Specular Reflection

In many ways, sound and light behave in a similar fashion.

Concepts such as reflection, scattering and refraction are common to both.

Reflection of the ultrasound pulse occurs when there is a change in acoustic impedance across a boundary between tissues.

In the image on the right, the diaphragm acts as a specular reflector and appears bright (arrowed) due to the high proportion of sound reflected by this soft tissue air interface.

Specular reflection occurs when the sound pulse encounters a large smooth boundary, such as an organ capsule.

Sound is reflected from interfaces where there is a change in tissue density and compressibility (impedance – described more fully later in the session).

In this image, if the incident pulse (A) hits the surface at an angle, the reflected component (B) will be directed at an equal and opposite angle.