Products Home / Optomechanical Components / Optical Cage Systems / Cage System Construction / 30 and 60 mm Cage System Construction Rods30 and 60 mm Cage System Construction Rods
- Building Blocks for 30 and 60 mm Cage Systems
- Ø6 mm Precision-Machined Stainless Steel Rods
- Ideal for Complex Optical Structures
ER4E
ER2
ER1
For 30 mm and
60 mm Cage Systems
C2A
Swivel Coupler
ERSCB
Cage Rod Adapter
(2 Shown)
C3A
Swivel Connector
ER90C
30 mm
ER90C
ER90C
ER90A
Spacer Rod
Right Angle Rods and Spacer
Please Wait
The Cage Assembly System provides a convenient way to construct large optomechanical systems with an established line of precision-machined building blocks designed for high flexibility and accurate alignment. This page offers cage assembly rods for our 30 and 60 mm Cage Systems. For cage rods to construct a 16 mm cage system, please see our SR construction rods page. Please see the Cage Overview tab for more details on this widely adopted construction standard.
Cage Rod Adapters
The ERSCB ER rod adapter allows for the end-to-end joining of two ER rods. It has an internal bore on one end that accepts Ø6 mm ER series rods. To join two rods, position the end of one rod inside the ERSCB, and lock it into place using the locking setscrew. Thread the other end of the ERSCB into the other rod (see photo at right).
3D Construction Using Cage Systems
These assembly rods are essential components when configuring cage systems in complex, multi-dimensional structures.
For 30 and 60 mm cage systems, the ER90C right angle rods offer a fixed 90° connection to a cage system (see photo to left). Using the ER90A spacer rod for 30 mm cage systems and the ER90L spacer rod for 60 mm cage systems will ensure center-to-center spacing. Alternatively, a cage cube can be used to create a rigid 90° connection.
Our jointed cage rods can be configured to any arbitrary angle before being locked into place. The C3A single-jointed cage rods and C5A double-jointed cage rods are each pictured to the right. We also offer the S3A connector for 16 mm cage systems.
When constructing complex optomechanical cage assemblies, it is sometimes necessary to couple one cage subsystem to another. Between the S1A cross coupler for 16 mm cages, the C1A cross coupler for 30 and 60 mm cage systems, and the C2A swivel coupler with 180° swing, virtually any configuration can be achieved.
The SRSCA SR rod adapters and ERSCB ER rod adapters are also useful for 3D construction in 16 mm cage systems or 30 and 60 mm cage systems, respectively. They can be used to connect two internally threaded cage components with SR (SRSCA) or ER (ERSCB) rods, and allow components to be easily added or removed from setups without causing misalignment. In the application shown to the left, four ERSCB adapters are used with ER rods to connect a 30 mm cage cube to an ST1XY-S micrometer-driven, XY translation mount. The four cage rods are directly threaded into four holes in the cage cube. Since the other end of each cage rod is internally threaded, they cannot be directly threaded into the translation mount. Instead, the threaded side of the ERSCB adapter is connected to the ST1XY-S translation mount. Each cage rod slides into the other side of each adapter and is secured in place with the setscrew.
Application Idea
The cage assembly components offered here can be used to couple 16 mm, 30 mm, and 60 mm cage systems. The following tables correspond to either the imperial or metric item list for the setup below.
Cage System Overview
The Cage Assembly System provides a convenient way to construct large optomechanical systems with an established line of precision-machined building blocks designed for high flexibility and accurate alignment.
16 mm, 30 mm, and 60 mm Cage System Standards
Thorlabs offers three standards defined by the center-to-center spacing of the cage assembly rods (see image below). The 16 mm cage, 30 mm cage, and 60 mm cage standards are designed to accomodate Ø1/2", Ø1", and Ø2" optics, respectively. Specialized cage plates that allow smaller optics to be directly inserted into our larger cage systems are also available.
Standard Threads
The flexibility of our Cage Assembly System stems from well-defined mounting and thread standards designed to directly interface with a wide range of specialized products. The three most prevalent thread standards are our SM05 Series (0.535"-40 thread), SM1 Series (1.035"-40 thread), and SM2 Series (2.035"-40 thread), all of which were defined to house the industry's most common optic sizes. Essential building blocks, such as our popular lens tubes, directly interface to these standards.
