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Polaris® Fixed Monolithic Mirror Mount for Laser System Design


  • Flexure Arm Provides Highly Stable Mirror Retention
  • Heat Treating Minimizes Temperature-Dependent Hysteresis
  • M6 x 1.0 Tap and Holes for Ø2 mm Alignment Pins in Base
  • Optic Face Centered on Post Axis

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

 

Related Items


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Monolithic Polaris Mount
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A Torque Driver is Recommended When Installing a Mirror
19 mm Mirrors

Features

  • Ultra-Stable Monolithic Design is Ideal for OEM Applications
  • Fixed Mount Designed for Ø19 mm Mirrors (See Ø19 mm Mirrors Tab for Our Selection)
  • 50 mm Beam Height (Custom Options Available; See Below)
  • Extensive Testing Guarantees <2 μrad Deviation After 12.5 °C Temperature Cycling
    (See the Test Data Tab for Details)
  • Non-Bridging Mounting Solution Prevents Table Distortion and Optical Misalignment
    (See the Clamping Arm Data Tab for Details)
  • Fabricated from Heat-Treated Stainless Steel
  • Materials are Vacuum Compatible to 10-9 Torr at 25 °C with Proper Bake Out
  • Optic Face Centered on the Post Axis Simplifies Alignment and Allows Pure Rotation
  • Precision Ø6 mm Bore for Angle Tuning and Alignment
  • Two Ø2 mm Alignment Pin Holes in the Base for Precision Mounting (Dowel Pins Not Included)
  • Bottom-Located M6 x 1.0 Tap (Custom Options Available; See Below)

Monolithic Construction
Polaris® Fixed Monolithic Mirror Mounts are the ultimate solution for OEM applications requiring stringent long-term alignment stability. These mounts are fabricated from a single piece of heat-treated stainless steel, ensuring high stability by minimizing the number of interfaces within the assembly and effectively reducing component creep over time.

Designed for Ø19 mm Optics
The Polaris fixed mirror mount is designed to securely hold 6 mm thick, Ø19 mm mirrors. The Ø19 mm optic size allows for a small Ø1" (Ø25.4 mm) footprint on the optical table, making these mounts ideal when trying to reduce the size of a system or create space in constrained setups. Thorlabs stocks a wide variety of Ø19 mm mirrors for use with this mount, including broadband dielectric, laser line, metallic, and blank mirrors. Please see the Ø19 mm Mirrors tab for our selection.

POLARIS-19S50/M Test Data
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
A long flexure arm and setscrew combination provides temperature-independent retention of the optic, unlike nylon-tipped setscrews, which are sensitive to temperature fluctuations. This mounting mechanism, along with the provided three points of axial contact, makes it so the optic does not need to be glued into the Polaris mount to achieve maximum stability and minimum wavefront distortion.

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.

Non-Bridging Clamping Arm
Industry Standard Clamping Fork Test DataClick to Enlarge
A Bridge is Created When an Industry-Standard Clamping Fork is Used with a Pedestal Post
Polaris Clamping Arm Test DataClick to Enlarge
The POLARIS-CA1(/M) Eliminates the Bridge Created by an Industry-Standard Clamping Fork

Non-Bridging Clamping Arm
The POLARIS-CA1(/M) Clamping Arm (sold separately) is the ideal mounting solution for our monolithic Polaris mount. Their design strongly reduces the gap, or “bridge,” that traditionally results between the back of a standard clamping fork and a Ø1" pedestal post base. When tightening the post to the table, this bridge causes the mounting screw to pull up on the mounting platform, permanently deforming it and disturbing the alignment of nearby optical components. In contrast, these clamping arms have a ±0.001" (±0.02 mm) flat top and bottom that helps to reinforce the board when the clamping arm is mounted, greatly reducing or eliminating platform deformation. For more information on the effects of bridging, please see the Clamping Arm Data tab.

