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Ø1" Pillar Post Mounts

  • Mount Ø1" (Ø25 mm) Pillar Post Extensions
  • Height and Rotational Adjustments
  • Flexure Clamping Mechanisms Provide High Clamping Force



BA2F Mounting a Ø1" Post
(Post not Included)

RB2 Mounting a Ø1" Post
(Post not Included)

POLARIS-CA1 Mounting a
Polaris Ø1" Monolithic Optic Mount
(Mount and Mirror Not Included)


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Thorlabs' Ø1" Post Mounts allow Ø1" (Ø25 mm) Pillar Posts to be secured to an optical table at various heights and angles of rotation. They provide mounting flexibility while remaining stable and secure. Additionally, the BA2F can be used to mount Ø1/2" post holders.

In addition to the post mounts offered here, we also carry Ø1" post holders that mount to an optical table using a clamping fork and offer a larger post height adjustment range.

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Polaris® Non-Bridging Clamping Arm

Click to Enlarge
Click for POLARIS-CA1/M Holding Torque Results*
The Polaris clamping fork design has undergone extensive testing to ensure high-quality performance. See the full presentation for more details.

*It is important to note that the 1/4"-20 and M6 x 1.0 clamping torque values have been adjusted to provide the same clamping post and table forces. Also note that the maximum recommended tightening torque for an 18-8 stainless steel screw is 75.2 in-lbs for a ¼-20 screw and 8.8 N-m for an M6 x 1.0 screw. Higher mounting torques can cause the screw to fail.
Click to Enlarge

Side-Located 1/4"-20 (M6) Screw Actuates Clamping Bore
  • 3-Point Contact Bore with Flexure Clamping Mechanism for Ø1" or Ø25 mm Post Mounting
  • Three Options Available:
    • POLARIS-CA1: Ø1" (Ø25.4 mm) Bore and 1/4"-20 Screw
    • POLARIS-CA1/M: Ø1" (Ø25.4 mm) Bore and M6 x 1.0 Screw
    • POLARIS-CA25/M: Ø25.0 mm (Ø0.98") Bore and M6 x 1.0 Screw
  • 0.60" (15.2 mm) Deep Mounting Bore for Height Adjustments and 360° Rotation
  • Heat-Treated, Stress-Relieved Stainless Steel Provides Large Clamping Force
  • Flippable Design Supports Left- and Right-Handed Orientations
    (See Image Below Right)
  • High Stability Ideal for Use with Our Fixed and Kinematic Polaris Mirror Mounts
  • Vacuum Compatible to 10-9 Torr at 25 °C with Proper Bake Out
  • ±0.001" (±0.02 mm) Surface Flatness
  • 1/4"-20 or M6 x 1.0 Clamping Screw

The Polaris Clamping Arm is the ideal solution for stably mounting any Ø1" or Ø25 mm post. Each clamping arm, which is constructed from heat-treated, stress-relieved stainless steel, provides extremely high holding forces with minimal torquing of the mounting screws.

The POLARIS-CA1 and POLARIS-CA1/M are designed to hold a Ø1" post, such as our fixed Polaris mount, while the POLARIS-CA25/M is designed to hold a Ø25 mm post or Ø1/2" post holder using a flexure clamping mechanism. The POLARIS-CA1 and POLARIS-CA1/M are not compatible with Ø25 mm posts; the bore diameter is too large and will not contact the post when clamping.

The side-located clamping mechanism, as shown in the photo to the above left, is actuated using a 1/4"-20 cap screw for the POLARIS-CA1 or an M6 x 1.0 cap screw for the POLARIS-CA1/M and POLARIS-CA25/M. Because the side-located clamp and mounting slot are tightened separately, the user can set the position of the fork and adjust the rotational alignment independently. The clamping arm has a compact 3.33" x 1.60" (84.5 mm x 40.6 mm) footprint for tight laser cavity setups, with a thickness of 0.60" (15.2 mm) for increased stability. A 1.30" (33.0 mm) long clearance slot allows for a variety of mounting solutions using a 1/4"-20 or M6 cap screw and washer. 

Both the imperial and metric clamping arm have been tested for holding strength. Based on the test results, recommended torques have been determined for both the flexure clamp and for tightening the slot to the table. The scales for these measurements, as seen in the figure above, are not direct conversions due to an efficiency difference between 1/4"-20 and M6 x 1.0 screws. The efficiency of M6 x 1.0 screws is about 5% less than that of 1/4"-20 screws due to differences in diameter and pitch. For optimal performance we recommend tightening this screw of the POLARIS-CA1 with 15 to 25 in-lb of torque and the screw of the POLARIS-CA1/M and POLARIS-CA25/M with 1.75 to 3 N•m of torque. When mounting the clamping arm to the platform we recommend using 40 to 65 in-lb of torque for the POLARIS-CA1 and 4.75 to 7 N•m of torque for the POLARIS-CA1/M and POLARIS-CA25/M. For best results, use the maximum recommended torques from each range. These torque values can be dialed in using a torque driver.

