Abstract: The present invention relates to an instrument for measuring in relatively short periods of time concentrations of constituents in optically dense materials using the spectra near infrared radiation transmitted through thick samples of the material while the material is either stationary or flowing. The invention uses a broadband incandescent intensity stabilized light source combined with collimating optics to transmit a parallel beam of light through the material under test. The light transmitted through the material is then collected by a focusing lens and imaged onto a rectangular entrance slit of a special purpose spectrometer. This spectrometer has no moving parts and employs a fixed diffraction grating to physically spread the image of the entrance slit into a continuous range of wavelengths. A portion of the diffracted slit images covering the selected portion of the near infrared range is focused onto an array of individual rectangular photodiodes.

Abstract: The present invention relates to an instrument for measuring in relatively short periods of time concentrations of constituents in optically dense materials using the spectra near infrared radiation transmitted through thick samples of the material while the material is either stationary or flowing. The invention uses a broadband incandescent intensity stabilized light source combined with collimating optics to transmit a parallel beam of light through the material under test. The light transmitted through the material is then collected by a focusing lens and imaged onto a rectangular entrance slit of a special purpose spectrometer. This spectrometer has no moving parts and employs a fixed diffraction grating to physically spread the image of the entrance slit into a continuous range of wavelengths. A portion of the diffracted slit images covering the selected portion of the near infrared range is focused onto an array of individual rectangular photodiodes.