Mounting Features
These Polaris mirror mounts are equipped with two Ø2 mm alignment pin holes for direct, precision mounting within a custom or OEM laser system. A centered, bottom-located M6 x 1.0 tap is also included. Versions with custom alignment pin hole locations, a 1/4"-20 tap, or no tap are available by using our Polaris configurator below.

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-CA1(/M). Please see the Usage Tips tab for more information and other usage recommendations.

Cleanroom and Vacuum Compatibility
The POLARIS-19S50/M is designed to be compatible with cleanroom and vacuum applications. They are chemically cleaned using the Carpenter AAA passivation method to remove sulfur, iron, and contaminants from the surface. After passivation, they are assembled in a clean environment and double vacuum bagged to eliminate contamination when transported into a cleanroom. Please contact techsupport@thorlabs.com for details.

Item #  POLARIS-19S50/M
Optic Sizea Ø19 mm
Optic Thickness (Min) 2 mm (0.08")
Beam Heightb,c 50 mm (1.97")
Clear Aperture Ø17.1 mm (0.68")
Beam Deviationd After Thermal Cycling <2 μrad
Recommended Optic Mounting Torque 5.5 - 6.0 oz-in for 6 mm Thick Optics
Mounting Tape M6 x 1.0 Tap
Alignment Pin Holes Two Ø2 mm Holes for DIN 7-m6 Ground Dowel Pins (Not Included)
Around Mounting Tap (See Drawing Below)
Vacuum Compatibilityf 10-9 Torr at 25 °C with Proper Bake Out; 10-5 Torr at 25 °C without Bake Out
Grease Vapor Pressure: 10-13 Torr at 20 °C ,10-5 Torr at 200 °C
Epoxy Meets Low Outgassing Standards NASA ASTM E595, Telcordia GR-1221
Operating Temperature Range -30 to 200 °C
Weight 0.16 kg (0.35 lbs)
  • Measured from the base of the mount to the center of the optic (optic not included).
  • For best performance, use optics with a diameter tolerance of up to +0/-0.1 mm.
  • Beam heights from 25 mm to 150 mm (1" to 6") are available as a custom option.
  • After a 12.5 °C temperature cycle, the beam returns to within 2 μrad of its original position for a beam height of 50 mm. Please see the Test Data tab for more details.
  • A 1/4"-20 tap or no tap is available as a custom option.
  • Vacuum-compatible Polaris mounts are assembled in a clean environment, chemically cleaned using the Carpenter AAA passivation method to remove sulfur, iron, and contaminants from the surface, and double vacuum bagged. Prior to placing any components in a sensitive vacuum system, a thorough pre-baking in a bake-out oven should be performed to remove all moisture and surface volatiles. Contact techsupport@thorlabs.com for details.

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 below. 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 10-5 Torr, we highly recommend using an appropriate bake out procedure prior to installing the mount in order to minimize contamination caused by outgassing.

Double Vacuum Bagging for Polaris Mounts
Click to Enlarge

All Polaris Mounts are Shipped Inside Two Vacuum Bag Layers
POLARIS-19S50 Test Data
POLARIS-19S50/M Mechanical Drawing

Ø19 mm Optics

The 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.

Item # Wavelength Coating Type Reflectance Reflectance Curvesa
(Click for Plot)
Broadband Dielectric Mirrors
BB07-E01 350 - 400 nm Broadband Dielectric Ravg > 99% for 350 - 400 nm
BB07-E02 400 - 750 nm Broadband Dielectric Ravg > 99% for 400 - 750 nm
BB07-E02Pb 400 - 750 nm Broadband Dielectric
(Backside Polished)
Ravg > 99% for 400 - 750 nm
BB07-E03 750 - 1100 nm Broadband Dielectric Ravg > 99% for 750 - 1100 nm
BB07-E03Pc 750 - 1100 nm Broadband Dielectric
(Backside Polished)
Ravg > 99% for 750 - 1100 nm
BB07-E04 1280 - 1600 nm Broadband Dielectric Ravg > 99% for 1280 - 1600 nm
Laser Line Mirrors
NB07-H01 193 nm ArF Excimer Laser Line R > 98% at 193 nm
NB07-K04 262 - 266 nm Nd:YAG Laser Line
(4th Harmonic)
Ravg > 99.0% for 262 - 266 nm
NB07-K05 300 - 308 nm Ar-Ion Laser Line 0° to 45° AOI: Ravg > 99.5% (S-Pol), Ravg > 98.0% (P-Pol) for 300 - 308 nm

