3D resolved mapping of optical aberrations in thick tissues

Zeng, Jun Ru; Mahou, Pierre; Schanne-Klein, Marie‐Claire; Beaurepaire, Emmanuel; Débarre, Delphine

doi:10.1364/boe.3.001898

Cited by 41 publications

(49 citation statements)

References 21 publications

(34 reference statements)

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“…Although per-point correction is not feasible in this way, considering that the wavefront changes gradually over the sample [53], we can measure and correct the wavefront on a coarser grid than what we are scanning, such that 6 2 to 8 2 wavefront measurements are needed per sample. We conclude that our method is, in principle, fast enough to be applied to real-time systems.…”

Section: Discussionmentioning

confidence: 99%

Snapshot coherence-gated direct wavefront sensing for multi-photon microscopy

Werkhoven¹,

Antonello²,

Truong³

et al. 2014

Opt. Express

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Abstract:Deep imaging in turbid media such as biological tissue is challenging due to scattering and optical aberrations. Adaptive optics has the potential to compensate the tissue aberrations. We present a wavefront sensing scheme for multi-photon scanning microscopes using the pulsed, near-infrared light reflected back from the sample utilising coherence gating and a confocal pinhole to isolate the light from a layer of interest. By interfering the back-reflected light with a tilted reference beam, we create a fringe pattern with a known spatial carrier frequency in an image of the back-aperture plane of the microscope objective. The wavefront aberrations distort this fringe pattern and thereby imprint themselves at the carrier frequency, which allows us to separate the aberrations in the Fourier domain from low spatial frequency noise. A Fourier analysis of the modulated fringes combined with a virtual Shack-Hartmann sensor for smoothing yields a modal representation of the wavefront suitable for correction. We show results with this method correcting both DM-induced and sample-induced aberrations in rat tail collagen fibres as well as a Hoechst-stained MCF-7 spheroid of cancer cells.

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Section: Discussionmentioning

confidence: 99%

Snapshot coherence-gated direct wavefront sensing for multi-photon microscopy

Werkhoven¹,

Antonello²,

Truong³

et al. 2014

Opt. Express

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“…In [32,34,35], the authors show that, for small aberrations, the image quality metric can be modeled using a quadratic polynomial. We denote a measurement of the image quality metric at time instant k withỹ k , so that…”

Section: Least-squares Estimation Of the Unknown Aberrationmentioning

confidence: 99%

“…3. The influence of the size of the region used for the aberration correction has been studied elsewhere [35]. For a certain setting of the DM r, the region is scanned using the xyz stage.…”

Section: A Description Of the Experimental Setupmentioning

confidence: 99%

“…For a certain setting of the DM r, the region is scanned using the xyz stage. The corresponding value of the image quality metricỹ is measured as the mean image intensity [32][33][34][35], i.e., the mean pixel value recorded over the region. The pixel dwell time is 0.5 ms and the sampling is 24 pixels × 24 pixels.…”

Section: A Description Of the Experimental Setupmentioning

confidence: 99%

“…Reducing the number of trial aberrations is critical in achieving short image acquisition times and in limiting side effects, such as photobleaching and phototoxicity. For small aberrations, the response of the image quality metric can be approximated using a simple model, such as a quadratic polynomial [25][26][27][28][29][30][31][32][33][34][35]. Model-based aberration correction algorithms [25][26][27][28][29][30][31][32][33][34][35][36][37][38] exploit the knowledge about the model of the metric to quicken the aberration correction, thus curtailing the aforementioned side effects.…”

Section: Introductionmentioning

confidence: 99%

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Optimization-based wavefront sensorless adaptive optics for multiphoton microscopy

et al. 2014

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Optical aberrations have detrimental effects in multiphoton microscopy. These effects can be curtailed by implementing model-based wavefront sensorless adaptive optics, which only requires the addition of a wavefront shaping device, such as a deformable mirror (DM) to an existing microscope. The aberration correction is achieved by maximizing a suitable image quality metric. We implement a model-based aberration correction algorithm in a second-harmonic microscope. The tip, tilt, and defocus aberrations are removed from the basis functions used for the control of the DM, as these aberrations induce distortions in the acquired images. We compute the parameters of a quadratic polynomial that is used to model the image quality metric directly from experimental input-output measurements. Finally, we apply the aberration correction by maximizing the image quality metric using the least-squares estimate of the unknown aberration.

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Correlative nonlinear optical microscopy and infrared nanoscopy reveals collagen degradation in altered parchments

Robinet

Dazzi

Portier

et al. 2016

European Microscopy Congress 2016: Proceedings

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This paper presents the correlative imaging of collagen denaturation by nonlinear optical microscopy (NLO) and nanoscale infrared (IR) spectroscopy to obtain morphological and chemical information at different length scales. Such multiscale correlated measurements are applied to the investigation of ancient parchments, which are mainly composed of dermal fibrillar collagen. The main issue is to characterize gelatinization, the ultimate and irreversible alteration corresponding to collagen denaturation to gelatin, which may also occur in biological tissues. Key information about collagen and gelatin signatures is obtained in parchments and assessed by characterizing the denaturation of pure collagen reference samples. A new absorbing band is observed near the amide I band in the IR spectra, correlated to the onset of fluorescence signals in NLO images. Meanwhile, a strong decrease is observed in Second Harmonic signals, which are a structural probe of the fibrillar organization of the collagen at the micrometer scale. NLO microscopy therefore appears as a powerful tool to reveal collagen degradation in a non-invasive way. It should provide a relevant method to assess or monitor the condition of collagen-based materials in museum and archival collections and opens avenues for a broad range of applications regarding this widespread biological material.In museums, libraries and archives, skin is largely present in collections as rawhide, parchment or leather since it has been used for utilitarian purposes, for example in clothes, vessels, writing supports and musical instruments or for decorative purposes. In Western Europe, parchment was the main writing support in the Middle Ages up to the growth of paper production in the 14-15 th centuries. Made from an untanned animal skin, it was preserved by liming, scraping and drying the skin under tension 1 . Compared to skin, parchment retains only the dermis layer, made mostly of fibrillar collagen (type I).Among conservators and scientists involved in the preservation of cultural heritage, gelatinization is a term commonly used for parchment alteration. It refers to the collagen denaturation to gelatin, where the triple helix is dissociated. Nevertheless, little is known about the actual transformation process in parchments and the influencing factors. UV radiation, heat or pH can cause perturbations in the bonding within and in-between collagen molecules but this might not be apparent unless water comes into contact with the material. In such a damaged structure, called a "pre-gelatinized" state, the access of water to the collagen molecules is considered to cause the loss of the hydrogen bonds holding the triple helix, resulting in the unfolding of the molecule. The gelatinization resulting from the action of water is accelerated by the additional energy provided by heating 2,3 . Given that gelatinization is irreversible, the major challenge for the conservation of parchment is to identify collagen in the "pre-gelatinized" state 2,3 so that suitable treatments or cons...

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3D resolved mapping of optical aberrations in thick tissues

Cited by 41 publications

References 21 publications

Snapshot coherence-gated direct wavefront sensing for multi-photon microscopy

Snapshot coherence-gated direct wavefront sensing for multi-photon microscopy

Optimization-based wavefront sensorless adaptive optics for multiphoton microscopy

Correlative nonlinear optical microscopy and infrared nanoscopy reveals collagen degradation in altered parchments

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