An example of the standard cage plate measurements determining cage system compatibility.
| Standard Cage System Measurements | |||
|---|---|---|---|
| Cage System | 16 mm | 30 mm | 60 mm |
| Thread Series | SM05 | SM1 | SM2 |
| Rod to Rod Spacing | 16 mm (0.63") | 30 mm (1.18") | 60 mm (2.36") |
| Total Length | 25 mm (0.98") | 41 mm (1.60") | 71.1 mm (2.8") |
| Cage Components | ||
|---|---|---|
| Cage Rods | 16 mm | These rods are used to connect cage plates, optic mounts, and other components in the cage system. The SR Series Cage Rods are compatible with our 16 mm cage systems, while the 30 mm and 60 mm cage systems use ER Series Cage Rods. |
| 30 mm | ||
| 60 mm | ||
| Cage Plates | 16 mm | These serve as the basic building blocks for a cage system. They may have SM-threaded central bores, smooth bores sized for industry standard optics or to accommodate the outer profile of our SM Series Lens Tubes, or specialized bores for other components such as our FiberPorts. |
| 30 mm | ||
| 60 mm | ||
| Optic Mounts | 16 mm | Thorlabs offers fixed, kinematic, rotation, and translation mounts specifically designed for our Cage Systems. |
| 30 mm | ||
| 60 mm | ||
| Cage Cubes | 16 mm | These cubes are useful for housing larger optical components, such as prisms or mirrors, or optics that need to sit at an angle to the beam path, such as beamsplitters. Our cage cubes are available empty or with pre-mounted optics. |
| 30 mm | ||
| 60 mm | ||
| Post and Breadboard Mounts and Adapters | Mounting options for cage systems can be found on our Cage System Construction pages. Cage Systems can be mounted either parallel or perpendicular to the table surface. | |
| Size Adapters | Cage System Size Adapters can be used to integrate components from different cage system and threading standards. | |
| Specialized Components | Thorlabs also produces specialized cage components, such as Filter Wheels, a HeNe Laser Mount, and a FiberPort Cage Plate Adapter, allowing a wide range of our products to be integrated into cage-mounted optical systems. Explore our Cage Systems Visual Navigation Guide to see the full range of Thorlabs' cage components. | |
| Posted Comments: | |
Craig Prater
(posted 2020-11-10 17:44:38.28) Hi. I wanted to comment on the packaging of the ERSCB rod adapters. The adapters come wrapped up in Scotch tape that leaves a sticky residue on the parts when the tape is removed. I don't like anything sticky around my optics, so I recommend a different way of packaging these items. I assume the tape is used to make sure the set screws don't get lost in shipping. If you believe that tape is really required to achieve this, I'd suggest using Kapton tape instead as it does not leave behind a residue. Thanks! YLohia
(posted 2020-11-11 09:45:16.0) Hello, thank you for your feedback -- we are always looking for ways to improve the quality and packaging of our products. I have posted your suggestion on our internal engineering forum for further consideration. Rowan MacQueen
(posted 2020-10-27 16:42:18.207) This article is also missing from the e.biss catalogue (at least at my institution, Helmholtz-Zentrum Berlin) along with the single article YLohia
(posted 2020-10-28 09:26:37.0) Hello, stock items can be purchased by contacting our German Sales Team at sales.de@thorlabs.com or +49 (0) 8131-5956-0. nikita.vladimirov
(posted 2018-06-07 15:01:16.527) Dear Thorlabs,
It would be great if you could offer cage rods with more common setscrews on both ends, like M2.5 or M3 instead of current 4-40 imperial thread. It is very hard to find a tap or buy nuts for 4-40 threads, especially for those who live outside US. All-metric option would be highly appreciated! Thank you. llamb
(posted 2018-06-07 03:22:07.0) Thank you for your feedback. Our cage rods all have #4-40 setscrews for consistency and compatibility among all of our cage system components. As a possible alternative, our metric Mini-Series Posts (such as part number MS1R/M) also feature the same Ø6 mm diameter as our cage rods, but have M3 taps and setscrews. We can offer custom lengths and tapped holes on our cage rods upon request as well. I will reach out to you directly in case custom cage rods would be preferred. jpaufiqu
(posted 2017-06-01 16:04:30.843) Hi,
SS4S025 are too short to ensure a good stiffness of the assembly using the 90° rods. That is probably why you deliver slightly longer screws with the 90° parts (by about 0.15"?).
