A 5mm catheter for constant resolution probing in Fourier domain optical coherence endoscopy

A 5mm biophotonic catheter was conceived for optical coherence tomography (OCT) with collimation optics, an axicon lens, and custom design imaging optics, yielding a 360 degree scan aimed at imaging within concave structures such as lung lobes. In OCT a large depth of focus is necessary to image a thick sample with a constant high transverse resolution. There are two approaches to achieving constant lateral resolution in OCT: Dynamic focusing or Bessel beam forming. This paper focuses on imaging with Bessel beams. A Bessel beam can be generated in the sample arm of the OCT interferometer when axicon optics is employed instead of a conventional focusing lens. We present a design for a 5mm catheter that combines an axicon lens with imaging optics and the coupling of a MEMS mirror attached to a micromotor that allow 360 degree scanning with a resolution of about 5 microns across a depth of focus of about 1.2mm.

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