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Polaris® Fixed Monolithic Mirror Mount for Laser System Design![]()
Heat-Treated, Monolithic Stainless Steel Precision Alignment Bore
POLARIS-19S50/M For Ø19 mm Mirrors (Mirror Sold Separately)
FRONT BACK Flexure Arm Optic Retention
POLARIS-CA1 Non-Bridging Clamping Arm
![]() Please Wait Features
Monolithic Construction Designed for Ø19 mm Optics ![]() Click to Enlarge The flexure arm used in the Polaris mount provides stable optic retention with minimal wavefront distortion. Please see the Test Data tab for test results. Flexure Arm for Optic Retention Polaris lens cells 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 have had their performance tested and verified with Ø19 mm optics that have a diameter tolerance of up to +0/-0.1 mm, so this tolerance range is recommended for optimal performance. Note that the mounts are not intended for use with optics that have an outer diameter tolerance greater than zero. Mounting Features In combination with our cage rods, the Ø6 mm +0.025/-0.000 mm precision bore in the Polaris fixed mount allows for the alignment of multiple mounts along a common optical axis, or for fine angle tuning when used with our Polaris clamping arms, sold below. Please see the Usage Tips tab for more information and other usage recommendations. Non-Bridging Clamping Arms Cleanroom and Vacuum Compatibility
![]() POLARIS-19S50/M Mechanical Drawing Polaris® Mirror Mounts Test DataPolaris Fixed Monolithic Mirror Mounts have undergone extensive testing to ensure high-quality performance.
Optical Distortion Testing Using a ZYGO Phase-Shifting InterferometerStress, strain, and displacement are all typical mounting forces experienced by an optic in any mount. Stress is the sum of all internal forces acting on a deformable object, strain is a measurement of deformation, and displacement is a measurement of how the stress and strain affect the shape and position of the object. Minimizing this effect is crucial; any distortion to the optic is transmitted to the light that is reflected from it. A ZYGO Phase-Shifting Interferometer was used to determine the recommended torque for retaining the optic while minimizing wavefront distortion. The results of these tests can be found below. Based on these tests, we recommend a torque of 5.5 - 6 oz-in for the flexure arm. These values provide a typical wavefront distortion of 0.1 waves.
Procedure: Results: ![]() Click to Enlarge 5 oz-in of Torque ![]() Click to Enlarge 5.5 oz-in of Torque ![]() Click to Enlarge 6 oz-in of Torque ![]() Click to Enlarge 6.5 oz-in of Torque ![]() Click to Enlarge 7 oz-in of Torque
Positional Repeatability After Thermal ShockThe Polaris was first secured to a stainless steel rigid platform in a temperature-controlled environment. The mirror is held using the stainless steel flexure arm, 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. Purpose: This testing was done to determine how reliably the mount returns the mirror, without hysteresis, to its initial position. These measurements show that the alignment of the optical system is unaffected by the temperature shock. Procedure: The temperature of each mirror mount tested was raised to 37.5 °C. The elevated temperature was maintained for 60 minutes (soak time). Then the temperature of the mirror mount was returned to the starting temperature. Each POLARIS-19S50/M was clamped to the table using the POLARIS-CA1 Clamping Arm. The results of these tests are shown below. Results: As can be seen in the plots below, when the Polaris mounts were returned to their initial temperature, the angular position (both pitch and yaw) of the mirrors returned to within 2 µrad of its initial position. The performance of the Polaris was tested further by subjecting the mount to repeated temperature change cycles. After each cycle, the mirror’s position reliably returned to within 2 µrad of its initial position. Conclusions: The Polaris Fixed Monolithic Mirror Mount is a high-quality, ultra-stable mount that will reliably return a mirror to its original position after cycling through a temperature change. As a result, the Polaris mount is ideal for use in applications that require long-term alignment stability. ![]() Click to Enlarge The plot above shows the pitch and yaw measured by a position-sensing detector before, while, and after a thermal shock was applied to the POLARIS-19S50/M mount.
Optical Distortion Testing Using a ZYGO Phase-Shifting InterferometerStress, strain, and displacement are all typical mounting forces experienced by an optic in any mount. Stress is the sum of all internal forces acting on a deformable object, strain is a measurement of deformation, and displacement is a measurement of how the stress and strain affect the shape and position of the object. Minimizing this effect is crucial; any distortion to the optic is transmitted to the light that is reflected from it. A ZYGO Phase-Shifting Interferometer was used to determine the recommended torque for retaining the optic while minimizing wavefront distortion. The results of these tests can be found below. Based on these tests, we recommend a torque of 5.5 - 6 oz-in for the flexure arm. These values provide a typical wavefront distortion of 0.1 waves.
