Abstract: A rotating optical coupler for coupling optical signals from a first set of rotating optical conductors to a second set of stationary optical conductors includes a plurality of annular lenses, each of which is optically associated with one of the optical conductors of the first set. The lenses are nested one inside another to form a lens assembly oriented in a plane perpendicular to optical axes of the lenses. A rotating holder supports each of the conductors of the first set in parallel orientation with respect to an optical axis of a central one of the annular lenses with each conductor being positioned at a different radial distance from the optical axis of the central lens. Ends of the conductors are positioned to direct light rays at a corresponding one of the annular lenses. A second stationary holder supports ends of each of the conductors of the second set at a focal point of a respective one of the annular lenses.

Abstract: A fiber-optic signal transmission link is used in place of electric audio cable to inter-connect performing musicians and all the necessary pieces of music processing equipment being used in a performance in order to isolate all the people involved in the performance from potential electrical and physical hazards created by the electric audio cables being used.

Abstract: A tuning device for tympani that displays the pitch of each instrument's tympanum. The pitch is determined by measuring the strain in an adjustable tensioning mechanism employed in all tympani to keep proper tension on the tympanum. The pitch or tone of the tympani is determined by the vibration frequency of the tympanum when the tympani is played and the frequency is determined by the tension in the tympanum. A transducer measures the strain in the tensioning mechanism to give an accurate indication of what the tympanum tension, and therefore the pitch, of the tympani would be when played. The transducer includes a resistance-type strain gage mounted on the tympanum tensioning mechanism. The length of the conductor in the strain gage and therefore its resistance, changes with stress changes in the tensioning mechanism used to tune the tympani.