What happens to temporal resolution when more focal zones are used?

• A. The better the temporal resolution
• B. The worse the temporal resolution
• C. The better the axial resolution
• D. The shorter the spatial pulse length

Answer: (B)

When more focal zones are used in imaging, the temporal resolution is negatively impacted, meaning it worsens. Temporal resolution refers to the system's ability to differentiate two events in time; essentially, how quickly images can be acquired.

Using multiple focal zones requires the system to spend more time transmitting and receiving signals to create a focused image at each zone. This additional time leads to delays between frame acquisitions, which results in a slower frame rate. As a result, while the image quality may improve due to better focusing in multiple zones, the ability to capture fast-moving objects or changes in the scene diminishes. Hence, temporal resolution decreases with the use of more focal zones.