Abstract: A method of tuning ultrasonic transducers by using the admittance of the transducer as the tuning parameter rather than the phase angle. The admittance magnitude of a transducer is not related to the phase angle and thus, using the admittance of the transducer as the tuning parameter allows tuning over a broad bandwidth. In addition, transducer performance can be normalized against the variation in admittance magnitude and frequency location of the series and parallel resonance points by quantifying these variations and continually adjusting the operational set point as a function of transducer drive voltage during transducer operation.

Abstract: Disclosed are improved methods and apparatus for implantation and extraction of osteal prostheses. Ultrasonic energy coupling adapters are disclosed for propagating ultrasonic energy along an incidence axis which deviates from a longitudinal axis of the prosthesis within a predetermined angular range. Methods of implantation and extraction of osteal prostheses are also disclosed, in which ultrasonic energy is propagated along an axis which extends at an angle with respect to a longitudinal axis of the prosthesis.

Abstract: An infusion sleeve for an ultrasonic tissue removal surgical tool includes a sleeve designed to surround the ultrasonically driven tip of the surgical tool and create an irrigation fluid channel thereinbetween. The sleeve includes a flexible portion which permits retraction of the distal end thereof to permit contact between the tip of the surgical tool and body tissue to be destroyed or removed. The infusion sleeve also includes a rigid portion which is designed to prevent collapse of the sleeve around the ultrasonically driven surgical tip and prevent blockage of irrigating fluid flow and subsequent overheating of the tip and damage to adjacent body tissue.

Abstract: Collapse of the cornea into the cavity formed when material such as the lens is removed from an eye in the irrigation-aspiration method is minimized by incorporating a pressure responsive, variable flow resistance element in the aspiration line of the irrigation-aspiration apparatus. A preferred pressure responsive, variable resistance element is a length of thin walled tubing which is easily collapsed to smaller flow path area in response to increasing negative pressure in the aspiration line.

Abstract: This invention is related to an improved method and apparatus for use in controlling the ultrasonic fragmentation of the body tissue. The ultrasonic apparatus includes a transducer assembly mounted in the handpiece assembly. The transducer is operable for converting electrical power to ultrasonic mechanical vibrational energy. A vibrational amplifying device is coupled to the transducer assembly and includes in series asymmetrical horn and symmetrical horn portions. Included in one of the horn portions is an operative tip.

Abstract: Collapse of the cornea into the cavity formed when material such as the lens is removed from an eye in the irrigation-aspiration method is minimized by incorporating a pressure responsive, variable flow resistance element in the aspiration line of the irrigation-aspiration apparatus. A preferred pressure responsive, variable resistance element is a length of thin walled tubing which is easily collapsed to smaller flow path area in response to increasing negative pressure in the aspiration line.

Abstract: An electronic fluorescent lamp ballast having at least an energy storing component, a controlling component which has two states, and two socket elements which enables the filaments of the fluorescent lamp to be connected in series with the energy storing component. A constant current flows through a portion of the energy storing component when the controlling component is in one state producing an "energy latching" effect which will enable the ballast to achieve a very high efficiency of energy transfer. The ballast also has a self adjustable frequency of operation as a function of lamp impedance variation due to age and enables constant ionization within the fluorescent lamp.