A new sensor developed by researchers at the Fraunhofer Institute for Microelectronic Circuits and Systems (IMS) in Duisburg, Germany, is expected to reduce the size of the spectrometer optics, enabling a more precise analysis in half the time previously required.
An optical emission spectrometer analyzes the composition of the metal on the basis of the emitted light spectrum. The spectrometer currently used by engineers in steel foundries and car factories to determine the characteristics of steel materials, analyze their chemical composition, and assess their quality, are considerably large and bulky.
“Whereas earlier high-resolution spectrometers were the size of a washing machine, those built using our sensor will be no bigger than a microwave oven,” says IMS department head Werner Brockherde.
Size isn’t the only advantage of the new sensor: the delivered results are also more precise and available in half the time. This can be beneficial, for example, when performing quality assurance in the automotive industry.
The spectrometer machine has to generate sparks at regular intervals to analyze a piece of steel. The sparks knock atoms out of the material, producing plasma that emits multicolored light. The plasma light is split into two beam channels and broken down into several wavebands, like the colors of a rainbow that are analyzed separately.
Light-sensitive electronic components known as CCD line sensors record the entire spectrum of the sample in the first beam channel, revealing the nature and concentration of particles suspended in the plasma. Using this, information on the composition of the steel sample is derived. This result is referred to as a space-resolved measurement.
The second beam channel produces time-resolved measurements of individual spectral lines – adjusted so that the instrument can distinguish between light emitted by the plasma and that emitted by the sparks. All previous solutions were based on separate time-resolved and space-resolved measurements, reports Fraunhofer.
“Our CMOS-based sensor enables these two sets of measurements to be conducted in parallel. As a result, we only require a single beam channel and thus a single optical unit,” says Brockherde.
The new photo-detector multiplies the dynamic range by 100 making the spectrometer faster. It has the ability to measure signals in the microvolt range at the same time as signals measuring some 100 millivolts. Until now, this required several measurement cycles.
“Because we can now measure the entire spectrum with a single series of pulses, the measurement accuracy is also higher,” reports Brockherde. “The market for spectroscopy equipment is dominated by German manufacturers,” says the scientist. “Our new sensor, which was developed in Germany and is not available anywhere else, will enable these manufacturers to secure a further competitive advantage.”
A demonstration version of the sensor will be presented at the Vision trade show in Stuttgart from November 4 to 6.
Image courtesy of Fraunhofer IMS