Master Slave Optical Coherence Tomography
- Master Slave optical coherence tomography1 (MS-OCT) operates like a time domain OCT1, selecting signal from a selected depth while scanning the laser beam across the sample.
Master Slave is a spectral (Fourier) domain OCT method, hence benefits from the sensitivity and speed advantage of the spectral (Fourier) domain methods in comparison with time domain method1, 3-5.
- Master Slave method allows collection of signals from any number of depths, as required by the user, ie of any number of en-face OCT images, from any depths, separated by any distance from the neighboring en-face slices1, 3-5. MS-OCT does not require resampling of data, hence no linearization, no calibration necessary, no clock needed in the
swept source OCT, no linearized spectrometer in spectrometer based OCT1, 3-5.
- MS-OCT is tolerant to dispersion7, so no need to optimize the quantity of glass in the interferometer. Since no data re-sampling is required, the sensitivity at large depths provided by the method proposed is slightly superior to that provided by the FFT based technique1, 3-5. The depth resolution does not depend on the way in which data are sampled, and reaches the theoretical expected limit1, 3-5.
- The Master Slave method is ideally suited to production of en-face OCT images from any tissue, including the eye, to satisfy the recent revival of interest in the en-face orientation7,8.
- The MS method is ideally suited for parallel computing algorithms on GPUs due to its parallel nature. Recently, we have demonstrated realtime production of MS based B-scan images of the human retina9 as well as a dual modality imaging system en-face SLO/OCT entirely based on MS method 10.
- A. Gh. Podoleanu and A. Bradu, “Master-slave interferometry for parallel spectral domain interferometry sensing and versatile 3D optical coherence tomography,” Opt. Express 21, 19324-19338 (2013).
- A. Gh. Podoleanu, “Principles of en-face optical coherence tomography: real time and post-processing en-face imaging in ophthalmology,” (in Clinical en-face OCT atlas, B. Lambruso, D. Huang, A. Romano, M. Rispoli, G. Coscas eds., J.P. Medical Ltd 2013), Chap. 1.
- A. Bradu and A. Gh. Podoleanu, “Calibration-free B-scan images produced by master/slave optical coherence tomography,” Opt. Lett. 39, 450-453 (2014).
- A. Bradu and A. Gh. Podoleanu, “Imaging the eye fundus with real-time en-face spectral domain optical coherence tomography,” Biomed. Opt. Express 5, 1233-1249 (2014).
- K. Kapinchev, F. Barnes, A. Bradu, A. Gh. Podoleanu, “Approaches to General Purpose GPU Acceleration of Digital Signal Processing in Optical Coherence Tomography Systems,” IEEE International Conference on Systems, Man, and Cybernetics (SMC), 2013, 2576-2580, (2013).
- A. Bradu, M. Maria, and A. Podoleanu, “Demonstration of tolerance to dispersion of master/slave interferometry,” Opt. Express 23, 14148-14161 (2015).
- First international congress of en-face OCT, Rome 2013.
- Second International Congress on “En-Face” OCT imaging New Developments in OCT, OCT Angiography, Rome, 2014.
- Adrian Bradu, Konstantin Kapinchev, Frederick Barnes, and Adrian Podoleanu, “On the possibility of producing true real-time retinal cross-sectional images using a graphics processing unit enhanced master-slave optical coherence tomography system,” J. Biomed. Opt., 20, 076008 (2015).
- Adrian Bradu, Konstantin Kapinchev, Frederick Barnes, and Adrian Podoleanu, “Master slave en-face OCT/SLO,” Biomed. Opt. Express 6, 3655-3669 (2015).
Researchers in the Applied Optics Group were the first to demonstrate en-face images from the retina, now known as C-scans. To mark the event, a special brick has been engraved in the Footstep project (part of the new Crab & Winkle Path alongside the Templeman Library in the campus).
The image was made possible by realizing that scattering in combination with a fixed coherence gating, can generate a C-scan. There is no need for an external phase modulator if the object to be imaged is scattering and the image size is sufficiently large. The modulation is, interestingly, created by scanning the beam over the target.
The OCT/SLO instrument was invented in 1998 by Adrian Podoleanu and David Jackson.
- Optical mapping apparatus with adjustable depth resolution
United States Patent 5975697 · Filed: 11/25/1998 · Published: 11/02/1999
- A. Gh. Podoleanu and D. A. Jackson, Combined Optical Coherence Tomograph and Scanning Laser Ophthalmoscope, Electronics Letters, Vol. 34, No. 11, (1998), pp. 1088-1090.
