An interface unit comprising: a cover; a catheter connector configured to receive a disposable imaging probe comprising: a rotatable optical fiber segment configured to transmit light along an optical path, an ultrasound transducer, and a catheter body, wherein the catheter connector is disposed within the cover and comprising an electrical connector in electrical communication with the ultrasound transducer, the cover defining an aperture; a stationary optical fiber segment configured to transmit the light, the stationary optical fiber segment disposed within the cover; an optical rotary joint comprising an optical coupler configured to couple the stationary optical fiber segment to the rotatable optical fiber segment, the optical rotary joint comprising a rotatable component and a stationary component proximal to the rotatable component; and an electrical rotary joint comprising a first annular ring defining a first annular opening and comprising a first conductive winding, the first conductive winding in electrical communication with the electrical connector; and a second annular ring defining a second annular opening and comprising a second conductive winding, wherein a first gap is defined between the first conductive winding and the facing second conductive winding and an elongate cavity is defined by the first and second annular openings, wherein the second conductive winding is proximal to the stationary component of the optical rotary joint, wherein the first conductive winding is rotatable and disposed between the second conductive winding and the stationary component of the optical rotary joint, wherein the optical rotary joint and the electrical rotary joint and the aperture are substantially coaxial and the light passes through the elongate cavity. a cover; a catheter connector configured to receive a disposable imaging probe comprising: a rotatable optical fiber segment configured to transmit light along an optical path, an ultrasound transducer, and a rotatable optical fiber segment configured to transmit light along an optical path, an ultrasound transducer, and a catheter body, wherein the catheter connector is disposed within the cover and comprising an electrical connector in electrical communication with the ultrasound transducer, the cover defining an aperture; a stationary optical fiber segment configured to transmit the light, the stationary optical fiber segment disposed within the cover; an optical rotary joint comprising an optical coupler configured to couple the stationary optical fiber segment to the rotatable optical fiber segment, the optical rotary joint comprising a rotatable component and a stationary component proximal to the rotatable component; and an electrical rotary joint comprising a first annular ring defining a first annular opening and comprising a first conductive winding, the first conductive winding in electrical communication with the electrical connector; and a second annular ring defining a second annular opening and comprising a second conductive winding, wherein a first gap is defined between the first conductive winding and the facing second conductive winding and an elongate cavity is defined by the first and second annular openings, wherein the second conductive winding is proximal to the stationary component of the optical rotary joint, wherein the first conductive winding is rotatable and disposed between the second conductive winding and the stationary component of the optical rotary joint, wherein the optical rotary joint and the electrical rotary joint and the aperture are substantially coaxial and the light passes through the elongate cavity. a first annular ring defining a first annular opening and comprising a first conductive winding, the first conductive winding in electrical communication with the electrical connector; and a second annular ring defining a second annular opening and comprising a second conductive winding, wherein a first gap is defined between the first conductive winding and the facing second conductive winding and an elongate cavity is defined by the first and second annular openings, wherein the second conductive winding is proximal to the stationary component of the optical rotary joint, wherein the first conductive winding is rotatable and disposed between the second conductive winding and the stationary component of the optical rotary joint, wherein the optical rotary joint and the electrical rotary joint and the aperture are substantially coaxial and the light passes through the elongate cavity.