System using a modified ultrasonic imaging tube

Claim 1

An ultrasonic imaging system comprising: a high-conductance ultrasonic conversion tube, a video projection system, a conversion plate forming the face of the conversion tube, a grounded membrane on one side of the plate contacting an ultrasonic medium, a high secondary emission coating on the other side of said plate, a transparent control screen parallel to and in close proximity to the other side of the plate, a collector electrode located in spaced relation from said screen, a cathode ray beam generating and sweeping means, the beam forming a space charge between the screen and the secondary emission coating of the plate, at its point of impact means including a discrete portion of the plate at point of cathode ray beam impact to generate an electrical potential in response to ultrasonic signal reception to accelerate electrons from the space charge, through the screen and to the collector electrode to form a signal current thereon, amplifier means, means for coupling said collector signal current to the input of the amplifier, and means for transmitting the output of the amplifier to the video projection system and in shunt therewith to the screen of the conversion tube as a feedback.