Laser Tracker measurements – basic concepts

Laser Tracker measurements – basic concepts

Precision measurement of three-dimensional components is essential in many industries, including but not limited to. In the automotive, aerospace and energy industries. One option that is very popular these days is measurement services performed with a laser tracker. Laser trackers first appeared on the market in the late 1980s. In the 1970s. What do they rely on? They are able to measure the 3D coordinates of a spherical probe by tracking a laser beam aimed at a retroreflective target.

What are the distinctive features of laser trackers?

The tools described are portable, three-dimensional devices that make it possible to measure over long distances with very high precision. Thanks to the use of high-precision long-range retroreflectors, measurements can be taken at a distance of 80 meters to the head of the device, or up to 160 meters in diameter! Light weight and small size are also characteristics of such devices. Thus, they can be successfully carried from place to place by one person. This also translates into ease of transportation. The accuracy of measuring a single point is very high and is about 0.025 mm, or 25 micrometers (applies to distances of up to a few meters) which is the diameter of a white blood cell (the human eye is unable to see objects smaller than 0.040 mm . Importantly, coordinate data is collected at high speed. All these features have caused laser tracker measurement services to displace many previously used solutions.

Systems of this type usually consist of a laser tracker (head), a control unit with power supply (MCU – master control unit) and additional accessories. A computer to run the measurement software is also part of the kit.

How do laser trackers work?

The system emits a red laser beam that reflects off a retroreflector target. Importantly, it is completely safe for the eyes of those in the vicinity. The beam then returns to the laser tracker and is reflected on the position detector. The light reflected from the target therefore returns by an identical path and reaches the device at the same point from which it was emitted. When it comes to measuring probes, the spherically mounted retroreflector, or SMR, is currently the most commonly used. As the light returns to the laser tracker, part of it goes to the distance meter. This one, in turn, determines the distance between the tool and the SMR retroreflector.

The device is equipped with two rotary angle encoders and a laser distance measuring system. By measuring two angles (vertical and horizontal) and distance, the target coordinates can be determined. To measure the radial distance to the target, the so-called “radial distance” is used. ADM (Absolute Distance Meter) system, which is defined as absolute distance measurement with phase shift.

Laser tracker measurement services are guaranteed to be accurate and fast. Another advantage of laser trackers is that they can operate even in harsh industrial environments. The high IP (Ingress Protection) rating provides resistance to water and dust.