SM2-Compatible Rotation Mounts


SM2-Compatible Rotation Mounts

  • 2.035"-40 Threading
  • Mount SM2 Lens Tubes
  • Mount Ø2"(Ø50 mm) Optics


  • Mounts Feature Internal SM2 (2.035"-40) Threads
  • Accept Ø2" (50.8 mm) Optics
  • 360° Continuous Rotation
  • Engraved Direct Read Scale

This page is a compilation of all of the SM2- (2.035"-40) threaded rotation mounts. Thorlabs also has a similar compilations of SM threaded rotation mounts for Ø1/2" (12.7 mm) and Ø1" (50 mm) optics. If SM threading is not a primary requirement for the rotation mount, please see our complete line of manual and motorized rotation mounts.

SM2-Threaded components are designed to mount or integrate Ø2" (50.8 mm) optics into optical systems. These SM2-threaded rotation mounts allow for the 360° degree rotation positioning of the optic.

Thorlabs introduced the SM Series Threading standards to ensure compatibility over a broad range of product lines. SM Series Threaded components offer a simple and efficient solution for building optomechanical structures. The SM Threaded products available, including lens tubes and cage system components, fixed and kinematic mounts, irises and diaphragms, provide flexibility when constructing complex optical systems. Please see the Threading Specs tab for more information on Thorlabs' SM thread standards.


Continuous Rotation Mount for Ø2" Optics

* Mount Ø2.0" Optics up to 0.51" (13 mm) Thick
* Thrust Bearing Design
* Compatible with SM2 Lens Tubes
* One SM2RR Retaining Ring Included
* Bottom-Located 8-32 (M4) Tapped Hole for Post Mounting

The RSP2(/M) Continuous Rotation Mount utilizes two precision bearings for smooth rotation. The aperture features internal SM2 (2.035"-40) threading and accepts Ø2" optics up to 0.51" (13 mm) thick as well as any SM2-threaded component. Secure the optic using the included SM2RR retaining ring.

The mount has a knurled edge for rotation. A 360° laser-engraved scale marked at 2° increments allows for precise, repeatable positioning and fine angular adjustment. A top-located 5/64" hex setscrew can be tightened to lock the rotation of the mount.


High-Precision Rotation Mount for Ø2.00" Optics


  • Accepts Ø2" (Ø50.8 mm) Optics up to 0.48" (12.2 mm) Thick
  • 360° Continuous Coarse Rotation
  • Direct Read 1° Graduations Engraved on Rotation Dial Face
  • ±7° of Micrometer-Driven Fine Rotation when Locked
  • Vernier Scale with 5 arcmin Resolution
  • Compatible with our SM2 Lens Tubes and 60 mm Cage System
  • One SM2RR Retaining Ring Included
  • Bottom-Located 8-32 (M4) Tapped Hole for Post Mounting

The PRM2(/M) high-precision rotation mount for Ø2" optics combines 360° of continuous coarse manual rotation with precise, backlash-free micrometer adjustment. The SM2-threaded (2.035"-40) inner bore accepts Ø2" optics up to 0.48" (12.2 mm) thick as well as any of our SM2-threaded components. Optics are secured with one SM2RR retaining ring (included with each mount).

The rotation dial face features a laser-engraved scale marked at 1° increments and can be rotated manually using the knurled outer surface (see drawing to the right). The thumbscrew, located on the lower right side of the mount, locks the dial face and engages the micrometer for fine adjustment. When locked, the micrometer provides ±7° of rotation at approximately 2.4 arcmin per micrometer division. This rotation mount also features a 0.05" hex setscrew on both sides that can lock both the fine and coarse rotational movement.

The PRM2(/M) is also compatible with our 60 mm cage system. The cage system can be mounted to the unit using ER cage assembly rods attached to the four 4-40 tapped holes located on the rotation dial face or the four 4-40 tapped holes located on the back side of the mount. The cage system attached to the back of the mount does not rotate.


60 mm Cage Rotation Mount

* Mounts Ø2" (Ø50.8 mm) Optics up to 13 mm (0.51") Thick
* Ø48 mm Clear Aperture
* 360° of Continuous Rotation
* 1° Engraved Graduations on Dial, Labeled Every 10°
* Setscrew Locking Mechanism
* Compatible with 60 mm Cage System
* 8-32 (M4) Tapped Hole for Post Mounting

The LCRM2 rotation mount is designed to mount Ø2" (Ø50.8 mm) optics up to 13 mm (0.51") thick in a 60 mm cage system. The optic is secured using the included SM2RR retaining ring (the SPW604 spanner wrench is ideal for tightening this retaining ring). For thicker optics, any of our SM2 lens tubes can be threaded into the carriage. The smooth rotation mechanism allows for precise positioning of the rotation carriage. The mount features a bottom-located 8-32 (M4) tapped mounting hole for post mounting, making it compatible with our Ø1/2" posts.


Ø2" Optic Holder

* Interchangeable Mounting Carriage
* Holds Ø2" (Ø50.8 mm) Optics Up to 0.48" (12.2 mm) Thick
* Laser Engraved Scale with Graduations Every 2°

This Nested Lens Mount Set is comprised of an inner optic carriage and an outer mounting ring (sold separately), allowing for easy exchange of optics while maintaining optical alignment. The LM2-A inner carriage is laser-engraved radially with graduation marks every 2° and labels every 20°. It accepts Ø2" (Ø50.8 mm) optics up to 0.48" (12.2 mm) thick into its SM2- (Ø2.035"-40) threaded bore. The mating LM2-B locks the position of the LM2-A using a top-located thumbscrew.

These mounts are post mountable via a bottom-located 8-32 (M4) tapped hole. Each LM2-A includes one SM2RR retaining ring.


Swivel Mounts/Plates for 60 mm Cage Systems


  • ±90° Angular Displacement Between Two Plates
  • Platform with 23 mm Vertical Height Adjustment
  • Independently Lockable Plates and Mounting Platform
  • Generous Array of Mounting Holes on Platform

The LC1A(/M) Swivel Mount is ideal for building spectrometers or other prism- and grating-based systems that require arbitrary angular alignment. The swivel plates are internally threaded for compatibility with our SM2 (2.035"-40) Series of Lens Tubes. In addition, the plates and mounting platform of the LC1A(/M) are independently lockable.

The pedestal can rotate through a full 360° and provides 20 mm of vertical height adjustment. To aid in alignment, there is a scribed scale with 2° increments below the pedestal. The platform has an array of threaded holes, making it easy to mount a variety of optical elements, such as prisms and gratings, as well as our PM3(/M) or PM4(/M) clamping arms. See the attached support drawing for more details.


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