Offering these longer setscrews as well as separate items would be very useufl (i.e. setscrews 4-40 with a length about 0.15" longer than usual; double-ended to simplify). Especially once the setup is re-used in a different context, the longer setscrews provided will get lost (i.e. used in the wrong place and not anymore available for this critical use). nbayconich
(posted 2017-06-13 05:23:47.0) Thank you for contacting Thorlabs. We do have setscrews available in longer lengths 4-40 x 3/8" long & 4-40 x 1/2" long as component pieces. Currently we have not seen the demand to offer these as stock options but we can provide these upon request. I will contact you directly with more information. user
(posted 2016-07-12 11:24:26.17) Hello Thorlabs, are long rods supposed to be perfectly straight? What is the tolerance on straightness? I've received two 24" long rods with about 0.1" bend over the whole length. They may have been bent during shipping (especially if packed with other items, heavy ones). ludoangot
(posted 2016-03-18 16:43:33.157) On the rods I have (ER6, ER8, ...), the holes on each end of the rods are deeper than the female thread length. In an application I need the thread to go deeper than the current length. Can I safely tap the thread further? What is the diameter of the hole beyond the threads (I can't find it documented in the drawings or description)? besembeson
(posted 2016-03-18 09:04:04.0) Response from Bweh at Thorlabs USA: The #4-40 x 1/4" set screw is designed to protrude up to 0.1" from the end of the rod to the cup point so the threaded whole is 0.15" deep to the end of the set screw SS4S025. You can remove the set screw and carefully drill appropriate hole and tap further as desired. loo
(posted 2016-03-02 10:57:00.017) It would be nice if the rods had a through hole to get extra torque with a hexkey, since using pliers will damage the rods beyond smooth sliding. besembeson
(posted 2016-03-02 11:34:27.0) Response from Bweh at Thorlabs USA: Thanks for your feedback. We will be reviewing this. We may also consider providing a special strip-free wrench/pliers for such purposes. smid
(posted 2016-01-27 15:14:19.387) We have made some precise measurements in laboratory condition with you ER series stainless steel rods. We would like to compare theoretical thermal expansion coefficient (CTE) of the rods to the measurement in our cage assembly to make the estimation of the possible errors. We estimate that your CTE lies somewhere between the general stainless steel with 1e-5/m/K and the invar stainless stell with 1e-6/m/K. Could you please confirm or send me a private message and provide the more detailed information?
Thank you very much. jlow
(posted 2016-02-01 09:40:43.0) Response from Jeremy at Thorlabs: The ER series cage rods is made from 303 stainless steel. The linear CTE is roughly around 17.3 µm/m/K. oliver.larkin
(posted 2015-07-07 12:50:36.387) You may want to consider threading all four holes in your ERSCA adapters as often the two screws end up facing a direction where it is difficult to reach them and there is no way to adjust this as the final position depends on the tapping/threading. This would allow moving the grub screws to accessable holes whilst also allowing two free to tighten the items. besembeson
(posted 2015-09-23 09:45:40.0) Response from Bweh at Thorlabs USA: Thanks for the feedback. I see the added mounting convenience. The only concern is that over time, the tapped holes may end up being stripped during tightening of the ERSCA. nicolas.perlot
(posted 2014-10-30 13:30:49.85) We purchased ER Rod Swivel Couplers (C2A) but one of the three screws has a damaged (enlarged) hex socket and cannot be tightened with a hex key anymore. We would like to replace this damaged screw. Do you sell these small screws separately? If not, what are their specifications? cdaly
(posted 2014-10-30 01:26:02.0) Response from Chris at Thorlabs: We do not sell this screw individually at the moment (2-56 x 1/4"). We will contact you directly and have some replacements sent out to you. user
(posted 2014-08-23 18:00:43.417) What do you think about offering the longer rods in Invar 36? I've sourced some for myself but of course it's not neatly machined with threaded ends like ER series. Invar's nice for things like resonator cavities where absolute lengths matter. I'd say having something like ER8I, ER12I and ER24I would be enough for most uses. cdaly
(posted 2014-08-26 09:49:14.0) Response from Chris at Thorlabs: Thank you for your suggestion. We will discuss the possibility of including this product internally. jrc3393