8° AOI

45° AOI
NB07-K07 333 - 364 nm Ar-Ion Laser Line 0° AOI: R > 99.5% (Unpolarized) at 352 nm
45° AOI: R > 99.0% (S-Pol), R > 98.7% (P-Pol) at 352 nm

8° AOI

45° AOI
NB07-K08 349 - 355 nm Nd:YAG Laser Line
(3rd Harmonic)
Ravg > 99.5% for 349 - 355 nm
NB07-K10 458 - 528 nm Ar-Ion Laser Line 0° to 45° AOI: Ravg > 99.0% (S-Pol), Ravg > 99.0% (P-Pol) for 458 - 528 nm
6° and 45° AOI
NB07-J11 520 - 647 nm Kr-Ion Laser Line Ravg > 99.7% for 520 - 647 nm
NB07-K12 524 - 532 nm Nd:YAG Laser Line
(2nd Harmonic)
Ravg > 99.0% for 524 - 532 nm
NB07-K13 532 nm and 1064 nm Nd:YAG Laser Line
(Fundamental and 2nd Harmonic)
R > 98% at 532 nm
R > 99% at 1064 nm
       
  532 nm    1064 nm
NB07-K14 1047 - 1064 nm Nd:YAG Laser Line
(Fundamental)
Ravg > 99.5% for 1047 - 1064 nm
Metallic Mirrors
PF07-03-F01 250 - 450 nm UV Enhanced Aluminum Ravg > 90% for 250 - 450 nm          
 12° AOI      45° AOI
PF07-03-G01 450 nm - 20 µm Protected Aluminum Ravg > 90% for 450 nm - 2 µm
Ravg > 95% for 2 - 20 µm
         
 12° AOI      45° AOI
PF07-03-P01 450 nm - 20 µm Protected Silver Ravg > 97.5% for 450 nm - 2 µm
Ravg > 96% for 2 - 20 µm
         
 12° AOI      45° AOI
PF07-03-P01Pd 450 nm - 20 µm Protected Silver
(Backside Polished)
Ravg > 96% for 400 - 700 nm
Ravg > 97.5% for 700 nm - 2 µm
         
 12° AOI      45° AOI
PF07-03-M01 800 nm - 20 µm Protected Gold Ravg > 96% for 800 nm - 20 µm          
 12° AOI      45° AOI
Mirror Blanks
PF07-03 N/A Mirror Blank N/A N/A
  • The shaded regions in the graphs denote the ranges over which we guarantee the specified reflectance, except where otherwise noted.
  • Transmission Plot at 0° AOI and 45° AOI
  • Transmission Plot at 0° AOI and 45° AOI
  • Transmission Plot at 0° AOI and 45° AOI

Polaris® Mirror Mounts Test Data

Polaris Fixed Monolithic Mirror Mounts have undergone extensive testing to ensure high-quality performance.

 

Optical Distortion Testing Using a ZYGO Phase-Shifting Interferometer

Stress, 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.

Torque (oz-in) Push Out Force (lbf)a Wavefront Distortion (Peak to Valley)b
5 <3.88 0.059λ to 0.102λ
5.5 3.88 0.067λ to 0.103λ
6 7.09 0.085λ to 0.136λ
6.5 7.93 0.090λ to 0.152λ
7 9.51 0.126λ to 0.172λ
7.5 >9.51 0.125λ to 0.216λ
  • Force Required to Move the Held Optic at the Given Torque Values
  • The Zygo interferometer aperture outer diameter was set to 80% for these measurements. These values represent the minimum and maximum values over multiple independent tests.

