Compact Quick-Connect Goniometer Stages with Crossed-Roller Bearings
- ±8° Pure Rotational Motion About a Fixed Point Above the Stage
- Vernier Scale Provides 7.5 arcmin Resolution
- Integrated 2" Dovetails for Multi-Axis Construction
- Crossed-Roller Bearings for High Load Capacity,
Rigidity, and Stiffness
74 mm to Point of Rotation
50 mm to Point of Rotation
50 mm to Point of Rotation,
±8° / ±8° Rotation
All goniometers feature
a fixed point of rotation
above the stage platform.
Shown with Adjuster
|Distance from Top Surface
to Point of Rotation
|Rotation Range||±8°||±8° / ±8°|
|Vernier Scale Resolution||7.5 arcmin (0.125°)|
|Adj. Knob Revolution||0.9°/rev (0.015 rad/rev)|
|Load Capacity||3.5 lbs (1.59 kg)||2.8 lbs (1.25 kg)|
|Bearing Type||Crossed-Roller Bearings|
|8-32 (M4 x 0.7), 5.08 mm Deep (2 Places)
1/4"-20 (M6 x 1.0), 7.6 mm Deep (7 Places)
2" Quick-Connect Dovetails
|Platform Size||2.00" x 2.00" (57.0 mm x 57.0 mm)|
|1.02" (26.0 mm)||1.97" (50.0 mm)|
|Base Dimensions||3.35" x 2.01" (85.0 mm x 51.0 mm)a|
|Base Mounting Features||2" Quick-Connect Dovetails|
|Four Mounting Slots for 1/4"-20 (M6) Cap Screws|
|Weight (Mass)||0.75 lbs (0.34 kg)||1.5 lbs (0.68 kg)|
- Pure Rotational Motion About a Virtual Point
- Anti-Backlash Leadscrew Drive and Removable Adjuster Knob
- Crossed-Roller Bearings for High Load Capacity, Rigidity, and Stiffness
- Quickly Connect Stages and Accessories Using 2" Dovetails
- Dual-Axis Versions Available
- Optional Accessories Provide Additional Functionality:
- Z-Axis Assembly Kits: Mount Stages Orthogonally to Breadboard (Available Below)
- Rail Carriers: Removable Plates with Additional Mounting Options
- Rail Plate: Deck Height Axis Matches XRN25 Series Stages
- Rotation Adapter: Coarse Rotation Between Components
- Mounting Adapters: Mount 2" Dovetail Stages to 3" Stages or Rails (Available Below)
- Base Plate: Coarse Alignment of Stage with Table Hole Matrix (Available Below)
- Stage Positioners: Alignment of Stages Along Rails
Thorlabs' XRNG Series Goniometers (or goniometric stages) provide ±8° of precise rotation about a fixed point in space. These goniometers use crossed-roller steel bearings to support precision motion and high load capacities. The top and bottom plates are machined from cast tool and jig aluminum for minimal internal stress and improved stability. The anti-backlash leadscrew drive and a vernier scale provide accurate and repeatable positioning. Stage rotation can be locked via a lock plate that accepts a 5/64" (2.0 mm) hex key or ball driver. The adjuster knob can be removed using by loosening the setscrew on its shaft using a 0.05" hex key, reducing the overall length of stage for constrained setups. With the knob removed, the drive shaft can be actuated using a 5/64" (2.0 mm) hex key.
The distance from the mounting surface to the point of rotation is designed so that an XRNG2(/M) may be stacked on top of an XRNG1(/M) stage and both stages will rotate about the same point. The XRNG-K1(/M) dual-axis kit consists of two such complementary stages which must be connected by the user. The stages may be mounted directly to a table or breadboard, onto a baseplate, or onto another XRN series compact stage. Refer to the table above and to the diagrams below for details.
The top and bottom of each stage feature quick-connect dovetails (as shown in the lower right image) that allow for the construction of multi-axis systems without the need for additional hardware. The stages are secured by a single dovetail locking mechanism that can be actuated with a 3/16" (5 mm) hex key. The 2" dovetails on our XRNG series stages are directly compatible with the dovetails on the stages shown in the selection guide below. Additional functionality is provided by a complete line of accessories that include multi-axis assembly kits, rail carriers, a rotation adapter, and rails. An adapter plate is also available for mounting these compact stages with an integrated 2" dovetail onto translation and rotation stages with a 3" dovetail. For more information about a specific accessory, please click on the link in the table below.
