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Polaris® Kinematic Mirror Mounts with Piezoelectric Adjusters![]()
POLARIS-K05P2 Ø1/2" Mirror Mount
POLARIS-K1S3P Ø1" Mirror Mount, 3 Adjusters
POLARIS-K2S2P Ø2" Mirror Mount Related Items ![]() Please Wait
Features
The Polaris® Kinematic Mirror Mounts with Piezoelectric Adjusters are the ultimate solution for applications requiring stringent, actively monitored, long-term alignment stability. We recommend driving the piezo actuators using our benchtop or Kinesis® K-Cube™ piezo controllers. A replacement piezoelectric adjuster for the Ø1" and Ø2" mounts is also available separately below. Optic Retention Polaris optic bores are precision machined to achieve a fit that will provide optimum beam pointing stability performance over changing environmental conditions such as temperature changes, transportation shock, and vibration. These mounts are not designed to be used with optics that have an outer diameter tolerance greater than +0/-0.1 mm, such as metric mirror sizes (Ø12.5 mm, Ø25 mm, or Ø50 mm). To order a mount designed for metric optics, please contact Tech Support. Design Our design incorporates high-adjustment-sensitivity piezoelectric stacks directly into the hardened stainless steel adjusters, enabling smooth coarse and fine movements along each axis. When used in an external feedback loop, as illustrated on the Applications tab, these mounts combine the exceptional thermal stability of our standard Polaris kinematic mirror mounts with the ability to actively correct the beam pointing. Like all Polaris mounts, they are machined from heat-treated stainless steel, utilize precision-matched adjusters, and incorporate ball contacts and sapphire seats at all contact points. Each Polaris piezo mount utilizes snap-on SMB connectors. This model is specifically designed to minimize cable twisting as the mount is actuated. Furthermore, the design of SMB cables prevents incidental movement of the mirror when the cord is attached. Please note that the piezo actuators do not include a strain gauge. Post Mounting Vacuum Compatibility
Polaris® Mirror Mount Test DataPolaris Kinematic Mirror Mounts undergo extensive testing to ensure high-quality performance. After mounting the Polaris to a Ø1" stainless steel post, the mirror and post assembly was secured to a stainless steel optical table in a temperature-controlled environment. The mirror was secured using the flexure spring, not glued; see the Usage Tips tab for additional mounting recommendations. A beam from an independently temperature-stabilized laser diode was reflected by the mirror onto a position sensing detector. Angular Tuning Range of Piezoelectric AdjustersPurpose: This test was done to determine the full adjustable range of the piezoelectric stack inside the adjuster screw. Procedure: Each axis was connected to one of our KPZ101 Single-Channel K-Cube Piezo Controllers (set in manual mode) or to a single channel on our MTD693B Three-Axis Benchtop Controller. The voltage was increased from 0 to 150 V, the maximum control voltage, in 5 V steps (blue line). Then the voltage was decreased from 150 V to 0 V, again using 5 V steps (red line). Results: The maximum deflection that can be imparted by the piezoelectric stack is shown in the plots in the expandable tables below. This maximum deflection is >490 µrad for the Ø1/2" mount, >500 µrad for the Ø1" mounts, and >280 µrad for the Ø2" mounts. The well-known hysteresis response of piezoelectric materials is also evident. That is, the displacement at a given voltage depends upon whether the applied voltage is increasing or decreasing.
