Abstract: A spectrometer may include: an input configured to receive optical radiation; a dispersion element configured to disperse by wavelength the optical radiation passing from the input; an output; and/or a spatial light modulator (SLM) configured to receive a wavelength region of the optical radiation dispersed by the dispersion element, and configured to selectively direct wavelength portions of the received wavelength region to the output. The input may be configured to provide a plurality of entrance field stops by which the dispersion element is, in use, illuminated. Each of the plurality of entrance field stops may cooperate with the dispersion element to generate a different dispersed wavelength region at the SLM.

Abstract: A spectrometer comprising an input for optical radiation; a dispersion element, such as a concave focussing reflection diffraction grating, for dispersing incident optical radiation passing from the input by wavelength; an output and a spatial light modulator “SLM” disposed to receive a wavelength region of in-put optical radiation dispersed by the dispersion element and operable to selectively direct wavelength portions of the received wavelength region for receipt at the output. The input is configured to provide a plurality of entrance field stops, such as entrance slits, by means of each of which the dispersion element is, in use, illuminated and each of which is positioned to cooperate with the dispersion element to generate a different dispersed wavelength region at the SLM.

Abstract: A method for recording images of small particles to detect cracking includes feeding particle samples to a place for image recording, illumination a particle sample from at least two directions simultaneously, the illumination occurring with different light wavelengths for each direction, recording partial images of the illuminated particle in different channels, which are sensitive to different wavelengths, and comparing the different partial images to analyze the particle sample. Each partial image shows the particle sample illuminated from one direction by the channel recording only one of the different light wavelengths.