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Retaining Rings![]()
CMRR C-Mount (1.00"-32), SM05LTRR SM05 (0.535"-40), SM1PRR SM1 (1.035"-40), SM75RR M75.5 x 0.5, SM4RR SM4 (4.035"-40), SM2RRC SM2 (2.035"-40), POLARIS-SM1RR SM1 (1.035"-40), SM1RRV SM1 (1.035"-40), ![]() Please Wait Retaining Rings Selection Guidea
Features
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 balck anodized aluminum, unanodized aluminum, extra-thick, stress-free, plastic, or stainless steel. For a table of available options, please see the Retaining Rings Selection Guide to the right. We offer extra-thick (5 mm) retaining rings which provide easier mounting for high-curvature lenses, such as aspheric lenses and condenser lenses (see the Lens Mounting Guide tab for more information). Our Stress-Free Retaining Rings (Item #'s SM05LTRR, SM1LTRR, and SM2LTRR) have a rubber O-ring that provides a light-tight seal around the optical components. The SM05PRR and SM1PRR Plastic Retaining Rings are produced from Delrin to provide gentler contact with an optic's surfaces than our standard retaining rings. 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. Two vacuum-compatible options are available and intended for use with threaded components of the same material: unanodized aluminum retaining rings for aluminum vacuum-compatible components and stainless steel retaining rings are ideal for use with our SM-threaded high-stability Polaris mirror mounts. Thorlabs also offers a line of fixed-diameter and adjustable spanner wrenches for rings for optic diameters from 5 mm to 3" and spanner bits for SM05, SM1, SM1.5, SM2, and SM3 retaining rings. For using multiple thread types in the same setup, please see our extensive line of thread adapters. For ordering convenience, the SM05RR and SM1RR Standard Retaining Rings are available in packs of 10, and the SM2RR Standard Retaining Ring is available in packs of 5. *Delrin® is a registered trademark of DuPont Polymers, Inc. Thorlabs' retaining rings are used to secure unmounted optics within lens tubes or optic mounts. These rings are secured in position using a compatible spanner wrench. For flat or low-curvature optics, standard retaining rings manufactured from anodized aluminum are available from Ø5 mm to Ø4". For high-curvature optics, extra-thick retaining rings are available in Ø1/2", Ø1", and Ø2" sizes. Extra-thick retaining rings offer several features that aid in mounting high-curvature optics such as aspheric lenses, short-focal-length plano-convex lenses, and condenser lenses. As seen in the animation to the right, the guide flange of the spanner wrench will collide with the surface of high-curvature lenses when using a standard retaining ring, potentially scratching the optic. This contact also creates a gap between the spanner wrench and retaining ring, preventing the ring from tightening correctly. Extra-thick retaining rings provide the necessary clearance for the spanner wrench to secure the lens without coming into contact with the optic surface. Thorlabs' Threading SpecificationsThorlabs' 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. We also offer products with C-Mount and RMS threadings, and the specifications for these threadings are also given below. Please note that other manufacturers may have different tolerances for these threads. For other thread specifications that are not listed here, please contact Tech Support.
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Our Standard Retaining Rings are manufactured from anodized aluminum and are offered in sizes to match our optic mounts and lens tubes. They maximize the clear aperture while providing sufficient holding force. Securing an optic using a retaining ring is a stable method for holding the optic since the optic is retained along its entire edge instead of just at a few points. Each retaining ring is machined with two slots for compatibility with our selection of spanner wrenches.
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Our Standard Retaining Rings are manufactured from anodized aluminum and are offered in sizes to match our optic mounts and lens tubes. They maximize the clear aperture while providing sufficient holding force. Securing an optic using a retaining ring is a stable method for holding the optic since the optic is retained along its entire edge instead of just at a few points. Each retaining ring is machined with two slots for compatibility with our selection of spanner wrenches. Our C-Mount-threaded (1.00"-32) retaining ring is ideal for securing optical components into our CMR lens mount or CP13 30 mm cage plate and C- or CS-Mount compatible CCD and CMOS cameras. This retaining ring is engraved with both the part number and "C-Mount" to distinguish it from our SM-threaded retaining rings.
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Our Standard Retaining Rings are manufactured from anodized aluminum and are offered in sizes to match our optic mounts and lens tubes. They maximize the clear aperture while providing sufficient holding force. Securing an optic using a retaining ring is a stable method for holding the optic since the optic is retained along its entire edge instead of just at a few points. Each retaining ring is machined with two slots for compatibility with our selection of spanner wrenches.
