ALAR MechanicalBearing DirectDrive Rotary Stage
Description
Design Features
 5 different aperture sizes: 100 mm, 150 mm, 200 mm, 250 mm, 325 mm
 Axial load capacity up to 595 kg; radial loads to 680 kg
 Excellent accuracy and repeatability
 Cog free motor provides smooth motion
 No accuracy changes over time from gear wear
 45300 rpm continuous rotation speed
 Vacuum compatible versions available
 Absolute encoder options
Aerotech’s ALAR series directdrive rotary stages provide superior angular positioning and velocity control with exceptionally large apertures. With the combination of a large aperture and directdrive motor, the ALAR series makes wormdrive large aperture stages a thing of the past.
Advantage ALAR
Now customers can get large aperture rotary stages with zero backlash and no gear wear or gear vibration as is commonly seen in wormdrive stages. The other added benefit is that direct drive is significantly faster than worm drive, so testing can be completed in less time. In production settings, this equates to 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. With higher accuracy and no backlash, customers can produce more accurate products because their test system is now more accurate.
Applications
Applications for the ALAR include single and multiaxis electrooptic sensor testing, missile seeker testing, antenna testing, inertial navigation device testing, photonic component alignment, highaccuracy laser machining and precision wafer inspection. These include testing in vacuum to 10^{6} torr. These rotary stages can also be configured as multiaxis gimbals.
High Speed
ALAR stages can operate between 45300 rpm, depending on the particular model selected. This speed range is significantly higher than geardrive stages of similar size.
Superior Mechanical Design
Angular contact bearings are used to maximize performance with respect to tilt error, moment stiffness and rotating friction. A precisionmachined shaft further minimizes tilt error. The design incorporates integral connections that minimize cable issues. The ALAR works especially well in applications that require 360° continuous motion but have limited space. The stage is 65160 mm tall and provides smooth motion without travel restrictions.
Brushless DirectDrive
To maximize positioning performance, the ALAR series utilizes Aerotech’s brushless, slotless motors. This motor has all of the advantages of a brushless directdrive 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 so it can handle 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 good for applications where the axis of rotation is parallel to gravity. Both the SP and LP units have the same aperture options and motor options. Either SP or LP stages can handle between 2601300 lb of axial load.
Accurate Positioning
Performance is assured with encoder line counts from 31000 to 76800 per rev, resulting in resolutions from 0.02 arc sec/count to 0.009 arc sec/count. The motor and highperformance rotary encoder are directly coupled to a common shaft. The absence of gear trains and mechanical couplings means no position errors caused by hysteresis, windup or backlash. As a result, accuracy of ±2 arc sec and bidirectional repeatability of ±0.5 arc sec is attainable.
Flexible Configurations
Aerotech manufactures a wide range of servo amplifiers and advanced controllers to provide a complete, integrated package.
Specifications
ALAR Series Specifications
Model  ALAR100SP  ALAR100LP  ALAR150SP  ALAR150LP  

Aperture  100 mm  100 mm  150 mm  150 mm  
Motor  S18044A  Brushless Slotless  S24043A  Brushless Slotless  
Continuous Current  A_{pk}  2.7 A  5.76 A  6.2 A  5.41 A 
A_{rms}  1.9 A  4.1 A  4.4 A  4.1 A  
Peak Current, Stall  A_{pk}  10.8 A  33.5 A  24.8 A  31.4 A 
A_{rms}  7.6 A  23.7 A  17.5 A  22.2 A  
Bus Voltage  Up to 340 VDC  
Length  250 mm  250 mm  300 mm  300 mm  
Width  250 mm  250 mm  300 mm  300 mm  
Height  100 mm  65 mm  100 mm  65 mm  
Unlimited Travel  Yes  
Maximum Limited Travel  ±170°  ±170°  ±170°  ±170°  
Maximum Velocity @ 160 V Bus^{(1)}  300 rpm  50 rpm  250 rpm  45 rpm  
Maximum Acceleration  1364 rad/s^{2}  1009 rad/s^{2}  1330 rad/s^{2}  829 rad/s^{2}  
Resolution^{(2)}  0.1 µrad (0.02 arc sec) 
0.1 µrad (0.02 arc sec) 
0.08 µrad (0.016 arc sec) 
0.09 µrad (0.018 arc sec) 

