Abstract: An ultrasound wattmeter for measuring the magnitude of energy radiated by a therapeutic ultrasound applicator includes a sealed, oil-filled housing within which a float assembly is suspended. The float assembly includes an ultrasound reflective float as well as a coil and a vane supported by the float. The float assembly assumes a null position in the absence of ultrasonic radiation. A window in the housing permits the application of ultrasonic energy from the applicator to the float for urging the float assembly in one direction from the null position. A magnet mounted on the housing adjacent the coil urges the float assembly in the opposite direction in response to energization of the coil. A light source and a light responsive device are located adjacent the vane for providing a position signal corresponding to the position of the float assembly.

Abstract: A diathermy apparatus includes a power oscillator for developing signals which are coupled to a patient by a tuned reactive coupling circuit. The magnitude of the oscillator signal is detected in the oscillator output circuit, and a corresponding control signal is developed. A reference signal is supplied by an output level selection circuit. The load imposed by the patient and the output circuit upon the power oscillator, and thus the magnitude of the oscillator signal, are maintained substantially constant by a servo control circuit. A motor driven variable impedance in the reactive coupling circuit is operated in response to differences between the control and reference signals.