In-Line Color Measurement Solution with Non-Contact, More Speed and Accuracy

Systems in the Market

Color measurement equipment currently available on the market are manual or desktop devices. Manual equipment involves taking color samples at specific points in production, which means continuous monitoring is not possible. In the case of desktop equipment, the process is even slower as a sample must be taken from the production line, cut, taken to the laboratory, and then analyzed with the equipment. Both methods make color deviation detection a much more time-consuming process, leading to increased waste costs.



Rainbow Technology

The System Rainbow is an online color measurement device based on remote laser lighting with supercontinuum white light. It allows for the color measurement of production online at large distances from the sample (>60 mm) every few seconds. This provides an effective solution for controlling color consistency online, tailored to the needs of the industry.

Figure 1. Image of the System Rainbow
Figure 1. Image of the System Rainbow.



Rainbow can illuminate at great distances with high intensity, allowing for measurements without influence from ambient light. It has up to three color measurement zones (see Fig. 2), with a default line width of 60mm in each zone, although this value is customizable (max. 100 mm). It digitally and automatically records the color produced, storing data for each coil in a database file.



The System Rainbow allows for connections to the production line to relate processes to real-time color measurements. For example, by connecting a production line meter signal to the System Rainbow, color deviation records can be obtained for each color measurement related to the coil meter in which it was taken. With this real-time record, color deviations in production can be identified early and costs incurred by color inconsistencies can be reduced.


Figure 2. Illumination geometry of the Rainbow System in each of the measurement areas.
Figure 2. Illumination geometry of the System Rainbow in each of the measurement areas.



Rainbow has a drawer compartment (No. 2 in Fig. 1) with a dual function:

  1. During online measurement, automatic self-calibration takes place in this compartment. Inside are three reference whites for color calculation with Calibration Certificates from PTB (Physicalisch Technische Bundesanstalt in Germany).


  1. Through this compartment and following software instructions, a new color code can be entered into the Rainbow system database. With an A6 size sample of the reference color, the color code for Rainbow can be measured without the need for an external laboratory device.



The software implemented in the device (Fig. 1, No. 3) has been specifically designed for the coil coating industry, making it very intuitive for sector users. The main screen displays color coordinates and deviations from the reference color code in real time, showing with visual indicators whether the color deviation is within the defined tolerance or not. Rainbow’s software automatically generates color measurement records for all production, enhancing and optimizing quality control in production lines.