Abstract: A method for determining the distance of a transceiver located within a lumen from the center of the lumen and for determining the radius of the lumen, the lumen cross-section being substantially circular at the transceiver location, the method applied on data received from a transceiver placed at a position within the lumen that is distance (r) from the center and distance (a) from the lumen wall, transmitting a signal of known velocity (v) that can be correlated with the time of flight and receiving a first signal and a second signal that are reflections of the transmitted signal, timing the time differences between the transmission of the transmitted signal and reception of the first (t1) and second (t2) reflection signals, the method comprising: Calculating the distance of the transceiver from the center of the lumen=(t1?t2)v/4; and Calculating the radius of the lumen=(t1+t2)v/4.

Abstract: A method for recovering an initial linear state of polarization, of an optical beam after the beam has passed through an optical fiber and whose polarization state was disrupted, attaining power which is directly proportional to the power of the beam before it has passed through the optical fiber. The method comprises: splitting the beam into two beams, a first beam with a first polarization state and a second beam with a second polarization state, the second polarization state being orthogonal to the first polarization state; changing the polarization state of the first beam; and combining the first and second beams in half of their intensities into at least one linearly polarized beam. This way a linearly polarized output beam with power that is directly proportional to the power of the beam prior to its passing through the optical fiber is achieved.

Abstract: A fibre optic coupler assembly for optically aligning a sectioned fibre optic cable, the cable having a first end and a second end and comprising one or more fibre optic cores. The assembly comprises a first holder for holding the first end; a second holder for holding the second end coupled to the first end; a retractor for retracting the second end; an aligning unit comprising a resilient construction having a conduit passing through it, for linear alignment of the ends; whereby the first and second ends are coupled by the respective holders and whereby the second end can be linearly aligned in the conduit of the aligning unit, retracted using the retractor, and rotated to obtain rotational alignment of the fiber cores of the ends.

Abstract: An optic fiber adapted for ultrasound imaging of the lumen of a vessel comprising: an inner core for transmitting light having an index of refraction that changes responsive to acoustic energy incident thereon; a ring core concentric with the inner core for transmitting light; a cladding material between the inner and ring cores that has an index of refraction smaller than the index of refraction of the material from which the inner core is formed; and at least one acoustic transducer comprising absorbing material formed on the surface of the ring core that absorbs optical energy transmitted along the ring core and generates ultrasound responsive thereto.