30 mm Cage Cube Cover Plates

  • Compatible with 30 mm Cage Cubes
  • Light-Tight Cage Accessories



Application Idea

B1C Mounted on a
30 mm Cage Cube

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30 mm Cage Cubes and Accessories
30 mm Cage Cubes Optic Mounts Platforms Rotating Platforms Cage Plates
Cage Cubes Optic Mounts Platforms Rotating Platforms Cover Plates


  • 30 mm Cage Cube-Compatible Platforms
  • Blank or SM1-Threaded Plate Options Available
  • Light-Tight Cage Accessories

The 30 mm cage cube plates offered here are ideal platforms for building light-tight cage cube systems. Our B1C(/M) and B2C Cage Cube Plates are compatible with Thorlabs' 30 mm Cage Cubes and accessories. The B1C Blank Plate can be used to create a light-tight environment within the C4W or C6WR cage cubes. The B2C SM1-Threaded Plate provides an additional SM1-threaded port on the top or bottom of our C4W or C6WR cage cubes.

Thorlabs offers a wide and growing complement of accessories for 30 mm cage cubes, including optic mounts, platforms, and rotating platforms. These tools provide a complete family of versatile building blocks suited for virtually any 30 mm cage cube optomechanical setup.

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
Replacement Setscrews Replacement setscrews are offered for our 16 mm (SS4B013, SS4B025, and SS4B038) and 30 mm (SS4MS5 and SS4MS4) cage systems products.
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.

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Blank Cover Plate

  • Cover Plate for C4W and C6WR Cage Cubes
  • Four #4 Counterbores that Align with Cage Cube; Includes Four 4-40 Cap Screws
  • 8-32 (M4) Post Mounting Tap

The B1C(/M) is a blank cover plate that is designed for the C4W and C6WR Cage Cubes. The top has a rubber o-ring that creates a light-tight seal, while the bottom, pictured to the left, has a centered 8-32 (M4) tapped hole for mounting purposes. The B1C(/M) ships with four 4-40 cap screws (3/32" hex).

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
B1C Support Documentation
B1CBlank Cover Plate
+1 Qty Docs Part Number - Metric Price Available
B1C/M Support Documentation
B1C/MBlank Cover Plate, Metric

SM1-Threaded Cover Plate

  • Cover Plate for C4W and C6WR Cage Cubes
  • Four #4 Counterbores that Align with Cage Cube; Includes Four 4-40 Cap Screws
  • Internal SM1 (1.035"-40) Threading

The B2C is an internally SM1-threaded (1.035"-40) cover plate, which allows components in SM1-threaded mounts to mate to the cube. This plate is designed for use with our C4W and C6WR Cage Cubes. The B2C(/M) ships with four 4-40 cap screws (3/32" hex).

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
B2C Support Documentation
B2CSM1-Threaded Cover Plate