Optical Measuring System

Optical measurement of prestressed concrete sleepers

The online optical measuring system for concrete sleepers measures the dimensions and surface orientations related to the product with an accuracy of ±0,2 mm and detects the product's embossed allocation numbers. The survey of moving concrete sleepers can take place during the ongoing production. Whenever a pre-set tolerance margin is exceeded, an alarm is displayed.


  • Laser light section process with 4  laser light curtains
  • Pixel-synchronous image readout with synchronous triggering
  • Camera and OCR software for detection of numbers
  • Real-time and statistical analysis
  • Detection of tolerance deviations
  • Identification of creeping changes on the molds
  • Definition of dimensions and orientations of surface normals for other large-size parts

More Details

Laser light section process

Due to the texture of the concrete sleepers, a laser light section process with 2 x 2 laser light curtains is applied. In addition, two mega pixel cameras with pixel-synchronous readout and synchronous triggering are used to ensure an accurate measurement of these large objects. Embossed numbers are detected with an additional camera, a striped illumination and an optimized OCR software.


The evaluation of the measured data is performed in a timely manner. This ensures a statistical analysis of measured data including a graphical presentation, a display of time series plus an automatic generation of customized analysis- and evaluation protocols according to DIN 55 302.

During the statistical evaluation process, measured data is allocated to the associating molds. Therefore, apparent tolerance deviations are observed (to avoid complaints) and slow shape changes of molds are detected, allowing a correction before exceeding any permissible tolerances (quality control loop).