Measurement of phase differences between two partially coherent fields

Fougères, Alain-Jérôme; Noh, Joseph J.; Grayson, Timothy P.; Mandeļ, L.

doi:10.1103/physreva.49.530

Cited by 22 publications

(4 citation statements)

References 15 publications

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“…However, one of the most common approach to remove coherent noise is positioning a rotating or vibrating ground glass diffuser in the beam path, producing a partially coherent light source [12][13][14][15][16][17][18][19][20][21][22][23][24]. To collect the scattered light from a diffuser single lenses with different focal lengths [20][21][22][23][24] or beam splitter cubes [16][17][18] are used in literature, offering only modest light collection. Additionally, by using a single lens as collector, the width of the collimated beam is in the order of the lens diameter, typically 25.4 mm, and needs to be reduced afterwards by adding additional lenses and therefore increasing alignment effort significantly.…”

Section: Introductionmentioning

confidence: 99%

“…To highlight the high light collection efficiency by using only one objective, we compare this scenario to a single lens collector as reported in literature [20][21][22][23][24]. For that purpose, we place a 60 mm lens (LA1134-A; Thorlabs) behind the ground glass diffuser, possessing a similar numerical aperture (N.A.)…”

Section: B Choice Of Collection Objective and Output Intensitymentioning

confidence: 99%

“…To realize the latter, several methods have been suggested including, induction of vibrations in a section of an optical fiber [9], scrambling the light by focusing the laser beam into a multi-mode optical fiber [10] or guiding the laser beam on a holographic diffuser [11]. However, one of the most common approach to remove coherent noise is positioning a rotating or vibrating ground glass diffuser in the beam path, producing a partially coherent light source [12][13][14][15][16][17][18][19][20][21][22][23][24]. To collect the scattered light from a diffuser single lenses with different focal lengths [20][21][22][23][24] or beam splitter cubes [16][17][18] are used in literature, offering only modest light collection.…”

Section: Introductionmentioning

confidence: 99%

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Step-by-step guide to reduce spatial coherence of laser light using a rotating ground glass diffuser

et al. 2017

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Wide field-of-view imaging of fast processes in a microscope requires high light intensities motivating the use of lasers as light sources. However, due to their long spatial coherence length lasers are inappropriate for such applications as they produce coherent noise and parasitic reflections, such as speckle, degrading image quality. Therefore, we provide a step-by-step guide for constructing a speckle-free and high contrast laser illumination setup using a rotating ground glass diffuser driven by a stepper motor. The setup is easy to build, cheap and allows a significant light throughput of 48 %, which is 40 % higher in comparison to a single lens collector commonly used in reported setups. This is achieved by using only one objective to collect the scattered light from the ground glass diffuser. We validate the stability and performance of our setup in terms of image quality, motor-induced vibrations and light throughput. To highlight the latter, we record Brownian motion of micro-particles using a 100x oil immersion objective and a high-speed camera operating at 2000 Hz with a laser output power of only 22 mW. Moreover, by reducing the objective magnification to 50x sampling rates up to 10 000 Hz are realized. To help readers with basic or advanced optics knowledge realizing this setup we provide; a full component list, 3D-printing CAD files, setup protocol, and the code for running the stepper motor.

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Section: Introductionmentioning

confidence: 99%

Section: B Choice Of Collection Objective and Output Intensitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Step-by-step guide to reduce spatial coherence of laser light using a rotating ground glass diffuser

et al. 2017

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“…At the time, most of what we were doing was, frankly, experimental demonstrations of Copenhagen theory and various aspects of fundamental quantum mechanics. [9][10][11][12][13][14][15][16][17][18] It was exciting stuff, it was really fun research. At the same time, there was sort of this practical side, nagging at me, that that said, you know, "Everyone already believes this, and accepts it, we just haven't demonstrated these particular principles".…”

Section: Innovation At Darpamentioning

confidence: 99%

Mosaic Warfare and Human–Machine Symbiosis

Grayson

Lilliu²

2021

SciVPro

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As the director of the Strategic Technology Office at the Defense Advanced Research Projects Agency (or DARPA), Timothy leads the office in development of breakthrough technologies to enable war fighters to field, operate, and adapt distributed, joint, multi-domain combat capabilities at continuous speed. He is also founder and president of Fortitude Mission Research LLC and spent several years as a senior intelligence officer with the CIA. Here he illustrates the concept of Mosaic Warfare, in which individual warfighting platforms, just like ceramic tiles in a mosaic, are placed together to make a larger picture. This philosophy can be applied to tackle a variety of human challenges including natural disasters, disruption of supply chains, climate change, pandemics, etc. He also discusses why super AI won’t represent an existential threat in the foreseeable future, but rather an opportunity for an effective division of labour between humans and machines (or human-machine symbiosis). See video at https://youtu.be/_5MkXD_m6Qc

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Quantization of the optical phase space in terms of the group

Kastrup¹

2003

Fortschritte der Physik

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The problem of quantizing properly the canonical pair “angle and action variables”, ϕ and I, is almost as old as quantum mechanics itself and since decades an intensively debated but still unresolved issue in quantum optics. The present paper proposes a new approach to the problem, namely quantization in terms of the group SO(1,2): The crucial point is that the phase space \documentclass{article}\pagestyle{empty}\begin{document}$\mathcal{S}^2 = \{\varphi \bmod{2\pi}, I> 0\}$\end{document} has the global structure \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$S^1 \times \mathbb{R}^+$\end{document} (a simple cone) and cannot be quantized in the conventional manner. As the group SO(1,2) acts transitively, effectively and Hamilton‐like on that space its irreducible unitary representations of the positive discrete series provide the appropriate quantum theoretical framework. The phase space \documentclass{article}\pagestyle{empty}\begin{document}$\mathcal{S}^2$\end{document} has the conic structure of an orbifold \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$\mathbb{R}^2/Z_2$\end{document}. That structure is closely related to a Z2 gauge symmetry which corresponds to the center of a 2‐fold covering of SO(1,2), the symplectic group \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$Sp(2,\mathbb{R})$\end{document}. The basic variables on the phase space are the functions h0 = I , h1 = I cos ϕ and h2 = ‐I sin ϕ the Poisson brackets of which obey the Lie algebra \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$\mathfrak{so}(1,2)$\end{document}. In the quantum theory they are represented by the self‐adjoint Lie algebra generators K0, K1, and K2 of a unitary representation, where K0 has the spectrum {k + n, n = 0, 1, ...; k > 0}. A crucial prediction is that the classical Pythagorean relation h12 + h22 = h02 can be violated in the quantum theory. For each representation one can define three different types of coherent states the complex phases of which may be “measured” by means of the operators K1 and K2 alone without introducing any new phase operators! The SO(1,2) structure of optical squeezing and interference properties as well as that of the harmonic oscillator are analyzed in detail. The additional coherent states can be used for the introduction of (Husimi type) “Q” distributions and (Sudarshan‐Glauber type) “P” representations of the density operator. The three operators K0, K1, and K2 are fundamental in the sense that one can construct composite position and momentum operators out of them! The new framework poses quite a number of fascinating experimental and theoretical challenges.

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Measurement of phase differences between two partially coherent fields

Cited by 22 publications

References 15 publications

Step-by-step guide to reduce spatial coherence of laser light using a rotating ground glass diffuser

Step-by-step guide to reduce spatial coherence of laser light using a rotating ground glass diffuser

Mosaic Warfare and Human–Machine Symbiosis

Quantization of the optical phase space in terms of the group

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