Positional Repeatability After Thermal ShockPurpose: This testing was done to determine how reliably the mount returns the mirror to its initial position so that the alignment of the optical system is unaffected by the temperature shock. Procedure: The ambient temperature was raised by 15 °C over a period of at least 45 minutes. Then the temperature was allowed to return to near room temperature. During these tests, the piezo actuators were not connected to a voltage source. The worst-case results obtained by this method are shown below. Results: The thermal shock data for each Polaris mount is shown in the plots in the expandable tables below. As shown in the plots, when the Polaris mount was returned to its initial temperature, the mirror position returned to within 6 µrad of its initial position for the Ø1/2" mount, within 1 µrad for the Ø1" mounts, and within 2 µrad for the Ø2" mount. For Comparison: To get a 1 µrad change in the mount's position, the 100 TPI adjuster on the Ø1/2" Polaris mount needs to be rotated by only 0.025° (1/14400 of a turn). A highly skilled operator might be able to make an adjustment as small as 0.6° (1/1200 of a turn), which corresponds to 12 µrad. Conclusions: These Polaris mirror mounts are high-quality, ultra-stable mounts that will reliably return a mirror to within several µrad of its original position after cycling through a temperature change in an open-loop setup. With a large adjustable range on each axis and a typical step size of 0.5 µrad (for a 0.1 V change in applied voltage), the Polaris mounts are capable of providing sub-µrad alignment stability in a closed-loop setup, even under punishing experimental conditions.
![]() Click for Details Polaris Kinematic Mirror Mount as Part of a Closed-Loop System Polaris® Mirror Mount in a Beam Stabilization SetupActive beam stabilization is often used to compensate for beam drift (unintended beam pointing deviations) in experimental setups. Drift can be caused by insecurely mounted optics, laser source instabilities, and thermal fluctuations within an optomechanical setup. In addition to correcting for setup errors, active stabilization is frequently used in laser cavities to maintain a high output power or used on an optical table to ensure that long measurements will take place under constant illumination conditions. Setups with long beam paths also benefit from active stabilization, since small angular deviations in a long path will lead to significant displacements downstream. An example of a beam stabilization setup is shown in the schematic to the left. A beamsplitter inserted in the optical path sends a sample of the beam to a position sensor that monitors the displacement of the beam relative to the detector's center. (For optimal stabilization, the beamsplitter should be as close as possible to the measurement.) The position detector outputs an error signal in X and Y that is proportional to the beam's position. Each error signal is fed into a channel of a piezoelectric controller that steers the beam back to the center of the sensor. The setup illustrated here stabilizes the beam to a point in space. In order to stabilize the beam over a beam path (i.e., over two points in space), two piezoelectric mirror mounts, as well as the associated electronics, are required. Suggested electronics for a beam stabilization setup are given in the table below.
![]() Click to Enlarge Details of the Polaris Design. The POLARIS-K05P2 uses a flexure spring and setscrew combination instead of the monolithic retention arm shown here. Several common factors typically lead to beam misalignment in an optical setup. These include temperature-induced hysteresis of the mirror's position, crosstalk, drift, and backlash. Polaris mirror mounts are designed specifically to minimize these misalignment factors and thus provide extremely stable performance. Hours of extensive research, multiple design efforts using sophisticated design tools, and months of rigorous testing went into choosing the best components to provide an ideal solution for experiments requiring ultra-stable performance from a kinematic mirror mount. Thermal Hysteresis The method by which the mirror is secured in the mount is another important design factor for the Polaris; these Polaris mounts offer excellent performance without the use of adhesives. Instead, they use a monolithic retention arm or a flexure spring that is pressed onto the edge of the mirror using a setscrew. Setscrews, when used by themselves to hold an optic, tend to move as the temperature changes. In contrast, the holding force provided by the Polaris design is sufficient to keep the mirror locked into place regardless of the ambient temperature. Crosstalk Drift and Backlash Integrated Piezoelectric Stacks Compatible with Vacuum Environments Please note that a high-voltage, coaxial feedthrough vacuum flange is required to pass the piezo control voltage into vacuum. ![]() Click to Enlarge Optic distortion of a BB1-E02 mirror mounted in a Ø1" Polaris mount. At zero torque, the sample mirror's flatness was λ/10 over the clear aperture (λ = 633 nm). The shaded region indicates the recommended amount of torque. Through thermal changes and vibrations, the Polaris kinematic mirror mounts are designed to provide years of use. Below are some usage tips to ensure that the mount provides optimal performance. General Usage TipsMatch Materials Use a Wide Post Optic Mounting Front Plate's Position Mount as Close to the Table's Surface as Possible Polish and Clean the Points of Contact
Piezo Usage TipsDisconnect Unused Channels Connect Cables only when Power Supply is Off Use Gentle Voltage Steps Stay within the 0 - 150 V Control Voltage Range Handle with Care
Not RecommendedWe do not recommend taking the adjusters out of the back plate, as it can contaminate the threading. This can reduce the fine adjustment performance significantly. Also, do not pull the front plate away as it might stretch the springs beyond their operating range, crack the sapphire seats, or break the piezoelectric stacks. Finally, do not overtighten the retaining screws that secure the flat spring that holds the optic in place; only slight force is required to secure the optic in place.
