Multispectral reflectometer

Claim 1

A system for measuring the absorption of light by a sample in selected regions of the light spectrum, comprising: means for illuminating the sample; a fixed fiber optic collector for directly collecting diffusely reflected energy from the sample, the optical fibers forming said collector being generally straight and short in order to control loss of the reflected light, the optical fibers being grouped in a bundle and extending from an entrance end that is generally circular to an exit end that is arranged in the shape of a rectangular slit, said entrance end being disposed immediately adjacent the sample so that said fibers each receive and transmit light from the entire sample, and said entrance end of each of said fibers in said bundle having an acceptance angle that is at least as large as the associated optical exit angle of each of said fibers; a holographic, concave diffraction grating for dispersing the reflected energy projected onto it through the slit of the collector into its component wavelengths on a flat spectral plane, said light transmitted by each of said fibers of said collector filling said grating; a photodetector array comprising a plurality of photodetectors located at the spectral plane for detecting the separated energy at its various wavelengths; and means for processing electrical signals generated by said photodetectors corresponding to the presence of light at the various wavelengths to obtain numerical data corresponding to a reflectance value within a wavelength bandwidth.

Claim 2

A system for measuring the absorption of light by a sample in selected regions of the light spectrum, comprising: means for illuminating the sample; a fixed fiber optic collector for directly collecting diffusely reflected energy from the sample, the optical fibers forming said collector being generally straight and short in order to control loss of the reflected light, the optical fibers being grouped in a bundle and extending from an entrance end that is generally circular to an exit end that is arranged in the shape of a rectangular slit, said entrance end being disposed immediately adjacent the sample so that said fibers each receive and transmit light from the entire sample, and said entrance end of each of said fibers in said bundle having an acceptance angle that is at least as large as the associated optical exit angle of each of said fibers; a holographic, concave diffraction grating for dispersing the reflected energy projected onto it through the slit of the collector into its component wavelengths on a flat spectral plane, said light transmitted by each of said fibers of said collector filling said grating; a photodetector array comprising a plurality of photodetectors located at the spectral plane for detecting the separated energy at its various wavelengths; and means for processing electrical signals generated by said photodetectors corresponding to the presence of light at the various wavelengths to obtain numerical data corresponding to a reflectance value within a wavelength bandwidth.

Claim 13

A method for measuring the absorption of light by a sample in selected regions of the light spectrum, comprising the steps: illuminating the sample with light from a light source; collecting optical energy reflected from the sample directly in a fixed fiber optic collector formed of short, generally straight fibers, the optical fibers being grouped in a bundle and extending from an entrance end that is generally circular to an exit end that is arranged in the shape of a rectangular slit projecting the reflected energy passing through the rectangular slit onto a holographic, concave diffraction grating; said collecting at each fiber entrance end adjacent said sample being from the entire sample and said projecting at each said fiber slit end filling said grating, the entrance angle over which said collecting occurs at each fiber being at least as great as the exit angle over which said projecting occurs at each said slit end; separating the reflected energy into its component wavelengths on a flat spectral plane by reflecting the energy off the grating; and detecting the separated energy.

Claim 14

A method for measuring the absorption of light by a sample in selected regions of the light spectrum, comprising the steps: illuminating the sample with light from a light source; collecting optical energy reflected from the sample directly in a fixed fiber optic collector formed of short, generally straight fibers, the optical fibers being grouped in a bundle and extending from an entrance end that is generally circular to an exit end that is arranged in the shape of a rectangular slit projecting the reflected energy passing through the rectangular slit onto a holographic, concave diffraction grating; said collecting at each fiber entrance end adjacent said sample being from the entire sample and said projecting at each said fiber slit end filling said grating, the entrance angle over which said collecting occurs at each fiber being at least as great as the exit angle over which said projecting occurs at each said slit end; separating the reflected energy into its component wavelengths on a flat spectral plane by reflecting the energy off the grating; and detecting the separated energy.