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Manual Rotation Mounts, High Precision![]()
Laser-Engraved PRM1 Precision PRM05 Post Not Included PRM1 Precision Also Available for Application Idea ![]() Please Wait Features
These high-precision rotation mounts combine 360° of coarse manual rotation with precise, backlash-free fine adjustment. These mounts are compatible with Ø1/2", Ø1", or Ø2" optics, as well as Thorlabs' SM05 (0.535"-40), SM1 (1.035"-40), or SM2 (2.035"-40) lens tubes, respectively. The PRM1 and PRM2 Ø1" and Ø2" mounts are also compatible with our cage systems. The 30 mm cage system can be attached to the PRM1, and the 60 mm cage system can be attached to the PRM2. The rotation dial features a laser-engraved scale, a knurled edge for smooth coarse rotation, and a locking mechanism. When the locking mechanism is engaged, the mount's rotation can then be adjusted via a fine drive adjuster located at the top of the mount (see below for item-specific rotation and locking information). These rotation mounts can be secured to our Ø1/2" posts via a bottom-located 8-32 (M4) tapped hole. Please see the Rotation Mounts and Stages tab for our entire selection of rotation mounts and stages. ![]() 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 scales 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, piezo inertia 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 for Details PRM05(/M) Mechanical Drawing
The PRM05(/M) high-precision rotation mount for Ø1/2" optics combines 360° of continuous coarse manual rotation with precise, backlash-free adjustment. The SM05 (0.535"-40) threaded inner bore accepts Ø1/2" optics up to 0.23" (5.9 mm) thick as well as any of our SM05-threaded components. Optics are secured between the rear lip and one SM05RR retaining ring, which is included with each mount. The edge of the rotation dial features a laser-engraved scale marked at 2° increments and can be coarsely rotated manually using the knurled ring located on the rear of the mount (see drawing to the right). Values read from the vernier scale can be converted to arcmins by multiplying by a factor of two. The 4-40 setscrew, which is inset into the side of the body of the mount, locks the dial face and engages the adjuster screw for fine rotation. When locked, the adjuster provides ±7° of rotation. The PRM05(/M) is ideal for mounting our SM05PM5 polarizing prism mount, which features compatible SM05 threading. The cover on the SM05PM5 can be rotated, thereby allowing the user to block the two side ports when they are not required. The PRM05(/M) can be purchased bundled with our SM05PM5 (Item# PRM05GL5(/M) below). Together, they provide 360° of high precision rotation for either our 5 mm Glan-Laser or Glan-Taylor Polarizer. ![]()
The PRM05GL5(/M) consists of our PRM05 rotation mount (featured above) and an SM05PM5 polarizing prism mount. The SM05PM5, which features external SM05 threading, is directly compatible with the PRM05. Its rotating cover allows the user to block the two side ports when they are not required. The PRM05GL5(/M) provides 360° of high-precision rotation for our either our 5 mm Glan-Laser or Glan-Taylor Polarizer (sold separately). ![]()
The PRM1(/M) high-precision rotation mount for Ø1" optics combines 360° of continuous manual rotation with precise, backlash-free micrometer adjustment. The SM1 (1.035"-40) threaded inner bore accepts Ø1" optics up to 0.50" (12.7 mm) thick as well as any of our SM1-threaded components. Optics are secured with one SM1RR retaining ring, which is included with each mount. The rotation dial face features a laser-engraved scale marked at 1° increments and can be rotated manually using the knurled outer surface (see drawing to the right). The thumbscrew, located on the lower right side of the mount, locks the dial face and engages the micrometer for fine adjustment. When locked, the micrometer provides ±7° of rotation at approximately 2.4 arcmin per micrometer division. The PRM1(/M) is ideal for mounting either our SM1PM10 or SM1PM15 Polarizing Prism Mounts, both of which feature compatible SM1 threading. It can be purchased bundled with our SM1PM10 (Item# PRM1GL10(/M) below). Together they provide 360° of high precision rotation for either our 10 mm Glan-Laser or Glan-Taylor Polarizer (sold separately). The PRM1(/M) is also compatible with our 30 mm cage system. The cage system can be mounted to the unit using ER cage assembly rods attached to the four 4-40 tapped holes located on the rotation dial face (there are no 4-40 tapped holes on the back of the mount). When using this product the entire 30 mm cage system will be rotated, not just the optic. Pairing this with our CPU1 Rotating Cage Plate will allow for a rotating cage segment between the PRM1 and a fixed cage system. ![]()
The PRM1GL10(/M) bundles our PRM1(/M) rotation mount featured above with our SM1PM10 polarizing prism mount. The SM1PM10, which features external SM1 threading, is directly compatible with the PRM1(/M). Its rotating cover allows the user to block the two side ports when they are not required. The PRM1GL10(/M) provides 360° of high-precision coarse rotation for either our 10 mm Glan-Laser or Glan-Taylor Polarizer (sold separately). The PRM1GL10(/M) is also compatible with our 30 mm cage system. The cage system can be mounted to the unit using ER cage assembly rods attached to the four 4-40 tapped holes on the rotation dial face (there are no 4-40 tapped holes on the back of the mount). When using this product, the entire 30 mm cage system will be rotated, not just the optic. Pairing this with our CPU1 Rotating Cage Plate will allow for a rotating cage segment between the PRM1 and a fixed cage system. ![]()
The PRM2(/M) high-precision rotation mount for Ø2" optics combines 360° of continuous coarse manual rotation with precise, backlash-free micrometer adjustment. The SM2-threaded (2.035"-40) inner bore accepts Ø2" optics up to 0.48" (12.2 mm) thick as well as any of our SM2-threaded components. Optics are secured with one SM2RR retaining ring (included with each mount). The rotation dial face features a laser-engraved scale marked at 1° increments and can be rotated manually using the knurled outer surface (see drawing to the right). The thumbscrew, located on the lower right side of the mount, locks the dial face and engages the micrometer for fine adjustment. When locked, the micrometer provides ±7° of rotation at approximately 2.4 arcmin per micrometer division. This rotation mount also features a 0.05" hex setscrew on both sides that can lock both the fine and coarse rotational movement. The PRM2(/M) is also compatible with our 60 mm cage system. The cage system can be mounted to the unit using ER cage assembly rods attached to the four 4-40 tapped holes located on the rotation dial face or the four 4-40 tapped holes located on the back side of the mount. The cage system attached to the back of the mount does not rotate. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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