(posted 2014-02-20 01:47:20.5) What are the diameter and straightness for the 16mm, 30mm and 60mm cage rods? Also, what material are they made from? cdaly
(posted 2014-02-25 04:16:40.0) Response from Chris at Thorlabs: Thank you for your inquiry. These specifications are somewhat close to proprietary information so I'm afraid I cannot post them here, but I will email you directly with the information. avner
(posted 2013-06-17 15:05:12.097) What are the tolerances on the diameter for 16mm, 30mm and 60mm rods jlow
(posted 2013-06-20 10:40:00.0) Response from Jeremy at Thorlabs: We will get in contact with you directly to provide this information. iain
(posted 2013-05-31 11:43:15.923) Do you sell any cage construction rods with metric (M3 or M4) taps? It is difficult to get #4-40 screws of the correct length. Is the cage system compatible with metric posts such as MS05R/M or PM3/M? tcohen
(posted 2013-06-06 11:52:00.0) Response from Tim at Thorlabs: You can use 6mm diameter posts for those with clearance holes but it will not be compatible with any of our cage system optomech with threads. We do sell screws separately as kits and in individual packs at http://www.thorlabs.de/Navigation.cfm?Guide_ID=2017. The part number for these setscrews is SS4S025. cbrideau
(posted 2013-03-21 13:45:20.57) Really glad to finally see 4-packs of ER rods for sale! It makes ordering much simpler. jlow
(posted 2013-03-27 10:28:00.0) Response from Jeremy at Thorlabs: Thank you for your feedback on this. We continually look at our sales statistics so that we can identify ordering trends. In this case a large number of people order four ER rods at a time. To make life easier we thought it would be good to offer them that way. It will also allow us to reduce packaging waste. |
Zoom- For use with Our Standard 30 mm and 60 mm Cage Systems
- Available Individually in Lengths Ranging from 1/4" to 24"
- Packs of Four Also Available for 1/2" to 8" Lengths
- Ø6 mm Precision-Ground Stainless Steel
- 4-40 Removable Setscrew at Both Ends
These 30 and 60 mm cage rods are made from stainless steel. The 4-40 threaded stud at each end of the cage rod can be removed, leaving a 4-40 tapped hole. This allows multiple cage rods to be connected end-to-end. As part of our sustainability initiatives to reduce packaging waste, we offer our most popular sizes in packs of four.
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- Engraved Scale (Increments of 1 mm) for Accurate Adjustments
- For Use with Standard 30 mm and 60 mm Cage Systems
- Available in Two Lengths: 4" and 6"
- Ø6 mm Precision-Ground Stainless Steel
- 4-40 Removable Setscrew at Both Ends
These graduated ER rods are identical to the 4" and 6" ER Rods above, but feature an engraved scale along the side. The rods have short tick marks every 1 mm, long tick marks every 5 mm, and a straight vertical line along the rod's entire length. The engraved rods simplify alignment issues, especially in complicated setups with multiple components and integrated cage systems. For custom lengths, please contact Technical Support.
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Click to Enlarge ST1XY-A translator with ERSCB adapters installed. This allows the translator to be mounted to other cage components with internal 4-40 threads.
- Internally Accepts Ø6 mm ER Series Rods
- 4-40 Threaded Stud and 8-32 Locking Setscrews with 5/64" (2.0 mm) Hex
- Easily Add or Remove Components from Cage Assemblies
Our ERSCB Adapters enable any cage assembly to be easily separated when adding or removing components. This adapter has an internal bore on one end that accepts a Ø6 mm ER series rod with its setscrew removed. The 8-32 locking setscrew with a 5/64" (2.0 mm) hex must be tightened to hold the ER rod in place. On the other side of the adapter, there is an externally 4-40 threaded stud that can be threaded into the end of another ER series rod or 4-40 internally-threaded cage component.
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C1A Couplers with ER Rods
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ER90B Bracket with Two ER Rods
- Compatible with 30 mm and 60 mm Cage Systems
- Couple ER Rods at 90°
These couplers can be used to join multiple 30 mm and 60 mm cage structures at 90°.
The C1A Cross Coupler clamps down onto the cage rods using the included 5/64" hex caphead screws.
The ER90B Bracket has one double-bored Ø6 mm hole and 4-40 taps on the top and bottom. An ER rod can be inserted into the hole and fixed in place using a 0.05" (1.3 mm) hex key or directly threaded into the taps.
