16 mm Cage System Components:

• Ø4.0 mm Cage Rods for 16 mm Cage System
• Cage Couplers and Adapters

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. Please see the Cage Overview tab for more details on this widely adopted construction standard.

Standard Assembly Rods

Our precision-ground cage assembly rods are basic building blocks used to construct optical systems. These rods are most commonly used as precision guides for our cage assembly plates and have a 4 mm diameter for 16 mm cage systems. Each rod has a removable 4-40 stud in each end, and all rods are designed to be stackable. An infinite array of systems can be assembled when used in conjunction with our cage plates and lens tubes. Please see the Construction tab for more information on building cage systems.

Cage Couplers and Adapters

The 16 mm cage rod adapters offered here enable the easy addition or removal of components from cage assemblies. The SRSCA cage adapter can be used to connect Ø4 mm SR rods to 4-40 internally threaded components.The S1A cage rod coupler provides a method of connecting rods at 90° angles.

Swivel Connector

The S3A swivel connector can be used to connect cage assemblies at arbitrary angles. These parts are made from stainless steel and provide an extremely rigid structure.

SRSCA 1D Construction
Click to Zoom

1D Construction

The SRSCA SR rod adapter allows for the end-to-end joining of two SR rods. It has an internal bore on one end that accepts Ø4 mm SR series rods. To join two rods, position the end of one rod inside the SRSCA, and lock it into place using the locking setscrew. Thread the other end of the SRSCA into the other rod (see photo at right).

3D Construction

These assembly rods are essential components when configuring cage systems in complex, multi-dimensional structures.

ER90C Right Angle Rod with
ER90L Spacer Rod

S3A Swivel Connectors
Click to Zoom

The S3A swivel connectors can be configured to any arbitrary angle before being locked into place (see photo at right).

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.

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.

ERSCA Adapters with ST1XY-S Mount and C4W Cage Cube
Click to Zoom

The ERSCA ER rod adapter is also useful for 3D construction. As shown in the image to the right, the ERSCA can be used to connect two internally-threaded cage components with ER rods. In the application shown to the left, cage rods are used 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.

As shown to the left, the threaded side of the ERSCA adapter is connected to the ST1XY-S translation mount. The cage rod slides into the other side of the adapter and is secured in place with the setscrew. Using the ERSCA adapters, components can easily be added to or removed from setups without causing misalignment.

Application Idea

The cage assembly components offered here can be used to couple 16 mm, 30 mm, and 60 mm cage systems. The parts used in the following setup are listed below:

Item #	Quantity	Image	Description
SRM05	1	Click to Zoom	16 mm Cage Rotation Mount
SR4 SR1	4 (each)	Click to Zoom	Cage Assembly Rod, Ø4 mm
S1A	4	Click to Zoom	Cage Rod Cross Coupler
SP03	1	Click to Zoom	16 mm Clear Aperture Cage Plate
SP05	1	Click to Zoom	30 mm to 16 mm Cage Adapter Plate
ER4	4	Click to Zoom	Cage Assembly Rod, Ø4 mm

An example of the standard cage
plate measurements determining
cage system compatibility.

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 to right). 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.