Characteristics; Definitions - Newport DL225 User Manual

DL Stage Series High-Performance Delay Line Stages
3.0

—Characteristics

3.1

Definitions

Specifications of our products are established in reference to ISO 230
standard part II "Determination of accuracy and repeatability of
positioning numerically controlled axes".
This standard gives the definition of position uncertainty which depends
on the 3 following parameters:
Absolute Accuracy
Difference between ideal position and real position.
Accuracy
Difference between ideal position and real position after the compensation
of linear errors.
Linear errors include: cosine errors, inaccuracy of screw or linear scale
pitch, angular deviation at the measuring point (Abbe error) and thermal
expansion effects. All Newport motion electronics can compensate for
linear errors.
The relation between absolute accuracy and on-axis accuracy is as follows:
Absolute Accuracy = On-Axis Accuracy + Correction Factor Travel
x
Repeatability
Ability of a system to achieve a commanded position over many attempts.
Reversal Value (Hysteresis)
Difference between actual position values obtained for a given target
position when approached from opposite directions.
Minimum Incremental Motion (MIM)
The smallest increment of motion a device is capable of delivering
consistently and reliably.
Resolution
The smallest increment that a motion device can theoretically move
and/or detect. Resolution is not achievable, whereas MIM, is the real
output of a motion system.
Yaw, Pitch
Rotation of carriage around the Z axis (Yaw) or Y axis (Pitch), when it
moves.
The testing of accuracy, repeatability, and reversal error are made
systematically with test equipment in controlled environment (20 ±1 °C).
A linear cycle with 21 data points on the travel and 4 cycles in each
direction gives a total of 164 points.
Guaranteed Specifications
Guaranteed maximum performance values are verified per Newport's A167
metrology test procedure. For more information, please consult the
metrology tutorial section in the Newport catalog or at www.newport.com
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EDH0391En1031 — 03/18