ABSTRACT
We present a method of shaping three-dimensional (3D) vector beams with prescribed intensity distribution and controllable polarization state variation along arbitrary curves in three dimensions. By employing a non-iterative 3D beam-shaping method developed for the scalar field, we use two curved laser beams with mutually orthogonal polarization serving as base vector components with a high-intensity gradient and controllable phase variation, so that they are collinearly superposed to produce a 3D vector beam. We experimentally demonstrate the generation of 3D vector beams that have a polarization gradient (spatially continuous variant polarization state) along 3D curves, which may find applications in polarization-mediated processes, such as to drive the motion of micro-particles.
ABSTRACT
A generalized phase-shifting method for three-wave shearing interferometry is proposed. The phase-shifting algorithm is derived by an optimal process based on least-squares fitting. With this generalized algorithm, the steps of phase-shifting can be reduced to five, which greatly simplifies the measurement and decreases the burden of computation. Both the numerical simulation and the optical experiment are carried out to demonstrate the adaptability of the method.
ABSTRACT
An improved multi-shear algorithm is proposed to reconstruct a two-dimensional wavefront from multiple phase differences measured by lateral shearing interferograms with different tilts. The effects of the tilt errors in the wavefront are analyzed and a compensation method is developed. Unbiased estimators are added to Fourier coefficients of the phase differences to eliminate the tilt errors adaptively. The algorithm is immune to the tilt errors and the wavefront under test can be recovered exactly. Computer simulation and optical test demonstrated that the proposed algorithm has higher recovery accuracy than the existing multi-shear algorithms.