Ø2" Lens Tubes


Ø2" Lens Tubes

  • Directly Accepts Ø2" (50 mm) Optics
  • Compatible with SM2-Threaded Components
  • Designed for use with our 60 mm Cage Systems


  • Easily Construct Multi-Element Optical Systems
  • Wide Range of SM2-Compatible Optomechanical Components Available
  • Compatible with Our 60 mm Cage Systems
  • Directly Accepts Ø2" (50.8 mm) Optics

Lens tubes are ideal for creating compact optical subassemblies. The Ø2" lens tubes sold here can be used to house one or several optical elements. Optics are separated and secured by retaining rings that are positioned at the desired depth within the lens tube using our SPW604 spanner wrench. Depending on the item purchased, one or two retaining rings will be included (see below for details). Additional retaining rings can be purchased separately. In addition to the Ø2" lens tubes featured on this page, Thorlabs also offers Ø1/2", Ø1", Ø30 mm, and Ø3", versions, each of which is equipped with an SM series thread standard that depends on the tube diameter.



Ø2" Stackable Lens Tubes

* SM2-Threaded (2.035"-40) Bore Accepts Ø2" (Ø50 mm) Optics
* Stackable Design Enables Multi-Element Optical Systems
* Compatible with Our 60 mm Cage Assembly Systems

These stackable Ø2" lens tubes provide a fast and easy means for building compact optical assemblies. Their stackable design and direct interfacing with all SM2-threaded (2.035"-40) components provide flexibility for complex optomechanical assemblies. One SM2RR retaining ring is included with each lens tube.  


Item #L1L2Thread Depth
SM2L03 0.45" 0.12" 0.30"
SM2L05 0.65" 0.12" 0.50"
SM2L10 1.15" 0.12" 1.00"
SM2L20 2.15" 0.12" 2.00"
SM2L30 3.15" 0.12" 3.00"


Ø2" Lens Tubes Without External Threads

* SM2-Threaded (2.035"-40) Bore Accepts Ø2" (Ø50 mm) Optics
* Unlike Stackable Lens Tubes, Optics can be Accessed from Both Ends
* Use Lens Tube Couplers to Stack Multiple Lens Tubes
* Allows Coupling of Two Components with External SM2 Threading
* Directly Compatible with Our 60 mm Cage Assembly Systems

Unlike our Ø2" stackable lens tubes featured above, these internally threaded lens tubes do not feature a lip at one end nor do they have external SM2 threading. Therefore, optics housed inside can be accessed from both ends. To join these lens tubes end-to-end, use an SM2T2 Lens Tube Coupler. Two SM2RR retaining rings are included with each lens tube.


Slotted Lens Tubes

* Easy Access to Optics
* Rotatable Slip Shield Protects Optics
* Compatible with SM2-Threaded Components

These stackable Ø2" lens tubes with side slots provide a fast and easy means for building complex optical assemblies and adjusting the optics without disassembling the setup. Several optics can be inserted into a single tube using multiple SM2RR retaining rings. Simply thread the first retaining ring to the desired depth, add the optic, and then use a second retaining ring to secure the optic. Optics can be manually adjusted via the side slots without the use of a spanner wrench. The rotatable slip shield included with the lens tube fits over the lens tube slots to prevent unwanted light from entering the system and to keep the optical setup free from debris. Two retaining rings and one black plastic dust cover are included with each lens tube.


SM2 Extension Tubes

The SM2E60 6" Long Extension Tube is designed to enable longer distances between optical components in lens tube systems that utilize lenses with large focal lengths. Although the ends of these extension tubes are threaded to accept our SM2 series stackable lens tubes, they feature thicker walls than our standard lens tubes, which leads to greater rigidity.


Ø2" Retaining Rings and Spanner Wrenches

* SM2RR Retaining Rings Secure Ø2" Optics
* SM2LTRR Retaining Rings Provide Stress-Free, Light-Tight Mounting of Ø2" Components
* Spanner Wrenches Provide One-Handed Adjustment of SM2RR Retaining Rings
* SPW801 Adjustable Spanner Wrench can Accommodate Diameters from 0.15" (3.8 mm) to 3.0" (75 mm)

Thorlabs offers two different kinds of SM2 retaining rings. The SM2RR is our standard retaining ring that ships with our Ø2" lens tubes as well as many other Thorlabs components. If desirable, the SM2RR can be swapped out for a SM2LTRR, which is a retaining ring equipped with a Buna-N O-ring designed to reduce stress on the optical component and to produce a light-tight seal. There are also two spanner wrench choices that can be used with these retaining rings. The SPW604 Spanner Wrench has a hollow design that enables retaining rings for our SM2 series of lens tubes to be adjusted and installed without obscuring the beam path. The handle is knurled for improved grip. Alternatively, the SPW801 Adjustable Spanner Wrench can also be used to position SM2RR or SM2LTRR retaining rings. Please note that the SPW801 wrench can withstand a maximum torque of 80 inch pounds.


Our Mission is to accelerate the advancement of optical technology for precision measurements and their applications from the table tops of research laboratories to standard use in communication and high technology industries. Our aim is to serve our customers. Our hope is to create a place for highly skilled people in an open environment

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