Olympus EPOCH 650 User Manual page 163

The calibration requires a test block with two known thicknesses, made from the
material to be measured. Ideally, the two thickness measurements are both below and
above the expected thickness of the material to be inspected. For this example, we are
using Olympus standard 5-step steel-test block, part number 2214E. The steps
measure 0.100 in., 0.200 in., 0.300 in., 0.400 in., and 0.500 in.
If the EPOCH 650 is set to work in metric units, the calibration process is exactly the
same, except that the entries are in millimeters rather than inches.
To calibrate using a delay line transducer
1. Follow the initial setup procedure outlined in "Basic Setup" on page 143.
2. Connect the transducer to an appropriate cable and then connect the cable to
either of the transducer connectors at the top of the instrument.
With a zero offset of 0.000 µs, the excitation pulse (or main bang) should appear
on the left side of the screen.
3. Choose Basic > Zero (group 1/5), and then increase the value until the excitation
pulse moves off the left side of the screen and the interface echo from the end of
the delay line tip appears on the screen.
4. Verify that the echo represents the end of the delay by tapping your finger on the
end of the couplant-coated delay line. This dampens the signal and the echo
should jump up and down on the screen.
5. Choose Basic > Zero, and then increase the value to move this echo to the left side
of the screen so that it is barely visible.
DMTA-10055-01EN, Rev. A, February 2015
Calibration 151