Thorlabs offers several different general varieties of Polaris mounts, including kinematic side optic retention, SM-threaded, low optic distortion, piezo-actuated, and glue-in optic mounts, as well as a fixed monolithic mirror mount and fixed optic mounts. Click to expand the tables below and see our complete line of Polaris mounts, listed by optic bore size, and then arranged by optic retention method and adjuster type. We also offer a line of accessories that have been specifically designed for use with our Polaris mounts; these are listed in the table immediately below. If your application requires a mirror mount design that is not available below, please contact Tech Support.
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Back and Front Views of the POLARIS-K05P2 Mirror Mount, Shown with a Ø1/2" Mirror and a Ø1" Polaris Post (Neither Included)
This Ø1/2" Kinematic Mirror Mount with Two Piezoelectric Adjusters is designed to provide long-term alignment stability in systems with an external feedback loop. It offers exceptional angular resolution of ~0.5 µrad for a 0.1 V step via piezoelectric adjustment. We recommend driving the piezo actuators using our benchtop or Kinesis K-Cube™ open-loop piezo controllers. The KPZ101 K-Cube controller will also require the use of one T4292 BNC-to-SMC adapter per axis. Please note that the piezo actuators do not include strain gauges. The Polaris design results in greater durability and thermal performance compared to non-Polaris mirror mounts. A flexure spring and setscrew combination provides temperature-independent retention of the optic, unlike nylon-tipped setscrews that are sensitive to temperature fluctuations. The setscrew that adjusts the flexure spring accepts a 1/16" (1.5 mm) hex key. We strongly recommend using a torque driver for securing the optic to prevent optical surface distortion and to improve thermal stability. This mirror mount comes with two adjuster lock nuts that can be tightened by holding the adjuster knob while lightly tightening the lock nut by hand or with an 11 mm thin-head, open-ended hex wrench. 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). These lock nuts hold in place the manual adjustment and will not affect the fine piezoelectric adjustment of this mount. The mount is designed so that the knobs and lock nuts are flush with the bottom surface of the housing, allowing it to be directly mounted to an optical table or breadboard. Post mounting is provided by two #8 (M4) counterbores located at right angles with respect to each other for right- or left-handed mounting. Due to the shallow design of the counterbores, low-profile 8-32 and M4 cap screws are included for mounting without obstructing the transmissive beam path. The 8-32 cap screw accepts a 5/64" (2 mm) hex wrench, while the M4 cap screw accepts a 2.5 mm hex wrench. For custom mounting configurations, Ø2 mm alignment pin holes are located on both sides of each counterbore for setting a precise location and mounting angle. Standard DIN 7-m6 ground dowel pins are recommended; see the Docs icon ( Two PAA236R cables are included with this mount. Each cable has a 90° SMB connector on one end and a straight BNC connector on the other. Note: The POLARIS-K05P2 mount incorporates 1/4"-100 adjuster screws and is not compatible with the POLARIS-P20 actuator (sold below), which has a 3/8"-100 thread. ![]()
Back and Front Views of the POLARIS-K1S3P Mirror Mount, Shown with a Ø1" Mirror and a Ø1" Post for Polaris Mounts (Neither Included)
