A holographic wavefront sensor based on a spatial light modulator (SLM) for displaying computer-generated holograms (CGH) is a flexible and simple method for analyzing the wavefront. This article discusses an algorithm for the synthesis of holographic structures based on a blazed diffraction grating (Echelette grating). As a result of the reconstruction of such CGHs the light diffracts predominantly into one diffraction maximum. The experiments carried out confirm the effectiveness of the proposed algorithm when measuring the wavefront described by one or several Zernike polynomials simultaneously.
Optical tweezers are of particular interest in various fields of science and technology such as atomic physics, nanotechnology and micromechanics. Today, there are many devices for manipulating microscopic objects using optical tweezers. In comparison with the most of known manipulation systems, the acousto-optic deflection is characterized by higher speed, the possibility to control several optical traps independently, high-precision movement of the trap within the field of view. In optical tweezers, longitudinal movement of micro-objects is also required. For this, special optical systems with variable characteristics, may be used. In this paper, we propose to combine these two approaches in one setup for 3D manipulation, i.e. to use acousto-optic scanning, using Bessel optical beams and an optical variosystem designed for longitudinal movement of the Gaussian beam waist at its constant diameter.
Laser radiation for a high precision measurement such as nanostructure measurement needed to be clean of wavefront aberrations. However, only expensive lasers with stabilization can achieve such robust parameters. The emission is needed to be corrected via adaptive optics. Nevertheless, high precision measurement of wavefront aberrations is necessary to high precision correction. The present work is dedicated to the problem of computer-generated Fourier holograms application for measurement of optical wavefront curvature with high precision. Mathematical modeling and experimental results of the method with the comparison of different approaches are presented.
Optical tweezers use a special class of light beams – the so-called Bessel beams. The field amplitude of these beams is described by the Bessel function of the first kind of a zero order. The traditional method of forming zero-order Bessel beams involves the use of a classical optical element – a conical axicon lens. We designed and assembled an experimental test bench to study the parameters of the Bessel beam formed by the axicon. In the course of experimental studies, it was confirmed that Bessel beam is a diffraction-free beam. In addition, an influence of a divergence of the Gaussian beam at the axicon input on the parameters of the Bessel beam was investigated. The transformation of such a beam by an optical system was considered. It is shown that when the Bessel beam is transformed by an optical system, the principle of similarity of optical fields in the optical conjugate planes is fulfilled. The results of modeling the formation of the Bessel beam by the axicon obtained in this work are consistent with the experimental studies.
An alternative holographic wavefront analiser scheme based on the light guide plate with computer-generated holograms and diffractive optical element is proposed. Advantages of the scheme are the absence of a maximum of zero order of diffraction in the photodetector plane and potentially better recognition of aberrations.
A holographic wavefront sensor scheme using a phase-only spatial light modulator (SLM) with reduced cross-talk noise influence is proposed. A novel method for plane wave aberration measuring using a phase-only computer-generated hologram is devised. The proposed scheme and algorithm are validated with numerical simulations and experiments.
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