Large optical phase shifts in hydrogels written with femtosecond laser pulses: elucidating the role of localized water concentration changes

Gandara-Montano, Gustavo A.; Stoy, V.; Dudič, Miroslav; Petrák, Václav; Knox, Wayne H.

doi:10.1364/ome.7.003162

Cited by 16 publications

(3 citation statements)

References 36 publications

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“…Although never reported in cell-laden hydrogels, fs laser writing within glass, polymers, silicone hydrogels, and BSA protein solutions have been reported to cause a change in refractive indices [15][16][17]. The change in RI, especially in glass and polymers has been exploited to create optical waveguides, diffraction gratings, and optical storage devices [10,18,19].…”

Section: Introductionmentioning

confidence: 99%

Femtosecond laser induced densification within cell-laden hydrogels results in cellular alignment

Xiong¹,

Li²,

Kunwar³

et al. 2019

Biofabrication

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Section: Introductionmentioning

confidence: 99%

Femtosecond laser induced densification within cell-laden hydrogels results in cellular alignment

Xiong¹,

Li²,

Kunwar³

et al. 2019

Biofabrication

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“…Histological analysis of Blue-IRIS in the cat cornea also showed markedly less cell death compared with femtosecond-laser in situ keratomileusis (LASIK) [6]. Meanwhile, our work in hydrogel materials demonstrated that 400 nm laser micromachining can locally decrease RI by increasing the water content of written regions, and it was assumed that this hydrophilicity was associated with depolymerization [7].…”

Section: Introductionmentioning

confidence: 65%

Tissue effects of intra-tissue refractive index shaping (IRIS): insights from two-photon autofluorescence and second harmonic generation microscopy

Brown

Huxlin

et al. 2019

Biomed. Opt. Express

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Intra-tissue refractive index shaping (IRIS) is a novel, non-ablative form of vision correction by which femtosecond laser pulses are tightly focused into ocular tissues to induce localized refractive index (RI) change via nonlinear absorption. Here, we examined the effects of Blue-IRIS on corneal microstructure to gain insights into underlying mechanisms. Three-layer grating patterns were inscribed with IRIS ~180 µm below the epithelial surface of ex vivo rabbit globes using a 400 nm femtosecond laser. Keeping laser power constant at 82 mW in the focal volume, multiple patterns were written at different scan speeds. The largest RI change induced in this study was + 0.011 at 20 mm/s. After measuring the phase change profile of each inscribed pattern, two-photon excited autofluorescence (TPEF) and second harmonic generation (SHG) microscopy were used to quantify changes in stromal structure. While TPEF increased significantly with induced RI change, there was a noticeable suppression of SHG signal in IRIS treated regions. We posit that enhancement of TPEF was due to the formation of new fluorophores, while decreases in SHG were most likely due to degradation of collagen triple helices. All in all, the changes observed suggest that IRIS works by inducing a localized, photochemical change in collagen structure.

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“…The most common alternatives for the ex vivo observation of contact lens engravings and for the evaluation of their surfaces include the use of commercial interferometers [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ] and microscopy techniques such as confocal, atomic-force, and scanning electron instruments [ 27 , 28 , 29 ]. Furthermore, Optical Coherence Tomography (OCT) [ 30 , 31 ] has supposed an efficient technique applied to the metrology of these lenses as well as, for instance, other technologies involving the introduction of fringe profilometry [ 32 ] and microtopography based on optical triangulation [ 33 ].…”

Section: Introductionmentioning

confidence: 99%

Soft Contact Lens Engraving Characterization by Wavefront Holoscopy

Vila-Andrés,

Esteve-Taboada,

Micó

2024

Sensors

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Permanent engravings on contact lenses provide information about the manufacturing process and lens positioning when they are placed on the eye. The inspection of their morphological characteristics is important, since they can affect the user’s comfort and deposit adhesion. Therefore, an inverted wavefront holoscope (a lensless microscope based on Gabor’s principle of in-line digital holography) is explored for the characterization of the permanent marks of soft contact lenses. The device, based on an in-line transmission configuration, uses a partially coherent laser source to illuminate the soft contact lens placed in a cuvette filled with a saline solution for lens preservation. Holograms were recorded on a digital sensor and reconstructed by back propagation to the image plane based on the angular spectrum method. In addition, a phase-retrieval algorithm was used to enhance the quality of the recovered images. The instrument was experimentally validated through a calibration process in terms of spatial resolution and thickness estimation, showing values that perfectly agree with those that were theoretically expected. Finally, phase maps of different engravings for three commercial soft contact lenses were successfully reconstructed, validating the inverted wavefront holoscope as a potential instrument for the characterization of the permanent marks of soft contact lenses. To improve the final image quality of reconstructions, the geometry of lenses should be considered to avoid induced aberration effects.

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Large optical phase shifts in hydrogels written with femtosecond laser pulses: elucidating the role of localized water concentration changes

Cited by 16 publications

References 36 publications

Femtosecond laser induced densification within cell-laden hydrogels results in cellular alignment

Femtosecond laser induced densification within cell-laden hydrogels results in cellular alignment

Tissue effects of intra-tissue refractive index shaping (IRIS): insights from two-photon autofluorescence and second harmonic generation microscopy

Soft Contact Lens Engraving Characterization by Wavefront Holoscopy

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