ULTRASONIC IMAGING
in air requires both a very wide bandwidth ultrasonic transducer and high energy radiation to achieve the necessary signal to noise ratio with large dynamic signal range (50 dB)
BAT Ltd has developed systems which achieve this, using continuous wave frequency modulated radiation (CWFM). One sensor system transducer arrangement is shown below together with a picture of an object and an image.
A 'cross section' image viewed from the side of a cylinder covered with corrugated paper using a focussed scanning sonar in air. The focussed beam which is being electronically scanned, is radiated from the 30 element strip transducer. Four angled receivers cover a 60 degree arc. The white base on which the cylinder is standing is marked to show where the focussed beams are in azimuth angle. The scan angle can be 60 degrees in azimuth, but to obtain the image with an update time of 10 per second the scan angle is restricted electronically to 15 degrees. Very noticeable is an area marked to show the 48 elements of distance resolution of 1.7 mm within the active region. The focal beam being scanned is 4.5mm wide.
Click here to download a video clip showing real-time motion perception.
Images of two objects - a cylindrical block and a square block both covered with corrugated cardboard. (Kay 1984) (Note: the x-y coordinates of the screen were not the same, thus distorting the images.)
Click here to download a video clip showing the blocks being moved relative to each other. The update rate is electronically slowed to allow for a larger active field of view.
Video files have been compressed to reduce the file size to about 1.5MB, which compromises the quality of the clips to some extent.
Custom Sensors For further inquiries e-mail: kaysonic@voyager.co.nz
© 1997-98
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