Abstract

Low-cost near infrared spectrometers have a potentially wide market used in material characterization, material sorting and food quality control (fat and proteins measurement). Such applications have relaxed demands for high diffraction efficiency and spectral resolution. The number of wavelengths used in the final calibration is often limited as seen in commercial solutions that comprise filter wheels or grating spectrometers. A standard grating can be replicated to a very low cost in large numbers [1]. The cost of detector arrays, optics for light collimation and the final production cost connected to careful alignment of a number of optical elements, will typically be much larger than the cost of a replicated grating. So, if we want to make a low-cost near infrared scanning spectrometer, we need to replace the detector array with a single detector and a scanning mechanism and integrate the functions of grating, collimating lenses and wavelength references into a Diffractive Optical Element (DOE). The design is based on the properties of diffractive lenses [2,3] and DOEs for multi-wavelength imaging [4].

© 2002 Optical Society of America