EDH0185En1020 — 07/11
2
VP-25XA
Precision Compact Linear Stage
2.0
Description
The VP-25XA translation stage features an all aluminum body and recircu-
lating preloaded ball bearing slides as guide ways to ensure accurate linear
travel.
The design and interface of VP-25XA fixtures enable XY mounting without
using an additional intermediate plate.
A standard top plate interface is supplied with each stage.
A preloaded, backlash-free ballscrew with a 1 mm pitch provides smooth
motion. The screw is accurately ground to reduce the heating factor to a
minimum and extend the lifetime of the stage.
The position is read on a metal optical scale with pitch of 20 µm and a 200x
interpolation of signals to obtain a 0.1 µm resolution.
The VP-25XA stage features end-of-run limit switches at both ends of the
stage to prevent bearing damage from over-travel. The origin (Mechanical
Zero) is at the center of travel, with a reference on the optical scale.
For optimal performance, we recommend the use of our ESP or MM series
motion controllers.
The VP-25XA stage is equipped with a cable of 1.5 m length and a 25-pin
sub-D connector for connection to our motion controllers.
3.0
Characteristics
3.1
Definitions
Specifications of our products are established in reference to ISO 230 stan-
dard part II “Determination of the position, precision and repeatability of
the machine tools with CNC”.
This standard gives the definition of position uncertainty which depends
on the 3 following quantities:
(Absolute) Accuracy
Difference between ideal position and real position.
On-Axis Accuracy
Difference between ideal position and real position after the compensation
of linear error sources.
Linear errors include: cosine errors, inaccuracy of screw or linear scale
pitch, angular deviation at the measuring point (Abbe error) and thermal
expansion effect. All Newport motion electronics can compensate for linear
accuracy errors by step encoder correction.
The relation between absolute accuracy and on-axis accuracy is as follow:
Absolute Accuracy = On-Axis Ac Slope x Travel
Repeatability
Ability of a system to achieve a commanded position over many attempts.
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