Polaris® Clamping Arm TestingVarious tests were conducted to show the performance of our Polaris Clamping Arms. Many of the results were then compared to other industry-standard products that were put to the same test to show the high-quality performance of the Polaris clamping arms when used with our Ø1" Posts for Polaris Mounts. Click the links below for more information about a specific test.
![]() Click to Enlarge Figure 1: Industry-Standard Clamping Fork Beam Drift Laser Platform DeformationPurpose: This testing was performed to determine the extent to which an industry-standard clamping fork deforms or permanently damages a stainless steel rigid platform and whether or not the Polaris clamping arm improves upon or prevents this damage. The POLARIS-CA1 clamping arm was used for this test; similar results can be expected for all other Polaris clamping arms. These measurements show that the Polaris clamping arm significantly reduces temporary deformation to the surface and that no permanent damage was measured during our extensive tests. Procedure: An industry-standard clamping fork was mounted in close proximity to another optical element that was used for aligning a beam onto a position detector. As the clamping fork was mounted to the platform at various torque values (blue data sets in Figure 1 and Figure 2), the yaw and pitch deviation of the beam was measured at the detector. At 75 in-lbs of torque, the fork was left attached to the platform for 16 hours. After the 16 hour period, the fork was released from the table and the final beam deviation was recorded (red data sets in Figure 1 and Figure 2). This procedure was repeated for the POLARIS-CA1 clamping arm. Each test was performed at different regions of the platform. A final deviation of anything but zero indicated that the surface had been permanently deformed. Results: As can be seen in the plots below and to the right, the industry-standard clamping fork created a yaw and pitch deviation of 131 µrad and 702 µrad, respectively, at 75 in-lbs, while the POLARIS-CA1 clamping arm created a yaw and pitch deviation of 12.2 µrad and 61 µrad, respectively, at 75 in-lbs. The POLARIS-CA1 also returned the beam to its initial position when released after a 16 hour hold. The industry-standard clamping fork did not return the beam to its original position; the beam stayed at a yaw and pitch deviation of 176 µrad and 321 µrad, respectively. The simulaton results shown in Figures 3 and 4 show the amount of deformation created by an industry-standard clamping fork compared to the POLARIS-CA1 clamping arm. Conclusion: The POLARIS-CA1 clamping arm caused no permanent damage to the optical mounting surface and it significantly minimized the deformation to the platform surface when it was in use (see Figures 3 and 4). The industry-standard clamping fork was shown to permanently damage the laser platform after use, and to create severe deformation to the surface while in use. As a result, the Polaris clamping arm is ideal for use in systems requiring long term stability and consistent, precision alignments. ![]() Click for Details Figure 2: Note that the distortion caused by the Polaris clamping arm at 75 in-lb is comparable to the distortion caused by the industry-standard clamping fork at 10 in-lb. ![]() Click to Enlarge Figure 4: In comparison, the POLARIS-CA1 clamping arm causes minimal deformations around the fork. Note that the scale on this second plot has been magnified by 10X in order to make these minimal deformations visible. ![]() Click to Enlarge Figure 3: The industry-standard clamping fork causes large deformations over a significant area surrounding the fork.
