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High-Precision Rotation Stage![]()
Ø0.94" (Ø23.9 mm) Clear PR01 Cube Beamsplitter on ![]() Please Wait
The PR01(/M) Rotation Stage provides 360° of coarse rotation and ±5° of fine rotation. Features
Thorlabs' PR01(/M) High-Precision Rotation Stage provides precise, fine rotation for large optics and optomechanical assemblies. As shown in the animation to the right, if the steel locking thumbscrew is unlocked, the stage can be smoothly and continuously rotated by hand through a full 360°, measured by the 1° graduation marks on the side of the stage. When the thumbscrew is locked, the micrometer provides ±5° of fine adjustment, measured with 5 arcmin resolution by the vernier scale. As shown to the right, the rotation stage features an array of 1/4"-20 (M6), 6-32 (M4), and 4-40 tapped holes, designed for standard optomechanics, our clamping arms (sold below), or our 30 mm cage systems. It attaches to an optical table or breadboard using the four 1/4" (M6) counterbored clearance slots. Solid Adapter Plate Rotation Adapter for 30 mm Cage Systems ![]() Click to Enlarge Figure 1: An example of how to read a vernier scale. The red arrow indicates what is known as the pointer. Since the tick mark labeled 10 on the vernier scale aligns with one of the tick marks on the main scale, this vernier scale is reading 75.60 (in whatever units the tool measures). Reading a Vernier ScaleVernier scales are typically used to add precision to standard, evenly divided scales (such as the scale on Thorlabs’ rotation mounts). A vernier scale has found common use in many precision measurement tools, the most common being calipers and micrometers. The direct vernier scale uses two scales side-by-side: the main scale and the vernier scale. The vernier scale has a slightly smaller spacing between its tick marks (10% smaller than the main). Hence, the lines on the main scale will not line up with all the lines on the vernier scale. Only one line from the vernier scale will match well with one line of the main scale, and that is the trick to reading a vernier scale. Figures 1 through 3 show a vernier scale system for three different situations. In each case, the scale on the left is the main scale, while the small scale on the right is the vernier scale. When reading a vernier scale, the main scale is used for the gross number, and the vernier scale gives the precision value. In this manner, a standard ruler or micrometer can become a precision tool. The 0 on the vernier scale is the “pointer” (marked by a red arrow in Figs. 1 – 3) and will indicate the main scale reading. In Figure 1 we see the pointer is lined up directly with the 75.6 line. Notice that the only other vernier scale tick mark that lines up well with the main scale is 10. Since the vernier 0 lines up with the main scale’s 75.6, the reading from Figure 1 is 75.60 (in whatever units the tool measures in). That is essentially all there is to reading a vernier scale. It's a very straightforward way of increasing the precision of a measurement tool. To expound, let’s look at Figure 2. Here we see that the pointer is no longer aligned with a scale line, instead it is slightly above 75.6, but below 75.7; thus the gross measurement is 75.6. The first vernier line that coincides with a main scale line is the 5, shown with a blue arrow. The vernier scale gives the final digit of precision; since the 5 is aligned to the main scale, the precision measurement for Figure 2 is 75.65. Since the vernier scale is 10% smaller than the main scale, moving 1/10 of the main scale will align the next vernier marking. This asks the obvious question: what if the measurement is within the 1/10 precision of the vernier scale? Figure 3 shows just this. Again, the pointer line is in between 75.6 and 75.7, yielding the gross measurement of 75.6. If we look closely, we see that the vernier 7 (marked with a blue arrow) is very closely aligned to the main scale, giving a precision measurement of 75.67. However, the vernier 7 is very slightly above the main scale mark, and we can see that the vernier 8 (directly above 7) is slightly below its corresponding main scale mark. Hence, the scale on Figure 3 could be read as 75.673 ± 0.002. A reading error of about 0.002 would be appropriate for this tool. As we've seen here, vernier sclaes add precision to a standard scale measurement. While it takes a bit of getting used to, with a little practice, reading these scales is fairly straightforward. All vernier scales, direct or retrograde, are read in the same fashion. ![]() Click to Enlarge Figure 2: An Example of a vernier scale. The red arrow indicates the pointer and the blue arrow indicates the vernier line that matches the main scale. This scale reads 75.65. ![]() Click to Enlarge Figure 3: An Example of a vernier scale. The red arrow indicates the pointer and the blue arrow indicates the vernier line that matches the main scale. This scale reads 75.67, but can be accurately read as 75.673 ± 0.002.
