Spectral Color Measurements with JENCOLOR

In applications that require very high color accuracy, three-element color detection quickly reaches its physical limitations, which are caused by limited light source availability and a relatively high error threshold. High-accuracy applications require spectral technologies that have a greater resolution than just three channels. A typical spectrometer would have the kind of resolution encountered in laboratory measurement devices, or in some OEM spectrometers for in-line measurements. Unfortunately, such spectrometers are too slow, too expensive and too big for most sensor applications.

With the MMCS6 Multiple Color Sensor, MAZeT is closing the gap between tri-color sensors and spectral analyzers. The MMCS6 employs compact, price-performance-optimized semiconductor sensors with integrated interference filters and combines these with seven spectral bands (ranging from 380 to 780 nm) to produce a color measurement based on spectral approximation.

In this sensor, the color is not analyzed on the colorimetric level but on the radiometric level. The output from the sensor does not indicate the color space but the color's spectrum, which is then used to compute the color space. The advantage of this method is that a lot more color information is produced.

With this sensor, metamerism effects are filtered out during capturing and analysis, which isn't possible with RGB and XYZ sensors. Metamerism effects are optically distinct spectrums that appear to be the same to the human eye when viewed in the same lighting conditions.

The spectral bands of the MMCS6 all overlap. As a result, there are virtually no gaps in the visible spectrum. This minimizes any erroneous color interpretation and increases the measurement accuracy. In typical usage scenarios, the sensor is not affected by the quality of the light source. The MMCS6's spectral approximation of the measured colors can indicate color variations that are imperceptible to the human eye.

The following table compares three sensor types and their typical measurement values. This demonstrates the different accuracy categories of color measurements using color sensors and white-light LEDs. The measurement values were attained by illuminating a set of predefined color plates with a white-light LED (lpeak = 450 nm).

MAZeT is offering the new sensor as part of OEM system solutions. It ships with an extensive software library for highly accurate and fast color measurement using hand-held or in-line devices. The amplifier component used with the sensor is MAZeT's own MTI08, which features eight programmable amplifier stages plus S&H and an MUX output. Evaluation boards are available for test measurements, which customers can integrate into their own testing software via DLLs if needed.

With the MMCS6, MAZeT is further expanding its line of color sensors with long-term stability and high temperature consistency.