METHOD OF MEASURING ATTENUATION INDEX Russian patent published in 2010 - IPC G01N21/59 

FIELD: physics; optics.

SUBSTANCE: method of measuring attenuation index involves illuminating an object and converting the optical signal which has passed through the object to an electrical signal using a measurement system. A test object made from three groups of light slits with high, medium and low spatial frequencies placed on a dark background is placed on the side of the object opposite the measurement system with possibility of contact with the object. To convert the optical signal into an electrical signal, a measurement system is used, which is in form of a video camera connected to a computer and placed from the test object at a distance greater than the focal distance of the lens of the video camera. The measurement system is tuned using a standard object. After illuminating the test object and passing light through the standard object, a real image of the test object is formed on a monitor, on the high spatial frequency of which zero contrast is observed. A signal profile is formed for the real image at high spatial frequency with fixation of the greatest signal value and at middle frequency with fixation of the least signal value between two slits. The obtained signal values are used to calculate initial contrast. The standard object replaces the analysed object and similar measurements are taken, from which the attenuation index is determined using the formula: where µ is the attenuation index of the object; x is the linear dimension of the object; K₀ is the initial contrast, K is the current contrast.

EFFECT: increased efficiency and accuracy of measurement, wider field of use.

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