This ultrasonic thickness gauge measures thickness by generating ultrasonic pulses through the coupling agent generated by the probe to reach the object being measured. A portion of the ultrasonic signal is reflected by the bottom surface of the object, and the probe receives the echo reflected by the bottom surface of the object. The round-trip time of the ultrasonic wave is accurately calculated, and the thickness value is calculated according to the following formula

H =（ v × t）/ 2

In the formula: H - measured thickness; V - material sound velocity; T - The propagation time of ultrasonic waves in the specimen for one round trip.