In an ultrasonic endscope apparatus for observing an optical image of a cavity of a body under inspection by forming the optical image with the aid of an objective lens arranged in a distal end of an insertion section of an endoscope and by transmitting the optical image by means of an image guide and...http://www.google.es/patents/US5054491?utm_source=gb-gplus-sharePatente US5054491 - Ultrasonic endoscope apparatus
