1. Karissa Thoma: Co-leader Tuan Tran: Co-leader Susie Samreth: BSAC Peter Kleinschmidt: Communicator Vidhya Raju: BWIG Prof. Walter Block (BME): Advisor Prof. Scott Sanders (ME): Client

2. Presentation Outline Background on Optical Coherence Tomography Introduction to biopsy imaging with needle Client Requirements: image resolution etc. Discussion of chromatic deflectors Evaluation of alternative designs Future work: continue work with best diffraction optic

3. Optical Coherence Tomography OCT image of finger http://www.romulomene.med.br/eng/index.html Analogous to ultrasound (light instead of sound) Light source: laser (short coherence) Penetration is on the order of mm Information encoded in wavelength Fourier transform performed to get image

4. Based on an image from: http://bil.nb.uiuc.edu/biophotonics/technology/oct/ OCT Schematic

5. Biopsy Imaging OCT image of normal retina vs. retina affected by tumor http://www.eyetumour.com/ocular_tumours_ investigation.php In vivo imaging Applications Characterizing tumor tissue in cancer patients Ophthalmology: cross- sectional structure of eye Early detection of disease

6. A Brief Primer: Diffraction and Gratings Basic Idea: monochromatic light Each wavelength potentially carries information (ENCODING) Chromatic Deflector: effects splitting

7. Prisms Prism www.physics.ohio- state.edu Snell’s Law describes behavior of light when it encounters two different media

8. Diffraction Gratings m: order d: groove distance λ: incident wavelength θ i : incident angle θ m : diffracted angle Diffraction Grating http://www.britannica.com/eb/art- 37362/Spectrum-of-white-light-by-a-diffraction- grating

9. Problem Statement Current imaging techniques: Complex design based on moving parts Lack of versatility Task: Use diffraction optics to eliminate movement Increased spatial/angular resolution

10. Client Requirements Maximize Angular field of view Image resolution (20 um) Durability Versatility Ultrasound transducer

11. Client Requirements Minimize Cost of administration Cost of manufacturing Cost of development Needle diameter Hypodermic Needles http://www.needles.cn/img/Sterile_Hypodermic_Need le_For_Single_Use.jpg

12. Design Alternatives Existing models with moving parts Prism Transmission Grating

13. Prism with Moving Parts Weights Prism w/ Moving Parts Angular field of view 0.2010 Image resolution 0.208 Durability0.204 Cost of Manufacturing (per needle) 0.104 Cost of development 0.102 Cost to Administer 0.105 Needle Diameter 0.056 Versatility 0.058 Total10 6.2

14. Prism WeightsPrism Optic Angular field of view 0.203 Image resolution 0.202 Durability0.207 Cost of Manufacturing (per needle) 0.109 Cost of development 0.109 Cost to Administer 0.108 Needle Diameter 0.057 Versatility 0.056 Total10 5.65

15. Transmission Grating Weights Transmission Grating Optic Angular field of view 0.207 Image resolution 0.207 Durability0.207 Cost of Manufacturing (per needle) 0.107 Cost of development 0.107 Cost to Administer 0.108 Needle Diameter 0.057 Versatility 0.057 Total10 7.1

16. Weights Transmission Grating Optic Prism OpticPrism w/ Moving Parts Angular field of view 0.207310 Image resolution0.20728 Durability0.20774 Manufacturing Cost (per needle) 0.10794 Cost of development 0.10792 Cost to Administer0.10885 Needle Diameter0.05776 Versatility0.05768 Total10 7.15.656.2

17. Future Work Investigate Reflection vs. transmission grating Immersion gratings Number of grooves Needle encapsulation

18. Conclusion OCT is a powerful imaging tool Eliminate moving parts by using basic optics Diffraction is most effective Explore further optical configurations

19. Acknowledgments Prof. Walter Block Biomedical Engineering Prof. Scott Sanders Mechanical Engineering Prof. Andrew Sheinis Astronomy

20. References Websites http://www.romulomene.med.br/eng/index.html http://www.eyetumour.com/ocular_tumours_investigation.php www.physics.ohio-state.edu http://www.britannica.com/eb/art-37362/Spectrum-of-white-light-by-a-diffraction-grating Literature Sources Boppart, S. A. (2005). Optical coherence tomography - an overview. Bouma, Brett et al. (2000). High-resolution imaging of the human esophagus and stomach in vivo using optical coherence tomography. [Electronic version]. Gastrointestinal Endoscopy, 51(4) Changhuei, Y. Forward scanning imaging optical fiber probe David Huang, Eric A. Swanson, Charles P. Lin, Joel S. Schuman, William G. Stinson, Warren Chang, et al. (1991). Optical coherence tomography. Science, 254, 1178. Fujimoto, J, Boppart, S, Tearney, GJ, Bouma, B, Pitris, C, Brezinski, M. (1998). High resolution in vivo-intra-arterial imaging with optical coherence tomography. [Electronic version]. Heart, 82, 128-133. Guillermo Jo, Tearney, et al. (1997). In vivo endoscopic optical biopsy with optical coherence tomography. [Electronic version]. Science, 276, 2037-2039. Hwang, Joo et al. (2005). Optical coherence tomography imaging of the pancreas: A needle-based approach. [Electronic version]. Clinical Gastroenterology and Hepatology, 3, 549-552.

21. Questions?

22. Interferometer