Abstract: What is described here is a relay lens system, specifically for endoscopes or the like, comprising two rod-type lens elements and two further optical elements in symmetrical arrangement relative to the center plane of the object plane and the image plane.The relay lens system according to the present invention is characterized by the fact that the rod-type lens elements are individual convex/concave optical elements and the further elements are individual bi-convex optical elements, and that one rod-type lens and one further lens, respectively, are bonded to each other.This structure according to the present invention contributes to an enhanced compensation, specifically of the field curvature and astigmatism, while furnishing a brighter image.

Abstract: A stiffening probe and tensioning device for use therewith. The probe comprises an elongated casing and a core longitudinally extending through the casing. This core includes front and back end portions respectively extending forward of and rearward of the casing, and respectively supported for longitudinal sliding movement relative to front and back ends of the casing. A stop element is connected to the front end portion of the core to limit rearward movement of that front end portion relative to the casing, and another stop element is connected to the back end portion of the core to facilitate pulling the core rearward relative to the casing. The tensioning device comprises a frame including front and back end pieces, and front and back thrust pieces mounted on and longitudinally displaceable along the frame. A spring is held between the front end and front thrust pieces, and another spring is held between the back end and back thrust pieces.

Abstract: A power generator is provided to drive an high power ultrasonic transducer at its resonant frequency even under changing conditions cause by e.g. load fluctuations, aging or heating. The power generator uses a variable-controlled oscillator driving a power amplifier; a three winding transformer has one winding coupled to the transducer, one winding coupled to the output of the power amplifier and the third winding coupled to a phase measuring means. The output of the phase measuring means is fed back to the variable-controlled oscillator.