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A Ø6 mm Post Mounted Perpendicularly to a Ø1/2" Post Using the RA90TR Clamp
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A Ø6 mm Post Mounted to a Ø1/2" Post With Continuous 360° Rotation Using the MSWCA Clamp
- Mounts a Ø6 mm Mini-Series Post or Cage Rod to a Ø1/2" Post
- Right-Angle and 360° Continuous Adjustment Available
- Imperial and Metric Versions Available
Thorlabs’ Ø1/2" to Ø6 mm angle post clamps are used to integrate Ø1/2" posts into mini-series constructions or cage system assemblies. These clamps are available as a fixed right-angle, for perpendicular mounting, or with continuous 360° angle adjustment. Individual locking mechanisms for each post, as well as the rotation angle, allow for independent adjustment of each component.
The MSWCA(/M) clamp allows a Ø6 mm cage rod or mini-series post to be mounted to a Ø1/2" post with 360° continuous adjustment. The clamp features witness lines marked every 45°, as well as a 3/16" (5 mm) hex thumbscrew to secure the swivel angle. Two additional 3/16" (5 mm) hex thumbscrews are used to secure the posts into place. The center-to-center distance between the two posts is 0.62" (15.7 mm).
The RA90TR(/M) clamp allows a Ø6 mm cage rod or mini-series post to be mounted perpendicularly to a Ø1/2" post. The design combines a highly stable clamp flexure lock for holding the Ø6 mm post that is secured using a 5/64" (2 mm) balldriver. A 3/16" (5mm) thumbscrew locking mechanism is used for attaching the clamp to the Ø1/2" post. The center-to-center distance between the two posts is 1/2" (12.7 mm).
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C2A Swivel Coupler on ER Rod
- Provides 180° of Total Swing
- Lockable Design for Greater Rigidity
- Ø6 mm Precision-Ground Stainless Steel
The C2A swivel coupler enables the connection of cage assemblies at arbitrary angles. They are constructed from stainless steel, adhere to close tolerances, and provide an extremely rigid structure.
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- 180° of Total Swing at Each Pivot
- Lockable Design for Greater Rigidity
- Ø6 mm Precision-Ground Stainless Steel Rods
- 5/64" Hex Locking Screw for Each Pivot
These jointed cage assembly rods allow users to introduce angular or translational offsets into a 30 mm or 60 mm cage system. Each consists of two or three Ø6 mm cage assembly rods with one or two pivot joints, respectively. Each joint is capable of swinging 90° in either direction and can be locked using a 5/64" (2 mm) hex key.
The C3A and C4A jointed cage rods allow cage assemblies to be connected at a range of angles up to ±90° from the system normal. The C3A consists of two rods of equal length (1.85" each), while the C4A has one 1.85" long rod and one shorter, 0.52" long rod for setups with strict spatial requirements.
The C5A double-jointed cage rod features a 2.85" long central rod, with a pivot joint and a shorter, 0.52" long rod on each end. This allows two cage plates to be mounted parallel to but off-axis from one another, as shown in the image to the far right.
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- Build Rigid 3D Structures
- ER90C Provides Rigid "T" Connection for Cage Assembly
- ER90A and ER90L Maintain Perfect Rod Separation for Cage Assemblies
- Increases Structural Rigidity When Used with Inline Applications
Insert the ER90C right-angle rod between two ER rods to form a "T" connection point. To form a complete 90° cage assembly a ER90A or ER90L spacer rod should be used for 30 mm or 60 mm cage systems, respectively. The spacer rod is placed between two ER90C right-angle rods to maintain the proper center-to-center spacing of the cage system (see image at right). Alternatively, a 30 mm or 60 mm cage cube can be used to create the rigid right-angle connection.
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ERCPS Cage Plate Stops snap onto cage rods without any disassembly of the cage system.
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ERCPS Cage Rod Stops can mark the position of cage components.
- Marks the Position of Cage Components
- Flexure Clamping Mechanism
- Sold in Packs of Four
ERCPS Cage Plate Stops mark the position of a cage plate, allowing it to be reliably moved and repositioned in a cage system. These clamps are 0.14" (3.6 mm) thick and are compatible with our Ø6 mm cage rods for 30 mm and 60 mm cage systems. Utilizing a flexure design, the clamps are secured in place using a 0.05" (1.3 mm) hex key. They can be easily clamped onto the middle of a cage rod without removing other components.
30 mm and 60 mm Cage System Construction Rods