Mounting TorquePurpose: This testing was performed to determine the ideal amount of clamping torque necessary to (1) securely mount a Ø1" post within the flexure clamp bore of a Polaris clamping arm and (2) to secure the clamping arm into a laser system. This data was then compared to the closest competitor's industry-standard clamping fork design. Procedure: The POLARIS-CA1(/M) was used to hold a standard Ø1" post. The clamping arm was first bolted to a stainless steel rigid platform, and the 1/4"-20 (M6 x 1.0) screw that controls the flexure clamp was actuated to specific torque values. At each torque value, the post had a rotational torque applied around its axis until it moved within the clamping arm's bore. The torque value at the moment directly before this "movement point" is called the holding torque (see plots below). Using similar methods, a mounting slot test was performed to find the ideal torque needed to secure the clamping arm to the laser platform. The mounting slot test was repeated for the POLARIS-SCA1 to determine if the slot size affects the torque measurements. Results Summary: For optimal performance, the flexure clamping screw of an imperial clamping arm should be tightened with 15 to 25 in-lb of torque and the flexure clamping screw of a metric clamping arm with 1.75 to 3 N•m of torque. When mounting to a table or platform, we recommend using 40 to 65 in-lb of torque for an imperial clamping arm and 4.75 to 7 N•m of torque for a metric clamping arm. Please see below for the detailed results. Conclusion: The Polaris clamping arm was shown to be the ideal solution for securely mounting a component to a laser system platform. At only 20 in-lb and 40 in-lb of clamping torque for the flexure clamp and mounting slot respectively, a post mounted in an imperial clamping arm can withstand up to 110 in-lb of opposing torque (corresponding torques for a metric clamping arm is 2.4, 4.8, and 12.4 N•m, respectively). This performance is superior to the closest competitor's industry-standard clamping fork, which needs a clamping torque of 70 in-lb in the close position to reach a similar value of 100 in-lb. As demonstrated in the Laser Platform Deformation test above, minimizing the amount of torque applied to the mounting surface prevents permanent damage. Test 1 Results: Flexure Clamp Holding TorqueAs can be seen in Figure 6 below, at 20 in-lbs of clamping torque, the POLARIS-CA1 provided 110 in-lb of holding torque. For reference, 110 in-lbs of torque is enough to damage the threading on a 1/4"-20 stainless steel cap screw. The corresponding torque for the POLARIS-CA1/M is a holding torque of 12.4 N•m at a clamping torque of 2.4 N•m. The torque values for imperial and metric clamps are not a direct conversion due to an efficiency difference between 1/4"-20 and M6 x 1.0 screws. The efficiency of M6 screws is about 5% less than that of 1/4"-20 screws due to differences in diameter and pitch. All imperial Polaris clamping arms will perform similarly to the POLARIS-CA1, while all metric Polaris clamping arms will perform similarly to the POLARIS-CA1/M. ![]() Click to Enlarge Click for POLARIS-CA1/M Flexure Clamp Holding Torque Results Figure 6: Results from Test 1. The blue shaded region indicates the recommended flexure clamp torque. All imperial Polaris clamping arms will perform similarly to the POLARIS-CA1, while all metric Polaris clamping arms will perform similarly to the POLARIS-CA1/M. ![]() Click to Enlarge Figure 5: Holding torque is measured at the moment directly before the "movement point" of the post being torqued. Test 2 Results: Mounting Slot Holding TorqueThe recommended torque for the mounting slot varies depending on the position of the 1/4"-20 (M6 x 1.0) cap screw within the slot (i.e. close to the post, midway along the slot, or far from the post). Figure 8 compares the slot holding torque of the POLARIS-SCA1 and POLARIS-CA1, and shows that the slot size does not affect the torque measurements. The recommended slot holding torque is 40 - 65 in-lb for imperial clamping arms, while for metric clamping arms the slot holding torque is 4.75 - 7 N•m. Similar to the Test 1 results, the torque values for imperial and metric clamps are not a direct conversion due to an efficiency difference between 1/4"-20 and M6 screws. The efficiency of M6 screws is about 5% less than that of 1/4"-20 screws due to differences in diameter and pitch. The performance of the closest competitor's clamping fork also depends on the position of the 1/4"-20 (M6 x 1.0) cap screw in the slot. However, as shown in Firgure 9, the performance of the fork degrades sharply at the mid and far positions. At the far position, the best holding torque achieved is 32 in-lb with a clamping torque of 70 in-lb. As shown in Figure 10, at 40 in-lbs of clamping torque, the POLARIS-CA1 provided 110 in-lb of holding torque, while at the same clamping torque, the competitor's fork only achieved a holding torque of 38 in-lbs. ![]() Click to Enlarge Click for POLARIS-CA1/M Slot Holding Torque Results Figure 8: Results from Test 2. The red shaded region indicates the recommended torque to secure the clamping arm to the optical table. This comparison between the POLARIS-SCA1 and POLARIS-CA1 shows that the slot size does not affect the slot holding torque. All imperial Polaris clamping arms will perform similarly to the POLARIS-CA1, while all metric Polaris clamping arms will perform similarly to the POLARIS-CA1/M. ![]() Click to Enlarge Figure 7: Holding torque is measured at the moment directly before the "movement point" of the clamping arm being torqued. ![]() Click to Enlarge Figure 9: Results from Test 2 on a competitor's clamping fork. See Figure 8 for results from POLARIS-CA1(/M). ![]() Click to Enlarge Figure 10: Comparison of Test 2 results for POLARIS-CA1 and a competitor's clamping fork, both at the middle position in the moutning slot.