This Ø1" Kinematic Mirror Mount with Three Piezoelectric Adjusters is designed to provide long-term alignment stability in systems with an external feedback loop. It offers exceptional angular resolution of ~0.5 µrad for a 0.1 V step via piezoelectric adjustment. We recommend driving the piezo actuators using our benchtop or Kinesis K-Cube™ open-loop piezo controllers. The KPZ101 K-Cube controller will also require the use of one T4292 BNC-to-SMC adapter per axis. Please note that the piezo actuators do not include strain gauges. The Polaris design results in greater durability and thermal performance compared to non-Polaris mirror mounts. A monolithic retention arm provides temperature-independent retention of the optic, unlike nylon-tipped setscrews that are sensitive to temperature fluctuations. The setscrew that adjusts the flexure arm accepts a 0.05" (1.3 mm) hex key. We strongly recommend using a torque driver for securing the optic to prevent optical surface distortion and to improve thermal stability. This mirror mount comes with three adjuster lock nuts that can be tightened by holding the adjuster knob while lightly tightening the lock nut by hand or with a 12 mm thin-head, open-ended hex wrench. 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). These lock nuts hold in place the manual adjustment and will not affect the fine piezoelectric adjustment of this mount. Post mounting is provided by two #8 (M4) counterbores located at right angles with respect to each other for right- or left-handed mounting. One 8-32 cap screw and one M4 cap screw are included for securing the mount to a post. The 8-32 cap screw accepts a 9/64" hex wrench, while the M4 cap screw accepts a 3 mm hex wrench. Three PAA236R cables are included with this mount. Each cable has a 90° SMB connector on one end and a straight BNC connector on the other. ![]()
Back and Front Views of the POLARIS-K1S2P Mirror Mount, Shown with a Ø1" Mirror and a Ø1" Post for Polaris Mounts (Neither Included)
This Ø1" Kinematic Mirror Mount with Two Piezoelectric Adjusters is similar to the 3-adjuster version sold above but features a hardened steel ball in place of the third adjuster. This mount is designed to provide long-term alignment stability in systems with an external feedback loop. It offers exceptional angular resolution of ~0.5 µrad for a 0.1 V step via piezoelectric adjustment. We recommend driving the piezo actuators using our benchtop or Kinesis K-Cube™ open-loop piezo controllers. The KPZ101 K-Cube controller will also require the use of one T4292 BNC-to-SMC adapter per axis. Please note that the piezo actuators do not include strain gauges. The Polaris design results in greater durability and thermal performance compared to non-Polaris mirror mounts. A monolithic retention arm provides temperature-independent retention of the optic, unlike nylon-tipped setscrews that are sensitive to temperature fluctuations. The setscrew that adjusts the flexure arm accepts a 0.05" (1.3 mm) hex key. We strongly recommend using a torque driver for securing the optic to prevent optical surface distortion and to improve thermal stability. This mirror mount comes with two adjuster lock nuts that can be tightened by holding the adjuster knob while lightly tightening the lock nut by hand or with a 12 mm thin-head, open-ended hex wrench. 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). These lock nuts hold in place the manual adjustment and will not affect the fine piezoelectric adjustment of this mount. Post mounting is provided by two #8 (M4) counterbores located at right angles with respect to each other for right- or left-handed mounting. One 8-32 cap screw and one M4 cap screw are included for securing the mount to a post. The 8-32 cap screw accepts a 9/64" hex wrench, while the M4 cap screw accepts a 3 mm hex wrench. Two PAA236R cables are included with this mount. Each cable has a 90° SMB connector on one end and a straight BNC connector on the other. ![]()
Back and Front Views of the POLARIS-K2S2P Mirror Mount, Shown with a Ø2" Mirror and a Ø1" Post (Neither Included)
