SM1-Threaded Irises and Shutter

• SM1 (1.035"-40) Threaded on Both Sides
• Lever-Controlled, Max Aperture up to Ø25.0 mm
• Black Spring Steel and Stainless Steel Leaf Versions Available
• Zero-Aperture Version Available

These lever-actuated iris diaphragms are SM1-threaded for compatibility with our Ø1" lens tubes and other SM1-threaded accessories. The housing of each iris features an engraved arrow which indicates the direction the lever must be moved to close the aperture.

Our SM1D12 and SM1D25 iris diaphragms offer maximum apertures of Ø12.0 mm and Ø25.0 mm, respectively. The SM1D12 iris has internal SM1 threading on one side and external SM1 threading on the other side (see drawing to the right). Our SM1D25 iris has internal SM1 (1.035"-40) threading on both sides of the housing (see drawing to the right) as well as a full Ø25.0 mm aperture.

The SM1D12SS iris features stainless steel leaves for use in higher power applications than traditional spring steel irises. The aperture can be continuously varied from the maximum aperture diameter of 12.0 mm to a minimum aperture diameter of 1.0 mm. The lever-activated diaphragm is designed to provide smooth operation for several thousand cycles. An engraved arrow indicates the position the lever must be in to close the iris. We use a magnetic stainless steel in this iris. Due to its hardness, it offers a longer lifetime than typical non-magnetic stainless steel. This iris also has internal SM1 (1.035"-40) threading on one side and external SM1 threading on the other.

The SM1D12SZ zero-aperture iris diaphragm is continuously variable from the maximum aperture diameter of 12.0 mm to completely closed (zero aperture). Our zero-aperture design achieves a completely closed aperture by utilizing two sets of steel leaves mounted in two adjacent planes. The iris leaves are made from black spring steel and the lever-activated diaphragm is designed to provide smooth operation for several thousand cycles. These irises feature an engraved arrow on the housing which indicates the direction the lever must be moved to close the aperture. As the aperture gets smaller, it also becomes slightly elliptical due to the design of the iris. This housing has internal SM1 (1.035"-40) threading on one side and external SM1 threading on the other.

The setscrews on the housings of these irises retain the internal aperture mechanism within the housing and should not be adjusted.

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SM1D12 Mechanical Diagram

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SM1D25 Mechanical Diagram

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SM1D12SS Mechanical Diagram

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SM1D12SZ Mechanical Diagram

• SM1 (1.035"-40) Threaded on Both Sides
• Ring-Controlled, Ø12.0 mm Max Aperture
• Graduated and Zero-Aperture Versions Available
• Black Spring Steel Leaves
• Locking Setscrew with 0.05" (1.3 mm) Hex

These ring-actuated iris diaphragms are SM1-threaded for compatibility with our Ø1" lens tubes, 30 mm cage systems, and other SM1-threaded accessories. One side of the iris is externally threaded, while the other is internally threaded. This allows for easy insertion into existing systems using standard lens tube components. The design of these irises is well suited for integration into a cage system with minimal alignment. To precisely optimize the centration of the iris hole to the optical axis of the cage system, Thorlabs recommends mounting the iris on an XY Translation Mount.

The SM1D12D is our standard SM1-threaded, ring-actuated iris with a Ø12.0 mm maximum aperture. Thorlabs also offers the CP20D Iris for 30 mm Cage Systems which is integrated into a cage plate for direct mounting to cage rods.

The SM1D12C Graduated Iris offers an additional laser-engraved scale, which indicates the actual diameter of the iris in millimeters to within ±0.5 mm. In applications where the iris cannot be easily viewed, such as the lens tube configuration shown to the lower right, this engraved scale greatly simplifies the process of optimizing the iris diameter.

The SM1D12CZ Zero-Aperture Graduated Iris provides the added benefit of being able to close completely. Our zero-aperture design achieves a completely closed aperture by utilizing two sets of steel leaves mounted in two adjacent planes. When the ring is in the closed position, the iris aperture is completely closed (zero aperture), unlike a standard iris, which has a non-zero diameter aperture when in the minimum position. Please note that as the aperture gets smaller, it also becomes slightly elliptical due to the design of the iris.

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SM1D12D Mechanical Diagram

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SM1D12C Mechanical Diagram

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SM1D12CZ Mechanical Diagram

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SM1D12C Shown Between Two SM1 Lens Tubes

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SM1SH1 Manual Beam Shutter Mounted in a CP33 Cage Plate

• Open/Close Lever Positions
• Clear Aperture when Open: Ø7.2 mm
• Internal and External SM1 Threads
• Shutter is Completely Light-Tight

The SM1SH1 Manual Beam Shutter provides a convenient, labeled switch for propagating a beam through an optical assembly. The lever-actuated shutter is firmly held in position with a precision detent mechanism at both the opened and closed locations. The shutter has a Ø0.29" (Ø7.2 mm) clear aperture when open. 

This aluminum shutter incorporates internal SM1 threads (1.035"-30) on one side and external SM1 threads on the other, making it ideal for use with our lens tube systems. The internally threaded side of the shutter has a metal plate enclosing the shutter mechanism, while the externally threaded side has exposed Delrin. It is recommended to orient the metal plate towards the incoming beam.

Please note that we do not recommend using the SM1SH1 shutter within a 30 mm cage system, as the cage rods will interfere with the shutter's lever actuator. If it is used in a cage system, we recommend placing the shutter at the end of a branch, as shown in the photo above.