Scott Scargle takes a look at spectroscopy and illustrates how it could be the solution to a range of problems

No day is ever the same for a manufacturing engineer, though it is likely they will experience similar issues on a regular basis. These could include problems with quality control or approaches to material quantification, all the while needing to continually monitor the production line. This becomes more difficult at a molecular level. The naked eye enables us to see if a material is deformed, broken or of poor quality from a bulk perspective, but it is much more difficult to see defects within the intrinsic structure of a material. How then, is spectroscopy the solution for a number of issues that could impact the output of a facility?

Continuous Monitoring
All materials contain some molecular sized defects, but this doesn’t always constitute a bad material. Insufficient packing of molecules or the incorrect composition within materials could comprise the safety of the product. Post-processing inspections can result in large amounts of product being lost as it is often too late to fix any pre-existing issues. But all of these issues can be negated with real-time spectroscopy monitoring.

Spectroscopy is the technique used to see how a material reflects, absorbs and generally interacts with light. How the material interacts provides information about its molecular composition and structure. The use of spectroscopy also extends to coatings on the surface of the products. Many commercially available products, have some type of coating to protect the surface from damage and degradation. Spectroscopy offers a way to measure if the coating has been deposited evenly across the surface and can isolate points where there is insufficient coating. It can be used on coating production lines to provide real-time, non-contact monitoring over a wide surface area by measuring multiple points simultaneously.

Display colour measurement
Display colour measurement could also be a crucial part of your role. A colorimeter tells you if you have a problem with colour, but will not tell you the part of the display with the problem. Simple colorimeters use red, green and blue filters in combination with diodes or sensor pixels for measurement. More advanced systems use tristimulus filters that mimic CIE colour matching functions. Such setups work well for incandescent light sources, but are less accurate for LEDs. Handheld colour meters may measure up to 20 wavelength bands, but this is not enough for research or other high-accuracy measurements.

You may need to measure different displays, and both low and high intensity cd/m2, and not want to go back and forth performing a range of manual steps. If this is the case you will want to be able to adjust the display appropriately using an alignment camera which will line up your measurement spot in the exact locations, and have a shutter that you can control via software to take dark measurements. Such a solution needs to be in line with the industry standard for measurement accuracy CAS 140 with the ability to handle fluctuating factory temperatures, and it’s likely you only want to send the equipment out for calibration once a year. Ideally measurements must be done with no contact to the display and in real-time.

Again, spectroscopy is the preferred solution in this instance, and working with the right supplier will allow you to develop bespoke specifications, including max/minimum cd/m2 and a maintenance schedule. The colour measurement made by a spectrometer allows careful and detailed analysis of data. Colour meters and analysers based on filters or detection over specific bands do not provide as much information for the accurate determination of colour as spectral measurements.

When colour measurements are made with a spectrometer, a full reflected or emissive spectrum is the starting point for all calculations. The complete spectrum is captured, enabling the data to be analysed in different ways, even recalculated to change the observer, the illuminat, or the colour space. This flexibility isn’t available using other measurement methods.

The Spectroscopy Solution
Founded in 1989 by three oceanographers, Ocean Optics offers a range of spectroscopy solutions. One of the most recent examples is the Ocean HDX spectrometer, which provides a high throughput, low stray light and excellent thermal stability for many industrial processes including non-contact, in-line transmission spectroscopy.

Composed of a charge coupled device (CCD) array and high definition optics, Ocean Optics delivers a spectral performance that outstrips the conventional spectrometers on the market today. The versatility is also a testament to the quality that these spectrometers offer and they can even be used with optically dense samples.

The Ocean HDX spectrometer is functional over a wide wavelength range (200-1100 nm) and is stable in processing environments of up to 40 °C. One major benefit for any production line is size, and this spectrometer has a very small footprint. Even though it is compact, its data processing and communication abilities are not, with the software having the capability to accommodate up to 50,000 spectra at any one time.

So many things can go wrong on a production line, and being able to monitor how a material reflects, absorbs and generally interacts with light could be a crucial part of the quality control system. Spectroscopy is premium analysis equipment, and using the best will provide consistent, stable, repeatable and robust results with zero loss of data. In-line, real-time quality control is the future.

Scott Scargle
Scott Scargle is Director of Strategic Markets at Ocean Optics, an international company with over 5000 products and OEM customers that range from Fortune 500 companies to start-ups in a wide range of industries.