Ultraviolet Nanosecond Research Articles

Study on ultraviolet laser processing of a single-crystal diamond along 〈1 0 0〉 and 〈1 1 0〉 crystal orientations

Single-crystal diamond has been widely used in precision cutting tools, micro-electronic devices, optical devices and biological fields. In this work, microgrooves were created on single-crystal CVD diamond {100} surfaces along 〈100〉 and 〈110〉 crystal orientations by an ultraviolet nanosecond laser. Experiment results revealed that the surface morphology within microgrooves, the ablation rate, and the material removal rate were found to be strongly dependent on crystal orientation. Microgrooves along 〈110〉 crystal orientation have better inner surface morphology and higher material removal rate than microgrooves along 〈100〉 crystal orientation. The difference in material removal rates of microgrooves along 〈100〉 and 〈110〉 orientations was explained. Raman analysis revealed that the attached nanoparticles within microgrooves were graphite, and the thickness of graphite layer on the sidewall of 〈110〉 microgrooves was thinner than that of 〈100〉 microgrooves. Transmission electron microscopy analysis expressed that the ablation products of diamond contained disordered graphite and nanocrystalline diamond. Therefore, these results could provide significant guidance for laser processing of diamond microgrooves.

Crack Growth Analysis of Ultraviolet Nanosecond Laser Scanning Glass with Acoustic Emission

Crack Growth Analysis of Ultraviolet Nanosecond Laser Scanning Glass with Acoustic Emission

Crack Growth Analysis of Ultraviolet Nanosecond Laser Scanning Glass with Acoustic Emission

Crack Growth Analysis of Ultraviolet Nanosecond Laser Scanning Glass with Acoustic Emission

Ultraviolet Nanosecond Laser Treatment to Reduce the Friction Coefficient of Silicon Carbide Ceramics

The determination of the possibility for the reduction of the friction coefficient of ceramic parts from silicon carbide by pulse-periodic treatment with an ultraviolet nanosecond laser was carried out in the framework of this research. The gas-dynamic seal of the compressor rotor of the gas-turbine engine after hot isostatic pressing and mechanical treatment was exposed to surface microstructuring in a pulse-periodic mode. For experimental investigations, a laser with a maximum energy of the pulse of 50 µJ, a wavelength of 355 nm, and a pulse duration below 10 ns was used. It was determined that the surface quality was improved, and the surface roughness was reduced as a consequence of the realized laser polishing modes in the beam exposure area. The average value of the friction coefficient of the ceramic material surface decreased by 15% as result of pulse-periodic laser processing.

Laser printing of large-scale metal micro/nanoparticle array: Deposition behavior and microstructure

In this study, a novel printing process is proposed to efficiently fabricate a large-scale micro/nanoparticle array via laser-induced forward transfer of femtoliter metal voxels. A sputtering metal film with sub-micrometer thickness was initially patterned to an independent voxel array using a picosecond laser. Then, an ultraviolet nanosecond laser induced the voxel transfer from the donor substrate to the receiver entirely after it was irradiated by a single laser pulse. The results indicated that single laser irradiation can print a microparticle array that covers an area of several millimeters. The printed microparticle size varied from 5 μm to 580 nm. Furthermore, the proposed printing process exhibited high controllability by adjusting the voxel volume. The morphology of the cross section of the printed copper microparticles exhibited a lower porosity and oxidation state, and ultrafine nanograins were generated within an amorphous shell. The location deviations of the printed microparticles obeyed the chi-square distribution with a mean value of 1 μm. Moreover, the proposed process can avoid the satellite microdroplets and debris for reducing the resolution because unstable jetting and microdroplet separation are eliminated. The proposed approach enables the printing of a large-scale microstructure array with high efficiency and flexibility.

Ablation Threshold Measurement and Chemical Modification of UV Nanosecond Laser Micromachining of Polycrystalline Diamond

Polycrystalline Diamond In article number 2100450, Jianlei Cui and co-workers study the ablation threshold and phase transition of polycrystalline diamond under the irradiation of an ultraviolet nanosecond laser with a wavelength of 355 nm. It reveals that the ablation threshold of polycrystalline diamond is approximately 3.7326 J cm−2. Furthermore, the sp3 structure of the diamond transforms into the sp2 graphite phase during the ultraviolet nanosecond laser micromachining.

