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Wigner transform approach to dynamic-variable partially coherent laser beam characterization

Jabczyński J., Gontar P., Gorajek Ł.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2020

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Vol. 68, nr 1

141--146

EN

1) Background: the modeling, characterization, transformation and propagation of high-power CW laser beams in optical (including fiberoptic) trains and in the atmosphere have become hot topics in laser science and engineering in the past few years. Single-mode output is mandatory for high-power CW laser applications in the military field. Moreover, an unstationary, dynamic operation regime is typical. Recognized devices and procedures for laser-beam diagnostics could not be directly applied because of dynamic behavior and untypical non-Gaussian profiles. 2) Methods: the Wigner transform approach was proposed to characterize dynamically variable high-power CW laser beams with significant deterministic aberrations. Wavefront-sensing measurements by means of the Shack-Hartmann method and decomposition into an orthogonal Zernike basis were applied. 3) Results: deterministic aberration as a result of unstationary thermal-optic effects depending on the averaged power of the laser output was found. Beam quality determined via the Wigner approach was changed in the same way as the measurements of the beam diameter in the far field. 4) Conclusions: such an aberration component seems to be the main factor causing degradation in beam quality and in brightness of high-power CW laser beams.

2

Application of Wigner transform for characterization of aberrated laser beams

Jaguś J., Jabczyński J. K., Żendzian W., Kwiatkowki J.

Optica Applicata

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2005

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Vol. 35, nr 1

33-41

EN

The slit scan method was implemented for registration of intensity profiles along the caustics of a laser beam. The inverse Radon transform of spatialy normalized intensity profiles enables direct computation of Wigner transform of real laser beam. The Rayleigh range, divergence angle, beam quality factor, global degree of coherence can be determined in such a simple way. A procedure enabling derivation of the shape of aberrated wavefornt and spherical aberration content was elaborated. This method was applied for investigation of the aberrated laser beams generated by cw and pulsed diode pumped laser.

3

Testing of plano-optical elements

Mikš A., Novák J.

Optica Applicata

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2003

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Vol. 33, nr 2-3

391-402

EN

The most common criteria of the quality of optical surfaces and elements are analysed in detail in this paper. Both geometrical-optics criteria and diffraction criteria are defined. The connection between different criteria is also described. Some terms lacking classical analogy in optics are described, e.g., the focal length of the plane parallel plate, prism, etc

4

Simple achromatic hybrid lens

Zając M., Nowak J.

Optica Applicata

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2003

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Vol. 33, nr 2-3

285-291

EN

The simplest achromatic hybrid lens consists of a refractive (glass) lens with a diffractive microstructure deposited on one of its surfaces. In such lens the reasonable aberration correction is possible only for very limited aperture and field angles. Better possibilities of aberration correction appear if we split the refractive lens onto two identical parts separated by certain distance and locate the diffractive element between the glass lenses. We show that in a such way it is possible to obtain a hybrid lens of the same or even smaller aberrations for substantially greater aperture and field angles.

5

Hybrid achromatic spectacle lens

Zając M.

Optica Applicata

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2003

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Vol. 33, nr 2-3

273-283

EN

Spectacle lens is a very particular optical imaging element of great practical importance. Although its construction is very simple, some demands are specific (in particular, remarkable shift of an output pupil). A number of classic spectacle lens designs have been known for a long time, however some new possibilities of aberration correction appear if we use a hybrid (diffractive-refractive). Hybrid lens is an optical system composed of a classic refractive (“glass”) lens and a diffractive microstructure deposited on one of its surfaces. Imaging properties of such lens can be expressed in terms of dimensionless parameters: z = -r1/r2 (describing the shape of a refractive part), b = za/zb (describing the geometry of diffraction fringes) and h = FD/FR (describing the distribution of focusing power between a diffractive and refractive part). By a proper choice of the parameter h we can compensate chromatic aberration. Thanks to the other free parameters astigmatism can also be corrected. In this contribution the possibilities of particular Seidel aberration correction of a hybrid lens are presented. As an illustration some examples of spectacle hybrid lenses are shown and their imaging characteristics are compared with imaging characteristics of commercially available refractive lenses.

6

Use of computer algebra system for recalculation of the fifth-order aberrations of GRIN media.

Magiera L.

Optica Applicata

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2001

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Vol. 31, nr 3

545-551

EN

The methodology of calculation of the fifth-order aberrations of gradient-index (GRIN) media by application of computer symbolic calculations (computer algebra) is presented. The software package applied was REDUCE. The results obtained enabled us to correct the results known from the literature. The designed computer program has also been added. A special computer program has also been designed.

7

Focusing large-aperture beams generated by high-peak-power lasers

Jabłoński S., Badziak J.

Optica Applicata

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2001

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Vol. 31, nr 3

625-634

EN

The properties of focusing large-aperture fight beams of parameters typical of the beams produced by picosecond terawatt lasers are analysed numerically with the use of 3-D computer code based on Fresnel-Kirchhoff integral formula. It is shown that, contrary to the case of small-aperture Gaussian-like beams, a peak intensity of light in the focus is a non-monotonic function of f/D with a local maximum at moderate f/D values (5 [left angle bracket]or= f/D [left angle bracket]or= 10), where f is the focal length and D is the aperture of a focusing system. For low f/D values (f/D [left angle bracket] 3) more than 80% of laser energy is scattered after focusing in a low-intensity large-dimension aureole round the central peak of focal intensity distribution. The amount of the scattered energy can be significantly decreased by an increase of f/D, and, as a result, the moderate values of this ratio seem to be optimum for most laser-target experiments. The above features appear for both spherical and aspherical focusing systems.