- A. Gh. Podoleanu, D. A. Jackson, Noise Analysis of a Combined Optical Coherence Tomograph and a Confocal Scanning Ophthalmoscope, Appl. Optics, Vol. 38, (1999), No. 10, pp. 2116 – 2127.
Our first OCT/SLO ever was an en-face OCT/SLO system, where the OCT channel operates based on en-face time domain OCT. After 2002, spectral domain OCT technology took off, and the SLO channel was then paired sequentially with a spectral domain OCT channel. Such a system is now sold by Optos Plc., based on the patent:
The acronym OCT/SLO lives on meaning now different formats of OCT. Spectral domain OCT technology is now so fast, that a fundus image can be created using spectral domain OCT. Several groups have by now reported generation of a fundus type image to guide the B-scan imaging based by the spectral domain OCT, and labelled their instruments as OCT/SLO.
Key publications on the OCT/SLO in the Applied Optics Group
- R.B. Rosen, M. Hathaway, J. Rogers, J. Pedro, G. Patricia, P. Laissue, G. M. Dobre, and A. Gh. Podoleanu “Multidimensional en-Face OCT imaging of the retina,”
Opt. Express 17, 4112-4133 (2009).
- A. Gh. Podoleanu and R. B. Rosen, “Combinations of techniques in imaging the retina with high resolution,” Progress in Retinal and Eye Research 27, 464-499 (2008).
- I. Trifanov, M. Hughes, R. B. Rosen, and A. Gh. Podoleanu, “Quasi-simultaneous OCT/confocal imaging,” J. Biomed. Opt. 13, 044015 (2008).
- R. B Rosen, M.E.J. vanVelthoven, P.M.T. Garcia, R.G Cucu, M.D de Smet, T.O. Muldoon, and A. Gh. Podoleanu, “Ultrahigh-Resolution Combined Coronal Optical Coherence Tomography Confocal Scanning Ophthalmoscope (OCT/SLO) : A pilot study,” Spektrum Augenheilkd 21, 36–47 (2007).
- M. E. J. Van Velthoven, F. D.Verbraak, L. A. Yannuzzi, R. B. Rosen, A.Gh. Podoleanu and Marc D. De Smet, “Imaging the Retina by En-Face Optical Coherence Tomography,”
Retina – the Journal of Retinal and Vitreous diseases 26, 129–136, (2006).
- R. G. Cucu, A. Gh. Podoleanu. A. Rogers, J. Pedro, R. B. Rosen, “Combined confocal scanning ophthalmoscopy/en face T-scan based ultrahigh resolution OCT of the human retina in vivo,” Opt. Lett. 31, 1684-1687 (2006).
- A. Gh. Podoleanu, G. M. Dobre, R. G. Cucu, R. Rosen, P. Garcia, J. Nieto, D. Will, R. Gentile, T. Muldoon, J. Walsh, L A. Yannuzzi, Y. Fisher, D. Orlock, R Weitz, J. A. Rogers, S. Dunne, and A. Boxer, “Combined Multiplanar Optical Coherence Tomography and Confocal Scanning Ophthalmoscopy,” J. Biomed. Opt. 9, 86–93 (2004).
- A. Gh. Podoleanu, G. M. Dobre, R. G. Cucu, and R. Rosen, “Sequential OCT and Confocal Imaging,” Opt. Lett. 29, 364-366 (2004).
- A. Gh. Podoleanu, R. Rosen, J. A. Rogers, G. M. Dobre, R. G. Cucu, D.A. Jackson, and Shane Dunne, “En-face optical coherence tomography in ophthalmology,” University Politehnica Bucharest, Sci. Bull, Serie A 65, 190-198 (2003).
- A. Gh. Podoleanu, R. G. Cucu, R. A. Rosen, G. M. Dobre, J. A. Rogers, and D.A. Jackson, “Quasi-simultaneous OCT en-face imaging with two different depth resolutions,” J. Phys. D: Appl. Phys. 36, 1696–1702 (2003).
- A. Gh. Podoleanu, J. A. Rogers, G. M. Dobre, R. G. Cucu, D. A. Jackson, R Rosen, et al, “Multi-planar OCT/ Confocal Ophthalmoscope,” Clinic Ophthalmic Research Supplement, Karger, Basel, ISSN 0030-3747, 112 (2002).