- 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).
Our Stress-Free Retaining Rings (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 stress-free and plastic retaining rings, 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. For using multiple thread types in the same setup, please see our extensive line of thread adapters.