Neotec Corporation

Isaac J Landa

An improved optical system is disclosed for rapid, accurate spectral analysis of the reflectivity or transmissivity of samples. A concave holographic diffraction grating oscillated at high speed is utilized to provide a rapid scanning of monochromatic light through a spectrum of wavelengths. The grating is positively driven at very high speed by a unique cam drive structure comprising identically shaped conjugate cams. The rapid scan by the grating enables the reduction of noise error by averaging over a large number of cycles. It also reduces the measurement time and thus prevents sample heating by excessive exposure to light energy. A filter wheel having dark segments for drift correction is rotated in the optical path and is synchronous with the grating. Source optics is employed to optimally shape the light source for particular applications. The system optics further includes a unique arrangement of lenses, including cylindrical lenses, to obtain the best light source shape which results in maximum light throughput. Fiber optics are also employed and arranged to meet the optimum requirements of the system for light collection and transmission through portions of the optical system.

Holographic diffraction grating system for rapid scan spectral analysis

An improved optical system is disclosed for rapid, accurate spectral analysis of the reflectivity or transmissivity of samples. A concave holographic diffraction grating oscillated at high speed is utilized to provide a rapid scanning of monochromatic light through a spectrum of wavelengths. The grating is positively driven at very high speed. The rapid scan by the grating enables the reduction of noise error by averaging over a large number of cycles. It also reduces the measurement time and thus prevents sample heating by excessive exposure to light energy. A filter wheel having opaque segments is rotated in the optical path and is synchronous with the grating. The filter wheel is divided into two arcuate segments separated by the opaque segments arranged approximately 180 degrees apart. One arcuate segment of the wheel transmits only first order light. The other arcuate segment transmits only second order light. Separate photodetectors are employed during infrared analysis of samples for detecting first order and second order wavelength transmissions and an electronic decoder apparatus is utilized for switching between detectors.

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Wheaton, MD, United States of America

Isaac J Landa