Dovetail Optical Rails

  • Dovetail Rails Designed for Our Snap-On Carriers
  • Stock Lengths from 3" to 24"
    (Metric Lengths: 75 - 600 mm)




Metric Indicator
Next to Counterbore

Laser-Engraved Scale

Counterbored 1/4" (M6)
Slots and Holes

Related Items

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RLA Dovetail Rail Accessories
Dovetail Rails Dovetail Rail Carriers Dovetail Rail Carrier Positioners Dovetail Rail Mounting Dovetail Rails
Rails Rail Carriers Rail Carrier
Mounting Cage Mounting
Dovetail Rail 

Click to Enlarge
View Imperial Product List
Item #QtyDescription
Imperial Product List
RC11Dovetail Rail Carrier, 1.00" x 1.00" (25.4 mm x 25.4 mm), 1/4" (M6) Counterbore
RC31Rail Carrier, Perpendicular Dovetail
DT1211/2" Dovetail Translation Stage, 8-32 Taps
RLA18001Dovetail Optical Rail, 18", Imperial
SD111/4" (M6) to #8 (M4) Counterbore Adapter Ring, 10 Pack
View Metric Product List
Item #QtyDescription
Metric Product List
RC11Dovetail Rail Carrier, 1.00" x 1.00" (25.4 mm x 25.4 mm), 1/4" (M6) Counterbore
RC31Rail Carrier, Perpendicular Dovetail
DT12/M112.7 mm Dovetail Translation Stage, M4 Taps
RLA450/M1Dovetail Optical Rail, 450 mm, Metric
SD111/4" (M6) to #8 (M4) Counterbore Adapter Ring, 10 Pack
RC1 and RC3 rail carriers and a DT12 miniature dovetail stage mounted on a dovetail rail.


  • Dovetail Design Accommodates Our Snap-On Rail Carriers
  • Compact Profile: 0.38" x 0.75" (9.5 mm x 19.1 mm)
  • Stock Lengths Range from 3" to 24" (Metric Lengths: 75 - 600 mm)
  • Laser-Engraved Scale for Precise Construction
  • Ends 8-32 (M4) Tapped

Thorlabs' RLA Optical Rails are our smallest option for building stable, rigid mechanical assemblies. They are machined out of solid aluminum and have a dovetail mounting surface that accommodates our snap-on rail carriers. Objects are easily slid along this dovetail before being secured. These rails measure only 0.75" (19.1 mm) wide and are available from stock in lengths ranging from 3" - 24" (metric lengths: 75 - 600 mm).

These dovetail rails offer numerous 1/4" (M6) counterbored holes for mounting flexibility. The end of each rail is 8-32 (M4) tapped for vertical mounting. Rails 12" (300 mm) and longer offer mounting slots to provide additional mounting options. As shown in the image at the top of the page, the rails are laser engraved with graduations every 1.0 mm and labels every 10.0 mm for precise placement of optomechanical hardware.

Thorlabs' product family for RLA dovetail rails includes our snap-on carriers as well as mounting accessories. Together with spacer sets and table clamps that allow the rails to be mounted both horizontally and vertically, these tools provide a complete family of rigid, versatile buliding blocks suited for virtually any optomechanical setup.

