OPTICAL ANALYZER FOR AGRICULTURAL PRODUCTS
First Claim
1. Optical apparatus for continuously shifting the bandwidth of light illuminating an object, comprising a source of wide band light for illuminating an object, a multiple filter assembly having a rotatable axle and a plurality of narrow bandwidth optical interference filters fixed to said axle and radiating therefrom at the same axial location in respective planes forming therewith a paddlewheel configuration, said filter assembly being positioned relative to the light path defined between said light source and the object such that said filters are swept through said light path individually during rotation of said axle, said wide band light impinging on each successive one of said filters as the orientation thereof relative to said light path is changing, whereby light passing through each one of said filters is restricted to continuously shifting bandwidths as a function of the instantaneous angle between said light path and a given filter during rotation.
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Accused Products
Abstract
An automatic test instrument for gaging the percentage of various constituents in organic substances by comparing the reflective optical density of the subject at various wavelengths. Narrow band optical filters are connected together in the form of a rotatable paddle wheel positioned so that the filters can be individually swept through the incident light path between the specimen and wideband light source. As the filter wheel turns, the band of light passed by each filter is progressively shifted with the changing angle of the filter relative to the light path. The filter wheel configuration includes opaque vanes extending from the ends of the filters to periodically interrupt the passage of light to the specimen. Photocells are positioned to sense the level of light reflected from the specimen. The output of the photocells is sampled at predetermined times relative to the rotation of the filter wheel to yield values indicative of reflected intensity at certain wavelengths. Using these values, an electronic circuit in one embodiment calculates three optical density difference values corresponding to moisture, protein and oil content of the specimen. The difference values are automatically inserted in three linear equations which are solved to obtain readings representing the true percentages of oil, water and protein contained in the specimen. Each time a new specimen is loaded for testing, the instrument is automatically calibrated against a standard sample, preferably Teflon (Trademark). The output of the photocells is amplified in a special circuit which subtracts the level of dark period current from the output when the photocells are illuminated.
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Citations
10 Claims
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1. Optical apparatus for continuously shifting the bandwidth of light illuminating an object, comprising a source of wide band light for illuminating an object, a multiple filter assembly having a rotatable axle and a plurality of narrow bandwidth optical interference filters fixed to said axle and radiating therefrom at the same axial location in respective planes forming therewith a paddlewheel configuration, said filter assembly being positioned relative to the light path defined between said light source and the object such that said filters are swept through said light path individually during rotation of said axle, said wide band light impinging on each successive one of said filters as the orientation thereof relative to said light path is changing, whereby light passing through each one of said filters is restricted to continuously shifting bandwidths as a function of the instantaneous angle between said light path and a given filter during rotation.
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2. The apparatus of claim 1, wherein said filters are equally spaced angularly about said axle, and the planes of said filters intersect approximately in a line coincident with the axis of rotation of said filter assembly.
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3. The apparatus of claim 2, wherein the axis of rotation of said filter assembly is approximately perpendicular to and spaced laterally from said light path.
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4. The apparatus of claim 3, wherein said filters are three in number.
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5. The apparatus of claim 1, wherein the optical characteristics of said filters are predetermined such that the respective ranges of wavelengths passed by said filters during rotation are approximately contiguous, whereby a composite range of wavelengths is spanned during each complete revolution of said filter assembly.
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6. The apparatus of claim 1, further comprising drive means operatively connected to said axle for imparting continuous rotation thereto, the position of said axle along the axis of rotation being fixed.
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7. The apparatus of claim 1, further comprising means fixed to and extending from the outer end of at least one of said filters for at least partially interrupting the passage of light from said light source to the object.
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8. The apparatus of claim 7, wherein said interrupting means includes a vane extending perpendicularly to the plane of the filter.
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9. The apparatus of claim 1, further comprising a substantially opaque vane fixed to the outer end of each of said filters and extending perpendicularly to the plane of said filter a predetermined distance such that the passage of light from said source to the object is interrupted for a period of time between sweeps of adjacent filters through said light path.
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10. The apparatus of claim 1, further comprising transducer means responsive to the rotation of said axle for providing a fixed number of pulses per axle revolution, counter means connected to receive the output of said transducer means for registering the number of pulses produced thereby per revolution, and logic means operatively connected to said counter means for providing a plurality of output signals at times corresponding approximately to predetermined discrete orientations of each of said filter in said light path.
Specification