Z-Trak2 3D Profiler Sensors
Theory of operation
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Z range (Measurement Range)
The Z range is the maximum height, in world measurement units, that the 3D profile sensor can
measure. The Z range, also called depth of field (DOF), is model dependent and factory calibrated,
and cannot be changed by users.
The start of the Z range (the 0 value) is the farthest point from the laser exit window; the end
(max Z value) is the closest to the exit window and represents the highest value that the sensor
can measure. In Figure 6, the Z range extends from the bottom to the top.
Field of view (FOV), Near-FOV (NFOV), Mid-FOV(MFOV), Far-FOV (FFOV)
In reference to Figure 6, the field of view is the section of the X-axis where Z measurements can
be made. Its size depends on the distance from the profiler; the FOV is larger at the start of the
measurement range than at its end. This implies that the resolution in X varies with the distance
from the profiler.
The FOV at the start of the measurement range is the far-FOV; it is the largest section where
measurements can be made.
The FOV at the end of the measurement range is the near-FOV; it is the smallest measurement
section, closest to the profiler.
The mid-FOV provides an indication of the size of the measurement section midway between the
near-FOV and far-FOV.
Note that for the Z-Trak2 family sensors, the laser line extends beyond the FOV; however, the
factory calibration ensures that Z measurements can take place in the entire trapezoidal region
delimited by the FOV in the XZ-plane (see measurement area definition).
Measurement area
The measurement area is the trapezoidal region in the XZ-plane that is delimited by the FOV, from
the near-FOV to the far-FOV. It is the largest region in which measurements can be made. The
measurement area is determined at the time of factory calibration and cannot be changed by
users. In Figure 6, the measurement area is represented by the black trapezoid.
Measurement AOI (M-AOI)
The measurement area-of-interest, called measurement AOI, is an area equal to or smaller than
the measurement area, where the measurements are to be made. The measurement AOI can be
changed by users: A smaller measurement AOI means that a larger number of profiles can be
processed for a given amount of time, thereby increasing scanning rate. In Figure 6, the
measurement AOI is depicted by the blue dash trapezoid.
Working distance
The working distance is the distance from the profiler
’s laser exit window
to the end of the
measurement AOI (closest to the near-FOV) (see Figure 6 above).
Working range
The working range corresponds to the height of the measurement AOI, starting at the working
distance (see Figure 6 above).
