Industry Development and Support

Instrumentation

There are currently over 65 different commercially available NIR instruments which include bench top, on-line and portable formats. Instruments can be split up in instruments working with a limited number of fixed frequencies (e.g. filter instruments, light-emitting diodes (LEDs)) and scanning instruments. Scanning instruments can be divided monochromators (grating, diode-array, acousto-optical tunable filter (AOTF)) and those working with Fourier transform techniques (Michelson or polarisation interferometers). The highest spectral resolution (<0.1 cm^-1) can be obtained with Fourier transform Michelson interferometer instrumentation. Speed of data acquisition is for most of the scanning instruments in the range of a few seconds. Extremely high scanning rates (>100 scans per second) can be achieved with AOTF and diode-array spectrophotometers, however, this speed comes usually at the expense of spectral resolution.

Specifications could differ in terms of wavelength scanning range (400 - 2500 nm, 400 - 1700 nm, 400 - 1100 nm or 1100 - 2500 nm), wavelength data point interval (number of absorption data points), noise, stability, and measurement time. Considerations when buying instruments would include the type of sample to be analysed, wavelength range needed, spectral resolution needed, the need for pre-calibrations, network requirements and most importantly after sales support.

Instrumentation at the AWRI

The AWRI has a range of spectrophotometers available for use in research and development. These include:

• Foss NIRSystems6500: This is capable of reflectance and transmission mode scanning over the Vis-NIR ranges (400 nm to 2,500 nm) and has a transport module for measurement in transmission, reflectance and transflectance cells of a wide range in sizes. In addition, a fibre optic probe is available for transflectance or interactance measurement.
• Zeiss Corona: This spectrophotometer provides rapid measurement in reflectance mode over the Vis and NIR ranges.
• Perkin Elmer: This spectrophotometer operates in MIR range and can be fitted with a wide variety of sample presentation modules including flow through transmission cell, and attenuated total reflectance (ATR) cell for samples on a macro or microscopic scale.
• Integrated Spectronics: Several configurations are available as a result of the collaborative research and development work carried out through the CRCV during the years 2003 to 2006. This instrument measures in the Vis and NIR range and operates in reflectance mode using a specially designed large sample cell.