Features

• Low Profile
• 150 mm of Linear Travel
• Lightweight Aluminum Body
• Microstepping Resolution
• XYZ Configurable
• Optional Calibration File

Introduction
The NRT Series of positioning stages are ideally suited for applications that require long travel, high precision, and high load capacity such as measurement and inspection. The main platform is supported by four recirculating ball carrier bearings mounted to precisely aligned linear guide rails, which together are capable of providing smooth motion for loads up to 20 kg. A backlash-free leadscrew produces smooth translation that is directly driven by a two-phase stepper motor capable of 25,600 microsteps per revolution, thus yielding a positional resolution of less than 100 nm. Magnetic limit switches allow homing and overdriving protection in both forward and reverse directions.

The stepper motor used in the NRT stage has 50 individual magnetic teeth and is ideally suited for microstepping applications. Aside from the obvious increase in resolution provided by increasing the steps per revolution from 200 to 25,600, microstepping also allows for much smaller and smoother low-speed motion than the discrete 1.8^o step angle, and as a result, lower vibrational noise. The use of a trapezoidal leadscrew in the NRT series also provides a number of benefits over other, more common thread styles. The benefits include improved durability, lower friction due to improved surface quality, and very little backdrive, which eliminates the need for the braking mechanism commonly required with ball screws.

The NRT series of stages are compact, making it possible to set up experiments in locations where space is minimal. Two stages can be directly stacked into an XY configuration or, with the use of the NRT150P1 vertical mounting bracket, three stages can be mounted into an XYZ configuration as pictured above. Alternatively, the NRT150P1 can be directly attached to an optical table for applications that require one axis of vertical translation. These various configurations are easily achieved using the assortment of mounting screws that are shipped with the NRT150P1.

Calibration File
Calibration enables the server to correct for any mechanical errors inherent in the system. Mechanical components, such as the leadscrew and linkages, can be machined only within a certain tolerance, e.g. the leadscrew may be nominally 1mm but actually 1.0005mm, giving a 0.5 micron error. In practice, these errors accumulate from a number of sources, however they are repeatable and therefore, can be compensated.

During calibration, the total positional error is measured at a large number of points and these errors are stored as a look up table (LUT). The LUT is saved as a calibration file, one file for each axis on a particular stage. These files are then linked to the appropriate axis as part of the Stage association process performed using the APT Config utility. Whenever the stage is moved, the LUT is consulted to ascertain the precise movement required to achieve the demanded position. The use of a calibration file is optional. Without it, the repeatability and resolution of the stage are unaffected, but no compensations are made to enhance the accuracy. Calibration must be requested at time of order.

Compatible Controller
The NRT series can be driven by Thorlabs' Stepper Motor Controllers, such as the BSC101, which comes with its own dedicated software package; however, any third party controller can also be used. When combined with our BSC101 apt™ stepper motor controller, the NRT Translation Stage provides micro-stepping resolution of 40 nm and speeds of up to 12 mm/s.