In an analytical form, the features of the image formation of the faces of a three-dimensional asymmetric edge of an object with an absolutely reflective inner surface are studied in relation to the dimensional inspection. Formulas are obtained for calculating the fields in images of object faces in ideal and diffraction-limited systems, depending on the value of the object’s bevel c, the phase shift (Formula presented.) of the wave reflected from the inner surface of the object, and the angular aperture (Formula presented.) of the coherent optical image formation and filtering system. It is found that for metallic three-dimensional (3D) objects (Formula presented.), the field value in the image of the back face at the point (Formula presented.) corresponding to the position of its boundary is negligible when the depth of focus of the system is much less than the thickness of the object. It is shown that at c bevels of the object, much smaller than the Fresnel zone (Formula presented.) ((Formula presented.)is the wavelength of light, and d is the thickness of the object) and greater than the depth of focus (Formula presented.), the shift of the intensity profile in the image of the front face is proportional to (Formula presented.) and depends on the phase (Formula presented.). For large bevels, when (Formula presented.) and (Formula presented.), the active face is the back one and the displacement of the back face boundary is inversely proportional to the value of (Formula presented.). These offsets can lead to systematic errors in the measurement of the position of the boundaries of the 3D-object faces, and they must be taken into account during precision dimensional inspection.
|Журнал||Optoelectronics, Instrumentation and Data Processing|
|Состояние||Опубликовано - мая 2021|
Предметные области OECD FOS+WOS
- 1.03 ФИЗИЧЕСКИЕ НАУКИ И АСТРОНОМИЯ