Fabrication and characterization of diffraction gratings in ophthalmic polymers by using UV direct laser interference patterning

Sola, D.; Alamri, Sabri; Lasagni, Andrés Fabían; Artal, Pablo

doi:10.1016/j.apsusc.2019.01.071

Cited by 16 publications

(13 citation statements)

References 47 publications

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“…It is worth noting that these marks were only visible in the phase contrast mode. It has been reported that this type of laser-induced structure is produced below the damage threshold [ 15 , 18 , 36 , 37 ]. Concerning the shape of the structured tracks, as in the previous case, they were circular in shape.…”

Section: Resultsmentioning

confidence: 99%

“…These phenomena lead to localized micro or sub-micrometric lattice damage, permanent weak local refractive index variation, the formation of nano-voids, crystallization processes, or chemical transformations [ 11 , 12 ]. Short and ultrashort laser radiation has been recently used to modify the refractive power of polymers for ophthalmic applications by inscribing diffractive optical elements on the surface or inside the material [ 15 , 18 , 19 , 22 , 36 , 37 , 38 , 39 , 40 ]. Nevertheless, the role that thermal accumulation plays on the optical properties of diffraction gratings produced by ultrashort direct laser writing for ophthalmic applications has not conclusively been solved.…”

Section: Introductionmentioning

confidence: 99%

“…We report here on the fabrication of diffractive gratings in PHEMA polymers used as soft contact lenses by using low- and high-repetition rate ultrashort laser pulses. This type of structure has been recently proposed to be used for refractive correction [ 15 , 18 , 36 , 37 ]. Periodic linear patterns were inscribed underneath the surface sample modifying laser pulse energy, laser wavelength, repetition rate, scanning speed, and inter-line spacing.…”

Section: Introductionmentioning

confidence: 99%

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The Role of Thermal Accumulation on the Fabrication of Diffraction Gratings in Ophthalmic PHEMA by Ultrashort Laser Direct Writing

2020

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The fabrication of diffraction gratings by ultrashort direct laser writing in poly-hydroxyethyl-methacrylate (PHEMA) polymers used as soft contact lenses is reported. Diffraction gratings were inscribed by focusing laser radiation 100 µm underneath the surface of the samples. Low- and high-repetition rate Ti:sapphire lasers with 120 fs pulsewidth working at 1 kHz and 80 MHz respectively were used to assess the role of thermal accumulation on microstructural and optical characteristics. Periodic patterns were produced for different values of repetition rate, pulse energy, laser wavelength, distance between tracks, and scanning speed. Compositional and structural modifications of the processed areas were studied by micro-Raman spectroscopy showing that under certain parameters, thermal accumulation may result in local densification. Far-field diffraction patterns were recorded for the produced gratings to assess the refractive index change induced in the processed areas.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Role of Thermal Accumulation on the Fabrication of Diffraction Gratings in Ophthalmic PHEMA by Ultrashort Laser Direct Writing

2020

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“…It is well known that the inscription of diffractive optical elements such as diffraction gratings can be used to modify the refractive index and hence the refractive power of an optical device by using short and ultrashort laser pulses with pulse energy below damage threshold [32][33][34][35]42,43]. In this work, we report on the fabrication of diffractive gratings in acrylic intra-ocular lenses by using high-repetition-rate ultrashort laser pulses.…”

Section: Introductionmentioning

confidence: 99%

High-Repetition-Rate Femtosecond Laser Processing of Acrylic Intra-Ocular Lenses

Sola

Cases

2020

Polymers

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The study of laser processing of acrylic intra-ocular lenses (IOL) by using femtosecond laser pulses delivered at high-repetition rate is presented in this work. An ultra-compact air-cooled femtosecond diode laser (HighQ2-SHG, Spectra-Physics) delivering 250 fs laser pulses at the fixed wavelength of 520 nm with a repetition rate of 63 MHz was used to process the samples. Laser inscription of linear periodic patterns on the surface and inside the acrylic substrates was studied as a function of the processing parameters as well as the optical absorption characteristics of the sample. Scanning Electron Microscopy (SEM) Energy Dispersive X-ray Spectroscopy (EDX), and micro-Raman Spectroscopy were used to evaluate the compositional and microstructural changes induced by the laser radiation in the processed areas. Diffractive characterization was used to assess 1st-order efficiency and the refractive index change.

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“…For a given laser wavelength and number of beams, both the pattern period and geometry can be easily adjusted by modifying the angle, the polarization, and the intensity of the interfering beams . This technique has been already employed to successfully pattern a wide range of materials such as metals, ceramics, and polymers and processing speeds near 1 m 2 min −1 have been reported . Moreover, DLIP is a single‐step process that does not require masks or solvents, and therefore it is suitable for industrial manufacturing.…”

Section: Introductionmentioning

confidence: 99%

How to Tailor Structural Colors for Extended Visibility and White Light Generation Employing Direct Laser Interference Patterning

Storm

Alamri

Soldera

et al. 2019

Macro Chemistry & Physics

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The appearance of a surface can be controlled by creating periodic microstructures designed to diffract light and produce structural colors. Nevertheless, since structural coloration is based on diffraction, the produced colors have a strong dependence on the viewing angle and absence of coloration takes place while tilting the samples. In this work direct laser interference patterning is used to firstly provide transparent polymer sheets a structural coloration with a high‐range observation angle, and secondly to demonstrate the combination of structural colors, producing a white coloring effect. The employed approaches are based on the fabrication of micro‐gratings with multiple periods in the same structured area and on the engineering of the diffraction orders of the diffraction spectrum. The patterned surfaces are characterized by confocal microscopy and angular spectrometry in reflection mode. The morphological characterization shows homogeneous surface patterns, while the spectral results demonstrate that combining four spatial periods on a single patterned surface, a white appearance is obtained over an angular observation range higher than 30°. The experimental results are supported by theoretical predictions by means of generalized formulas based on the diffraction of light.

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Fabrication and characterization of diffraction gratings in ophthalmic polymers by using UV direct laser interference patterning

Cited by 16 publications

References 47 publications

The Role of Thermal Accumulation on the Fabrication of Diffraction Gratings in Ophthalmic PHEMA by Ultrashort Laser Direct Writing

The Role of Thermal Accumulation on the Fabrication of Diffraction Gratings in Ophthalmic PHEMA by Ultrashort Laser Direct Writing

High-Repetition-Rate Femtosecond Laser Processing of Acrylic Intra-Ocular Lenses

How to Tailor Structural Colors for Extended Visibility and White Light Generation Employing Direct Laser Interference Patterning

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