refibri is a refractometer designed for concentration measurements by means of a fiber optic sensor key features: remote control, continuous precise sensing, real-time measurement, user-friendly interface
Who we are
Promete is a small company that focuses its business on R&D and on bringing to the market new ideas from research to approach new business opportunities in selected niche markets. The company considers as main growth drivers the investment in IP, in the expertise in frontier applications and in high value-added and innovative products/services jointly developed through partnerships and collaborative actions with public and private entities.
In recent years PROMETE enhanced its R&D effort on a fiber optic laser refractometer developed as a sensor system for satellite heat pipes in aerospace application. The device has been developed in collaboration with the Industrial Engineering Department of the University of Napoli Federico II within the ESA MAP PROGRAM Innovative Wickless Heat Pipe Systems for Ground and Space Applications (INWIP) and with Eng. Antonio M. Calabrò. The optical diagnostic device is able to perform concentration measurements in mixtures used inside the heat pipes, but it obviously has wider possible applications. Refractometry is the measurement of the refractive index, and refractometric measurements can be used e.g. for purity tests, dilution control or sample composition. The methodology is used for the characterization of substances or for the determination of substance data, in particular organic liquids. An important area of application is the analysis of food products: e.g. the search for oils or fats, sugar and substances containing sugar. Beer and alcoholic drinks are also studied with refractometric methods, which are also used in the field of clinical chemistry. In addition, refractometers are used as universal detectors in the investigation of liquids.

Typical Physical Properties

Central laser wavelength: 1550 nm
Typical operating voltage: 8 (V) – DC
Max Rev voltage: 2 V
Typical Output Power 55 mW
Storage Temp: -10 to 65 °C
Operating Temp: 0 to 50 °C
Typical Weight: 1 Kg
Typical dimension: 200 mm x 150 mm x 80 mm (main box) + 95 mm x 87 mm (external card)
Fiber optics cable: Single mode fiber - glass
Length of Fiber optics cable: to be decided based on the application
Range of measurement of refractive index: 1<n<2
Phase of sample: Liquid


Class 3R laser product
Class 3B laser product


Precise measurement of the liquid concentration is important due to its applications in bio-chemical analysis, environments and contamination assessment, diagnostics, food and chemical industry. So far, many different techniques offer the liquid concentration measurement, among them the current technique which is based on Fresnel reflection gained attentions for the advantages of having real-time measurement, easy to operation, cheap setup and remote monitoring.

Laser light at wavelength of 1550 nm passes through a single mode fiber optic cable. Changing the medium at the interface between the fiber optic tip and the liquid sample results in changing the refractive index, therefore the reflected light (feedback signal) has an angle proportional to the refractive index of the second medium. Here, in the case of single mode fiber, the incidence beam is normal to the interface plane so θ1= θ2=0. According to the Fresnel reflected, the intensity of input and output are following the equation: where Iout is the signal output, Iin original input light intensity, K the calibration coefficient, nf is the refractive index of fiber optics and nx the refractive index of liquid. Since refractive index is depending on concentration, easily we can calculate the percentage of components of binary solution.

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INWIP - Innovative Wickless Heat Pipe Systems for Ground and Space Applications - ESA MAP PROGRAM

TOPDESS - Two-phase passive thermal devices for deployable space systems / ESA SciSpacE Microgravity Application Promotion Programme

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