The flat, non-bridging (see drawing below) top and bottom allow the clamping arm to be used on either side depending on the needs of the application. This allows optical components to be placed in near contact to one another while minimizing the footprint, as shown in the image to the bottom right. A relief cut is included around the top and bottom slot; this protects the ±0.001" (±0.02 mm) flat surface that contacts the optical table from any marring due to the screw and washer. Minimizing damage to this surface of the fork allows for more stable mounting of components using the clamping arm.

Note: The POLARIS-CA1 requires a 3/16" hex key and the POLARIS-CA1/M and POLARIS-CA25/M requires a 5 mm hex key.

Click to Enlarge

The Top and Bottom of the Fork can be Used for Mounting, Minimizing the Overall Footprint and Distance Between Components

Non-Bridging Design

Industry-standard clamping forks are designed with a bridge, as shown in the below diagram, for clamping to pedestal style posts or post holders. This design will slightly damage the laser platform during each use by pulling up the part of the platform located under the bridge. The Polaris clamping arm is designed with a flat top and bottom to eliminate this problem.

Industry Standard Clamping Fork Test Data
Click to Enlarge

A Bridge is Created When an Industry-Standard Clamping Fork is Used with a Pedestal Post
Polaris Clamping Arm Test Data
Click to Enlarge

The POLARIS-CA1 Eliminates the Bridge Created by an Industry-Standard Clamping Fork
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
POLARIS-CA1 Support Documentation
POLARIS-CA1Flexure Clamping Arm for Ø1" Posts, Non-Bridging, Stainless Steel, 1/4"-20 Clamping Screw
+1 Qty Docs Part Number - Metric Price Available
POLARIS-CA1/M Support Documentation
POLARIS-CA1/MFlexure Clamping Arm for Ø1" Posts, Non-Bridging, Stainless Steel, M6 Clamping Screw
POLARIS-CA25/M Support Documentation
POLARIS-CA25/MFlexure Clamping Arm for Ø25 mm Posts, Non-Bridging, Stainless Steel, M6 Clamping Screw

Ø1" Pillar Post Mount

RB2 Mounting a Ø1
Click to Enlarge
Deep Base Allows Height Adjustment
  • RB2 Base Allows Post Extensions to be Used as a Variable Height Mounting Structure
  • Hollow Base Allows Post Extension to Pass Through for 0.5" of Height Adjustability
  • Convenient Vertically Accessed Locking Screw

The RB2(/M) pillar post base mounts Ø1" (25 mm) optical posts at a variable height (shown to the right). The hollow base allows the post to pass through, allowing 0.5" of post height adjustment. Translation is locked via a top-located clamping screw.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
RB2 Support Documentation
RB2Adjustable Height Post Base for Ø1" RS Series Post Extensions
+1 Qty Docs Part Number - Metric Price Available
RB2/M Support Documentation
RB2/MAdjustable Height Post Base for Ø25 mm RS Series Post Extensions

Flexure Clamping Ø1" Pillar Post Mount

  • Post Mount with a Ø1" (Ø25 mm) Double Bore and Flexure Clamping Mechanism
  • Mounts Ø1" Posts or Ø1/2" Post Holders
  • 0.325" (8.3 mm) of Height Adjustment and 360° Coarse Rotational Adjustment
  • 8-32 (M4) Tapped Hole for Rotation Hard Stop with the RM1B Ø1" Post Collar

The BA2F Post Mount features a Ø1" (Ø25 mm) double bore and flexure clamping mechanism. This clamp allows for both height and rotational adjustment of either an Ø1" optical post or a Ø1/2" post holder. The clamping mechanism is actuated by a 3/8"-24 (M10 x 1.5) clamping screw with 3/16" (5 mm) hex key. A permanent steel insert* at the end of the flexing mechanism prevents damage to the clamp from overtightening.

An RM1A or RM1B Ø1" post collar can be used with Ø1" posts or Ø1/2" post holders as a hard stop for repeatable height adjustment. The base also features an 8-32 (M4) tapped hole near the double bore; when a cap screw or setscrew is inserted into this hole, the post collar can also function as a rotational stop (see photo on the top right).

Each base has two 1.25" (31.8 mm) long counterbored slots for 1/4"-20 (M6) cap screws for attachment to an optical table or breadboard.

*Since our Ø1/2" post holders are slightly smaller in diameter than our Ø1" posts, the flexure mechanism will contact the steel insert when mounting Ø1/2" post holders. This is normal and will not harm the mounting base.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
BA2F Support Documentation
BA2FFlexure Clamping Base / Post Mount, Ø1" Double Bore, 2.00" x 3.00" x 0.48"
+1 Qty Docs Part Number - Metric Price Available
BA2F/M Support Documentation
BA2F/MFlexure Clamping Base / Post Mount, Ø25.0 mm Double Bore, 50.8 mm x 75.0 mm x 12.1 mm
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