EO (Electro-Optic) sensors


A shift from mass production and mass consumption to multiple small-lot production of personalized products has rapidly progressed in recent years, and the creation of added value using advanced functional materials has garnered particular interest. Along with these changes in industrial structure and the technical advances that support those changes, there is demand for technologies that facilitate stable manufacturing and high-precision quality control.

Technologies that accurately measure manufactured products are essential for high-precision quality control. Yokogawa is working on research and development of accurate sensing technology, particularly electric field sensing technology using applied optical measurements, to help our clients solve problems they encounter in the manufacturing setting.

electric field sensing

electric field sensing


We are focusing on applied optical measurement technology using electro-optic (EO) effects to achieve advanced electric field sensing. EO sensors sense the electric field by measuring the polarization of laser beams transmitted by EO crystals (optical crystals with the Pockels effect as a primary EO effect) whose birefringence changes in response to the applied electric field. EO sensors have the following characteristics that make them applicable to the measurement of high-speed signals in electric circuits and radiation noise from electronic devices. 

  • High spatial resolution: Specialized in measurement of millimeter-scale microregions of interest. 
  • Low disturbance: Does not disturb the electric field from the target object, enabling measurement of the intact electric field distribution.
  • Wideband: Applicable in a wide frequency bandwidth from a few hertz to a few gigahertz.
  • High voltage resistance: The floating technique enables measurement under high-voltage conditions. 

We are working to find new applications of EO sensors in order to solve problems related to high-quality manufacturing. For example, we aim to infer the characteristics of materials on manufacturing lines from the attenuation of transmitted/reflected electric field signals after irradiation of the materials. We have already confirmed that this technique enables inference of the thickness and electrical characteristics of common plastic materials on manufacturing lines. We will continuously work on research and development of completely new techniques that enable safer, simpler, and more affordable sensing of material characteristics compared with the radiation-based techniques commonly used today.

EO sensor

EO sensor

Vision for the future

The above are just a few examples of applications, and we are working to enter various markets where our EO sensing technology can be used to its fullest potential to create added value.
At Yokogawa, we will continuously work to optimize the manufacturing process and create new value together with our customers by providing key devices that support the manufacturing industry, such as sensors and our control technology.