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Our Standard Retaining Rings are manufactured from anodized aluminum and are offered in sizes to match our optic mounts and lens tubes. They maximize the clear aperture while providing sufficient holding force. Securing an optic using a retaining ring is a stable method for holding the optic since the optic is retained along its entire edge instead of just at a few points. Each retaining ring is machined with two slots for compatibility with our selection of spanner wrenches.
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Our Standard Retaining Rings are manufactured from anodized aluminum and are offered in sizes to match our optic mounts and lens tubes, are designed to maximize the clear aperture while providing sufficient holding force. Securing an optic using a retaining ring is a stable method for holding the optic since the optic is retained along its entire edge instead of just at a few points. Each retaining ring is machined with two slots for compatibility with our selection of spanner wrenches.
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These extra-thick SM05, SM1, and SM2 retaining rings are manufactured from anodized aluminum and are designed with a 5 mm thickness for easier mounting of high-curvature lenses, such as aspheric lenses and condenser lenses. The SM threading on the outside of the ring does not extend down the entire thickness of the ring. For best performance, the retaining ring should be used with the non-threaded side contacting the lens. Please see the table below for a list of compatible spanner wrenches.
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Our Stress-Free Retaining Rings are available with our standard SM05, SM1, or SM2 threadings. This design uses an O-ring made of Buna-N nitrile rubber to reduce the stress on the optic surface and completely seal out sources of stray light. Like our standard retaining rings, our stress-free retaining rings contain two slots for compatibility with our selection of spanner wrenches. Due to the rubber O-ring, the clear aperture is slightly reduced relative to our standard retaining rings. Please see the table to the upper right for details.
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The SM05PRR and SM1PRR Delrin (Plastic) Retaining Rings provide gentler contact with the surface of optics than our standard retaining rings. They are compatible with any internally SM05- or SM1-threaded optic mount, respectively. Each of these plastic retaining rings is thicker than the standard retaining ring of the same diameter featured above. Please note that due to the increased thickness, the maximum optic thickness that can be accommodated inside our standard SM05- and SM1-compatible mounts will be slightly diminished. In addition, the clear aperture of SM1PRR plastic retaining ring is slightly reduced compared to its standard counterpart. Refer to the table below for compatible spanner wrench options, and see the table to the upper right for the diameter of each plastic retaining ring relative to our standard retaining rings. ![]()
These aluminum SM05-, SM1-, or SM2-threaded retaining rings have identical thread specifications, thickness, and clear aperture when compared to our standard retaining rings of the same size. Their lack of anodization and 6061-T6 alumimun construction allows them to be used at vacuum levels down to 10-6 Torr. They are designed for use with our SM-threaded vacuum-compatible components. Each ring is double vacuum-bagged for clean room use. Vacuum-compatible versions of other retaining rings can be requested by contacting Tech Support. Please refer to the table below for compatible spanner wrench options.
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These stainless steel SM05, SM1, and SM2 retaining rings have identical thread specifications when compared to our standard SM05 (Item # SM05RR), SM1 (Item # SM1RR), and SM2 (Item # SM2RR) retaining rings. They are designed for use with our SM-threaded Polaris mirror mounts. The matched material (stainless steel) helps reduce thermal hysteresis by having a matched coefficient of thermal expansion (CTE) to the Polaris mount. Please refer to the table below for compatible spanner wrench options, and see the table to the upper right for the diameter of each stainless steel retaining ring relative to our standard retaining rings.
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These spanner wrenches enable adjustment or installation of many of our standard retaining rings. The hollow construction of each spanner wrench allows the retaining ring to be adjusted without obscuring the beam path. They feature knurled handles for improved grip as well as flanges to keep the retaining ring on the end of the spanner wrench while inserting or removing the ring. As shown below, the SPW602, SPW603L, and SPW608 wrenches feature an engraved scale to indicate spanner wrench depth in both imperial and metric increments (0.02" and 0.5 mm, respectively), thereby enabling precise positioning of optics. For retaining rings not covered by these cylindrical spanner wrenches, please see the SPW801 Adjustable Spanner Wrench sold at the bottom of the page. The SPW801 features an adjustable spanning range as well as long blades that extend 1.6" (40.7 mm) from the body of the wrench. Hence, for lenses with a high radius of curvature, we recommend using the SPW801 over the cylindrical spanner wrenches, whose guide flanges may come into contact with the lens. ![]() Click to Enlarge An SPW602 spanner wrench is used to place an optic in a lens tube via a retaining ring. This spanner wrench features an engraved scale to indicate spanner wrench depth. ![]() Click to Enlarge Stackable spanner wrenches, like the SPW603, can be fitted together to reach retaining rings in long lens tubes. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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