Rotation Mount and Stage Selection GuideThorlabs offers a wide variety of manual and motorized rotation mounts and stages. Rotation mounts are designed with an inner bore to mount a Ø1/2", Ø1", or Ø2" optic, while rotation stages are designed with mounting taps to attach a variety of components or systems. Motorized options are powered by a DC Servo motor, 2 phase stepper motor, or an Elliptec™ resonant piezo motor. Each offers 360° of continuous rotation. Manual Rotation Mounts
Manual Rotation Stages
Motorized Rotation Mounts and Stages
![]() ![]() Click to Enlarge PR01(/M) Schematic
The PR01(/M) Rotation Stage is a heavy-duty stage designed to precisely rotate optics, standard optomechanical assemblies, and segments of 30 mm cage systems. The rotating platform is engraved with 1° graduations and includes a vernier scale that directly provides 5 arcmin resolution. It contains 1/4" (M6) counterbored mounting slots, as well as two 1/4"-20 (M6) taps for mounting in the vertical plane. For additional stability in vertical configurations, it can be attached to our CAM1 Right-Angle Bracket. ![]() ![]() Click for Details PR01A Mounting Hole Pattern
The PR01A(/M) Adapter Plate fastens to the top of the PR01(/M) Rotation Stage via four #4 counterbored holes. The imperial version contains twelve 2-56 taps, positioned to provide direct mechanical compatibility with our miniature translation stages and goniometers, while the metric version contains four 2-56 taps and eight M2 x 0.4 taps that serve the same function. Alternatively, optics can be fixed on top of the adapter plate with our PM3(/M) or PM4(/M) Clamping Arms and rotated about the PR01's axis of rotation, as shown in the image at the top of the page. Six 6-32 (M4) taps are provided along the outer perimeter for the clamping arms. Four 8-32 (M4) taps are also included, which can be used with the PM5(/M) stainless steel clamping arm. ![]() ![]() Click for Details Mechanical Drawings
![]() Click to Enlarge Clamping Arm Extension Posts with Metric Indicator Groove Thorlabs' Clamping Arms provide clamping force to secure optics to our kinematic platform mounts, stages, and V-clamps. The PM3(/M) accommodates optics up to 0.97" tall and features a 0.69" center-to-center distance between the post and the nylon-tipped setscrew that holds the optic. The PM4(/M) accommodates optics up to 1.61" and features a 1.16" center-to-center distance between the post and the nylon-tipped setscrew. The maximum optic height of the PM3(/M) or PM4(/M) Clamping Arms can be extended using our PM3SP(/M) or PM4SP(/M) Extension Posts, respectively. These extension posts are identical to the posts included in each complete clamping arm. Each clamping arm features 6-32 (M4) threads. The PM3 and PM4 can be mounted in 8-32 tapped holes by using the AS6E8E thread adapter, which features internal 6-32 threads and external 8-32 threads. This thread adapter has an outer diameter of 0.24", which is the same as the PM4SP extension post and the post included with the PM4 clamping arm. This allows the clamping arm to be adjusted across the seam between either post and the adapter. The smaller diameters of the included post for the PM3 clamping arm and the PM3SP extension post cause the thread adapter to act as a stop for the clamping arm. The PM5(/M) clamping arm is made entirely from heat-treated stainless steel, which helps maintain stability in fluctuating temperatures and provides vacuum compatibility. This clamping arm is recommended for use with the POLARIS-K1M4(/M), but it can be used with any platform mount or stage that has one or more 8-32 (M4) tapped holes. The PM5(/M) can hold optics up to 1.65" tall, and the distance from the post center to the contact point that holds the optic is 0.90". Each clamping arm is attached to its post using a flexure mechanism that locks with a 5/64" (2.0 mm) balldriver or hex key. The setscrew on top of the clamping arm also accepts a 5/64" (2.0 mm) balldriver or hex key in order to clamp down on the optic. The post includes a through hole which can be leveraged for added torque when tightening down the post. Please see the diagram above for additional information. ![]() ![]() Click to Enlarge
30 mm Cage System Mounted on a PR01 Rotation Stage Using a CRA30 Adapter
The CRA30 Cage Rotation Adapter connects a 30 mm cage segment to a PR01(/M) Rotation Stage, allowing the cage segment to be precisely aligned via the stage's micrometer. The adapter uses a single-screw clamping mechanism that simultaneously tightens around two cage rods in a 30 mm cage system. Preassembled cage segments can simply be dropped into the open clamp; it is not necessary to feed the cage rods through the adapter. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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