HomeProductsMotion ControlActuators / AdjustersFine Adjustment Screws Polaris™ 1/4"-100 Matched Adjuster/Bushing Pairs

Polaris™ 1/4"-100 Matched Adjuster/Bushing Pairs


1/4"-100 Polaris™ Matched Adjuster/Bushing Pairs and Accessories

  • 1/4"-100 Matched Adjusters
  • Adjuster/Bushing Pairs Based on POLARIS-K1 Ultra-Stable Mount Adjuster Design
  • Thread Tolerances Exceed Class 3 Standards


  • Matched Actuators as Used in Our Ø1" POLARIS-K1 and POLARIS-K1-H Ultra-Stable Mirror Mounts
  • Threads with Better than Class 3 Fit Prevent Alignment Drift
  • 0.75" or 1" Long with 100 Threads per Inch (TPI)
  • High Temperature and Vacuum-Compatible Versions Available
  • Adjust Using a 5/64" Hex Key or HKTS-5/64 Hex Adjuster Knob (Available Below)
  • Phosphor Bronze Bushing with Stainless Steel Adjuster
  • Adjuster Accessories Include Lock Nuts, Knobs, and Sapphire Contact Pads

The P25SB Series of Matched Adjuster/Bushing Pairs are those used in several of our Polaris™ Ultra-Stable Mirror Mounts. The minimal lubrication and tight tolerances result in alignments that can be extremely stable, even after being adjusted. In addition, these adjusters have an extremely smooth feel that allows the user to make small repeatable adjustments. Test data of our ultra-stable Ø1" Polaris Mirror Mount shows how the P25SB100L results in accurate movements that do not change over time.

These matched 100 TPI adjusters and bushings are manufactured to tighter tolerances than the ASME/ANSI Class 3 UTS standard so that very little adjuster lubricant is needed. In typical adjusters, actuator adjustments cause the lubricant to be squeezed out of some spaces and built up in others. Over time this nonequilibrium lubricant distribution will relax slowly back into an equilibrium state, which may cause the adjuster screw to move. Polaris adjusters do not suffer from these problems due to their tighter tolerances.

The P25SB100L includes an unmounted ball bearing, providing the option to freely mount the ball or to secure it with epoxy to the tip of the screw. The P25SB075 and P25SB100 are sold with the ball mounted using our 353NDPK High-Temperature Epoxy, which provides constant performance up to 200 °C, while the P25SB075V and P25SB100V use the TS10 Vacuum Epoxy, which provides a reliable seal of leaks in vacuum equipment down to 10-9 Torr.

Polaris adjusters may be actuated using a 5/64" hex key, screw-on knobs (sold below), or the HKTS-5/64 hex key knob (sold below). Lock nuts are available below for long-term stability.


Thread Pitch 100 TPI (Threads per Inch)
Mounting Hole Size Ø0.350" +0.002"/-0.000"
Ø0.405" Counterbore
Adjuster 5/64" Hex
Materials Bushing: Phosphor Bronze
Adjuster: Stainless Steel


1/4"-100 Adjuster Lock Nut, Stainless Steel

  • Lock Nuts Compatible with the 1/4"-100 Adjusters Sold Above
  • Also Compatible with the Adjusters Included on our Polaris Mounts for Ø1" Optics
  • Tighten Using a 13 mm Hex Thin-Head or Cone Wrench
  • 0.08" (1.9 mm) Thick

The POLARIS-LN1 stainless steel lock nuts can be used with any 1/4"-100 adjuster for long-term stability. Lock nuts only need to be lightly tightened to a torque of approximately 4 to 8 oz-in (0.03 to 0.06 N·m). The beam can be held on target with the adjuster thumbscrew or hex key while lightly tightening the lock nut by hand or with a 13 mm thin-head wrench or cone wrench. These lock nuts are compatible with many of our Ø1" Polaris mounts, excluding the POLARIS-K1PZ Piezo-Driven Polaris, the POLARIS-K1-H, and the POLARIS-K1-2AH.

Cleanroom and Vacuum Compatibility
This lock nut is compatible with cleanroom and vacuum applications. The lock nuts are chemically cleaned using the Carpenter AAA passivation method to remove sulfur, iron, and contaminants from the surface. After passivation, they are double vacuum bagged to eliminate contamination when transported into a cleanroom.


Polaris Sapphire Contact Pads


P25SK2 Specifications
Diameter 0.160" ± 0.001"
Thickness 0.020" ± 0.001"
Flatness 5 Fringes/Inch
Surface Polish 80-50 Scratch-Dig
Parallelism 3.5 arcmin
Hardness 9 Mohs
1800 Knoop Parallel to C-Axis
2200 Knoop Perpendicular to C-Axis
Coefficient of Friction 0.15 Against Steel


Sapphire Contact Pads
P25SK2 Sapphire Contact Pads are used in our Polaris Mirror Mounts because they improve the adjustment precision and durability of the mount. They are highly durable, scratch resistant, and ideal for thermally demanding applications. Sapphire is the material of choice for very demanding applications that require reliability and strength at both high and low operating temperatures. A sapphire-to-steel interface has a very low coefficient of friction, which allows for very smooth movement. With exceptional surface hardness, sapphire can be scratched by only a few substances other than itself. It is chemically inert and insoluble to water, common acids, or alkalis for temperatures up to ~1000 °C.


1/4"-100 Removable Adjustment Knobs

  • Use with 1/4"-100 Hex Adjusters
  • Clearance Hole Allows Access to Hex Socket
  • Knurled Knob Increases Adjustment Sensitivity
  • Available in 2 Sizes (See Table to the Right)

These removable adjustment knobs are compatible with our 1/4"-100 adjusters, including those used in the Ø1" Polaris Kinematic Mounts. These knobs enable quick and easy tweaking of an actuator without needing a hex key.

We offer two sizes of adjustment knobs. The Ø0.58" standard size (F25USK1) is similar in size to the stainless steel knobs included with our Polaris mount, while the larger Ø0.925" size (F25USK2) provides additional angular resolution.

Item #Knob Diameter
F25USK1 0.58"
F25USK2 0.925"


5/64" and 2 mm Hex Key Adjusters

  • For Convenient Adjustment of 5/64" and 2 mm Hex-Driven Actuators
  • Red Anodized Adjustment Knob with Engraved Hex Size
  • Replaceable Hex Tip
  • Sold in Packages of 4

These 5/64" and 2 mm Hex Key Adjuster Thumbscrews allow for quick adjustment of many 5/64" (2 mm) hex-driven actuators (or standard actuators with the knobs removed). These temporary knobs can be left in the screw's hex socket between adjustments for convenience (see photo to the right). An 8-32 setscrew (5/64" hex) secures the replaceable hex bit, which can be reversed if the tip is stripped. Contact Tech Support to order replacement hex key bits.

We offer hex key thumbscrews in sizes from 0.050" to 3/16" and 2 mm to 5 mm.



Our Mission is to accelerate the advancement of optical technology for precision measurements and their applications from the table tops of research laboratories to standard use in communication and high technology industries. Our aim is to serve our customers. Our hope is to create a place for highly skilled people in an open environment

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Email             CEO.Ehab@Aitc-group.com