METHOD TO MEASURE PARAMETERS OF RETROREFLEXION Russian patent published in 2013 - IPC G01M11/02 G01N21/55 

FIELD: measurement equipment.

SUBSTANCE: method includes illumination of a sample, registration of reflected radiation, averaging of measurements in different points of the sample. Angles of sample illumination are selected, based on angles of observation: β_i=α_i/2, where α_i - angle of observation of the i photodetector, including α_i=0. The first measurement is carried out at α=0 and β=0, half-width w is assessed in the indicatrix of diffusion I(α) at β=0 by the level 0.1 from the maximum value. The angle of scattering β_i is changed by β_i+1, and registration of averaged values is continued, until in the range from α=0 to α=2β_w distribution I(α) becomes double-modal with local minimum with the value of less than 15%-20% from the value 0.5·(I(α=0, β=0)+I(2β_w)). The type of the indicatrix of diffusion is defined relative to the direction of mirror reflection I(α-2β) and is approximated with the function f_A(x), where x=α-2β. Intensity values are defined in the direction of mirror reflection I_m(β), and this function is approximated in the range from β>w/2 (or 15°) to 45° by the function I_A(β). Extrapolation I_A is carried out (β) into the area β<w/2, and the value I_A is determined (β=0). The retroreflexion and the diffusion components are defined as the difference of the following: I_i=I(α=0, β=0) - I_A(β=0); for the non-zero (standard) angle β_s is calculated as: I_i=I(α=0, β=β_s)-f_A(β_s)·I_A(β_s). If I_i(β=0)<<I_a(β=0), then the investigated sample does not have the true retroreflexion.

EFFECT: increased accuracy of measurements, definition of the ratio between the retroreflexion and diffusion components and the directivity pattern, and minimised measurement time.

7 dwg