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120results about How to "Eliminate dispersion" patented technology

Method for testing resolution of each imaging region of digital camera

The invention provides a method for testing the resolution of each imaging region of a digital camera. A camera to be tested is used for shooting resolution test plates to obtain photos, and the photos are treated according to the following steps: 1. converting into gray level images; 2. calculating the diameters of the photo images; 3. carrying out dark corner light loss correction; 4. carrying out binaryzation on the images; 5. dividing a plurality of pixel blocks to be used as foreground pixel blocks; 6. removing the foreground pixel blocks positioned at edges or corners of the photos or the foreground pixel blocks with too small area; 7. establishing a plurality of concentric circles for dividing the photo images into a plurality of annular regions; and calculating the astigmation of each annular region; and 8. calculating the relative astigmation and the resolution of each annular region in the photo images. The invention can determine the clear usable region of the photos shot by a set of camera equipment, and can also compare the resolution difference in different proportions between the whole shooting picture and the middle cut image, and the shooting method with the maximum resolution can be found, so the required shooting number is minimum on the premise that the resolution in the conversion is maximum or the resolution is ensured.
Owner:ZHEJIANG UNIV

Method for visually testing resolution of each imaging area of digital camera

The invention provides a method for visually testing the resolution of each imaging area of a digital camera, which comprises the following steps of: converting a photo into a gray level image; calculating the diameter of the image of the photo; performing vignetting glossiness loss correction; performing binaryzation on the image; marking a plurality of pixel blocks as foreground pixel blocks; removing the foreground pixel blocks from the corners of the photo or the foreground pixel blocks with small areas; by taking the centre of the image of the photo as the centre of a circle, establishing a plurality of concentric circles to divide the image of the photo into a plurality of circular areas and representing image divergence degrees in each circular area by using rectangular images; and according to neighboring relations of the circular areas, sequentially splicing all the obtained rectangular images into a test result graph. The method not only can determine a clear and available area of the photo shot by a set of shooting equipment, but also can compare the resolution of the fully-shot photo with that of middle screenshots of different ratios to find a shooting method through which maximum resolution can be realized, thereby ensuring that the definition in copying can be maximal or the number of the shot photos is the smallest on the premise of ensuring the definition.
Owner:ZHEJIANG UNIV

Compact double reflection-type photovoltaic condenser based on compound eyes

The invention relates to the photovoltaic power generation technology, and aims at providing a compact double reflection-type photovoltaic condenser based on compound eyes. The compact double reflection-type photovoltaic condenser based on the compound eyes comprises a photovoltaic cell and an optical collector, wherein the upper surface of the optical collector comprises a free curved surface and a refraction curved surface, the lower surface of the optical collector comprises a transmission plane and a reflection plane, the center of the refraction curved surface and the center of the reflection plane are positioned at the same vertical position, the center of the free curved surface and the center of the transmission plane are positioned at the same vertical position, and the free curved surface is arranged at a focal position of the refraction curved surface; and the photovoltaic cell is arranged outside the optical collector and adjoins to the transmission plane, the photovoltaic cell is positioned at a focal position of the free curved surface, and the aperture of the transmission plane is larger than that of the photovoltaic cell. The compact double reflection-type photovoltaic condenser has the advantages that the photovoltaic conversion efficiency of the photovoltaic cell is improved, the service life of the photovoltaic cell is prolonged, an optical plastic PMMA (polymethyl methacrylate) is adopted and is prone to injection molding and processing, light in weight and applicable to large-scale processing, and the processing cost is reduced.
Owner:ZHEJIANG UNIV

Broad spectrum optical fiber collimator

The invention discloses a broad spectrum optical fiber collimator. The broad spectrum optical fiber collimator comprises a thermal-expanding core optical fiber head, an achromatic lens and an outer sleeve, wherein the thermal-expanding core optical fiber head and the achromatic lens are arranged in the outer sleeve in a straight line, and an air layer is arranged between the thermal-expanding core optical fiber head and the achromatic lens, the thermal-expanding core optical fiber head and the achromatic lens have the same optical axis, and the outer sleeve is provided with a fixed central axis; the broad spectrum optical fiber collimator has the characteristics that a rear end face of the achromatic lens is vertical to the outer sleeve, the distance between the rear end face of the achromatic lens and a front end face of the thermal-expanding core optical fiber head is the thickness of the air layer in the middle, and is equal to the difference of an effective focus length of the achromatic lens and the distance between the rear end face of the achromatic lens and a primary side of the achromatic lens. Compared with the traditional collimator, the broad spectrum optical fiber collimator provided by the invention greatly reduces the insertion loss of an incident light beam; the core diameter of the thermal-expanding core optical fiber head is magnified by 3-5 times; an emergent light beam has a large spot diameter, and a small emergent aperture angle; and the chromatic dispersion caused by the broad spectrum is eliminated, the system transmission performance is improved, and the alignment error is low.
Owner:UNIV OF SHANGHAI FOR SCI & TECH

Plate structure multi-defect detection method based on DBSCAN and k-means algorithm

The invention relates to a plate structure multi-defect detection method based on DBSCAN and k-means algorithm. The method comprises the following steps: 1) collecting a damage signal of a plate structure, and performing difference processing on the damage signal and a health signal acquired under the same condition to acquire a difference signal; 2) acquiring a direct wave difference feature signal based on the difference signal; 3) determining candidate defect data points based on a pre-selected feature signal threshold; 4) performing defect quantitation and positioning by utilizing the DBSCAN and k-means algorithm according to the candidate defect data points. Compared with the prior art, the defect amount can be accurately judged by utilizing an intelligent algorithm when multiple defects are existent and the amount of the defect is unknown, the influences from the external noises, the frequency dispersion of the Lamb wave, the boundary reflection and the modal conversion at the defect can be effectively eliminated, the signal-to-noise ratio is improved, multi-defect can be accurately positioned, and the method has relatively high engineering application value.
Owner:EAST CHINA UNIV OF SCI & TECH
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