Growth of highly oriented graphite by ultraviolet nanosecond pulsed laser ablation of monocrystalline diamond

Inducing highly oriented graphite layer as buried conductive media in diamond by laser ablation is crucial for promoting the electronic functionalities of structured monocrystalline diamond. In the present work, we fabricate surface microgrooves with high precision and limited heat affected zone on monocrystalline diamond by low cost ultraviolet nanosecond pulsed laser micromachining. In particular, fruitful highly oriented graphite layer is formed between top transformed amorphous layer and bottom pristine diamond, with visible regular boundaries among them. Raman spectroscopy and high-resolution transmission electron microscopy characterization are jointly utilized to identify the phase transformation-induced microstructure evolution in subsurface of ablated diamond. Furthermore, molecular dynamics simulations are performed to elucidate the underlying ablation mechanisms, as well as predict the dynamic ablation process of nanosecond pulsed laser micromachining of diamond. Finally, the effect of laser fluence on the machined surface morphology and the phase transformation characteristics of the ablated diamond is addressed.

Surface micro-texture on sapphire fabricated by laser ablation trajectory regulation

Fabrication of the surface micro-texture on the C-plane sapphire is undertaken by a 355 nm Ultraviolet (UV) pulsed laser. The surface micro-textures of sapphire with different laser scanning line spacing ranging from 10 μm to 100 μm are obtained, where the selection range of scanning line spacing is controlled in the range of the groove width and plasma width to obtain a surface of high Peak-Valley (PV) value. A reasonable processing order is proposed to manufacture different types of surface micro-textures on sapphire by laser ablation trajectory regulation. In the multiple-passes laser ablation of sapphire by the UV nanosecond pulsed laser, the scanning lines in each direction is treated as once scanning. On this basis, the multiple processing can be carried out to avoid the influence of the subsequent scanning on the machined groove. In addition, the effect of different scanning line spacing on the PV value is quantified and different types of surface micro-textures on sapphire, including the squares, the rhombuses and the hexagons, are successfully fabricated, which can be applied in the friction reduction or anti-reflection field.

Temperature Field-Assisted Ultraviolet Nanosecond Pulse Laser Processing of Polyethylene Terephthalate (PET) Film.

Understanding the mechanism of and how to improve the laser processing of polymer films have been important issues since the advent of the procedure. Due to the important role of a photothermal mechanism in the laser ablation of polymer films, especially in transparent polymer films, it is both important and effective to adjust the evolution of heat and temperature in time and space during laser processing by simply adjusting the ambient environment so as to improve and understand the mechanism of this procedure. In this work, studies on the pyrolysis of PET film and on temperature field-assisted ultraviolet nanosecond (UV-ns) pulse laser processing of polyethylene terephthalate (PET) film were performed to investigate the photothermal ablation mechanism and the effects of temperature on laser processing. The results showed that the UV-ns laser processing of PET film was dominated by the photothermal process, in which PET polymer chains decomposed, melted, recomposed and reacted with the ambient gases. The ambient temperature changed the heat transfer and temperature distribution in the laser processing. Low ambient temperature reduced the thermal effect and an increase in ambient temperature improved its efficiency (kerf width: 39.63 μm at −25 °C; 48.30 μm at 0 °C; 45.81 μm at 25 °C; 100.70 μm at 100 °C) but exacerbated the thermal effect.

Microprocesses at the brass surface after impact of scanning beam of pulse-frequency ultraviolet nanosecond laser

A mode of laser heat treatment of the brass surface prior to conducting of diffusion bonding is proposed. We used the frequency-pulse radiation of a nanosecond ultraviolet laser at a pulse energy density W = 0.15 - 0.52 J/cm2. The metal sample was moved relative to a stationary laser beam along a raster trajectory (“snake”) so that adjacent spots were overlapped with an overlap ratio of ⩾ 99 %. The impact of radiation on brass was carried out in a subthreshold mode excluding crater formation. The process took place while the metal remained in a condensed state. A regular rough structure with a height of individual uplifts of the order of 1 micron was formed on the surface of the brass. article is devoted to creation of aerosolized detergent compositions, needful for use during operation of high-precision metal mirrors, as a rule, in field conditions. The created detergent compositions with inhibitory properties allow, simultaneously with carrying out the process of physicochemical cleaning of optical surface from technological impurities, to ensure its protection from the influence of adverse climatic factors during storage, transportation, installation and exploitation of the element with the possibility of its alignment. The high climatic resilience of the protective films investigated in this article, which are formed during the cleaning of the optical surface, is shown. In this case, the optical characteristics of the processed elements after climatic tests do not get worse.

