Dmitry A. Terpelov,
Pavel A. Shilyagin,
Valentin M. Gelikonov,
Grigory V. Gelikonov,
Institute of Applied Physics RAS, Russia,
"BioMedTech" LLC, Nizhny Novgorod, Russia
In spectral-domain optical coherence tomography the resulting interference signal is spectrally dispersed and recorded by multiple detectors. The individual spectral components of low coherence light are detected separately by the use of a spectrometer and a charge-coupled device (CCD) array. Fourier transformation of this cross-spectral density yields a signal comprising several terms, including a component containing depth-resolved information on the structure of the backscattering sample and artifacts. These artifacts are a strong DC signal, i.e. autocorrelation signal caused by the source light itself, the auto- and self-cross-correlated terms introduced by the reflections from various interfaces present in the optical system and the complex conjugate image .
Presented technique of artifacts removing in SD-OCT is based on a separate measurement of an informative optical spectrum and artifacts. For this purpose the actual value of optical path difference should be precisely changed during an exposition. The phase depended term of interference between reference and sample wave is averaged during exposition while path difference is modulated at the certain low and the informative component in a registered spectrum is nulled. After subtraction from the informative signal, the signal received on such averaging method, we have a signal without autocorrelation terms and additional modulation, caused by electrical circuit.
A catheter based optical setup with common-path dual interferometer is presented. Spectrometer optimization directed to fast numerical processing is described. A complex of electronic interface systems with coherence noise reduction for SD-OCT is developed.
Developed prototype of 1.3 um SD-OCT provides diagnostic quality images at a rate more then 20 fps (10,800 A-lines per second with 512x256 pixels) and can effectively eliminate the complex conjugate image, the DC noise terms, the auto- and self-cross-correlation terms.
The developed system setup is optimized for using as a base of new generation of OCT devices produced by “BioMedTech” LLC (Nizhny Novgorod, Russia).
Dr. Dmitry Alexandrovich Terpelov
Institute of Applied Physics RAS, Nizhny Novgorod, Russia, research fellow
Nizhny Novgorod, Russia
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