Maximum Torque  23.9 N·m  17.5 N·m  42.9 N·m  22.9 N·m  
Continuous Torque  6.0 N·m  3.0 N·m  10.7 N·m  4.0 N·m  
Stage Mass 
16.3 kg 
8.3 kg 
18.6 kg 
9.8 kg 

Stage Mass with Limits  17 kg 
8.9 kg 
19.6 kg 
10.8 kg 

Shaft Inertia  0.022 kg·m^{2}  0.022 kg·m^{2}  0.040 kg·m^{2}  0.031 kg·m^{2}  
Shaft Inertia with Limits  0.026 kg·m^{2}  0.026 kg·m^{2}  0.051 kg·m^{2}  0.042 kg·m^{2}  
Axial Load  1550 N (348 lb)  1175 N (264 lb)  1950 N (438 lb)  1325 N (298 lb)  
Radial Load  1350 N (303 lb)  950 N (214 lb)  1925 N (433 lb)  1275 N (287 lb)  
Moment Load  250 N·m  150^{(3)} N·m  450 N·m  225^{(3)} N·m  
Repeatability  ±2.4 µrad (±0.5 arc sec)  
Accuracy^{(4)}  ±9.7 µrad (±2 arc sec)  
TiltError Motion  9.7 µrad (2.0 arc sec) 
 Squarewave digital encoder options will limit maximum speed below the listed value. Contact factory for specific stage and encoder speed combination.
 Resolution assumes AS encoder with 2000X controller multiplication.
 The ALARLP base must be fully supported by a rigid mounting plate to achieve this moment load.
 Certified with each stage. Requires the use of an Aerotech controller.
ALAR Series Specifications
Model  ALAR200SP  ALAR200LP  ALAR250SP2  ALAR250SP3  ALAR250LP  

Aperture  200 mm  200 mm  250 mm  250 mm  250 mm  
Motor  Brushless Slotless  
Continuous Current  A_{pk}  5.3  5.3  5.3  7.95  5.3 
A_{rms}  3.75  3.75  3.75  5.62  3.75  
Peak Current, Stall  A_{pk}  34.8  34.8  34.8  52.2  34.8 
A_{rms}  24.6  24.6  24.6  36.9  24.6  
Bus Voltage  Up to 340 VDC  
Length  400 mm  400 mm  450 mm  450 mm  450 mm  
Width  400 mm  400 mm  450 mm  450 mm  450 mm  
Height  150 mm  100 mm  150 mm  150 mm  100 mm  
Unlimited Travel  Yes  
Maximum Limited Travel  ±170°  ±170°  ±170°  ±170°  ±170°  
Maximum Velocity^{(1)}  90 rpm  90 rpm  140 rpm  140 rpm  90 rpm  
Maximum Acceleration  361 rad/s^{2}  570 rad/s^{2}  287 rad/s^{2}  287 rad/s^{2}  407 rad/s^{2}  
Resolution^{(2)}  0.06 µrad (0.012 arc sec) 
0.07 µrad (0.014 arc sec) 
0.05 µrad (0.01 arc sec) 
0.05 µrad (0.01 arc sec) 
0.05 µrad (0.01 arc sec) 

Maximum Torque  126.8 N·m  126.8 N·m  137.8 N·m  206.7 N·m  147.9 N·m  
Continuous Torque  19.3 N·m  19.3 N·m  21.0 N·m  31.5 N·m  22.5 N·m  
Stage Mass 
40.4 kg 
28.2 kg 
51.3 kg 
51.3 kg 
35.0 kg 

