School of Physical Sciences

Welcome to the
Land of En-face optical coherence tomography (OCT)

This is where the first en-face OCT image of the retina was created and where the OCT/SLO was invented
Recently, we have created a novel technology, Master Slave, an ideal tool for en-face imaging. This represents a revival of the en-face view, whereby the values of the first OCT/SLO are re-enacted using the modern principles of spectral (or Fourier) domain OCT


En-face optical coherence tomography revival


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 dispersion6, 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.

Principle of operation of the MS method illustrated here using a multi-layered object. Decoding of the depth information can be obtained by comparing the reference (mask) channeled spectrum (mask) with the three channeled spectra (CS1, CS2, CS3) produced by interference between the reference beam and the back-reflected light by the three reflecting structures in the object.



  1. 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). 
  2. 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.
  3. A. Bradu and A. Gh. Podoleanu, "Calibration-free B-scan images produced by master/slave optical coherence tomography," Opt. Lett. 39, 450-453 (2014). 
  4. 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).
  5. 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). 
  6. A. Bradu, M. Maria, and A. Podoleanu, "Demonstration of tolerance to dispersion of master/slave interferometry," Opt. Express 23, 14148-14161 (2015). 
  7. First international congress of en-face OCT, Rome 2013. 
  8. Second International Congress on "En-Face" OCT imaging New Developments in OCT, OCT Angiography, Rome, 2014. 
  9. 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(7), 076008 (2015). 
  10. Adrian Bradu, Konstantin Kapinchev, Frederick Barnes, and Adrian Podoleanu, "Master slave en-face OCT/SLO," Biomed. Opt. Express 6, 3655-3669 (2015). 


Pillars of En-Face


Revival in Rome

Third International “En-face” OCT and OCT Angiography Congress, 2015

Second International Congress on "En-Face" OCT imaging New Developments in OCT, OCT Angiography, Rome, 2014. ANNOUNCEMENT

First international congress of en-face OCT, Rome 2013. ANNOUNCEMENT


Recent Publications from other groups

D. C. Hood, B. Fortune, M. A. Mavrommatis, J. Reynaud, R. Ramachandran, R. Ritch, R. B. Rosen, A. Dubra and T. Y. O. Chui, Details of glaucomatous damage are better seen on OCT en-face images than on OCT retinal nerve fiber layer thickness maps. Invest Ophthalmol Vis Sci. 56, 6208–6216 (2015).

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School of Physical Sciences, Ingram Building, University of Kent, Canterbury, Kent, CT2 7NH

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Last Updated: 19/10/2015