Rotary Stages provide 45-300 rpm continuous rotation.

Press Release Summary:

Available in 100, 150, 200, 250, and 325 mm aperture sizes, ALAR Rotary Stages provide angular positioning and velocity control with axial load capacity of 300-1,000 lb. Stages are 65-160 mm tall and deliver smooth motion without travel restrictions. They utilize brushless, slotless motors with zero cogging and no torque ripple. Performance is assured with encoder line counts from 31,000-74,000 per rev, resulting in resolutions from 0.02-0.009 arc-sec/count.

Original Press Release:

Alar Series Direct-Drive, Large-Aperture, Rotary Stages

Alar Series Direct-Drive, Large-Aperture, Rotary Stages

o 5 different aperture sizes: 100 mm, 150 mm, 200 mm, 250 mm, 325 mm
o 45-300 rpm continuous rotation speed
o Continuous or limited travel
o Axial load capacity of 300-1000 lb
o Excellent accuracy and repeatability
o Low wobble and bearing run out
o Cog free motor provides smooth motion
o Vac 10-6 torr compatible versions available

ALAR series direct-drive rotary stages provide superior angular positioning and velocity control with exceptionally large apertures, load capability, and very high speeds. With the combination of a large aperture and direct-drive motor, the ALAR series offers significant performance benefits compared to worm-drive large aperture stages. Now customers can get large aperture rotary stages with zero backlash and no gear wear or gear vibration as is commonly seen in worm-drive stages. Another benefit is that direct drive is significantly faster than worm drive, so you get faster testing, lower cost manufacturing, and higher profits. From the standpoint of system accuracy and repeatability, the stage will maintain its performance over time with no need for maintenance because there are no gears to wear out.

Applications for the ALAR include single and multiaxis electro-optic sensor testing, missile seeker testing, antenna testing, inertial navigation device testing, photonic component alignment, high-accuracy laser machining, and precision wafer inspection. The ALAR is also applicable to testing in vacuum to 10-6 torr. These rotary stages can also be configured as multiaxis gimbals.

High Speed
Conventional worm-drive rotary stages with similar apertures and payload capacity only operate to 15 rpm or less. ALAR direct-drive stages operate from 45 to 300 rpm continuous rotation - significantly faster than worm-drive stages.

Superior Mechanical Design
Angular contact bearings are used to maximize performance with respect to wobble, moment stiffness, and rotating friction. A precision-machined shaft further minimizes wobble. The ALAR works especially well in applications that require 360° continuous motion but have limited space - the stage is 65-160 mm tall and provides smooth motion without travel restrictions.

Brushless Direct-Drive
To maximize positioning performance, the ALAR series utilizes Aerotech's brushless, slotless motors. This motor has all of the advantages of a brushless direct-drive motor - no brushes to wear, no gear trains to maintain, and high acceleration and high speeds. Since it is a slotless, ironless design, there is zero cogging, meaning there is absolutely no torque ripple. This makes the ALAR ideal for applications requiring outstanding contoured motion, smooth scan velocity, or precise incremental steps.

High Payload Capacity and Large Moment Load Stiffness
The ALAR comes in two different configurations. The standard profile (SP) unit has high payload capacity and high moment load stiffness for applications where its rotation axis is parallel or perpendicular to gravity and the payload center of gravity is cantilevered away from the stage. The low profile (LP) unit has high payload capacity and is for applications where the axis of rotation is parallel to gravity.

Accurate Positioning
Performance is assured with encoder line counts from 31000 to 74000 per rev, resulting in resolutions from 0.02 arc-sec/count to 0.009 arc-sec/count. The motor and rotary encoder are directly coupled to a common shaft. Accuracy is ±3.9 arc-sec and bi-directional repeatability is ±0.5 arc-sec.

For further information, please contact Steve McLane at 412-967-6854 (direct), or via e-mail at In addition, the ALAR series data sheet is available at

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