Procedure:
A BB07-E02 Ø19 mm Broadband Dielectric Mirror was installed into a POLARIS-19S50/M Fixed Mount using the setscrew to clamp down the flexure arm. The Zygo interferometer aperture diameter was set to 80% for these measurements to stay within the clear aperture of the front face of the mount. Measurement increments of 0.5 oz-in were used, and the mirror was checked for push-out force at each torque value to ensure optic retention. The values in the table above represent the peak-to-valley distortion across the entire optic, illustrating the worst-case scenario; the center of the optic shows significantly better distortion effects.

Results:
As seen in the table to the right and the images below, the peak-to-valley wavefront distortion was found to remain at approximately 0.1λ when 5.5 - 6 oz-in of torque was applied to the setscrew.

POLARIS-19S50 Optic Distortion
Click to Enlarge

5 oz-in of Torque
POLARIS-K1F6 Optic Distortion
Click to Enlarge

5.5 oz-in of Torque
POLARIS-K1F6 Optic Distortion
Click to Enlarge

6 oz-in of Torque
POLARIS-K1F6 Optic Distortion
Click to Enlarge

6.5 oz-in of Torque
POLARIS-K1F6 Optic Distortion
Click to Enlarge

7 oz-in of Torque

 

Positional Repeatability After Thermal Shock

The 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.

POLARIS-19S50 Thermal Data
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.

Polaris-19S50 Thermal Shock Tests
Click to Enlarge

Test Series 2
The plot above shows the final angular position of a second POLARIS-19S50/M for 20 consecutive thermal shock tests. The change in temperature is the difference between the starting temperature and the temperature at the end of the test and includes factors such as the variation in room temperature. This shows the repeatability of the tests.

Polaris-19S50 Thermal Shock Tests
Click to Enlarge

Test Series 1
The plot above shows the final angular position of the POLARIS-19S50/M for 20 consecutive thermal shock tests. The change in temperature is the difference between the starting temperature and the temperature at the end of the test and includes factors such as the variation in room temperature.

 

Optical Distortion Testing Using a ZYGO Phase-Shifting Interferometer

Stress, 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-19S50/M Wavefront Distortion Test Results
Torque (oz-in) Push Out Force (lbF)a Wavefront Distortion (Peak to Valley)b
5 0.059λ to 0.102λ
5.5 3.88 0.067λ to 0.103λ
6 7.09 0.085λ to 0.136λ
6.5 7.93 0.090λ to 0.152λ
7 9.51 0.126λ to 0.172λ
7.5 - 0.125λ to 0.216λ
  • Force Required to Loosen the Held Optic at the Given Torque Values
  • The Zygo interferometer aperture outer diameter was set to 80% for these measurements. These values represent the minimum and maximum values over multiple independent tests.

Laser Platform Deformation

Purpose: 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-CA1(/M) improves upon or prevents this damage. These measurements show that the POLARIS-CA1(/M) significantly reduce 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. If the final deviation is anything but zero, then the surface has 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.

Optic Distortion as a Result of Torque
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.
Polaris Table Distortion
Click to Enlarge

Figure 4
In comparison, the POLARIS-CA1 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.
Fork Table Distortion
Click to Enlarge

Figure 3
The industry-standard clamping fork causes large deformations over a significant area surrounding the fork.

 

Mounting Torque

Purpose: 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 the POLARIS-CA1(/M) 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 the stainless steel rigid platform and the flexure clamp was actuated, using the side-located 1/4"-20 (M6) cap screw, to specific torque values. At each specific torque value of the flexure clamp, the post had a rotational torque applied around its axis until it moved within the fork's bore. The torque value at the moment directly before this "movement point" is called the holding torque (see plots below). A similar test was then applied to find the ideal torque need to secure the clamping arm to the laser platform.

