Epson USN 52L, USN 52R manual Calibration with a dual T/R probe, Flank mode, Path error

USN 52 R calibration Operation

Example:

Calibration on a semicylinder having a radius of R=50 mm at a test range of 200 mm.

–Set RANGE to 200 mm.

–Set DELAY and ZERO to 0.

–Set MEASURE to MULTECHO.

–Couple the probe and peak the echoes.

–Adjust the gate so that the first arc echo (® 50 mm

sound path) in Gate a and the second arc echo

(® 150 mm sound path) in Gate b are evaluated.

–Set the sound velocity MTL VEL so that

“S=100" is displayed in the measurement line

–Set MEASURE to 0 TO 1st

–Set Gate a to an echo

–Set ZERO so that “S=50" is displayed in the measurement line

The calibration has now been completed.

Calibration with a dual (T/R) probe

Above all, dual (T/R) probes are mainly used for thick- ness measurement. When applying these probes ob- serve the following characteristics:

The FLANK mode

Most dual (T/R) probes have a roof angle (an element which is at an angle to the surface of the test object). Due to this, mode conversions occur with sound entry and at the reflection on the backwall which can cause rugged, wide echoes. This is the reason why you should always select FLANK in TOF.

In order to obtain steep increasing flanks, which enable a higher measurement accuracy, you can use the Re- ject function if necessary. In this regard, refer to the information on the DAMPING function.

V-path error

With dual (T/R) probes, there is a V-shaped sound path from the pulser to the receiver element via the reflec- tion from the backwall. This “V-path” influences the measurement accuracy. Therefore, you should select two thicknesses which include the expected thickness range. The V-path error can be largely compensated in this way.

Krautkramer USN 52R/USN 52L Issue 05, 02/00 5-21