This Ø2" Kinematic Mirror Mount with Two Piezoelectric Adjusters is designed to provide long-term alignment stability in systems with an external feedback loop. It offers exceptional angular resolution of ~0.5 µrad for a 0.1 V step via piezoelectric adjustment. We recommend driving the piezo actuators using our benchtop or Kinesis K-Cube™ open-loop piezo controllers. The KPZ101 K-Cube controller will also require the use of one T4292 BNC-to-SMC adapter per axis. Please note that the piezo actuators do not include strain gauges. The Polaris design results in greater durability and thermal performance compared to non-Polaris mirror mounts. A monolithic flexure arm provides temperature-independent retention of the optic, unlike nylon-tipped setscrews that are sensitive to temperature fluctuations. The setscrew that adjusts the flexure arm accepts a 5/64" (2 mm) hex key. We strongly recommend using a torque driver for securing the optic to prevent optical surface distortion and to improve thermal stability. This mirror mount comes with two adjuster lock nuts that can be tightened by holding the adjuster knob while lightly tightening the lock nut by hand or with a 12 mm thin-head, open-ended hex wrench. 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). These lock nuts hold in place the manual adjustment and will not affect the fine piezoelectric adjustment of this mount. Post mounting is provided by four #8 (M4) counterbores for right- or left-handed mounting. One 8-32 cap screw and one M4 cap screw are included for securing the mount to a post. The 8-32 cap screw accepts a 9/64" hex wrench, while the M4 cap screw accepts a 3 mm hex wrench. Two PAA236R cables are included with this mount. Each cable has a 90° SMB connector on one end and a straight BNC connector on the other. ![]()
The POLARIS-P20 is the piezoelectric actuator used in the Ø1" and Ø2" mirror mounts sold above. It can be used as a replacement adjuster by removing the adjuster screw from the bushing. The actuator can be manually adjusted for up to 0.375" of travel, while the piezoelectric fine adjustment has a maximum travel range between 15.4 µm and 19.4 µm. The adjuster screw and bushing are machined from stainless steel, which has a low coefficient of thermal expansion (CTE) for stability in environments with large temperature fluctuations. For details on using this piezoelectric actuator, please see the spec sheet. The piezo actuator features a male SMB connector; an SMB-to-BNC cable is not included. We offer the PAA236R cable with a 90° SMB connector on one end and a straight BNC connector on the other. The actuator includes an adjuster lock nut that can be tightened or loosened by hand or with a 12 mm thin-head, open-ended hex wrench. Holding the adjuster in place with the lock nut will not affect the piezoelectric adjustment. We recommend driving this piezo actuator with the KPZ101, MDT693B, or MDT694B open-loop piezo controllers. Note: The POLARIS-P20 actuator has 3/8"-100 threads and is not compatible with the POLARIS-K05P2 mount (sold above), which incorporates 1/4"-100 adjuster screws. ![]()
This 13 mm hexagonal lock nut is designed for use with our Polaris mounts with 3/8"-100 adjusters. Manufactured for long-term adjuster stability or applications that are exposed to shock and vibration, these lock nuts are pre-greased with the same ultra-high-vacuum-compatible, low-outgassing PTFE grease as the Polaris mounts and have been tested for adjuster fit. For applications that require frequent tuning of the adjusters, the lock nuts only need to be lightly tightened by hand to a torque of approximately 4 to 8 oz-in (0.03 to 0.06 N·m). For long term stability, we recommend tightening to a torque of 32 oz-in, which can be achieved by using our TW13 preset torque wrench. To avoid cross threading the lock nut, place it against the adjuster and "unscrew" the lock nut until you feel a slight drop; then thread the lock nut onto the adjuster. Note: The POLARIS-P20 actuator includes a 12 mm 3/8"-100 locking nut, which will need to be removed in order to install a POLARIS-LN4 locking nut. By using this 13 mm locking nut, users may take advantage of the TW13 preset torque wrench. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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