Rail Platform Positioners for 66 mm Rails

  • Fine Adjustment of Platforms Along the Rail Axis
  • Positioner Provides Up to 0.75" (19.0 mm) of Translation
  • Return Positioner Travels Up to 0.34" (8.6 mm)


Rail Platform Positioner

Application Idea

Fine Tuning the Position of a Platform-Mounted Lens


Rail Platform Return Positioner

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XT66N1 Mechanical Drawing
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XT66N Mechanical Drawing
XT66N Rail Platform Positioner and XT66N1 Rail Platform Return Positioner Optical Alignment


  • XT66N Positioner:
    • 1/4"-80 Adjuster Screw Translates Rail-Mounted Platform
    • 0.013" (320 µm) of Translation per Revolution
    • Max Translation Range of 0.75" (19.0 mm)
    • Adjuster Screw Accepts 5/64" (2.0 mm) Balldriver
  • XT66N1 Return Positioner:
    • Spring-Loaded Plunger that Clamps onto 66 mm Rails
    • Use with XT66N Positioner for Bidirectional Adjustment

Thorlabs' XT66N Rail Platform Positioner and XT66N1 Rail Platform Return Positioner are designed to aid in fine alignment of optics mounted on a 66 mm rail platform. The XT66N consists of an F25SS150 1/4"-80 adjuster screw incorporated into a 66 mm rail clamp. The screw provides smaller, smoother movement than coarse translation by hand. The included adjuster screw travels 0.75" (19.0 mm) from beginning to end before the interior of the bushing is exposed; longer adjuster screws can be installed if desired.

The XT66N1 is comprised of a spring-loaded plunger integrated into a 66 mm rail clamp. The plunger can travel a maximum range of 0.34" (8.64 mm), and the compression spring tension can also be adjusted with a 5/32" (4.0 mm) hex key. When used in conjunction, the XT66N positioner and XT66N1 return positioner provide precision alignment in either direction on the rail's axis. When a platform is placed between the platform positioners, actuating the adjustment screw pushes the platform toward the XT66N1 return positioner, compressing the spring loaded plunger. Retracting the adjustment screw on the XT66N positioner causes the spring-loaded plunger on the XT66N1 return positioner to expand, which keeps the carrier in contact with the actuating screw of the XT66N. Additionally, the return positioner provides stability while making adjustments.

To use, place the positioners along the rail so that both positioners are in contact with the platform or return carrier, and secure the XT66N and XT66N1 positioners with a 3/32" (2.5 mm) balldriver. Loosen the clamp holding the platform or carriage to the rail, then turn the adjuster screw with a 5/64" (2.0 mm) balldriver to push the platform until the desired amount of translation is achieved.

We do not recommend using this positioner with assemblies that use our XT66C1 or XT66C2 Double Dovetail Clamps to attach to the rail. Since it is necessary to loosen the clamp to translate the assembly, any optomechanics held by the clamp will also be loose, potentially leading to unintended movements. The 66 mm rail components best suited for use with the positioner are the XT66C4 Clamping Platform, XT66P2 Rail Carriage, XT66C5 Blank Clamping Platform, and XT66RP1 Rotation Slide Platform.

Thorlabs offers an extensive selection of accessories for 66 mm rails, including clamps and angle brackets, breadboard mounts, mounting platforms, rail carriages, rotation slide platforms, rail joiners, and lens tube adapters. Together with size adapters that incorporate 34 mm and 95 mm rails into an XT66 setup, these tools provide a complete family of rigid, versatile building blocks suited for virtually any optomechanical setup.

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Rail Platform Positioners for 66 mm Rails

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
XT66N Support Documentation
XT66NRail Platform Positioner for 66 mm Rails
XT66N1 Support Documentation
XT66N1Customer Inspired! Rail Platform Return Positioner for 66 mm Rails
Last Edited: Aug 29, 2013 Author: Dan Daranciang