Stage Mass with Limits  43.1 kg 
30.1 kg 
54.5 kg 
54.5 kg 
37.4 kg 

Shaft Inertia  0.320 kg·m^{2}  0.190 kg·m^{2}  0.500 kg·m^{2}  0.500 kg·m^{2}  0.310 kg·m^{2}  
Shaft Inertia with Limits  0.359 kg·m^{2}  0.229 kg·m^{2}  0.573 kg·m^{2}  0.573 kg·m^{2}  0.383 kg·m^{2}  
Axial Load  4675 N (1051 lb)  4350 N (978 lb)  4950 N (1113 lb)  4950 N (1113 lb)  4950 N (1113 lb)  
Radial Load  4775 N (1073 lb)  4125 N (927 lb)  5200 N (1169 lb)  5200 N (1169 lb)  5050 N (1135 lb)  
Moment Load  1600 N·m  1075^{(3)} N·m  1825 N·m  1825 N·m  1475^{(3)} N·m  
Repeatability  ±2.4 µrad (±0.5 arc sec)  
Accuracy^{(4)}  ±9.7 µrad (±2 arc sec)  
TiltError Motion  9.7 µrad (2.0 arc sec) 
 Squarewave digital encoder options will limit maximum speed below the listed value. Contact factory for specific stage and encoder speed combination.
 Resolution assumes AS encoder with 2000X controller multiplication.
 The ALARLP base must be fully supported by a rigid mounting plate to achieve this moment load.
 Certified with each stage. Requires the use of an Aerotech controller.
ALAR Series Specifications
Model  ALAR325SP2  ALAR325SP3  ALAR325LP  

Aperture  325 mm  325 mm  325 mm  
Motor  Brushless Slotless  
Continuous Current  A_{pk}  5.1  7.65  5.1 
A_{rms}  3.63  5.41  3.63  
Peak Current, Stall  A_{pk}  31.2  46.8  31.2 
A_{rms}  22.1  33.1  22.1  
Bus Voltage  Up to 340 VDC  
Length  525 mm  525 mm  525 mm  
Width  525 mm  525 mm  525 mm  
Height  150 mm  150 mm  100 mm  
Unlimited Travel  Yes  
Maximum Limited Travel  ±170°  ±170°  ±170°  
Maximum Velocity^{(1)}  150 rpm  150 rpm  120 rpm  
Maximum Acceleration  185 rad/s^{2}  185 rad/s^{2}  339 rad/s^{2}  
Resolution^{(2)}  0.04 µrad (0.009 arc sec)  0.04 µrad (0.009 arc sec)  0.04 µrad (0.009 arc sec)  
Maximum Torque  213.8 N·m  320.8 N·m 
213.8 N·m 

Continuous Torque  35.0 N·m  52.4 N·m  35.0 N·m  
Stage Mass 
61.2 kg 
61.2 kg 
44.5 kg 

Stage Mass with Limits  64.9 kg 
64.9 kg 
49.9 kg 

Shaft Inertia  1.01 kg·m^{2}  1.01 kg·m^{2}  0.55 kg·m^{2}  
Shaft Inertia with Limits  1.2 kg·m^{2}  1.2 kg·m^{2}  0.675 kg·m^{2}  
Axial Load  5825 N (1310 lb)  5825 N (1310 lb)  5825 N (1310 lb)  
Radial Load  6650 N (1495 lb)  6650 N (1495 lb)  6450 N (1450 lb)  
Moment Load  2650 N·m  2650 N·m  2200^{(3)} N·m  
Repeatability  ±2.4 µrad (±0.5 arc sec)  
Accuracy^{(4)}  ±9.7 µrad (±2 arc sec)  
TiltError Motion  9.7 µrad (2.0 arc sec) 
 Squarewave digital encoder options will limit maximum speed below the listed value. Contact factory for specific stage and encoder speed combination.
 Resolution assumes AS encoder with 2000X controller multiplication.
 The ALARLP base must be fully supported by a rigid mounting plate to achieve this moment load.
 Certified with each stage. Requires the use of an Aerotech controller.
Dimensions
Ordering Information
ALAR Series
Option  Description 