Posted Comments:
Paul J  (posted 2023-10-04 15:52:06.36)
Hi, on the webpage diagram, the mounting hole is shown to be 4.4 mm from the bottom of the rail, but it appears to be 5.08 mm high in the CAD file for the RLA600/M. Could you confirm the value as it is important for our design? Thank you for your assistance.
cdolbashian  (posted 2023-10-19 10:10:38.0)
Thank you for for finding this discrepancy and notifying us. The correct measurement should be 5.08mm, measured from the bottom of the rail to the mounting hole.
Matthias Müller  (posted 2021-05-17 11:05:57.95)
Hi, could you tell me the accuracy/bow/warp of a rail based on a certain length? Thank you.
YLohia  (posted 2021-05-20 11:35:35.0)
Hello, thank you for contacting Thorlabs. While we don't spec the accuracy/bow/warp of these rails, we do spec their straightness (+/- 0.001"). This spec is valid for all the stock lengths that we offer (300 mm to 2400 mm).
Drew Shields  (posted 2020-10-18 01:56:34.857)
Hi, I am wondering about using three of these rails to make a large (450mm square) x/y measuring grid. So I'd have two parallel rails for one axis, and a third rail, attached on each end to a rail carrier, sliding along those for the other axis. My question is if you anticipate this working well, sliding without resistance, and overall easy to use. Also wondering if others have tried this in the past.
llamb  (posted 2020-10-22 02:43:00.0)
Thank you for contacting Thorlabs. Somewhat similar setups have been constructed in the past, so as long as both sliding rail carriers are given an even load to avoid more friction in one rail than the other, I do not see any major issues with your arrangement.
c  (posted 2015-02-11 10:21:47.5)
Do you have any advice for mounting the rail straight onto an optical table? That is to match the axis of the rail with the line of holes of the optical table since there is a little play in the orientation as you screw the rail onto the table.
cdaly  (posted 2015-02-12 02:01:28.0)
Response from Chris at Thorlabs: There's no specified way to ensure it is aligned, but what I have found is useful when using these is to put a screw through a mounting hole at either end and thread them down into the table somewhat, deep enough that the head of the screw is in the counterbore but loose enough that the rail is still able to move about with the small amount of play that exists. Then you can apply a small pressure to one side of the rail so that the rail is in contact with both screws. Tighten them down while doing this and this should help aligned the rail parallel to the grid of holes, or at least more so than just mounting it to the table without doing so.
LNicoletti  (posted 2014-04-14 18:29:36.723)
Good morning, I have a question on product RLA600/M. is it possible to attach two of them in order to make a 1200mm length? thank you in advance Luisa Nicoletti
jlow  (posted 2014-04-17 10:43:59.0)
Response from Jeremy at Thorlabs: We do not currently have a rail joiner for this. There are tapped holes on both ends of this and there's not really a good way to ensure good alignment when two rails tighten against each other. You can bolt one piece to the table and then adjust the position of the 2nd one until a rail carrier slides somewhat smoothly between the two. We can also offer the rails in longer lengths but without features like slots, holes, and anodization.
gyg2101  (posted 2013-09-04 11:01:06.24)
Hi, I would like to automate a system based on your dovetail rails. Is there any way to "motorize" the rail carriers? I would need a couple of inches of computer-controlled motion. guy
jlow  (posted 2013-09-10 15:32:00.0)
Response from Jeremy at Thorlabs: Unfortunately we do not have an easy way to motorized the dovetail optical rail carrier at this moment. You could possibly put a motorized stage on top of the rail, but that better on the 66mm rail than the RLA dovetail rails. I will get in contact with you directly to discuss about your application.
tcohen  (posted 2012-02-22 17:15:00.0)
Response from Tim at Thorlabs to Jiabin: Thank you for your interest in our dovetail optical rails. Unfortunately, we are currently unable to provide longer lengths than 600mm for this series. As an alternative, we are able to offer the XE25-CUSTRAIL/M up to 2000mm. We have contacted you with more information.
jiabin.tuo  (posted 2012-02-20 11:54:52.0)
I would like to buy a Dovetail Optical Rail for my test, I am wondering can I custom the length to 2000mm? Thank you for your time. Regards, Jiabin
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Dovetail Optical Rails

Dovetail Rail Cross Section
Click to Enlarge
A cross-sectional view of the dovetail rails.
  • Our Smallest Optical Rails for Compact Construction
  • 8-32 (M4 x 0.7) Tapped Holes on Both Ends
  • Compatible With Our Snap-On Rail Carriers
  • Engraved Scale for Precision Alignment of Optical Elements

Our Dovetail Optical Rails are designed for the construction of stable one-dimensional assemblies. Objects can be secured in place anywhere along the dovetail mounting surface. The rail ends are tapped with 8-32 (M4 x 0.7) holes for compatibility with standard optomechanics.

These rails are offered from stock in lengths ranging from 3" to 24" (75 mm to 600 mm). They have engraved graduations every 1.0 mm and labels every 10.0 mm. These rails can easily be clamped to an optical table or breadboard using our CL6 table clamps, and are extremely compact.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
RLA0300 Support Documentation
RLA0300Dovetail Optical Rail, 3", Imperial
RLA0600 Support Documentation
RLA0600Dovetail Optical Rail, 6", Imperial
RLA1200 Support Documentation
RLA1200Dovetail Optical Rail, 12", Imperial
RLA1800 Support Documentation
RLA1800Dovetail Optical Rail, 18", Imperial
RLA2400 Support Documentation
RLA2400Dovetail Optical Rail, 24", Imperial
+1 Qty Docs Part Number - Metric Price Available
RLA075/M Support Documentation
RLA075/MDovetail Optical Rail, 75 mm, Metric
RLA150/M Support Documentation
RLA150/MDovetail Optical Rail, 150 mm, Metric
RLA300/M Support Documentation
RLA300/MDovetail Optical Rail, 300 mm, Metric
RLA450/M Support Documentation
RLA450/MDovetail Optical Rail, 450 mm, Metric
RLA600/M Support Documentation
RLA600/MDovetail Optical Rail, 600 mm, Metric