Results: As can be seen in Figures 5 - 10 below, the POLARIS-CA1(/M) flexure clamp had higher holding torque at a lower clamping torque when compared to the closest competitor's design. At 20 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 25 in-lbs. 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 scales for these measurements, as seen in Figures 6 and 8 below, 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 recommended torque for the mounting slot (Figure 8) varies depending upon the position where a 1/4"-20 (M6) cap screw is secured into the slot (i.e. close to the post, midway along the slot, or far from the post). The performance of the closest competitor's clamping fork (see Figure 9) is also dependent on the position where the 1/4"-20 (M6) cap screw is secured into the slot. However, the performance of the fork degrades sharply at the mid and far positions, as seen in Figure 9. At the far position, the best holding torque achieved is 32 in-lb with a clamping force of 70 in-lb.

Conclusion: The POLARIS-CA1(/M) 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 slot mounting respectively, the post mounted in a POLARIS-CA1 can withstand up to 110 in-lb of opposing torque (corresponding torques for the POLARIS-CA1/M are 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 force of 70 in-lb in the close position to reach a similar value of 100 in-lb. Minimizing the amount of torque applied to the mounting surface prevents permanent damage. 

Test 1: Flexure Clamp Holding Torque
POLARIS-CA1 Mounting Torque
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.
Competitors Mounting Torque
Click to Enlarge

Figure 5
Holding torque is defined as the moment directly before the "movement point" of the post being torqued (see the plot to the right).
Test 2: Slot Mounting Holding Torque
POLARIS-CA1 Mounting Torque
Click to Enlarge

Click for POLARIS-CA1/M Slot Holding Torque Results
Figure 8
Results from Test 2. The blue shaded region indicates the recommended torque to secure the clamping arm to the optical table.
Competitors Mounting Torque
Click to Enlarge

Figure 7
Holding torque is defined as the moment directly before the "movement point" of the clamping arm being torqued (see the plot to the right).
Competitors Mounting Torque
Click to Enlarge

Figure 9
Results from Test 2 on a competitor's clamping fork. See Figure 8 above for results from POLARIS-CA1(/M).
Competitors Mounting Torque
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.

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
The temperature in most labs is not constant due to factors such as air conditioning, the number of people in the room, and the operating states of equipment. Thus, it is necessary that all mounts used in an alignment-sensitive optical setup be designed to minimize any thermally induced alignment effects. Thermal effects can be minimized by choosing materials with a low coefficient of thermal expansion (CTE), like stainless steel. However, even mounts made from a material with a low CTE do not typically return the mirror to its initial position when the initial temperature is restored. The monolithic body of the Polaris fixed mirror mount is heat treated, thus removing internal stresses that can cause a temperature-dependent hysteresis. As a result, the alignment of the optical system will be restored when the temperature of the mirror mount is returned to the initial temperature.

Optic Retention
The method by which the mirror is secured in the mount is another important design factor for the Polaris; this Polaris mount offers excellent performance without the use of adhesives. Instead, it uses a flexure arm, which is part of the single-piece design, 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 stainless steel flexure arm is sufficient to keep the mirror locked into place regardless of the ambient temperature.

Optic Distortion as a Result of Torque
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
The Polaris fixed mirror mount is fabricated from a single piece of stainless steel because of this material's relatively low coefficient of thermal expansion (CTE), thus reducing the magnitude of temperature-induced beam misalignments. Being constructed from a single piece of stainless steel also ensures high stability by minimizing the number of interfaces within the assembly, effectively reducing component creep over time. When mounting, we recommend using components fabricated from the same material, such as our POLARIS-CA1(/M) Clamping Arm, in order to match thermal expansion coefficients.

Ø6 mm Precision Bore
A Ø6 mm alignment bore is located 20 mm from the base at the horizontal center of the mount. This bore, which is precision machined to a tolerance of +0.025 mm/-0.000 mm, can be used for fine angle tuning of the mount when used with our POLARIS-CA1(/M) Clamping Arm, as shown in the image to the right below. It can also be used with our Ø6 mm cage rods for aligning multiple mounts, as shown in the image below. Please note: We recommend only using our cage rods with the precision bore, as large amounts of torque applied with another tool could damage the bore.