100LP  65 mm high directdrive rotary stage with 100 mm clear aperture, dual precision bearings, 3.0 N·m continuous torque and 31488 line amplified sine encoder 
100SP  100 mm high directdrive rotary stage with 100 mm clear aperture, dual precision bearings, 5.9 N·m continuous torque and 31488 line amplified sine encoder 
150LP  65 mm high directdrive rotary stage with 150 mm clear aperture, dual precision bearings, 4.0 N·m continuous torque and 36000 line amplified sine encoder 
150SP  100 mm high directdrive rotary stage with 150 mm clear aperture, dual precision bearings, 10.7 N·m continuous torque and 40000 line amplified sine encoder 
200LP  100 mm high directdrive rotary stage with 200 mm clear aperture, dual precision bearings, 19.3 N·m continuous torque and 47200 line amplified sine encoder 
200SP  150 mm high directdrive rotary stage with 200 mm clear aperture, dual precision bearings, 19.3 N·m continuous torque and 55040 line amplified sine encoder 
250LP  100 mm high directdrive rotary stage with 250 mm clear aperture, dual precision bearings, 22.5 N·m continuous torque and 55040 line amplified sine encoder 
250SP2 
150 mm high directdrive rotary stage with 250 mm clear aperture, dual precision bearings, 21.0 N·m continuous torque and 64800 line amplified sine encoder 
250SP3  150 mm high directdrive rotary stage with 250 mm clear aperture, dual precision bearings, 31.5 N·m continuous torque and 64800 line amplified sine encoder 
325LP  100 mm high directdrive rotary stage with 325 mm clear aperture, dual precision bearings, 35.0 N·m continuous torque and 64800 line amplified sine encoder 
325SP2LT  160 mm high directdrive rotary stage with 325 mm clear aperture, dual precision bearings, 35.0 N·m continuous torque and 74612line amplified sine encoder; typically used in applications where the axis of rotation is horizontal or vertical. NOTE: The 325SP2LT is limited travel only. It must include the LI limit option. Customer must provide hardstops appropriate for their application. 
325SP2CT  160 mm high directdrive rotary stage with 325 mm clear aperture, dual precision bearings, 35.0 N·m continuous torque and 76800line amplified sine encoder; typically used in applications where the axis of rotation is horizontal or vertical. NOTE: The 325SP2CT is unlimited travel. If LI limit option is required, customer must provide hardstops appropriate for their application. 
325SP3LT  160 mm high directdrive rotary stage with 325 mm clear aperture, dual precision bearings, 52.4 N·m continuous torque and 74612line amplified sine encoder; typically used in applications where the axis of rotation is horizontal or vertical. NOTE: The 325SP3LT is limited travel only. It must include the LI limit option. Customer must provide hardstops appropriate for their application. 
325SP3CT  160 mm high directdrive rotary stage with 325 mm clear aperture, dual precision bearings, 52.4 N·m continuous torque and 76800line amplified sine encoder; typically used in applications where the axis of rotation is horizontal or vertical. NOTE: The 325SP3CT is unlimited travel. If LI limit option is required, customer must provide hardstops appropriate for their application. 
Note: SP is for horizontal or vertical axis applications; LP is for vertical axis applications.
Encoder Type
Option  Description 

CT  Continuous Travel Internal Encoder 
Encoder Output Options
Option  Description 

AS  Standard feedback device; 1 V_{pp} sine wave output; multiply the selected stage resolution by the encoder multiplier to get final resolution of counts per rev 
X5  Squarewave digital output which includes a 5times multiplier; multiply the selected stage encoder lines by 20 to get the final resolution of counts per rev* 
X10  Squarewave digital output which includes a 10times multiplier; multiply the selected stage encoder lines by 40 to get the final resolution of counts per rev* 
X25  Squarewave digital output which includes a 25times multiplier; multiply the selected stage encoder lines by 100 to get the final resolution of counts per rev* 
X50  Squarewave digital output which includes a 50times multiplier; multiply the selected stage encoder lines by 200 to get the final resolution of counts per rev* 
REABS  Rotary encoder, absolute  contact factory (compatible with HPe, HLe, CP, and CL drives only) 
Note: * indicates this includes controller quadrature; X5, X10, X25, X50 squarewave encoder options have limited bandwidth and may not reach stage max speed. Please contact factory to confirm speed per stage.
Limit Options
Option  Description 

UNLIMITED  No travel limits or hardstops; valid only with CT encoder type 
LIx  Normallyclosed limits at x degrees total travel, where x = 10/20/30/60/90/120/180/240/300/340; integrated hardstops 5 degrees past LI limit switch angles; other travel angles available by special order; increases stage height by 10 mm; can be used with CT or LT encoder types; ALAR250 and ALAR325 hardstops are special order only; contact the factory for pricing 