- Standard (Aluminum) Retaining Rings Available for Optics Ranging from Ø5 mm to Ø4"
- Stress-Free Retaining Rings are Compatible with the SM05, SM1, and SM2 Thread Standards
- Delrin (Plastic) SM1 Retaining Ring Provides Gentler Contact with Optic Surface
Thorlabs offers a wide selection of retaining rings for securing optical components into our threaded mounts, lens tubes, and unmounted optic adapters. Two retaining rings can be used to secure the optical component inside the center of a lens tube: one as a stopper and the other to lock in the component. Depending on the size needed, these retaining rings are available in one or more of the following types: standard (aluminum), stress-free, or plastic (see table below for details).
The stress-free versions (SM05LTRR, SM1LTRR, and SM2LTRR) have a rubber O-ring that provides a light-tight seal around the optical components. The SM1PRR plastic retaining ring is produced from Delrin to provide gentler contact with an optic's surfaces than our standard SM1RR retaining ring. Please keep in mind that due to the increased thickness of the plastic retaining ring, the thickness of the optic that can be accommodated in the mount may be reduced.
Thorlabs also offers a line of compatible fixed diameter and adjustable spanner wrenches for rings with diameters ranging from 1/4" to 3" and spanner bits for SM05, SM1, SM2, and SM3 retaining rings. Additionally, we offer retaining rings for RMS threads and an extensive line of thread adapters.
SM Series Threading Specifications
Thorlabs' lens tubes utilize a series of non-standard threadings. Threading specifications are given below for our SM threadings utilized in our lens tube and cage system components so that you can machine mating components to suit your application. For threading specifications other than what is listed here, please contact Tech Support.
|SM05 Threading: Ø1/2" Lens Tubes, 16 mm Cage Systems|
|External Thread, 0.535"-40.0, UNS-2A||Internal Thread, 0.535"-40.0, UNS-2B|
|Max Major Diameter||0.5340"||Min Major Diameter||0.5350"|
|Min Major Diameter||0.5289"||Min Pitch Diameter||0.5188"|
|Max Pitch Diameter||0.5178"||Max Pitch Diameter||0.5230"|
|Min Pitch Diameter||0.5146"||Min Minor Diameter (and 83.3% of thread)||0.508"|
|Max Minor Diameter||0.5069"||Max Minor Diameter (and 64.9% of thread)||0.514"|
|SM1 Threading: Ø1" Lens Tubes, 30 mm Cage Systems|
|External Thread, 1.035"-40.0, UNS-2A||Internal Thread, 1.035"-40.0, UNS-2B|
|Max Major Diameter||1.0339"||Min Major Diameter||1.0350"|
|Min Major Diameter||1.0288"||Min Pitch Diameter||1.0188"|
|Max Pitch Diameter||1.0177"||Max Pitch Diameter||1.0234"|
|Min Pitch Diameter||1.0142"||Min Minor Diameter (and 83.3% of thread)||1.008"|
|Max Minor Diameter||1.0068"||Max Minor Diameter (and 64.9% of thread)||1.014"|
|SM30 Threading: Ø30 mm Lens Tubes|
|External Thread, M30.5x0.5||Internal Thread, M30.5x0.5|
|Max Major Diameter||30.480 mm||Min Major Diameter||30.500 mm|
|Min Major Diameter||30.371 mm||Min Pitch Diameter||30.175 mm|
|Max Pitch Diameter||30.155 mm||Max Pitch Diameter||30.302 mm|
|Min Pitch Diameter||30.059 mm||Min Minor Diameter (and 83.3% of thread)||29.959 mm|
|Max Minor Diameter||29.938 mm||Max Minor Diameter (and 64.9% of thread)||30.094 mm|
|SM2 Threading: Ø2" Lens Tubes, 60 mm Cage Systems|
|External Thread, 2.035"-40.0, UNS-2A||Internal Thread, 2.035"-40.0, UNS-2B|
|Max Major Diameter||2.0338"||Min Major Diameter||2.0350"|
|Min Major Diameter||2.0287"||Min Pitch Diameter||2.0188"|
|Max Pitch Diameter||2.0176"||Max Pitch Diameter||2.0239"|
|Min Pitch Diameter||2.0137"||Min Minor Diameter (and 83.3% of thread)||2.008"|
|Max Minor Diameter||2.0067"||Max Minor Diameter (and 64.9% of thread)||2.014"|
|SM3 Threading: Ø3" Lens Tubes|
|External Thread, 3.035"-40.0, UNS-2A||Internal Thread, 3.035"-40.0, UNS-2B|
|Max Major Diameter||3.0337"||Min Major Diameter||3.0350"|
|Min Major Diameter||3.0286"||Min Pitch Diameter||3.0188"|
|Max Pitch Diameter||3.0175"||Max Pitch Diameter||3.0242"|
|Min Pitch Diameter||3.0133"||Min Minor Diameter (and 83.3% of thread)||3.008"|
|Max Minor Diameter||3.0066"||Max Minor Diameter (and 64.9% of thread)||3.014"|
Thorlabs' Stackable Lens Tubes provide an easy and fast solution for assembly of an optical system with a single optical axis. Using lens tubes one can easily assemble several optical components on a common optical axis without the need for X-Y alignment of each component to the common axis. Thorlabs offers Ø1/2”, Ø1”, Ø2” and Ø3” lens tubes, for use with different optics sizes, as well as adapters to convert between the four different sizes.
Thorlabs also offers many of our optical components in pre-mounted 1” lens tubes as well as specially developed components and mounts, all of which are pre-aligned to the optical axis, including:
Thorlabs has also added alignment tools for lens tubes for working with IR optics, such as infrared alignment disks and alignment targets. Additionally, with the use of retaining rings, any standard optical component can be easily mounted into the lens tubes.
For more complex optical systems Thorlabs has developed sets of post mounting rings, mounting brackets, and construction cubes to enable building complex, rugged systems.
Thorlabs lens tubes can also easily interface with our cage system components such as the cage plates, kinematic turning mirror mounts, pre-mounted beamsplitter cubes and pre-mounted turning mirrors.