![]() Click to Enlarge Figure 12: Breaking force recorded with the post mounted at 14 different heights above the platform. This shows that upwards of 110 in-lb of torque is required to loosen the PLS-P150 post from the clamping arm when the post is in contact with the work surface. ![]() Click to Enlarge Figure 11: Breaking torque is defined as the moment directly after the "movement point" of the post being torqued. Breaking TorquePurpose: This test was performed to determine the amount of torque needed to break a Ø1" PLS-P150 post loose from a Polaris clamping arm. The POLARIS-CA1 clamping arm was used for this test; similar results can be expected for all other Polaris clamping arms. This test was repeated at various heights above the work surface. Procedure: A PLS-P150 1.5" long, Ø1" post was secured with 25 in-lb of torque at various heights within a POLARIS-CA1 clamping arm, which was then secured to a custom laser platform. As shown in Figure 11, torque was then applied to the post axis until it reached its "movement point." This torque was recorded as the breaking torque. Results: As can be seen in Figure 12, upwards of 110 N•m of torque is required to loosen the PLS-P150 post from the clamping arm. When the post was raised off of the platform by 13 mm, a torque of about 40 N•m was still required to loosen the post. It is important to note here that the clamping arm is only 15.2 mm (0.60") thick. Conclusion: The PLS-P150 post and clamping arm create an extremely stable system that is resistant to large forces acting upon it, even when the post is raised off of the platform by 13 mm. This is ideal for any custom or OEM system that requires components to stay aligned when faced with vibrations caused by shipping and installation.
Post Deflection![]() Click to Enlarge Figure 13: A force was applied to the PLS-P150 post 0.90" (22.9 mm) above the edge of the clamping arm with the post mounted at nine different heights off of the mounting surface. At each mounting height, the post deflection was measured during and after the application of the force. Purpose: This test was performed to determine the amount of temporary and permanent deflection of a Ø1" post for Polaris mirror mounts secured in a Polaris clamping arm when a force is applied. The POLARIS-CA1 clamping arm was used for this test; similar results can be expected for all other Polaris clamping arms. Procedure: A PLS-P150 1.5" long, Ø1" post was secured with 25 in-lb of torque at various heights within a POLARIS-CA1 clamping arm, which was then secured to a custom laser platform. A force was then applied to the center of the post, 0.90" (22.9 mm) above the top edge of the clamping arm (see Figure 13 for details). This test was conducted with the post mounted at nine different heights off of the platform, ranging from 0 mm to 8 mm. The amount of deflection was measured while the force was being applied (Figure 14) and after the force was removed (Figure 15). Results: Figure 14 shows that the PLS-P150 post will deflect by <0.01 mm as a force of ≤40 N is applied for any post height ≤8 mm, and by <0.17 mm as a force of ≤133 N is applied for any post height ≤8 mm. These values show the temporary deflection of the post while the force is being applied. For all of the post mounting heights tested (0 to 8 mm), an applied force ≤35 N caused a permanent deflection of the post smaller than 0.005 mm, measured after the force was removed. For the two lowest mounting heights, 0 and 2 mm, no permanent deflection was measured for applied forces of 45 N or less. At 133 N, the maximum force applied, permanent deflection for all tested mounting heights remained below 0.07 mm. Conclusion: Our Ø1" posts and POLARIS-CA1 clamping arm create an extremly stable system that is able to resist large forces acting upon it. This is ideal for any custom or OEM system that requires components to stay aligned when faced with vibrations caused by shipping and installation. ![]() Click to Enlarge Figure 15: Post deflection measured after the applied force was removed. The measurement was repeated with the bottom of the post positioned 0 to 8 mm above of the mounting surface (see the Procedure section for details). For post-to-mounting-surface distances of 2 mm or less, no permanent deflection was measured if the force was ≤45 N. ![]() Click to Enlarge Figure 14: Post deflection measured while a force was applied to the post. The measurement was repeated with the bottom of the post positioned 0 to 8 mm above of the mounting surface (see the Procedure section for details). 