Final Design

The test setup consists of a few key components mounted to a carrier baseplate that is secured to a tank. This minimizes the amount of hardware that needs to be submerged in the water. In order to capture the required data, both the transducer and hydrophone are mounted on a 3-axis stage. Each movement axis is powered by a linear actuator, controlled by a DC motor controller. Each set of translation stages is secured directly to the baseplate, promoting good alignment between the movement axes. On each translation stage, an offset plate allows the V-block mount and sensor to be submerged while the rest of the components remain above water. 

The modular nature of the baseplate mounts allows for efficient detachment of the key hardware components from the tank. This allows for the tank to be easily emptied for storage when not in use. Additionally, components can be easily serviced without requiring the tank to be drained.

For the hardware aspect of the project, the tank chosen to hold the setup was a 40.6 cm x 20.3 cm x 25.4 cm polycarbonate tank for noise reduction and portability. The translation stages used were the Thorlabs PT3-Z9 which had a 3-axis translation and moved at a micron level, enough to meet the 50 micron requirement. A 43.49 cm x 25 cm x 0.64 cm aluminum base plate was placed on top of the tank to hold the 3-axis translation stages. Aligning the baseplate are four corner brackets which constrained any side by side movement from the baseplate using thumbscrews to clamp onto the tank walls. Resin V-block mounts were attached to the translation stages. The V-blocks held the transducer and hydrophones, and were designed in a way to hold any other transducer or hydrophone that is needed. The transducer used was an Olympus V306-SU transducer and the hydrophone used was an Onda HNP-0200 Needle Hydrophone, both proven to match the specifications of our sponsor. Holding the phantom skull piece for the transducer and hydrophone to scan was a custom resin frame clip mount, able to hold many irregular bone shapes in different orientations rigidly. The entire setup can be seen above in the Final Tank Setup figure, with figures of specific hardware shown around.

For the software aspect of the project, MATLAB was used to control the waveform generator and oscilloscope for wave generation and capturing. Additionally, MATLAB was used to control the translation stages by allowing the user to control the stage’s velocity, step size, and range of movement through its connection to the motor controllers. A grid can also be created to complete a 2D scan of a section of a sample. In order to keep the transducer and hydrophone aligned with each other in parallel, a homing system was created in MATLAB, where the transducer and hydrophone could align themselves before the start of a scan. The transducer and hydrophone were moved around the x and y axis, creating signals and finding the position of the highest amplitude of the signals using a heatmap. The results of the alignment can be seen in the heatmap figures below.