Ø1" Wedge Prism Mounting Shims

  • Shims Aid in Mounting Wedge Prisms with Retaining Rings
  • Wedge Angles Complement Thorlabs' Wedge Prisms
  • Slots for Compatibility with Spanner Wrenches


18° 9' Wedge Angle


7° 41' Wedge Angle


11° 22' Wedge Angle


3° 53' Wedge Angle

Application Idea

PS814 Prism with 18° 9' Wedge Mounted in a PRM1 Rotation Mount Using an SM1W189 Shim and SM1RR Retaining Ring

Related Items

Please Wait
Mounting Shim
Click for Details

Four Wedge Angles are Available that Match our Wedged Prisms
Mounting Shim
Click to Enlarge
The left image shows one shim being used to mount a wedge prism, while the right image shows two shims being used to mount a filter at an angle to reduce back reflections. An SM1L30C slotted lens tube is used to help confirm the proper fit.


  • Mount Ø1" Wedge Prisms in SM1-Threaded Lens Tubes or Rotation Mounts
  • Four Wedge Angles Available to Match Our Wedge Prisms:
    • 3° 53' for PS810 Wedge Prisms
    • 7° 41' for PS811 Wedge Prisms
    • 11° 22' for PS812 Wedge Prisms
    • 18° 9' for PS814 Wedge Prisms
  • Mount Planar Optics at an Angle Within an SM1 Lens Tube
  • Spanner Wrench Slots for Easy Positioning
Mounting Shim
Click to Enlarge

Each Shim Includes Engraved Witness Lines and Spanner Wrench Slots

Thorlabs' Wedge Prism Mounting Shims are designed to provide a flat, uninterrupted mounting surface between a Ø1" wedge prism and one of our retaining rings. Normally a retaining ring will only contact a small portion of the wedged optic, potentially causing incorrect seating or unexpected shifts. These shims have a wedge on one side to ensure that the wedged optic is properly mounted within an SM1 lens tube or rotation mount when secured with a retaining ring. The shim does not impinge upon the clear aperture of our wedge prisms, as shown in the drawings to the right. Four shims are available, each with a wedge angle that matches one of our wedge prisms: 3° 53', 7° 41', 11° 22', or 18° 9'.

Each mounting shim has two slots for compatibility with our SPW602 and SPW606 Spanner Wrenches. When aligning these rings within an SM1 lens tube or mount, we recommend holding the mount or lens tube vertically while using a spanner wrench to roughly align the shim's wedge against the optic. When roughly aligned, tighten the retaining ring down until it binds and then slightly loosen it. Alternate between tightening and loosening the retaining ring until the shim and optic are well aligned with one another. Then secure the optic and shim with the retaining ring.

In addition, these shims can be used in pairs to mount Ø1" planar optics, such as filters or windows, at a predefined angle within an SM1 lens tube to reduce back reflections. Simply place the filter between two shims with the same wedge angle and follow the mounting instructions recommended above. When mounting planar optics with this method the optic thickness is critical. The maximum optic thickness is 6 mm when using two SM1W353 mounting shims, or 1 mm when using two SM1W741 or SM1W1122 mounting shims. Due to its large wedge angle, we do not recommend mounting planar filters with the SM1W189. Regardless of the optic thickness, the optic diameter is not large enough, which creates a gap that can allow unfiltered light through.

Posted Comments:
No Comments Posted
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
SM1W353 Support Documentation
SM1W353Wedge Prism Mounting Shim, 3° 53' Wedge Angle
SM1W741 Support Documentation
SM1W741Wedge Prism Mounting Shim, 7° 41' Wedge Angle
SM1W1122 Support Documentation
SM1W1122Wedge Prism Mounting Shim, 11° 22' Wedge Angle
SM1W189 Support Documentation
SM1W189Wedge Prism Mounting Shim, 18° 9' Wedge Angle