Laser distance sensor using mode-locking external cavity laser

TEM Messtechnik GmbH contributes to the development of a novel laser distance sensor.


A laser distance sensor is being developed which is based on a novel measuring principle. In contrast to conventional measuring methods, the measuring surface is included in the generation of the laser light (see figure). This is done by the measuring surface itself forming an end mirror of the laser resonator. By selective control of an anti-reflective laser diode as amplifier medium, it is achieved that a laser pulse circulates between laser diode and measuring object. The orbital frequency is a measure of the distance between the sensor and the target.

Compared to conventional methods, the MoLECL measurement method has the advantage that collinear measurement arrangements can be realized. The method is highly accurate with a resolution of better than 1 µm and is characterized by a very fast response time of less than 100 µs.

The MoLECL-method combines the following advantages in a single sensor:

  • Collinear measurement (little shadowing)
  • Interferometric resolution
  • High measuring rate
  • Measurement on technical surfaces
Design of the MoLECL laser distance sensor
Design of the MoLECL laser distance sensor

Funding ID: BMBF 13N8317

Project duration: 15.02.2008 – 1.02.2014

Funding body: BMBF →

Keywords:distance measurement, MoLECL, metrology, laser diode, collinear measurement

Cooperation partner: Laser Zentrum Hannover →, Sacher Lasertechnik GmbH →

Contact at TEM Messtechnik

Dipl.-Phys. Dr. Thomas Müller-Wirts
+49 (0) 511 / 510896 – 31