LISG Laser Interferometric Sensor for Glass


The LISG was developed more than 20 years ago to measure the variations in the diameter of the optical fiber at the exit of the furnace during the fiber drawing process. Thanks to performances that far exceeded what was achieved at the time, it immediately met with tremendous success. First in Europe, then in Asia and since then used by the biggest names in optical fibers worldwide.

Diameter measurement of the bare optical fiber  

Initially used for ultra-fast diameter measurement, CERSA then equipped it with other features for the detection of flaws such as airlines, that can appear in the glass.  Fine air cavities in the glass like these can weaken the optical fiber.

The LISG is also able to calculate the frequency and the spinning profile of the process. That is, the rotation of the fiber about itself, a technique regularly used by manufacturers. A complete system that has won over a demanding public in terms of performance, functionality and robustness. A very large number of fiber drawing towers worldwide are now equipped with an LISG, based on the principle of optical interferometry.

100% laser control and real-time measurements of optical fiber

Its real-time measurement is a real advantage for fiber drawing towers whose speeds are increasing all the time. An indispensable instrument which, together with other optical fiber measuring products, ensures 100% certification of the quality of your fiber.

The LISG is available in 2 versions: Base and Full

The functionalities of the Base LISG (5,000 measurements/s):

  • Absolute measurement of the bare optical fiber diameter (125µm).
  • Detection of airlines in the glass
  • Detection of surface defects and impurities inside the cladding
  • Precise measurement of the fiber position (assists with the positioning and alignment of the drawing tower)
  • The additional features of the Full version (50,000 measurements/s):
  • Calculation of the spinning process and its period
  • Measurement of the non-circularity of the fiber
  • Calculation of peak-to-peak diameter for monitoring the stability of the drawing process

Digital and analog inputs and outputs, RS232 output, fieldbus options, are used to connect the LISG to the tower PLC for control loop needs and measurement analysis.