Full-range spectral domain optical coherence tomography using fiber-based sample scanner as self-phase shifter

We propose full-range spectral domain optical coherence tomography equipped with a fiber-based sample scanner, which is used for sample scanning and phase shifting for full-range image at the same time. For a fiber-based sample scanner, since the fiber tip oscillates as a free standing cantilever in general, unintentional phase shift occurs inevitably. The unintentional phase shift was used for eliminating the bothersome complex conjugate ghost image of OCT. In addition, fiber was tilted a few degree to give proper phase shift. In this scheme, moreover, image can be obtained without any physical modification of the scanner. To realize this technique, we constructed the SD-OCT system and fabricated a magnetically actuated single-body lensed fiber scanner due to advantages of simple design, low operating voltage, cost-effectiveness and low insertion loss. The scanner was made of lensed fiber loaded with an iron-based bead and a solenoid which is placed perpendicular to the lensed fiber. When a sinusoidal current is applied into the solenoid, the lensed fiber oscillated due to magnetic force between the iron-based bead and the solenoid. With the suggested full range method, we obtained contrast enhanced full-range SD OCT images of pearl and tooth. This simple and effective method can be applied to any fiber-based scanner and it has great potential as a handheld probe/endoscopic probe in biomedical imaging field.