A dual detection technique for Optical Coherence Tomography (OCT) preserves the phase information in the acquired spectra by the retrieval of quadrature components of the complex interferometric signal. A rotatable non-polarizing beam splitter cube provides the required p/2 phase shifted interference signal.
Optical coherence tomography (OCT) is an imaging modality for in vivo, noninvasive, high-resolution cross-sectional images of biological tissues. OCT can be used for imaging three dimensional structures, such as the retina in a human eye. In a Doppler mode, OCT can measure velocity, direction and profile of blood flow in veins. Clinical applications include ophthalmology for retinal imaging, dermatology, and in coronary and peripheral artery disease to detect lipid-rich plaques. It is expected that this improved OCT in an endoscopic configuration can replace intravascular ultrasound by providing superior resolution.
The technique enables full range imaging by removing the obscuring object structure caused by the mirror images generated in the Fourier transform. The technique is done without loss of speed using robust, low cost optical components. Moreover, with the dual detection beam splitter cube, the instrument is intrinsically less sensitive to phase error generated by involuntary movements of the subject. When applied with Doppler imaging, the mirror imaging is eliminated without loss across the full velocity dynamic range, enabling information in the often interesting region around zero velocity.