Polaris Mount Alignment
Click to Enlarge

The Ø6 mm Precision Bore can be Used with a Cage Rod to Align Two or More Fixed Polaris Mounts
Polaris 1/2" mounted on 1" post
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
Since an optic is prone to movement within its mounting bore, all optics should be mounted before installing the Polaris into the setup to ensure accurate mounting that will minimize misalignment effects. We recommend using a torque wrench when installing an optic in the Polaris mounts. Over torquing the flexure-arm optic retainer can result in dramatic surface distortions. The graph to the right shows surface distortions that result from increasing torque values delivered by the TD24 torque wrench for a POLARIS-19S50/M with a Ø19 mm, 6 mm thick BB07-E02 mirror mounted in it. The test was stopped once the distortion was greater than 0.175 waves.

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
To minimize the impact of vibrations and temperature changes, it is recommended that your setup has as low of a profile as possible. Using short posts will reduce the vertical translation caused by temperature variations and will minimize any movements caused by vibrations. They can be stably mounted directly to a laser platform using our POLARIS-CA1(/M) Clamping Arms. Although Ø1" posts can be used to increase the height of the mount, it is not recommended due to the increase in component creep over time. Custom fixed Polaris mounts can be ordered with beam heights ranging from 25 mm to 150 mm (1" to 6").

Attach the Clamping Arm to the Table First
The video to the left shows the optimal way to mount a post and clamping arm to an optical table. Note that the first step is to secure the clamping arm to the table. If, instead, the monolithic mount is first attached to the clamping fork and then the pair is attached to the table, a bridge may result, thereby altering the optical alignment and potentially damaging the surface of the optical table or breadboard (see Overview tab for details).

Polish and Clean the Points of Contact
We highly recommend that the points of contact between the post and the table are clean and free of raised scratches or defects. For best results, we recommend using a polishing stone to clean the platform's surface and a LFG1P polishing pad for the  bottom of the post as well as the bottom of clamping arm. Any hand oils that are on the mounting surfaces will significantly reduce holding forces. It is recommended that all the mounting contact surfaces on the clamping arm, table top, and post be cleaned with methanol, acetone, or alcohol to remove all unwanted oils.


Posted Comments:
seungeun_oh  (posted 2017-10-06 02:45:16.393)
Do you make the monolithic mirror mount without the hole for mirror? I want to glue a prism mirror on the vertical surface.
nbayconich  (posted 2017-10-06 05:44:38.0)
Thank you for contacting Thorlabs. We can provide this as a custom service. I will reach out to you directly about our custom capabilities.
user  (posted 2016-10-11 14:59:54.42)
I couldn't understand the large deformations due to "bridging" that you modeled. I measured table deformation using a Thor optics table, Thor pedestal, Thor clamping fork. Even with 10 ft-lb(!) of torque on the screw, the maximum table deviation was 0.0001". The fork however, flexed quite a bit. I think the modeling isn't valid. Also, why is this "bridging" a problem?
tfrisch  (posted 2016-10-25 08:57:48.0)
Hello, thank you for contacting Thorlabs. The bridging is an effect by which the top skin of a breadboard or optical table will be pulled up by the screw between the clamp's points of contacts with the table. The reason this is undesirable is that it may tilt other post mounted optics nearby. In some applications where beam steering is critical (such as coupling into single mode fiber), bridging can affect performance significantly. However, in some applications, the tolerance for deviations of the beam is much looser and may not be noticed. If you would like more details on our testing, please contact us at TechSupport@Thorlabs.com.
tmorgus  (posted 2015-09-11 14:14:33.953)
While we don't currently have a 0.5" version in design it is something that Thorlabs could offer. One of the primary goals of the Polaris line of mounts is stability. 19mm was the largest diameter optic that could be held in a monolithic mount that met our performance criteria when starting from a 1" diameter cylinder. I'll send you an email as I would be interested in your thoughts on expanding the product line. Sincerely, Tyler, Thorlabs Mechanics Business Unit
j.fischer  (posted 2015-09-11 10:48:26.807)
Are there any plans for a version designed for 0.5" Optics? What is the reason for the 19mm choice?
Polaris Mount Optic Retention Methods (Click Image to Enlarge)
Side Lock SM Threaded Low Distortion Glue In
Polaris Mount Adjuster Types (Click Image for Details)
Side Hole Hex Adjuster Knobs Adjuster
Lock Nuts
Piezo Adjusters

