New analytical diffraction expressions for the Fresnel–Fraunhofer transition regime

Glückstad, Jesper; Madsen, Andreas Erik Gejl

doi:10.1016/j.ijleo.2023.170950

Cited by 8 publications

(3 citation statements)

References 12 publications

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“…The working principle of HoloTile requires a Fourier transform relationship between input and output planes in order to achieve proper separation of frequency components and PSF shaping. Therefore, a lens-less configuration could be constructed where the modulated beam is allowed to propagate until the far-field condition is met [31]. However, we have chosen to employ an additional quadratic lens phase profile that can be coded directly on the SLM in conjunction with the tiled sub-holograms and the PSF-shaping phase:…”

Section: Lens-less Holotilementioning

confidence: 99%

HoloTile light engine: new digital holographic modalities and applications

Glückstad,

Gejl Madsen

2024

Rep. Prog. Phys.

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HoloTile is a patented computer generated holography approach with the aim of reducing the speckle noise caused by the overlap of the non-trivial physical extent of the point spread function in Fourier holographic systems from adjacent frequency components. By combining tiling of phase-only of rapidly generated sub-holograms with a PSF-shaping phase profile, each frequency component - or output ``pixel" - in the Fourier domain is shaped to a desired non-overlapping profile. In this paper, we show the high-resolution, speckle-reduced reconstructions that can be achieved with HoloTile, as well as present new HoloTile modalities, including an expanded list of PSF options with new key properties. In addition, we discuss numerous applications for which HoloTile, its rapid hologram generation, and the new PSF options may be an ideal fit, including optical trapping and manipulation of particles, volumetric additive printing, information transfer and quantum communication.

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Section: Lens-less Holotilementioning

confidence: 99%

HoloTile light engine: new digital holographic modalities and applications

Glückstad,

Gejl Madsen

2024

Rep. Prog. Phys.

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“…Considering that the actual FGB pump light passes through a Φ = 5 mm aperture, an ideal plane wave passing through a hard-edged circular diaphragm of radius R a , with uniform intensity and phase distributions, was selected as the reference beam in the calculations. Taking into account axial symmetry, its far-field distribution I ref (r, f ) was simulated based on the Fraunhofer diffraction formula in polar coordinates, the Bessel function, and the generalized Jinc Function, and thus can be deduced as I normalr normale normalf ( r , f ) = ( π R a 2 λ f ) 2 true[ J i n c ( 2 π r R a λ f ) true] 2 …”

Section: Improvement Of the Raman Beam Qualitymentioning

confidence: 99%

Inhibiting Effect of Topological Charge on Laser-Induced Breakdown of Gases: Miniaturization of an SRS Laser with Vortex Raman Outputs

Sun,

Jia,

Cai

et al. 2024

ACS Photonics

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Stimulated Raman scattering (SRS) lasers equipped with bulky gas cells have been widely criticized. The special "donut″-shaped intensity distribution of vortex light (VL) is expected to reduce the pump laser intensity, suppress laser-induced breakdown, and fulfill the laser miniaturization. In this work, spiral phase plates of different topological charges (l = 1,2,4) have been employed to convert the l = 0 flattened Gaussian beam (FGB) into VLs, which served as pump sources. Lenses with focal lengths of F = 1000, 400, and 200 mm were chosen and coupled with Raman cells of L = 1.8, 0.9, and 0.23 m, respectively, to investigate the effects of l on photon conversion efficiency (PCE), beam quality, and the output orbital angular momentums (OAMs). The optimal l under different focusing parameters was proved to be dependent on the pump energy and gas pressure. By focusing the l = +4 laser via an F = 200 mm lens into a L = 0.23 m Raman cell, a first-order Stokes (S1) PCE of up to 61.5% was achieved at a pump energy of 62.1 mJ, which is comparable with the 66.4% obtained with an F = 1000 mm lens focusing the l = 0 FGB in a L = 1.8 m cell. Next, the S1 Raman beam quality at high pressure was verified to be significantly improved from β o0 = 6.3 (l = 0) to β o2 = 3.6 (l = 2) at 0.8 MPa H 2 . Furthermore, moduli and signs of average Raman OAMs were visualized with an F = 1.5 m cylindrical lens, and the results verified the law of OAM conservation in our SRS scheme.

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“…Glückstad and Madsen described how the predictions of Fraunhofer diffraction by a circular aperture can be extended into the Fresnel regime by renormalizing to the axial amplitude, which can be very simply calculated by the Fresnel diffraction expression [78].…”

Section: Historical Backgroundmentioning

confidence: 99%

The Fresnel Approximation and Diffraction of Focused Waves

Sheppard

2024

Photonics

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In this paper, diffraction of scalar waves by a screen with a circular aperture is explored, considering the incidence of either a collimated beam or a focused wave, a historical review of the development of the theory is presented, and the introduction of the Fresnel approximation is described. For diffraction by a focused wave, the general case is considered for both high numerical aperture and for finite values of the Fresnel number. One aim is to develop a theory based on the use of dimensionless optical coordinates that can help to determined the general behaviour and trends of different system parameters. An important phenomenon, the focal shift effect, is discussed as well. Explicit expressions are provided for focal shift and the peak intensity for different numerical apertures and Fresnel numbers. This is one application where the Rayleigh–Sommerfeld diffraction integrals provide inaccurate results.

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New analytical diffraction expressions for the Fresnel–Fraunhofer transition regime

Cited by 8 publications

References 12 publications

HoloTile light engine: new digital holographic modalities and applications

HoloTile light engine: new digital holographic modalities and applications

Inhibiting Effect of Topological Charge on Laser-Induced Breakdown of Gases: Miniaturization of an SRS Laser with Vortex Raman Outputs

The Fresnel Approximation and Diffraction of Focused Waves

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