Ablation Threshold Measurement and Chemical Modification of UV Nanosecond Laser Micromachining of Polycrystalline Diamond

The effects of pulsed laser interaction with matter have become a center for research. The pulsed laser has become an indispensable manufacturing tool in the efficient machining of polycrystalline diamond (PCD) and other materials. Herein, the ablation threshold and chemical modification of PCD irradiated using ultraviolet (UV) nanosecond laser is scrutinized. Using a UV nanosecond laser source, a bulk of PCD is ablated in air, and multipulse processing is executed at a wavelength of 355 nm. The ablation threshold of PCD is reported to be ≈3.7326 J cm−2 based on the linear relationship between the laser pulse energy density and the crater diameter, with a Gaussian distribution of the laser intensity on the cross‐section. Furthermore, the sp3 structure transitioned to the sp2 graphite phase when the PCD is exposed to UV nanosecond laser irradiation. Consequently, this study provides a theoretical and experimental reference for UV nanosecond laser micromachining of PCD materials in the research and metal‐working industries.

Antifriction effect of 316L stainless steel textured surface with superhydrophilic properties in brain tissue insertion

To reduce the tissue damage caused by the cannula electrodes during the operation of deep brain stimulation, laser matching micro texture on the surface of the electrodes was proposed to reduce the friction force. Different grooves and pit arrays were fabricated on the 316L stainless steel surface using an ultra-violet nanosecond laser. The wettability of textured surfaces with different morphologies was measured by distilled water and artificial cerebrospinal fluid. Insertion experiments were carried out on porcine brains using textured steel needles. The results showed that textured steel needles have an obvious antifriction effect under the condition of the lubricant. The elliptical pit texture has the best effect of reducing friction, and the friction force can be reduced by 37.6% on average.

Precision cutting of PDMS film with UV-nanosecond laser based on heat generation-diffusion regulation

Laser precision cutting of polydimethylsiloxane (PDMS) films technology will greatly promote development of flexible electronics industry. However, mechanism and optimization method of PDMS films laser cutting is still unclear. On one hand, mechanism of ultraviolet (UV) nanosecond laser precision cutting of PDMS films with laser ablation as the core was explored based on analysis of by-product components. On the other hand, laser cutting quality optimization method of heat generation- diffusion co-regulation was proposed based on the mechanism of laser ablation. The minimum width of the groove and the heat affected zone were obtained by regulating the heat generation process at room temperature, 67.1 ± 1.7 μm and 6.8 ± 0.8 μm, respectively. In addition, the heat diffusion process can be regulated by lowering ambient temperature to further optimize the quality of cut. Using this optimization method, a spring-shape flexible electrode was prepared, and circumferential stretch limit of this spring-shape flexible electrode has been increased from 10% to 150% compared with planar PDMS film flexible electrodes.

Fabrication of PCD Skiving Cutter by UV Nanosecond Laser.

Polycrystalline diamond (PCD) skiving cutter has dominated research in recent years. However, the traditional methods of fabrication have failed to cut the diamond with high quality. We propose the two-step laser machining process combining roughing machining with orthogonal irradiation and finishing machining with tangential irradiation. In addition, the processing effect and mechanism of different lasers on the diamond were investigated by a finite element analysis. It’s proved that the ultraviolet nanosecond laser is an excellent machining method for the processing of diamond. Furthermore, the effect of the processing parameters on the contour accuracy (Rt) was studied. The result indicates that the Rt value decreases first and then increases as the increase of the line interval, scanning speed and defocusing amount (no matter positive or negative defocus). Further, Raman spectroscopy was applied to characterize the diamond surface under different cutting methods and the flank face of the tool after processing. Finally, a high-quality PCD skiving cutter was obtained with an Rt of 5.6 µm and no phase transition damage.

Thermal ablation regulation for ultraviolet (UV) nanosecond laser precision cutting of polycarbonate (PC) film

With the refinement of polycarbonate (PC) film application, higher demands are placed on shape, dimensional accuracy, and cross-sectional quality of PC film. Ultraviolet (UV) nanosecond laser is one of the feasible methods for patterned precision cutting of PC films, but the cutting mechanism and the influence of process parameters on cutting quality have not deeply researched. Using UV nanosecond laser with maximum power of 3 W and 0.2 mm thick PC film, on the one hand, laser cutting mechanism was evaluated based on by-product composition analysis, and laser ablation in process path is the principle of UV-nanosecond laser cutting of PC film. On the other hand, influence of laser cutting process on cutting quality was analyzed by orthogonal experiments. When parameter combination was 0.1 W-40 mm/s-15 (laser power - cutting speed - number of cuts), a smaller cutting seam width (40.7 ± 1.2 μm) and heat-affected zone width (26.8 ± 0.8 μm) were obtained, and there was no obvious seam taper.

Ablation characteristics and material removal mechanisms of a single-crystal diamond processed by nanosecond or picosecond lasers.

