Method and apparatus for detecting the distance between an object and an ultrasonic objective

摘要

Method and apparatus for detecting the distance between an ultrasonic objective and an object to be imaged in order to prevent contact between the two. For this purpose, light rays, after entering into an immersion means (water) between the objective and the object, being reflected by the object, and emanating from the immersion means are fed through the ultrasonic objective to a photo-receiver and converted into electric signals. The front face of the lens body of the ultrasonic objective is provided with an opaque ring zone. This arrangement makes it possible simultaneously to illuminate the object.