Applications for a broadband NIR spectrometer with scanning mirror device

Abstract

Spectral analysis has gained a lot of interest throughout the last decades. Nondestructive and non-contact evaluations can provide multiple information: appearance and composition, but also more complex details, which can be accessed by means of sophisticated methods like fluorescence or Raman scattering. Spectrometers have been widely used for the UV to NIR spectral range. There are applications, where a broad spectral range is beneficial. Typically, the spectral range of a grating based system is limited by higher diffraction orders. Either one decade can be detected or order filters have to be applied to discriminate different orders. A novel concept for a broadband spectrometer is the use of a scanning mirror device to illuminate a fixed grating. Due to the optical path inside, the double wavelength range can be addressed for the identical MEMS deflection. Two or more detectors, each optimized for the relevant spectral range, can be placed in the setup. A first sample of a scanning mirror micro spectrometer (“SMMS”) has been realized and tested successfully. In the NIR spectral range from 1000 nm to 1900 nm a resolution of 10 nm (FWHM) has been achieved. Application examples can be found in the field of agriculture - soil, plant growth and watering, directly leading to food, e.g. ripeness and freshness. Spectrometer with broad spectral range enable simultaneous detection of appearance (color) and composition (NIR); also fungus and aflatoxins can be detected by means of UV to VIS fluorescence. Similar task arise in textile, recycling and other fields where color, composition and conditions are of interest.

Improved scanning mirror micro spectrometer for material recognition in recycling applications

“…The spectra (fig. 6) show significantly reduced noise compared to the forerunner used before [6]. The main classes of plastic materials can be simply identified in a 1000 nm to 1900 nm range.…”