Methods of resolution enhancement of laser diameter measuring instruments

• The implementation of diffraction and spectral analysis methods is presented.
• The function suggested allows detecting boundaries of object׳s shadows.
• The real-time detection algorithm is described for diffraction extreme values.
• A method of improvement of resolution is shown on the basis of spectral analysis.

The paper presents the implementation of diffraction and spectral analysis methods allowing 1 μm resolution enhancement of optical instruments intended for measurements of such round wire materials as cables, wires, cords, etc. with diameters exceeding the wavelength (~0.5 mm and large). The transformation function suggested allows detecting geometrical boundaries of object׳s shadows that are used to calculate its diameter independently from its location in the gaging zone. The real-time detection algorithm is described for diffraction extreme values in the analog video signal produced by the charge-coupled device sensors. A method of additional improvement of resolution is shown on the basis of spectral analysis.