3D Imaging Method for an Air-Coupled 40 kHz Ultrasound Phased-Array
* Presenting author
We present a three-dimensional far-field imaging method using a 40 kHz 8x8 ultrasound phased-array in air. A waveguide is attached to the array which reduces the aperture to 3 cm x 3 cm and the inter-element spacing to λ/2 for grating lobe free beamforming. Using transmit beamforming, a pulse echo detection is performed sequentially for each direction of the rasterized region of interest. All transducers are used for pulse transmission and echo reception. The echo signals are FIR band-pass filtered and sinc-interpolated. The conventional Delay & Sum beamformer generates a spatial filtered and summed echo signal. The envelopes of the summed echo signals extracted by Hilbert filters are used for generating B-Scans and 3D C-Scans. The signal processing and image generation is performed by a GPU using OpenGL.The imaging properties are characterized in an anechoic chamber. The localization of objects is validated for a range of 0.5 to 6 m in a vertical and horizontal field of view of +-50°. The system is able to detect sound-absorbing objects and objects hidden by obstacles. The implementation has limitations in frame rate and lateral resolution. In this context, future optimization options are outlined.