What is the main difference between a parallel and focused sound beam?

The primary distinction between a parallel and a focused sound beam lies in the impact on lateral resolution. A focused beam is designed to converge at a point, which enhances its ability to resolve details within that focus. This concentration of energy allows for improved lateral resolution, particularly at specific depths where the beam is focused.

In contrast, a parallel beam spreads uniformly and does not have the same capability to distinguish between closely spaced structures laterally. Thus, as the focused beam restricts the area of sound energy to a smaller region, it allows for better imaging quality and detail in that specific area, which is particularly beneficial in ophthalmic imaging where clarity of fine details is crucial.

This understanding underlines the significance of optimizing the sound beam's focal characteristics to achieve enhanced resolution in diagnostic imaging.