Dr. Arlene Maclin, NSU n References: n n n R. J. Zawadzki et al. , “Adaptive Optics- Optical Coherence Tomography: optimizing visualization of microscopic retinal structures in three dimensions, ”J Opt. Soc. Am. A /Vol. 24, No. 5 (2007) ¨ J. W. Evans et al. , “Characterization of an AO-OCT System, ” Proceedings of the 6 th International workshop on adaptive optics for Industry and Medicine : University of Galway, Ireland, June 2007. ¨ This work has been supported by the National Science Foundation Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under cooperative agreement No. AST - 9876783. 13

Element measured power (m. W) coupler Light Budget Reflectivity/ Transmistivity 1. 2 0. 19

Element measured power (m. W) coupler Light Budget Reflectivity/ Transmistivity 1. 2 0. 19 1. 22 Collimation optics 0. 98 1. 20 achromatizing lens 0. 98 1. 17 aperture 0. 85 1. 00 pellicle 0. 92 S 1 0. 87 0. 98 0. 90 Iris 0. 78 0. 87 0. 78 0. 98 0. 66 0. 7 0. 46 0. 98 0. 45 56 0. 98 0. 44 0. 98 0. 43 0. 98 37. 9 0. 42 0. 98 0. 41 0. 98 0. 40 0. 98 0. 39 Transmitted Power ratio (%) /Through Bimorph DM put (%) S 2 n Pellicle 1 Light throughput is always important Pellicle 2 S 3 S 4 92 MEMS 92 75 n 32% throughput in original system; 29% in current system S 6 0. 45 90 51. 9 Horiz scanner S 7 MEMS 0. 67 69. 1 S 5 Bimorph DM S 8 0. 43 70 34. 9 Vert scanner Total input to the eye predicted power (m. W) S 9 S 10 29 0. 39 Flat mirror Total to Eye 0. 36 Power ratio 0. 98 0. 77 before Far Field 0. 9 0. 69 (%) 75 31. 7 14 0. 39

Extra Images Aberrator Extras 15

Extra Images Aberrator Extras 15