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A vertical setscrew allows for fine adjustment of the post height.

• 0.44" (11.2 mm) Thick
• Includes Vertically Aligned 4-40 Setscrew
• Packs of Five Also Available

The R2(/M) Slip-On Collar locks onto a Ø1/2" post with a thumbscrew. By positioning the collar on a post so that it rests on the top of the post holder, the post can be rotated without altering the height of the mounted component. In addition, the R2 is equipped with a 4-40 setscrew. By using a 0.050" (1.3 mm) hex key, this adjustment screw allows for approximately 0.25" (6.4 mm) of post height adjustment (see photo to the right) without the need for a translating post or post holder. To restrict the rotation of the post, the R2 can be paired with the TRK05 anti-rotation adapter. 

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Turning the 8-32 brass-tipped screw locks the RT2 collar onto a post. 

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The R2T collar marks the vertical position of a post inside a post holder.

• 0.23" (5.7 mm) Thick
• Thin Design Enables Easy Incorporation in Tightly Spaced Setups
• Sold in Packs of Five

The R2T is a thinner version of the R2 Post Collar featured above and can be secured to a Ø1/2" post by turning the included 8-32 brass-tipped locking screw. By placing the collar on a post so that it rests on the top of the post holder, the post can be rotated or removed and replaced without altering the height of the mounted component. At a thickness of only 0.23", the R2T collar occupies minimal space on the post and allows any mounted component to be positioned vertically close to the post holder.

To restrict the rotation of the post, the R2T can be paired with the TRK05 anti-rotation adapter. Alternatively, each R2T has a small groove, shown in the photo to the left, that allows it to be used as an extra post collar in setups using the RMC Position-Maintaining Post Collar (available below).

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RMC Post Collar Maintains Height and Rotational Orientation

• Two-Piece Post Collar Maintains Height and Rotational Orientation
• Steel Ball and V-Groove Provides ≤0.5° Angular Repeatability
• Holds Height Position to within 0.010" (0.3 mm)

Thorlabs' RMC Position-Maintaining Post Collar is designed to maintain the established height and rotational orientation of a Ø1/2" Post and Post Holder within a setup. The collar is a two-piece set: a 0.47" (11.9 mm) thick, engraved post holder collar and a thinner, 0.23" (5.7 mm) thick post collar. A steel ball and matching V-groove combination provide ≤0.5° angular repeatability.

As seen in the animation to the right, to use the RMC, slip the post holder collar on top of a Ø1/2" post holder and then secure its position using a 5/64" (2 mm) hex key to tighten the 8-32 nylon-tipped setscrew. Then, set the post height position by seating the post collar such that the V-groove sits on top of the protruding steel ball (see the image to the right). Secure the post collar to the post using a 5/64" (2 mm) hex key to tighten the brass-tipped 8-32 setscrew. Once assembled, small rotational adjustments can be achieved by loosening the setscrew in the lower collar and rotating until the desired position is reached.

The RMC post collar can be used to quickly swap optomechanical components between different posts while keeping the same height and rotational orientation. Each component to be swapped should be fitted with the post collar at the desired height. For best results, the post holder collar should be positioned so that the setscrew is opposite the spring-loaded thumbscrew (as shown in the image to the right). While making adjustments to the rotational position of the bottom collar, ensure that there is a preload from the post holder’s thumbscrew against the post; this ensures that the two-line contact between the post holder and mating post is maintained during the adjustment.