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Cage System Iris Diaphragms

  • 30 mm or 60 mm Cage System Compatible Irises
  • Continuously Variable Lever-Actuated Aperture
  • Button Head Lever Allows Actuation while Iris is Installed


For 30 mm
Cage Systems


For 60 mm Cage Systems

Application Idea

CP20S Iris in a Cage System with a KCB1C Right-Angle Kinematic Mount and a CP02 Cage Plate Holding an SM1L10 Lens Tube

Related Items

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Item # Cage System Standard Aperture Thickness
CP20S 30 mm Ø0.8 mm to Ø20.0 mm 0.25" (6.3 mm)
LCP50S 60 mm Ø2.0 mm to Ø50.0 mm 0.33" (8.3 mm)

Thorlabs’ Cage System Irises are designed for use within a cage system. The button head lever on these irises clears the fourth cage rod, allowing for aperture adjustments within the cage system.

Click to Enlarge

The cage system irises are actuated using a button head lever, wihch is accessible within the cage system. Here, the CP20S is shown with its iris in two positions.


  • One-Piece Iris for 30 mm or 60 mm Cage System
  • Continuously Variable Iris Diaphragms
    • CP20S: Ø0.8 mm to Ø20.0 mm Aperture
    • LCP50S: Ø2.0 mm to Ø50.0 mm Aperture
  • Ultra-Thin Cage Plate Design
    • CP20S: 0.25" (6.3 mm) Thick
    • LCP50S: 0.33" (8.3 mm) Thick
  • Black-Anodized Aluminum Housing Limits Reflection

These lever-actuated, continuously variable, cage-system-compatible iris diaphragms are designed to provide smooth operation over many thousands of cycles. These irises are mounted in ultra-thin, cage-system-compatible plates that engage three cage rods with a flexure mechanism that tightens using a 5/64" (2 mm) hex. The steel leaves that comprise the iris are actuated by a button head lever that clears the fourth cage rod, as shown in the picture to the right, allowing for operation within a cage system. These large-aperture irises provide the maximum aperture available for use within a cage system and are permanently installed in the cage plates.

In addition to the cage system irises sold on this page, our SM-Threaded Ring-Actuated Irises can also be utilized in a cage system with the use of an SM-threaded cage plate. However, the cage system irises featured on this page offer larger apertures and thinner profiles than the ring-actuated irises. For non-cage system use, we also offer Post-Mountable Irises, SM-Threaded Lever-Actuated Irises, and Unmounted Irises with no mounting holes. Please see the selection guide above for a link to the full web presentations for these other options.

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Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
CP20S Support Documentation
CP20SCustomer Inspired! 30 mm Cage System Iris, Ø20.0 mm Maximum Aperture
LCP50S Support Documentation
LCP50SCustomer Inspired! 60 mm Cage System Iris, Ø50.0 mm Maximum Aperture
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