Enter the distance from the element to the focal point and the velocity of sound in the material into the calculator to determine the time delay. This calculator can also evaluate any of the variables given the others are known.

## Focal Law Formula

The following formula is used to calculate the time delay for each element in a phased array ultrasonic technology.

TD = d / v

Variables:

- TD is the time delay (s)
- d is the distance from the element to the focal point (m)
- v is the velocity of sound in the material (m/s)

To calculate the time delay, divide the distance from the element to the focal point by the velocity of sound in the material. This will give the time delay required for each element to transmit and receive signals, allowing for precise control of the ultrasonic beam in terms of angle, focus, and sweep.

## What is the Focal Law?

A Focal Law is a principle used in phased array ultrasonic technology that determines the timing for each element in an array to produce a focused beam at a specific point in the material being tested. It calculates the time delays required for each element to transmit and receive signals, allowing for precise control of the ultrasonic beam in terms of angle, focus, and sweep. This enables the detection and characterization of defects within the material.

## How to Calculate Focal Law?

The following steps outline how to calculate the Time Delay (TD) using the formula TD = d / v.

- First, determine the distance from the element to the focal point (d) in meters.
- Next, determine the velocity of sound in the material (v) in meters per second.
- Next, gather the formula from above = TD = d / v.
- Finally, calculate the Time Delay (TD).
- After inserting the variables and calculating the result, check your answer with the calculator above.

**Example Problem : **

Use the following variables as an example problem to test your knowledge.

distance from the element to the focal point (d) = 0.5

velocity of sound in the material (v) = 343