The microstructures on a diamond surface have attracted extensive attention in microelectronics, ultra-precision machining tools, and optical elements, etc. In this work, microgrooves were fabricated on a single-crystal diamond surface using ultraviolet nanosecond or infrared picosecond laser pulses. The surface and internal morphologies of the microgrooves were characterized. The chemical composition and phase transition of the diamond after laser irradiation were analyzed. Furthermore, the ablation threshold, ablation rate, and material removal rate of the diamond processed by nanosecond or picosecond lasers were also calculated. In addition, the temperature distributions of the diamond ablated by nanosecond or picosecond lasers were simulated. Finally, the material removal mechanisms of a single-crystal diamond processed by nanosecond or picosecond lasers were revealed. This work is expected helpful to provide a guidance for the laser fabrication of microstructures on diamond.

Phenolic resin plate precision cutting by ultraviolet nanosecond laser ablation regulation

Laser precision cutting process of phenolic resin plates (PRP) has attracted widespread attention, but at this stage, this work is carried out without understanding the hazards of process by-products and process mechanism. Here, mechanism of PRP ultraviolet (UV) nanosecond laser precision cutting process has been assessed based on by-product composition analysis. Composition of solid residue in cutting seam and generating gas during cutting process are analyzed, while benzene and phenol in gas by-products are potentially toxic. Quality of PRP UV nanosecond laser precision cutting process have been also analyzed using orthogonal experiment analysis. The smallest width (50.3 ± 3.1 µm) of cutting seam were obtained at UV laser cutting parameters combination of 4.04 W-1000 mm/s-9, and width of burr-like heat affected zone (HAZ) was 57.5 ± 4.7 µm. It turned out that UV laser precision cutting of PRP is feasible, but corresponding protective measures must be taken.

Precision cutting of polyvinyl chloride film by ultraviolet nanosecond laser

ABSTRACT Ultraviolet (UVUV) nanosecond laser cutting of polyvinyl chloride (PVC) films was evaluated by experimental design and laser ablation principle. Factors such as laser power, cutting speed, and repetition numbers of laser cutting will influence the quality of cutting seam. Narrower width of cutting seam (55.14.6 ) and smaller area of heat-affected zone (HAZ) (25.52.4 ) were obtained when processing parameters combination chosen as 0.2 W-20 mm/s-5 (laser power, laser cutting speed, repetition numbers of laser cutting). In the meantime, no obvious taper was observed. The feasibility of UV laser precise cutting of PVC film was quantitively demonstrated. Mechanism of laser cutting of PVC film was laser ablation according to Raman analysis and rapid pyrolysis analysis. Gas by-products such as hydrogen chloride, carbon dioxide, carbon monoxide, and organic compounds with benzene ring structure generated during laser cutting process were potentially toxic. Therefore, corresponding protective measures must be taken during laser processing of PVC film.

Precision cutting of epoxy resin board (ERB) by ultraviolet (UV) nanosecond laser ablation with consideration of hazardous gas protection

Mechanism and processing technology of ultraviolet (UV) nanosecond laser precision cutting of epoxy resin board (ERB) were investigated based on by-products analysis and orthogonal experiment. Interactions between UV nanosecond laser and ERB was studied, and by-products generated during laser cutting process were analyzed. Among them, gaseous by-products such as CO and benzene were potentially toxic. Under premise of cutting off ERB (0.5 mm thick), minimum seam width (75 ± 3 µm) was obtained at laser cutting parameters combination of 4.04 W - 1000 mm/s – 8 (cutting times). Meanwhile, there was no obvious burr and thermal deformation of the seam. Overall, UV nanosecond laser is a viable process for precision cutting of ERB, but protective measures must be taken during the process.

Ablation of binary As2S3, As2Se3, GeS2, GeSe2 and GeSe3 bulk glasses and thin films with a deep ultraviolet nanosecond laser

Binary (As2S3, As2Se3, GeS2 GeSe2 and GeSe3) bulk glasses and corresponding thin films were prepared and illuminated with deep ultraviolet nanosecond (DUV ns) pulsed laser operating at 213 nm. The illumination of samples led to the reproducible crater's formation. Subsequently, the influence of the pulses number and laser fluence on their creation was studied. The ablation rate and laser-induced ablation threshold (LIAT) were determined based on these experiments. The craters with the help of digital holographic microscopy (DHM), atomic force microscopy (AFM), phase shift imaging mode of AFM, Raman scattering, scanning electron microscopy and energy-dispersive X-ray spectroscopy were characterized. As an application possibility, the formation of the diffraction gratings by laser direct writing is presented and their functionality is demonstrated.