CONTACT-FREE PHOTOMETRIC METHOD OF MEASUREMENT OF HEIGHT OF ROUGHNESS OF SAMPLE SURFACE Russian patent published in 2006 - IPC G01B11/30 

FIELD: control equipment.

SUBSTANCE: method can be used for control of quality of surface, for measurement of height of roughness, for selection of rational technological processes when creating polished super-smooth surfaces. Monochromatic radiation flux is directed onto controlled surface at angle, which doesn't exceed 10°. Intensity J₀ of mirror reflected radiation and radiation intensity J (Θ₁) reflected in the direction being different from mirror one. Relation measured intensities R₁=J (Θ₁)/ J₀ is calculated at specified angle Θ_1. Additionally the intensity J (Θ₂) of radiation is measured, which radiation was reflected from controlled surface at second angle of Θ₂≠Θ₁ and R₂= J (Θ₂)/ J₀ relation is determined for additionally measured and mirror reflected intensities. Radiation, which passed through the sample, is rejected from measuring circuit through optical wedge with bloomed side faces. Optical wedge is mounted at opposite side of controlled object onto layer of immersion liquid. Refractivity of optical wedge is chosen to be equal to refractivity of controlled sample. Mean-square deviation of heights of roughness is found from formula of σ = λ² /π²a√R₁/2(cos Θ₁+1)⁴ sin Θ₁exp[-(πa/λ)sin Θ₁)²]Δω, where a=λ/π√(lnR₂/R₁-ln[(cosΘ₁+1)⁴sinΘ₁/(cos Θ₂+1)⁴sin Θ₂]/sin²Θ₂-sin² Θ₁), λ is radiation wavelength, Δω is solid angle where reflected radiation is collected during process of measurement.

EFFECT: improved precision; widened range of measurement.

1 dwg