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.

Polaris Mounts for Ø1/2" Optics 

Polaris Mounts for Ø19 mm (3/4") Optics

Polaris Mounts for Ø25 mm Optics

Polaris Mounts for Ø1" Optics

Polaris Mounts for Ø1.5" Optics

Polaris Mounts for Ø50 mm Optics

Polaris Mounts for Ø2" Optics

Polaris Mounts for Ø3" Optics

Polaris Kinematic Platform Mount

Polaris® Fixed Ø19 mm Mirror Mount

Specificationsa
Optic Size Ø19 mm
Optic Thickness (Min) 2 mm (0.08")
Beam Heightb, c 50 mm (1.97")
Recommended Optic Mounting Torque 5.5 - 6.0 oz-in for 6 mm Thick Optics
Mounting Tapd M6 x 1.0 Tap
Alignment Pin Holes Two Ø2 mm Holes for DIN 7-m6 Ground Dowel Pins (Not Included)
Around Mounting Tap (See Drawing in Specs Tab)
Operating Temperature Range -30 to 200 °C
  • Please See the Specs Tab for Complete Specifications
  • Measured from the base of the mount to the center of the optic (optic not included).
  • Beam heights from 25 mm to 150 mm (1" to 6") are available as a custom option (see below).
  • A 1/4"-20 tap or no tap is available as a custom option (see below).
Based on your currency / country selection, your order will ship from Newton, New Jersey  
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POLARIS-19S50/M Support Documentation
POLARIS-19S50/MPolaris® Fixed Mirror Mount for Ø19 mm Optics, 50 mm Beam Height
$94.55
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Build Your Polaris Mirror Mount
Enter Beam Height [a]:
Metric   Imperial
  mm

Choose Mounting Option:
None   1/4"-20   M6

Dowel Pin:
None   2 mm Dowel Pins on a 10 mm Pitch

Include 6 mm Alignment Hole [b]:
No   Standard 20 mm Height
Your Configuration [c]

Bottom


Price per unit: --
Ships: 6 weeks
Quantity:   




Item(s) added to cart!
FrontBack
Footnotes
a) Beam height must be between 1" and 6" (25.4 mm and 152.4 mm). Allowable precision is thousandths for inches and hundredths for mm.
b) Not available for beam heights less than 1.50" (38.0 mm)
c) Dimensions are not to scale

Polaris® Non-Bridging Clamping Arm

POLARIS-CA1 Test Data
Click to Enlarge
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 additional test results.

*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.
POLARIS-CA1 Test Data
Click to Enlarge

Side-Located 1/4"-20 (M6) Screw Actuates Clamping Bore
  • 3-Point Contact Bore with Flexure Clamping Mechanism for Ø1" Post Mounting (Not Compatible with Ø25.0 mm Posts or Ø1/2" Post Holders)
  • Two 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
  • 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" 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 the fixed Polaris mount above, using a flexure clamping mechanism. They 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. 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 x 1.0 cap screw and washer. 

All clamping arms 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 a direct conversion 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 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. 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 while the POLARIS-CA1/M requires a 5 mm hex key (not included).

POLARIS-CA1 Test Data
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
$80.08
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POLARIS-CA1/M Support Documentation
POLARIS-CA1/MFlexure Clamping Arm for Ø1" Posts, Non-Bridging, Stainless Steel, M6 Clamping Screw
$80.08
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