In-plane displacement measurement using optical vortex phase shifting

Abstract

In this paper, we propose a new method for in-plane displacement measurement by application of phase shifting based on an optical vortex. The phase shifts are obtained by displaying computer-generated fork holograms on the screen of a liquid-crystal spatial light modulator (LC-SLM). Furthermore, the vortex beam that is generated by the LC-SLM can be used as a reference light in the experiment. Eight speckle patterns with phase-shift increments of 0, π/2, π, and 3π/2 were captured by a CCD camera before and after the deformation. The displacement of the deformed object was obtained by unwrapping. Experimental results demonstrated the efficacy of the proposed method for in-plane displacement measurement.

Experimental micrometer-displacement measurements based on optical vortices

“…These OVs are localizations in space were the amplitude of the wave is zero and its phase is undefined [1][2][3], while in the surroundings the phase takes a helicoidal form, usually represented with the term exp(imθ), where θ is the azimuthal angle and m is the topological charge representing the number of 2π discontinuities of the wavefront [4]. Due to these features, OVs have been widely used in metrological applications [5,6], phase shifting interferometry [7], stellar choronography [8], among others. To generate the OVs, computer generated holograms (CGHs) [9], spiral phase plates (SPPs) [10] and vortex-producing lenses (VPL) [11] are commonly used.…”

Deep-learning-based high-resolution recognition of rotating interference images in vortex beam interferometry

“…The vortex beam with peculiar phase and amplitude structures has been widely used in the fields of optical micromanipulation, 1-3 optical communication, 4,5 astronomy detection, 6,7 ect. Recently, vortex beams have attracted increasing attention for their fascinating optical properties and potential applications in nano-scale metrology, such as profilometry 8 and thin film measurement. In 2017, Sokolenko proposed phase shifting interferometry (PSI) with the optical vortices imbedded into the probe beam.…”

A high accuracy measurement method based on vortex polar axis rotation phase-shifting interferometry (VPAR-PSI)

“…With a coupling of scroll light beam phase displacement and phase unpacking technique, contactless, higher resolutions and a wider range of metrology solutions such as micro-deformations of materials, micro-displacement and optical device shapes can be realized [ 36 ]. There is a new methodology presented by Sun and others for the measurement of in-plane movements of bodies via the speckle interference principle by means of applying optical swirl phase transfers to spot measurements [ 37 ]. Additionally, Zhang and others took an oval vortex lens into phase-shifted image-planar digital holography and tested the multi-planar focal points of the target and the baroscopic lens [ 38 ].…”