Gaussian content as a laser beam quality parameter

Ruschin, S.; Yaakobi, Elad; Shekel, Eyal

doi:10.1364/ao.50.004376

Cited by 9 publications

(5 citation statements)

References 15 publications

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“…3(b) is partially similar to the rectangular and top-hat type of beam profiles as described in Ref. 50 (see Table 1 [50]. Considering reference to these values, M 2 -parameter for this beam must lie between 1 and infinity (see Table 1 of Ref.…”

Section: +supporting

confidence: 61%

“…Such a non-basic Gaussian mode carries far-field divergence larger than the far-field divergence of a basic Gaussian mode provided beam waist radii are constant. Beam-divergence of the laser beam at far-field can be characterized quantitatively using the M 2 -parameter which has been computed for this case following the approach illustrated by Ruschin et al [50]. The intensity profile of our beam (with blue colour) shown in Fig.…”

Section: +mentioning

confidence: 99%

“…Considering reference to these values, M 2 -parameter for this beam must lie between 1 and infinity (see Table 1 of Ref. 50) and is calculated to be 9.4. It is imperative to highlight that no curve fitting is implemented in intensity profile of beam shown in Fig.…”

Section: +mentioning

confidence: 99%

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Role of Arbitrary Intensity Profile Laser Beam in Trapping of RBC for Phase-imaging

Kumar

Srivastava

Mehta

et al. 2016

Journal of the Optical Society of Korea

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Red blood cells (RBCs) are customarily adhered to a bio-functionalised substrate to make them stationary in interferometric phase-imaging modalities. This can make them susceptible to receive alterations in innate morphology due to their own weight. Optical tweezers (OTs) often driven by Gaussian profile of a laser beam is an alternative modality to overcome contact-induced perturbation but at the same time a steeply focused laser beam might cause photo-damage. In order to address both the photo-damage and substrate adherence induced perturbations, we were motivated to stabilize the RBC in OTs by utilizing a laser beam of 'arbitrary intensity profile' generated by a source having cavity imperfections per se. Thus the immobilized RBC was investigated for phase-imaging with sinusoidal interferograms generated by a compact and robust Michelson interferometer which was designed from a cubic beam splitter having one surface coated with reflective material and another adjacent coplanar surface aligned against a mirror. Reflected interferograms from bilayers membrane of a trapped RBC were recorded and analyzed. Our phase-imaging set-up is limited to work in reflection configuration only because of the availability of an upright microscope. Due to RBC's membrane being poorly reflective for visible wavelengths, quantitative information in the signal is weak and therefore, the quality of experimental results is limited in comparison to results obtained in transmission mode by various holographic techniques reported elsewhere.

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Section: +supporting

confidence: 61%

Section: +mentioning

confidence: 99%

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Role of Arbitrary Intensity Profile Laser Beam in Trapping of RBC for Phase-imaging

Kumar

Srivastava

Mehta

et al. 2016

Journal of the Optical Society of Korea

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“…x 4π • Δx rms • Δθ rms ∕λ put too much emphasis upon distant wings of distributions I 0 x and I 1 θ x , e.g., [4][5][6][7]. This includes an experimental paper by Lantigua et al [7].…”

Section: Introductionmentioning

confidence: 99%

Metric for the measurement of the quality of complex beams: a theoretical study

et al. 2015

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We present a theoretical study of various definitions of laser beam width in a given cross section. Quality of the beam is characterized by dimensionless beam propagation products (BPPs) Δx·Δθ(x)/λ, which are different for the 21 definitions presented, but are close to 1. Six particular beams are studied in detail. In the process, we had to review the properties for the Fourier transform of various modifications and the relationships between them: physical Fourier transform (PFT), mathematical Fourier transform (MFT), and discrete Fourier transform (DFT). We found an axially symmetric self-MFT function, which may be useful for descriptions of diffraction-quality beams. In the appendices, we illustrate the thesis "the Fourier transform lives on the singularities of the original."

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“…A variety of measures of beam quality have been presented in the literature to describe the deviation of a beam from that of an ideal Gaussian beam. For example, Ruschin et al propose using the overlap integral of the field with that of an optimally defined Gaussian [2] , while Kaim et al study a variety of metrics [3] . However, the most common measure is the M 2 parameter, or "beam quality factor" [4] .…”

Section: Introductionmentioning

confidence: 99%

The limitations of using M-squared for input beam characterization in simulation software

Hasenauer

Stone

2015

SPIE Proceedings

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The M-squared (M 2 ) parameter for defining laser beam quality is a convenient metric to characterize the variation of the beam size and far field divergence of a "real" propagated optical beam, compared with that of an ideal Gaussian beam of the same wavelength.However, it can be problematic to use this parameter solely to characterize an input beam for propagation simulation software. Similar to RMS wavefront error or Strehl ratio, which can be used to define image quality, but do not characterize the shape of the wavefront, different factors can result in beams with identical M 2 values, but very different propagation behavior. Beams that differ due to aberrations, non-Gaussian amplitude envelopes, and/or partial spatial coherence may have similar or identical M 2 values, but very different far-field and/or near-field intensity and/or phase distributions. The situation is complicated further if the beam encounters non-ideal optics.In this paper, we investigate a number of beams that all have (approximately) the same M 2 . While M 2 is invariant for propagation through an ideal optical system, we show that when an optical system introduces aberrations, it can alter different beams with the same, non-unity M 2 in ways that differ significantly from one beam to another.

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Gaussian content as a laser beam quality parameter

Cited by 9 publications

References 15 publications

Role of Arbitrary Intensity Profile Laser Beam in Trapping of RBC for Phase-imaging

Role of Arbitrary Intensity Profile Laser Beam in Trapping of RBC for Phase-imaging

Metric for the measurement of the quality of complex beams: a theoretical study

The limitations of using M-squared for input beam characterization in simulation software

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