Olympus EPOCH 1000 Series - Straight Beam Modes; Angle Beam Modes

910-269-EN, Rev. B, June 2011
136 Chapter 9
9.2.1 Straight Beam Modes
Straight beam calibrations can be performed by two methods. For the purposes of this
calibration discussion, straight beam refers to all zero-degree probes, including contact,
dual, delay line, immersion, etc. The two methods of straight beam calibration are:
Thickness
This standard straight beam calibration mode requires you to provide two
different, known material thicknesses to properly calibrate the instrument. The
thin material thickness allows for zero offset calibration, and the thick material
thickness allows for velocity calibration.
Echo-to-echo
This calibration mode allows you to use any echo-to-echo measurement to
calibrate for material velocity only. In echo-to-echo calibration, the effects that
cause zero offset are eliminated by gating a particular indication that represents
the start point of the measurement. A second gate is set to track that gated
indication to acquire a measurement.This means that you must only calibrate for
the material velocity of the inspection to acquire accurate echo-to-echo
measurements. You can perform echo-to-echo measurements using the following
pairs of gates: G2 - G1, G2 - IF, or G1 - IF (see section 6.6 on page 116).
9.2.2 Angle Beam Modes
Angle beam calibrations can be performed by two methods:
Sound path
This standard angle beam calibration mode uses the sound path measurement of
two different, known material thicknesses to properly calibrate the instrument.
Typically, these sound path measurements are made from the radius of a
calibration test block. The thin material thickness allows for zero offset
calibration, and the thick material thickness allows for velocity calibration.
Depth
This angle beam calibration mode uses the known depth of two different
reflectors to properly calibrate the instrument. Typically, these depth
measurements are made from side-drilled holes of equal size. For accurate
measurements, you must first verify the refracted angle of the transducer, as the
EPOCH 1000 Series calculates depth values based on sound path and known
refracted angle. The shallow reflector depth allows for zero offset calibration, and
the deep reflector depth allows for velocity calibration.
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