Inline refractive index technology

KxS Technologies DCM concentration monitors employ the physical phenomenon of Refractive Index to define liquid concentration.

Optical concentration measurement

The optical concentration measurement is based on Snell’s law and critical angle of total reflection. Light is transmitted from the LED to the interface between the optical window and the liquid. With the concentration of the liquid, defined angles are reflected back creating light and shadow interface images on the digital camera. The interface of the light activated pixels is converted to refractive index units RIU and Brix concentration values. The measurement signal is given instantaneously.

Refractive index utilized in inline process refractometers

Turning refractive index into a fully functional inline liquid concentration monitor to meet critical process conditions is proven to be a learning curve of decades. Demanding applications, aggressive chemicals, process heat transfer, process temperature changes all have to be managed in orchestra for an automated and reliable measurement signal. When successfully implemented, inline refractive index becomes a very attractive liquid concentration technology in niche applications in various industry segments like Food & Pharmaceuticals, Chemicals, Semiconductors and Bioprocess.

How a refractometer is made


The work follows a design thinking process with a human-centered approach by embracing multi-directional partnership with people representing both suppliers as well as system integrators and client user groups. The strength of KxS Technologies lies in its agility to respond to custom design requests and therefore the design process is maintained forward-thinking.

The “BRUTAL BRICK“ design emphasizes robustness, quality and easily recognizable brand. Robust design is essential in protecting critical optical and electronic components. Critical chemical applications ask for a reliable concentration output signal and in order to secure a sharp optical measurement, computational fluid dynamics are used to simulate wetted part shapes. 3D prints are utilized in verifying interfunctionality of components. Modular structure minimizes material usage and provides flexibility in product assembly.


The instrumentation design is certified against industry relevant standards to ensure a reliable measurement performance for years to come. The DCM product family is tested for external disturbances like heat, pressure, electromagnetic compatibility, shocks and vibration. Inspection of electronics is reported in the printed circuit board PCB manufacturing and assembly services with certified quality standards.


KxS Technologies’ business continuation builds on supplier performance to secure overall product quality. Critical parts are machined to specification or sourced as is by chosen global suppliers. Material certificates or inspection reports are provided for every manufacturing batch.


The assembly of the modular solid optics and electronics is carried out at the Technology Center. NIST traceable refractive index liquid calibration procedures are followed to provide a sensor specific camera-to-refractive index unit RIU multi-sample reference correlation. An important step is to verify sensor optics alignment and optical image accuracy. A sensor individual zero-point adjustment is prepared for sensor interchangeability in field. In order to maintain quality traceability, the entire assembly process is initiated and signed off by the same engineer. Production assembly follows the philosophy: One person, one refractometer.


Each optical concentration monitor is individually calibrated with traceable refractive index RI liquids for concentration and temperature to ensure an accurate optical performance in the entire measurement range. A defined procedure is in place to verify the correct calibration parameters are activated. The final validation is documented in a Sensor Identity Profile linked to each sensor.

A zero-point calibration function serves the purpose of defining a temperature profile and standard concentration baseline for each refractometer. The setup is prepared in a liquid circulation line serving as run-in for sensor overall functionality.

User interface and integration
Digital precision

Real-time data acquisition is right on time in the process industry. Automation decisions are typically made in control systems relying on pumps, valves, flow and pressure meters play in orchestra. The user experience of inline concentration monitors is judged based on a reliable measurement signal and seamless system integration. Various standard communication protocols are used globally, and preference of instrumentation stand-alone setups versus display availability is based on process environment. The agility of KxS Technologies lies in the product platform flexibility to accommodate different user interfaces and integration combinations.

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