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 fixed mirror mount. Thermal Hysteresis Optic Retention ![]() Click to Enlarge All Polaris Mounts are Shipped Inside Two Vacuum Bag Layers Vacuum Compatible and Low Outgassing Each Polaris® mount is packaged within two vacuum bag layers after assembly in a clean environment, as seen in the image to the right. These vacuum bags do not contain any desiccant materials and tightly wrap the mount, preventing friction against the mount during shipping. This packing method protects the mount from corrosion, gas or liquid contamination, and particulates during transport. The first vacuum bag should be opened in a clean environment while the second vacuum bag should only be opened just prior to installation. When operating at pressures below ![]() Click to Enlarge At zero torque, the sample mirror's flatness was λ/20 over the clear aperture (λ = 633 nm). The shaded region in this plot denotes the recommended optic mounting torque for a 6 mm thick optic. Through thermal changes and vibrations, the Polaris fixed mirror mount is designed to provide years of use. Below are some usage tips to ensure that the mount provides optimal performance. Monolithic Design Ø6 mm Precision Bore ![]() Click to Enlarge The Ø6 mm Precision Bore can be Used with a Cage Rod to Align Two or More Fixed Polaris Mounts ![]() Click to Enlarge A cage rod can be used for fine angle tuning in combination with the precision bore and a POLARIS-CA1 Clamping Arm (all items sold separately). Optic Mounting Extensive testing was also performed to see the performance when the flexure clamp is hand tightened without a torque wrench. The results of this test can be found here. When hand-tightening the flexure arm to retain the optic, sufficient torque should be applied to feel the contact between the arm and optic. Once that is achieved, the optic will be secured within the cell. Though this method is repeatable and will maintain low optic distortion, we recommend using a torque wrench for the best results. Do not actuate the flexure arm without an optic installed. The POLARIS-19S50/M mount is calibrated to minimize mirror distortion at 5.5 - 6 oz-in of optic mounting torque; if the flexure arm is forced beyond the point when it would normally contact the optic, this calibration will no longer be valid. Installing the post in the clamping arm before attaching the clamping arm to the table can create a bridge, which can alter optical alignment and damage the surface of the optical table or breadboard. Mount as Close to the Platform Surface as Possible Attach the Clamping Arm to the Table First Polish and Clean the Points of Contact Ø19 mm OpticsThe POLARIS-19S50/M is designed to securely hold 6 mm thick, Ø19 mm mirrors. This mirror size allows the mounts to maintain a Ø1" footprint while maximizing the clear aperture of the mirror face. The flexure arm and setscrew combination provide three points of axial contact to minimize distortion as well as increasing the holding force and stability of the optic. Thorlabs stocks a wide variety of Ø19 mm mirrors for use with our POLARIS-19S50/M Fixed Monolithic Mirror Mount. This includes broadboad dielectric, laser line, metallic, and blank mirrors. See the table below for all of our stocked options.
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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![]() ![]() 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 Clamping Arm Data tab 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 1/4"-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 The arm can be mounted with either flat surface in contact with the table, allowing for compact setups. ![]() Click to Enlarge Side-Located 1/4"-20 (M6) Screw Actuates Clamping Bore
The Polaris® Clamping Arms are the ideal solution for stably mounting our Ø1" Monolithic Polaris Mount or Ø1" Posts for Polaris Mounts. Each clamping arm, which is machined from heat-treated, stress-relieved stainless steel bar stock, provides extremely high holding forces with minimal torquing of the mounting screws (see the graph to the right). The flat, non-bridging top and bottom surfaces of each clamping arm allow it to be used with either side in contact with an optical table or other mounting surface. This feature allows the clamp to be positioned in left- or right-handed orientations and optical components to be placed in near contact to one another while minimizing the footprint (see the image to the left). On each side of the arm, a relief cut around the slot protects the ±0.001" (±0.02 mm) flat surface from any marring due to the screw and washer, allowing for more stable mounting. Two choices of slot length, 0.75" (19.1 mm) or 1.30" (33.0 mm), provide flexibility for applications such as tight laser cavity setups. The clamping arms available here are designed to only hold Ø1" posts. They are not compatible with Ø25 mm posts; the bore diameter is too large and will not contact the post when clamping. For Ø25 mm post systems, we also offer clamping arms with Ø25 mm mounting bores. Non-Bridging Design: Industry Standard Clamping Fork
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Item # | Compatible Post Size |
Clamping Screw |
Slot Length | Footprint |
---|---|---|---|---|
POLARIS-SCA1 | Ø1" (25.4 mm) |
1/4"-20 (3/16" Hex) |
0.75" (19.1 mm) |
2.78" x 1.60" (70.5 mm x 40.6 mm) |
POLARIS-CA1 | 1.30" (33.0 mm) |
3.33" x 1.60" (84.5 mm x 40.6 mm) |
||
POLARIS-SCA1/M | M6 x 1.0 (5 mm Hex) |
0.75" (19.1 mm) |
2.78" x 1.60" (70.5 mm x 40.6 mm) |
|
POLARIS-CA1/M | 1.30" (33.0 mm) |
3.33" x 1.60" (84.5 mm x 40.6 mm) |
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