30 mm Cage System Iris Diaphragm

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


For 30 mm Cage Systems

Application Idea

CP20D Iris in a Cage System with a KCB1C Right-Angle Kinematic Mount and a CP33 Cage Plate Holding an SM1L10 Lens Tube

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Thorlabs’ 30 mm 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.

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The CP20D cage system iris is actuated using a button head lever. The aperture of the CP20D is adjustable from Ø0.8 mm to Ø20.0 mm.


  • One-Piece Iris for 30 mm Cage Systems
  • Continuously Variable Iris Diaphragm: Ø0.8 mm to Ø20.0 mm Aperture
  • Ultra-Thin Cage Plate Design: 0.28" (7.0 mm) Thickness
  • Black-Anodized Aluminum Housing Limits Reflection

This lever-actuated, continuously variable, cage-system-compatible iris diaphragm is designed to provide smooth operation over many thousands of cycles. This iris is mounted in an ultra-thin, cage-system-compatible plate that engages three cage rods with locking screws that accept a 5/64" (2.0 mm) hex key. The steel leaves within 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 the cage system. This large iris provides the maximum aperture available for use in a 30 mm cage system and is permanently installed in the cage plate.

Item # Cage System Standard Aperture Thickness
CP20D 30 mm Ø0.8 mm to Ø20.0 mm 0.28" (7.0 mm)

In addition to the 30 mm cage system iris sold on this page, we also offer a 60 mm Cage System Iris. Alternatively, our SM-Threaded Ring-Actuated Irises can also be utilized in a 30 mm cage system with the use of an SM1-threaded cage plate. However, the cage system iris featured on this page offers a larger aperture and thinner profile than the equivalent ring-actuated iris. For non-cage system use, we also offer Post-Mounted Irises, SM-Threaded Lever-Actuated Irises, and Unmounted Irises with no mounting holes.

Posted Comments:
adubra  (posted 2016-02-11 14:46:23.633)
Could you make it graded like SM1D12C? Thanks! Alf
besembeson  (posted 2016-03-03 11:47:48.0)
Response from Bweh at Thorlabs USA: Thanks for your suggestion. We will review this. In the mean time, a not so compact alternative will be the SM1D12C in a CP02 cage plate.
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30 mm Cage System Iris Diaphragm

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
CP20D Support Documentation
CP20D30 mm Cage System Iris Diaphragm (Ø0.8 - Ø20 mm)