Development of sector scanning ultrasonic backscatter microscope

The Ultrasound Backscatter Microscope (UBM) is a noninvasive high frequency imaging tool used frequently for imaging the eye, skin and blood vessels. Currently, most UBM systems employ a linear motor control to obtain a transverse scan. This paper reports the implementation of a UBM that performs sector scan with a servo-controlled motor to manipulate a single element transducer. The advantage of applying a sector scan versus transverse linear scan is that the transducer needs to travel less distance to acquire an image of the same area. The transducer sector movement is achieved by a brief sweep that needs only a small open area for scanning. The servomotor's sweep angle has a small are of 5 degrees and provides enough width for an image. Because of the small angle sweeping, the image can be displayed in a linear format as the image in transverse scan without further calculation. The UBM system can be operated within the 50-100 MHz frequency range. Images have been acquired with this approach on excised human eye specimen. The quality of the image compares favorably with that obtained with the conventional UBM. The results indicate that the sector scan is an alternative method for UBM scanning. Future work includes the development of a hand held probe that houses a small transducer and servomotor capable of sector scanning.