DeFelsko PosiTector RTR Guide D'utilisation page 8

Linearize
This is the default measurement mode. Linearize mode is ON when
this box is ticked and the "H " appears on the display.
L
An undesirable characteristic of replica tape is that measurements
made with analog spring micrometers are most accurate near the
middle of each grade's range and least accurate at the outer ends
of each grade's range. That is why two other grades, Coarse Minus
and X-Coarse Plus, are used to check and, if necessary, adjust
measurements at the lower and upper ends of the primary range of
20-115 µm (0.8-4.5 mils).
Inside the primary range, the upper end of Coarse grade's range
and the lower end of X-Coarse grade's range share a 38 - 64 µm
(1.5 - 2.5 mils) "overlap" region. Current Testex instructions describe
a relatively complicated and time consuming procedure (the
average of one reading using Coarse grade and one reading using
X-Coarse grade) that is used to knit the Coarse and X-Coarse sub-
ranges together to achieve reasonably accurate readings over the
primary range. This method is a compromise between accuracy and
ease of use.
When the Linearize box is NOT ticked, the PosiTector RTR
displays a height value of H comparable to the value an analog
spring micrometer would display after the 50.8 µm (2 mils) of
incompressible polyester film has been subtracted. In other words,
it is the average of the maximum peak-to-valley distances obtained
by measuring the thickness of the replica tape without any
correction.
When the Linearize box IS ticked, the PosiTector RTR displays a
more accurate peak-to-valley height measurement H that has
L
been adjusted for the non-linearity of replica tape. There is no need
to average 2 or more replicas from different grades of tape AND
there is no need to subtract the 50.8 µm (2 mils) of incompressible
polyester film. Ensure the proper tape grade, C or XC, has been
selected (pg. 6) and appears in the upper left corner of the display.
During measurement, if the linearized measurement falls outside
of the selected tape grade's range, the Gage will suggest a more
suitable tape grade to perform the measurement.
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