Parallelism
There are different ways of measuring parallelism. For specific information please consult the type of measurement. For example, cylindricity, flatness, straightness.
Parameter
Terms used to analyse characteristics of a measured component in quantitative terms. For example, Ra is a parameter that quantifies Roughness Average of a surface profile.
PGI
Phase Grating Interferometric transducer. This device is housed within a gauge and converts the movements of the stylus into an electrical signal. This type of transducer employs a laser diode in conjunction with a fine optical grating to detect very small movements of the stylus and provides a high resolution output of both amplitude and direction.
Pick up
Also referred to as the
gauge. This can take the form of an electrical transducer which converts movement of styli into electrical signals.
Pitch
The “straight line,” or Euclidean distance, between the origin and the feature or measurement point. For example, the centres of two circle.
Plug Gauge Circle
See
Maximum Inscribed Circle definition.
Primary Filter
This is a low pass filter used on the measured data in order to remove or reduce wavelengths around or below the value of this filter.
Primary Parameters
Parameters used to quantify the primary profile.
Primary Profile
The primary profile is the traced profile after subtracting the form
(see
Form Analysis) and subjecting it to a low pass filter.
Profile
A section taken through a workpiece. When using surface finish equipment, the profile is the trace made of the real profile. The Roughness, Waviness and Primary analyses show the
modified profile.
