Fast-Change Lens Tube Filter Holders

  • Quickly and Easily Exchange Filters Without Disassembly
  • Features Internal and External SM1 Threads
  • Lock Nut Allows for Precise Orientation Within a Setup



Lens Tube Filter Holder for Filters ≤3.5 mm Thick


Extra Carriage for Filters 3.5 - 6.3 mm Thick


Extra Slotted Lens Tube with Included Locking Ring

Application Idea

SM1QP Lens Tube Filter
Holder Threaded onto a
PDA50B2 Detector

Pre-Load Multiple Filter Carriages for Fast and Easy Filter Exchange


Extra Carriage for Filters ≤3.5 mm Thick


Lens Tube Filter Holder for Filters 3.5 mm to 6.3 mm Thick

Related Items

Please Wait
Lens Tube Filter Holder in Lens Tube System
Click to Enlarge

Using an SM1QP Filter Holder, filters can be swapped into a lens tube system without disassembly.
Lens Tube Filter Holder Top View
Click to Enlarge

The Filter Carriages are laser engraved to indicate how to install the filter.


  • Exchange Filters in an Optomechanical Setup Without Disassembly
  • Accept Ø1" or Ø25 mm Filters
    • SM1QU Holds Unmounted Filters (0 - 3.5 mm Thick)
    • SM1QP Holds Mounted Filters (3.5 - 6.3 mm Thick)
  • Extra Filter Carriages and Slotted Lens Tube Sold Separately
  • Filter Secured via Spring-Loaded Clamp
  • Stackable SM1 Lens Tube Construction
  • Included Lock Nut Allows the User to Select a Specific Rotational Orientation

Thorlabs' Fast-Change Lens Tube Filter Holders allow Ø1" and Ø25 mm filters to be quickly exchanged within an experimental setup without disassembling connected lens tubes. These holders are comprised of two pieces: a filter carriage and a slotted lens tube, which are magnetically coupled to each other, enabling fast insertion and removal.

To install a filter in the carriage, first separate the filter carriage from the slotted lens tube by gripping the recessed grooves on either side of the carriage and pulling gently. Slide the top-located stainless steel knob in the direction of the engraved arrows (as shown in the photo above). This opens the spring-loaded clamp located on the underside of the carriage. Insert the filter, pressing it firmly against the underside of the holder, and release the knob. See the animation below for details.

Filter Holder Installation Procedure

There are two preconfigured filter holder options: the SM1QU accepts an unmounted filter with a thickness ≤ 3.5 mm, while the SM1QP accepts a mounted filter with a thickness from 3.5 mm to 6.3 mm. The filter holders are 1.02" long with a 1.31" (33.3 mm) outer diameter and a Ø21 mm (Ø0.83") clear aperture. Please note that the clear aperture of the assembly may be further restricted by the filter.

Extra filter carriages are available separately. The SM1QTU carriage (included in the SM1QU) holds an unmounted filter with a thickness ≤ 3.5 mm, while the SM1QT carriage (included in the SM1QP) holds a mounted filter with a thickness from 3.5 mm to 6.3 mm.

The SM1QB extra slotted lens tube, included in both the SM1QU and SM1QP filter holders, is also available separately. The slotted lens tube can accept either filter carriage described above. It features internal SM1 (1.035"-40) threading on one side and external SM1 threading on the other, making it compatible with all of our SM1-threaded components. One included lock nut (item # SM1NT) allows the user to set the rotational orientation of the filter holder at any angle.

We also offer a variety of removable filter holders for cage systems, as well as SM-Threaded Adapters for Square Filters.

Posted Comments:
Anqi Wu  (posted 2020-09-16 01:16:49.367)
I would like to know whether you have a similar fast change filter holder like SM1QU for C-mount threads (external and internal on each side) that is more popular for the camera and lens. I need to order it soon. Thanks! Anqi Wu
YLohia  (posted 2020-09-16 09:58:21.0)
Hello Anqi, thank you for contacting Thorlabs. Unfortunately, we do not currently offer a C-mount version of this at the moment. That being said, your C-mount system can be adapted to the SM1 system using the SM1A9 or SM1A10 adapters (depending on which way you intend to convert your threads).
sbilek  (posted 2017-03-28 03:55:05.363)
do you have c-mount version of this product? but it should be able to hold 1 inch filters? I would be great for using in front of a c-mount camera.
tfrisch  (posted 2017-03-31 09:35:35.0)
Hello, thank you for contacting Thorlabs. SM1A9 has an external C-Mount Thread and internal SM1 which can be used to mount Fast Change Lens Tube Filter Holders on a C-Mount Camera. As a word of caution, placing a filter in between the lens and sensor will greatly increase the image distance. I will reach out to you directly about your application, but this should not be used to place a filter between a camera and C-mount lens.
ludoangot  (posted 2015-01-22 16:30:51.46)
This drop-in filter is an excellent idea. I would like to use it to swap ND filters, but your ND filters are either unmounted or mounted in an SM1 compatible tube with external thread. None of these options seem to allow me to fit ND filters in your Fast-Change Lens Tube Filter Holder. What solution can you propose? Could you consider offering ND filter in the same 1" dia. mount as some of your other filters; or offer the empty filter mount so that one can assemble the ND oneself?
cdaly  (posted 2015-01-22 04:22:43.0)
Response from Chris at Thorlabs: We do offer 1" unmounted ND filters, but they are too thin to be used with the SM1QT mount. They can however be used with the CFH2 removable filter holder, which also has internal SM1 threading making it compatible with the same types of mounts.
b.povazay  (posted 2014-08-19 18:51:52.62)
Does the slot mount also fix the filter carriage such that the intalled filters stay inside the mount even when rotating the detector?
cdaly  (posted 2014-08-21 04:26:58.0)
Response from Chris at Thorlabs: Generally the filter mount would be held so that the filter would be removed from the top, there is enough thread to ensure that by using the locking nut this should be possible in most cases. however if you are constrained to having this piece rotate, the magnets which hold the filter holder in the tube will have sufficient force to hold the item even when upside down, provided it is a light weight optic such as one of our bandpass filters.
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Fast-Change Lens Tube Filter Holders

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
SM1QU Support Documentation
SM1QUCustomer Inspired! Fast-Change, SM1 Lens Tube Filter Holder for Filters ≤3.5 mm Thick
SM1QP Support Documentation
SM1QPFast-Change, SM1 Lens Tube Filter Holder for Filters 3.5 - 6.3 mm Thick
SM1QTU Support Documentation
SM1QTUCustomer Inspired! Extra Filter Carriage for Filters ≤3.5 mm Thick
SM1QT Support Documentation
SM1QTExtra Filter Carriage for Filters 3.5 - 6.3 mm Thick
SM1QB Support Documentation
SM1QBExtra Slotted, SM1 Lens Tube for Fast-Change Lens Tube Filter Holders