SU1562692A1 - Method of measuring roughness of surface of articles - Google Patents

Abstract

This invention relates to a measurement technique. The purpose of the invention is to improve the accuracy as well as the informativeness of the method by determining the correlation interval of micro unevenness heights. The surface of the article 9 is illuminated by a beam of radiation. Then, the diffraction angular spectrum of the coherent radiation of the illuminating beam is formed, the angular intensity distribution in this spectrum is recorded, the dispersion S _{I of the} angular distribution of the intensity of the illuminating radiation beam is determined, the diffraction angular spectrum of the coherent radiation is generated, the angular distribution of the intensity of the scattered radiation is recorded radiation, the reflection coefficient T and the dispersion S _{S of the} angular distribution of the intensity of the scattered and The radiation, on which the root-mean-square height of asperities is judged and the ρ correlation range of heights of asperities, the latter is determined from the condition ρ = √-T LN T / (S _S -S _I ). 1 il.

Description

The invention relates to measuring technique and can be used, in particular, for measuring the surface roughness of the product 5 during metal processing

The purpose of the invention is to increase the accuracy of measurement, as well as the information content of the method by determining the interval of correlation of the heights of micronerities - 10 nost.

The drawing shows a schematic diagram of a device that implements the proposed method for measuring the surface roughness of the product. fifteen

The device contains a source of coherent radiation 1, for example, a laser focusing the illumination optical system 2 located along the radiation path, a receiving optical system 20 3 located along the radiation reflected from the controlled surface, a Fourier lens 4, in which the receiver 5 is mounted in the rear focusing plane image 25, the output of which is connected to the input of the analog-to-digital converter 6, the input unit 7 of the digital signals and the microprocessor 8.

The method is carried out as follows 30.

Previously, using the coherent radiation source 1, the focusing lighting optical system 2, the receiving optical system 3 and 35 of the Fourier lens 4, the angular diffraction spectrum of the illuminating radiation beam is formed in the rear focusing plane of the latter. In this case, instead of the controlled surface 9, a mirror is placed, on a smooth-smooth reflective surface (not shown).

The distribution of the radiation intensity in the diffraction spectrum of the illuminating beam, formed in the above manner, is recorded using the image receiver 5, the output video signal of which is fed to the analog input of the analog-to-digital converter 6. Digital codes corresponding to the intensity values on the photocells of the receiver 5 of the image. The signals from the digital output of the analog-to-digital converter 6 are transmitted via the digital input unit> 5 to the random access memory of the microprocessor 8, where they form an array of numbers and perform program digital processing of this array. Processing consists in normalizing the values of the array to the total intensity equal to the sum of all values of the elements of the array, and determine the variance S, the angular distribution of the intensity of the diffraction spectrum of the illuminating beam. Then, using a coherent radiation source 1 and a focusing illumination optical system 2, a controlled surface 9 is illuminated with a coherent radiation beam, using an optical system 3 and a Fourier lens 4, an angular diffraction spectrum of radiation reflected from the controlled surface 9 is formed, and the sequence of previously mentioned actions is performed with the exception of determining the variance S. of the angular distribution of the intensity of the diffraction spectrum of the illuminating beam, previously determined „Thus, form the diffraction angular spectrum of the coherent radiation of the illuminating beam, register the angular distribution of intensity in this spectrum, determine the variance S. of the angular distribution of the intensity of the illuminating radiation beam, form the diffraction angular spectrum of the coherent radiation reflected from the surface. 9 of the product, register the angular distribution of the intensity of the scattered radiation determine the specular reflection coefficient t _S s and the variance of the angular distribution of scattered light intensity, f which the judge. the root-mean-square height of microroughnesses and the interval p of correlation of microroughness heights, the latter being determined from the condition ϋ = if -tint / (Sg-S.), 'where p is the correlation interval of microroughness heights. . ,

Claims (1)

Claim The method of measuring the surface roughness of the product, which consists in illuminating the surface of the product with a radiation beam, measuring the intensity of radiation reflected from the surface of the product, and judging the rms height of the microroughness of the surface of the product, characterized in that, in order to improve the measurement accuracy, and the information content of the method by determining the correlation interval of the heights of microroughnesses, form the diffraction angular spectrum of the coherent radiation of the illuminating beam, register the angular distribution dividing the intensity in this spectrum, determine the variance S. of the angular distribution of the intensity of the illuminating radiation beam, form the diffraction angular spectrum of the coherent radiation reflected from the surface of the product, record the angular distribution of the intensity of the scattered radiation, determine the coefficient t of specular reflection and the dispersion S _{s of the} angular 5 distribution of the intensity of the scattered radiation beam, which are taken into account when determining the root mean square height of the microroughness of the product’s surface, and interval p correlation heights of asperities is determined from the expression P = l | -tlnt / (Sj-S;).