Leica Absolute Tracker AT901

Changing laser trackers forever

The Leica Absolute Tracker AT901 from Leica Geosystems is a portable measurement system that relies on a laser beam to accurately measure and inspect in a spherical volume of up to 160 m [525 ft]. The Leica Absolute Tracker AT901 can gather 3D coordinates in 3 ways: by following a small mirrored sphere, also known as a reflector; by tracking a Leica T-Probe, a hand-held “walk-around” wireless contact probe; or by tracking a Leica T-Scan, a contactless high-speed laser scanner. Which measurement method you should use will depend on your application.

With the combination of the Absolute Interferometer (AIFM) and PowerLock, you can forget about the laser beam forever. In the past, operators had to worry about losing or “breaking” the beam because they had to lock back onto it somehow. This process has been constantly evolving ever since our first laser tracker was introduced in 1990. First was the Absolute Distance Meter (ADM) that allowed absolute distances to be reset to the laser interferometer (IFM) automatically, then the “fast” ADM’s that sped this process up, then the Absolute Interferometer, that removed any accuracy loss due to the dynamic lock-on process, and now PowerLock with the ability to lock the laser back onto the Reflector or Probe automatically.

Depending on your measurement needs, there are three Leica Absolute Tracker AT901 types available.

Leica Absolute Tracker AT901-Basic
If your application requires positioning machines, fixtures or jigs, or if you are in the business of installing and aligning machine tools, roll mills, presses or gantry based machines, the Leica AT901-Basic is your tracker. Operating solely with a reflector, it is optimized for inspections within a typical measurement volume of up to 160 m (525 ft), and comes standard with our Leica Absolute Interferometer and PowerLock technologies.

Leica Absolute Tracker AT901-Mid Range
Since the introduction of the Leica T-Products in 2004, practically all leading automobile manufacturers have joined the ranks of our customers. When a reflector simply won’t cut it because there is no clear line of sight to the part you are trying to inspect, the part is hidden or sunken deep beneath surrounding sheetmetal, or because you need to reverse-engineer a part right there on the spot, the Leica AT901-MR is all you will need. When coupled to the Leica T-Scan, T-Probe, or T-Mac the Leica AT901-MR gives you a measurement volume of up to 18 m (59 ft). Of course, it can also be used with a standard corner cube, in which case its measurement volume goes up to a full 50 m (164 ft). The sensor is designed for large vehicle size objects and of course comes standard with our Leica Absolute Interferometer and PowerLock technologies.

Leica Absolute Tracker AT901-Long Range
This is the laser tracker that set the new benchmark for aerospace and other large scale precision measurements such as windmill blade inspection or industrial machinery alignment. It gives you hand-held wireless probing (Leica T-Probe), hand-held contactless scanning (Leica T-Scan), and full machine control abilities (Leica T-Mac) in a volume of up to 30 m (98 ft). Of course, it can also be used with a standard corner cube, in which case its typical measurement volume goes past 160 m (525 ft). This is the laser tracker that set new standards for usability with the Leica Absolute Interferometer and PowerLock, and continues to be the best selling 6DoF laser tracker in the world.

PowerLock

By utilizing an active vision system built into the sensor the Leica Absolute Tracker AT901 can determine where a target is without the need for the laser beam to be locked on and without operator intervention. This revolutionary vision system works with all standard reflectors and all Leica T-products and can lock on to the target as soon as it is within view of the sensor.

Absolute Interferometer (AIFM)

In the ideal world, a laser tracker would combine the ability to instantly re-establish a broken laser beam and immediately start measuring a moving target. At the same time, it would measure absolute distances with the highest precision and would be arbitrarily fast with near zero integration times (the time required to determine the target’s position). Until now no single distancing unit was capable of this, so laser tracker manufacturers were forced to use both laser interferometers (IFM) and Absolute Distance Meters (ADM) separately.

The AIFM combines the best of both worlds and measures absolute distances to a moving target without a loss in accuracy. It represents Leica Geosystems’ most accurate and stable dynamic distancing unit.

6 Degrees of Freedom

The Leica T-Cam, part of every Leica Geosystems Portable Coordinate Measurement System (PCMM) or as an add-on option for existing Leica Geosystems Laser Trackers migrating from reflector measurements to other target devices, is a CMOS digital camera system operating with visible light and near infrared (IR) radiation, with an optical vario zoom and a motor for vertical, angular movement.

A reflector integrated in a target device, together with a set of LEDs embedded on the surface of the target device, represent the measurement targets of the system. Six measurement parameters describe the target device in relation to the laser tracking system completely. These are 3 position parameters (x, y and z) and 3 orientation parameters (pitch, yaw and roll). Together, they comprise the Six Degrees of Freedom (6DOF) principle. These parameters are determined by the Leica Absolute Tracker AT901 (position) and the Leica T-Cam (orientation).

Feature	Benefit
PowerLock	For the first time in the history of laser trackers, the laser beam moves to the user, not the other way around.
The AIFM or “Absolute Interferometer” combines the absolute measurement from the ADM with the almost instantaneous update rate of the interferometer to produce the most accurate, stable, technologically mature distancing unit we have ever created.	Waiting for the tracker to “lock-on” is now a thing of the past. Simply catch the beam and you are measuring again without delay. No matter if you are using a reflector, Leica T-Probe, Leica T-Scan or Leica T-Mac, the AIFM can instantly re-establish a broken laser beam and immediately start measuring the moving target.
Robust construction and superior thermal stability with homogenous internal design and non-heat emitting tracker sensor head	Continuous on-spec operation in tough industrial environments with no need for frequent compensation routines; a yearly calibration is all your Leica Absolute Tracker AT901 will ever need
6 Degrees of Freedom (6DOF) Portable CMM available as an option	The world’s only technologically mature PCMM system that can probe like a fixed CMM, scan like a laser scanner and track automated applications − all in one system
Lean construction and compact dimensions, weighing 22 kg and 620 mm in length	Easy one-person transportation and installation, in full compliance with labor department regulations; whole system fits in an average-sized station wagon
ADM/IFM with small beam diameter	Use of 0.5” reflectors over full measurement range
Versatile Mounting	Mounts vertically and horizontally providing versatility in measurement volume.* ** * Typical results within specifications. ** Can not be used with the T-Cam in the horizontal position.

Leica Absolute Tracker AT901 type	AT901-B	AT901-MR	AT901-LR
Absolute Interferometer	yes	yes	yes
Typical measurement volume	160 m	50 m	160 m
Compatible with T-Products	no	yes	yes
Max. measurement volume with T-Products	n/a	18 m	30 m