Universal Journal of Physics and Application Vol. 11(5), pp. 176 - 181
DOI: 10.13189/ujpa.2017.110506
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Development of a Free Space, LED Illuminated Spectral-domain Optical Coherence Tomography Setup


Nyasha J. Suliali 1,*, Peter Baricholo 1, Pieter H. Neethling 2, Erich G. Rohwer 2
1 Optics Research Group, Department of Applied Physics, National University of Science and Technology, Zimbabwe
2 Laser Research Institute, Department of Physics, Stellenbosch University, South Africa

ABSTRACT

Free-space spectral domain optical coherence tomography has been demonstrated using an 8 mW ultra-bright 850 nm light-emitting diode with a 40 nm spectral width. The system detects longitudinal reflectivity of surface and sub-surface layers of optical elements to depths of a millimetre with high fidelity. Development stages included mathematical analysis of light interference by superposition of electric field phasors of reference and sample arms of a Michelson interferometer. A method by which depth-resolved reflectivity is acquired is described. A locally assembled Czerny Turner monochromator was aligned such that the interferometer output beam is dispersed into its spectral components before image re-construction. Calibration of the 2048-pixel detecting charge-coupled device line camera was performed using a Mercury vapour lamp with 8 spectral lines spanning from the ultra-violet to yellow region of the electromagnetic spectrum. Processing of interference fringe signals from spectral domain data is described and an analysis of variations in frequency of the interference fringe signal and threshold illumination with depth into the sample presented. A test of sensitivity of the depth imaging algorithm to low-amplitude signals is also reported.

KEYWORDS
Optical Coherence Tomography, Spectral Interferometer, Interferometry, Axial Scan

Cite this paper
Nyasha J. Suliali , Peter Baricholo , Pieter H. Neethling , Erich G. Rohwer . "Development of a Free Space, LED Illuminated Spectral-domain Optical Coherence Tomography Setup." Universal Journal of Physics and Application 11.5 (2017) 176 - 181. doi: 10.13189/ujpa.2017.110506.