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1

Optimal mass transportation problem and freeform optics design – the identity of optimization scheme and the numerical solution method

Wojtanowski J.

Optica Applicata

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2018

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Vol. 48, nr 3

399--412

EN

Due to outstanding light shaping potential, freeform optical surfaces have been considered theoretically from centuries. Recently, they gained increased interest due to the availability of manufacturing technologies. Nevertheless, the design of freeform surfaces still becomes a challenge, associated with advanced mathematical concepts and significant computing power. In this work, a very interesting unification of theories is mentioned. It is shown how the problem of optimal redistribution of mass, analyzed in the 18th century, corresponds to the problem of optical beam shaping realized by freeform surface. Both issues are governed by the same partial differential equation. In the paper, a novel numerical algorithm for solving this partial differential equation is discussed. As an example, a design of freeform lens, capable of casting completely arbitrary shapes, is presented.

2

Diffractive wavefront correction of remote sensing systems based on pulsed laser diodes

Wojtanowski J., Traczyk M., Mierczyk Z., Zygmunt M., Przybyszewski B.

Opto-Electronics Review

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2015

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Vol. 23, No. 3

222-229

EN

A variety of optoelectronic devices (rangefinders, velocity meters, terrestrial scanners, lidars, free space optics communication systems and others) based on semiconductor laser technology feature low-quality and highly asymmetric beams. It results from optical characteristics of the applied high-peak-power pulsed laser sources, which in most cases are composed of several laser chips, each containing one or a few active lasers. Such sources cannot be considered as coherent, so the resultant beam is formed by the superposition of many optically uncorrelated sub-sources. Far-field distribution of laser spots in such devices corresponds to the shape of laser emitting area, which instead of desired symmetry shows layout composed of one or several discrete lines or rectangles. In some applications, especially if small targets are concerned, it may be crucial to provide more symmetrical and uniform laser beam cross-section. In the paper, the novel strategy of such correction, combining coherent and incoherent approaches, is presented. All aspects of technological implementations are discussed covering general theoretical treatment of the problem, diffractive optical element (DOE) design in the form of computer generated hologram (CGH), its fabrication and testing in case of selected laser module beam correction.

3

Beam shaping based on intermediate zone diffraction of a micro-aperture

Zeng D., Sun Z.

Optica Applicata

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2008

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Vol. 38, nr 3

511-517

EN

We analyze optical diffraction of a micro-aperture (slit or hole) in a metal screen in the intermediate zone and report its application for beam focusing and collimating in micro-optics. Both finite-difference time-domain simulations and Rayleigh-Sommerfeld diffraction formula were applied to calculate the intermediate-zone diffraction patterns. It is shown that, by controlling the aperture size, the focal length and depth can be adjusted in a very wide range, from subwavelength to tens of wavelengths, while the focal width maintains in an order of wavelength.