High-resolution underwater acoustic imaging with lens-based systems
✍ Scribed by B. Kamgar-Parsi; B. Johnson; D. L. Folds; E. O. Belcher
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 352 KB
- Volume
- 8
- Category
- Article
- ISSN
- 0899-9457
No coin nor oath required. For personal study only.
✦ Synopsis
In recent years, several sonars designed for high-resolu-
The imaging systems have a focal plane, or retina, populated tion, short-range underwater imaging have been developed. These with a large array of transducer elements. There are two basic imaging systems use an acoustic lens to focus the incoming waves approaches to beamforming. The first is the phase-change-only on an array of transducers. In this article we describe three prototype method that assumes the signal is a sinusoidal pulse that is long systems that use a line-focus or a point-focus lens and operate at a enough to be present at all elements in the array simultaneously.
frequency of 300 kHz or 3 MHz. The line-focus lens produces two-This technique adjusts the phase of each element's signal based on dimensional (2D) intensity images, while the point-focus lens proan assumed direction and then adds the adjusted signals. If the duces 3D intensity images. We present sample images taken from acoustic wave is coming from the assumed direction, the adjusted moving and stationary platforms, and discuss the techniques used for processing the acoustic backscatter data to reconstruct and visu-signals will add coherently, and a large output will be present. If alize the scene. The images, particularly those taken with a pointthe signal is coming from another direction, the additions will not focus lens, show a remarkable degree of detail. ᭧ 1997 John Wiley & be coherent and the output will be small. The second is the delay-