Note: Using mounting hardware that exceeds the tap depth of the mounting holes will damage the stage. Before mounting components onto the goniometers, please review the mounting hole tap depths listed in the table above and on the support documents, accessible by clicking on the red Docs () icon next to each Item # below.
Click to Enlarge
The 2" female dovetails on the bottom of the stage mate with the male dovetails on another stage to form multi-axis configurations. The left female dovetail is on a retractable clamping arm, allowing stages to be dropped into place.
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 Scale
Vernier 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.
|No Comments Posted|
Click for Details
XRNG2 Goniometer Mounted Vertically Using XRN-XZ Kit
and XRN-B1 Base Plate
- Kits Consist of Angle Bracket and Mounting Plate
- Support Vertical Mounting Configurations
- Compatible with 2" Mating Dovetail Stages
- Dovetail Clamp Screw has a Max Torque of 15 in•lbs
The XRN-XZ(/M) and XRN-YZ(/M) Assembly Kits enable vertical mounting of an XRNG Series Goniometer Stage. These assembly kits can be directly mounted onto a base plate or onto other stages with 2" mating dovetails, as illustrated in the photos to the right. When used to mount a goniometer stage vertically on a linear translation stage, the XRN-XZ kit positions the surface of the goniometer (at 0°) parallel to the direction of linear motion, while the XRN-YZ kit would orient the goniometer stage platform perpendicular to the direction of motion.
Each kit includes an angle bracket and a mounting plate. The female dovetail on the vertical stage attaches to one of the mounting plate's male dovetails. The mounting plate's other male dovetail is then mated to an arm of the angle bracket. The other arm of the angle bracket attaches to the base plate or horizontal stage.
|Mounting Adapter Compatibility|
|Item #||Orientation||Top Component||Bottom Component|
- XRN-A1 Adapter Enables Perpendicular Mounting of 2" Dovetail Components onto 3" Dovetail Components
- XRN-A2 Adapter Enables Parallel Mounting of 2" Dovetail Components onto 3" Dovetail Components
- Adapters Add 0.275" (7.0 mm) to the Overall Stacked Height of Components
These adapters enable mounting of quick-connect, crossed-roller bearing stages or accessories with a female 2" dovetail to components with a male 3" dovetail, as illustrated in the photos below. The XRN-A1 adapter enables perpendicular mounting while the XRN-A2 enable parallel mounting. The second photo below illustrates a parallel mounting configuration with a smaller footprint.
To assemble, first loosen the dovetail locking screw on the end of the top stage or accessory. Position the adapter on the bottom stage or rail, as illustrated in the photos below, then align the top component on the adapter. Lastly, tighten the dovetail locking screw (maximum torque: 15 in•lbs) on the end of the top component until the entire assembly is secure. Please note that the deep-set screws in the sides of the adapter are not user adjustable.
Click to Enlarge
Stages can be mounted vertically using a vertical assembly kit and the XRN-B1 base plate.
- 1.26" Long, 1/4" (M6) Counterbored Slots for Additional Mounting Flexibility
- Orthogonal Male Dovetails for Two Stage Mounting Orientations
- Compatible with 2" Mating Dovetail Stages
The XRN-B1(/M) baseplate offers additional mounting flexibility for coarse positioning of the XRNG series goniometric stages within a setup. Three 1.26" long, 1/4" (M6) counterbored slots allow for coarse translation adjustment of the stage. The orthogonal dovetails on the top of the base plate allow the stage to be mounted in two orientations. The middle slot is designed to be secured by two 1/4"-20 (M6) cap screws onto an optical table or breadboard, which allows the stage to be aligned with the table's or breadboard's hole pattern.
Vertical Stage Configuration
For situations where a vertically mounted rotation stage is needed, either the XRN-XZ or the XRN-YZ angle bracket (sold above) can be secured directly to the baseplate. This configuration is illustrated in the photo to the right and described in more detail in the Vertical Stage Assembly Kits section above.