Effects of aberrations in spatiotemporal focusing of ultrashort laser pulses

Sun, Bangshan; Salter, Patrick S.; Booth, Martin J.

doi:10.1364/josaa.31.000765

Cited by 38 publications

(33 citation statements)

References 32 publications

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“…As shown in detail in Supplementary Fig. 1-3, the FWHM was as small as 7 µm at the centre of the FOE and increased both in the x-y plane (~0.4% and 0.5% per µm for the x and y direction, respectively) and, as previously observed 56 , in the z-direction (~0.4% per µm) as we moved away from the centre of the FOE. Two main effects could cause such axial resolution broadening.…”

Section: Multiplexed Temporally Focused Computer-generated Holographysupporting

confidence: 84%

“…First, large axial shifts required beams highly converging or diverging at the back aperture of the objective, whereas large lateral shifts corresponded to strongly tilted beams after SLM2. Therefore, in both cases, the optical elements that the beam propagated through after SLM2 introduced 5 strong aberrations 56 and a possible cropping of the beam with consequent loss of spectral frequencies. A second possible contribution to the axial broadening may come from spatiotemporal coupling effects related to the spatial separation of the spectral frequencies at the position of SLM2 ( Supplementary Fig.…”

Section: Multiplexed Temporally Focused Computer-generated Holographymentioning

confidence: 99%

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Multiplexed temporally focused light shaping for high-resolution multi-cell targeting

Accanto

Tanese

Ronzitti

et al. 2017

Preprint

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15Patterning light at the single-cell level over multiple neurons in the brain is crucial for optogenetic photostimulation that can recapitulate natural activity patterns and, thereby, determine the role of specific components of brain activity in behavior. To this end we have developed a method for projecting three-dimensional, 2-photon excitation patterns that are confined to many individual neurons. The new versatile optical scheme generates multiple extended excitation spots in a large volume with micrometric 20 lateral and axial resolution. Two-dimensional temporally focused shapes are multiplexed several times over selected positions, thanks to the precise spatial phase modulation of the pulsed beam. This permits, under multiple configurations, the generation of tens of axially confined spots in an extended volume, spanning a range in depth of up to 500 µm. We demonstrate the potential of the approach by performing multi-cell volumetric excitation of photoactivatable GCaMP in the central nervous system of Drosophila 25 larvae, a challenging structure with densely arrayed and small diameter neurons, and by photoconverting the fluorescent protein Kaede in zebrafish larvae. Our technique paves the way for the optogenetic manipulation of a large number of neurons in intact circuits.

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Section: Multiplexed Temporally Focused Computer-generated Holographysupporting

confidence: 84%

Section: Multiplexed Temporally Focused Computer-generated Holographymentioning

confidence: 99%

Multiplexed temporally focused light shaping for high-resolution multi-cell targeting

Accanto

Tanese

Ronzitti

et al. 2017

Preprint

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“…This dimension D x determines the monochromatic beam size at the pupil, which can be adjusted to control the lateral ellipticity of each SSTF focus [15,16]. A smaller D x extends the dimensions of the spatio-temporal focus axially and laterally (in a direction orthogonal to the spatial chirp) [34]. A 4f system was used to image the SLM into the pupil of the objective lens (Zeiss EC Epiplan 50×, 0.75 NA and a pupil diameter of 4.95 mm).…”

Section: Experimental Systemmentioning

confidence: 99%

Four-dimensional light shaping: manipulating ultrafast spatiotemporal foci in space and time

Sun

Salter

Roider³

et al. 2017

Light Sci Appl

Self Cite

102

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The spectral dispersion of ultrashort pulses allows the simultaneous focusing of light in both space and time, which creates so-called spatiotemporal foci. Such space–time coupling may be combined with the existing holographic techniques to give a further dimension of control when generating focal light fields. In the present study, it is shown that a phase-only hologram placed in the pupil plane of an objective and illuminated by a spatially chirped ultrashort pulse can be used to generate three-dimensional arrays of spatio-temporally focused spots. By exploiting the pulse front tilt generated at focus when applying simultaneous spatial and temporal focusing (SSTF), it is possible to overlap neighboring foci in time to create a smooth intensity distribution. The resulting light field displays a high level of axial confinement, with experimental demonstrations given through two-photon microscopy and the non-linear laser fabrication of glass.

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“…Most objective lenses contain a considerable amount of glass, which can significantly increase the GDD of the pulse depending on the bandwidth of the pulse. This can drastically affect the PFT of the pulse and introduce other unwanted aberrations [35]. In our experiment, the bandwidth of our laser is relatively small (ß 8 nm); the effect of glass is negligible so all spatialtemporal couplings are controlled solely by the grating setups.…”

Section: Methodsmentioning

confidence: 97%

Non‐paraxial polarization spatio‐temporal coupling in ultrafast laser material processing

Patel

Tikhonchuk

Zhang

et al. 2017

Laser & Photonics Reviews

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Two hundred years after Malus' discovery of optical anisotropy, the study of polarization‐driven optical effects is as active as ever, generating interest in new phenomena and potential applications. However, in ultrafast optics, the influence of polarization is frequently overlooked being considered as either detrimental or negligible. Here we demonstrate that spatio‐temporal couplings, which are inherent for ultrafast laser systems with chirped‐pulse amplification, accumulate in multi‐pulse irradiation and lead to a strongly anisotropic light‐matter interaction. Our results identify angular dispersion in the focus as the origin for the polarization dependence in modification, yielding an increase in modification strength. With tight focusing (NA ≥ ∼0.4), this non‐paraxial effect leads to a manifestation of spatio‐temporal couplings in photo‐induced modification. We devise a practical way to control the polarization dependence and exploit it as a new degree of freedom in tailoring laser‐induced modification in transparent material. A near‐focus, non‐paraxial field structure analysis of an optical beam provides insight on the origin of the polarization dependent modification. However, single pulse non‐paraxial corrected calculations are not sufficient to explain the phenomena confirming the experimental observations and exemplifying the need for multi‐pulse analysis.

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Effects of aberrations in spatiotemporal focusing of ultrashort laser pulses

Cited by 38 publications

References 32 publications

Multiplexed temporally focused light shaping for high-resolution multi-cell targeting

Multiplexed temporally focused light shaping for high-resolution multi-cell targeting

Four-dimensional light shaping: manipulating ultrafast spatiotemporal foci in space and time

Non‐paraxial polarization spatio‐temporal coupling in ultrafast laser material processing

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