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Characterization of manufacturing-induced surface scratches and their effect on laser damage resistance performance of diamond fly-cut KDP crystal
摘要： Manufacturing-induced defects have drawn more and more attentions to improve the laser damage resistance performance of KDP crystal applied in high-power laser systems. Here, the morphology of surface scratches on diamond ?y-cut KDP crystal is characterized and their e?ect on the laser damage resistance is theoretically and experimentally investigated. The results indicate that surface scratches could lower laser-induced damage threshold (LIDT) by modulating incident lasers and producing resultant local light intensi?cations. The induced maximum light intensity enhancement factors (LIEFs) are dependent on scratch shapes and dimensions. The di?raction e?ects originating from scratch edges are responsible for the strongest light intensi?cation. Even for ultra-precision ?nished KDP surface with scratches that well satisfy the currently applied scratch/dig speci?cation, the induced LIEFs are quite high, indicating that the actual defect dimension allowance should be amended and speci?ed according to the defect-induced LIEFs. The e?ect of scratches on laser damage resistance is experimentally veri?ed by the tested LIDT, which is approximately consistent with the simulation one. The morphologies of laser damage sites further con?rm the role of scratches in lowering LIDT. This work could o?er new perspective and guidance for fully evaluating the performance of ultra-precision manufactured optical materials applied in high-power laser facilities.
关键词： Laser damage resistance performance,KDP crystal,Manufacturing-induced defects,Diamond ?y-cutting,Light intensi?cation
更新于2025-09-16 10:30:52
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Effect of laser texturing on the performance of ultra-hard single-point cutting tools
摘要： This paper investigates the cutting performance and anti-adhesive properties of textured single-point polycrystalline diamond (PCD) cutting tools in machining Aluminium 6082 alloys. The micro/nano textures were first milled using a fibre laser (1064-nm wavelength) at different power intensities, feed speeds and pulse durations, and finally characterised using scanning electron microscopy, white light interferometry and energy dispersive X-ray spectroscopy. The effect of different textures on the cutting performance was investigated in turning tests under dry cutting conditions. The test was stopped at regular lengths of cut to allow analysis of height of adhesion through 3D white light interferometry. The data processing of the cutting forces and the microscopical characterisation of the tested cutting tools enabled the evaluation of the effects of texture design, friction coefficient and adhesive properties. The results indicated that feed force in tools with grooves perpendicular to the chip flow direction (CFD) was more stable (20–40 N) than the benchmark (6–41 N). Similarly, the thrust force for tools with grooves parallel to CFD and grooves perpendicular to CFD showed a homogeneous trend fluctuating between 60 and 75 N as compared with the benchmark (ranging between 73 and 90 N). For texture depth in the order of 260 nm and post process roughness in the order of tens of nanometers, a reduction of average friction coefficient (0.28 ± 0.14) was reported when using lasered inserts with grooves parallel to the chip flow direction compared with the benchmark tools (0.34 ± 0.26) corroborated by reduced stiction of workpiece material on the rake face. In machining via textured tools with grooves perpendicular to CFD, the cutting forces were reduced by 23%, and the surface quality of the machined workpiece was improved by 11.8%, making this geometry the preferred choice for finishing applications. Using grooves parallel to CFD reduced the cutting forces by 11.76%, adhesion by 59.36% and friction coefficient by 14.28%; however, it increased the surface roughness of the machined workpiece, making this geometry suitable for roughing operations. For the first time, laser manufacturing is proposed as a flexible technique to functionalise the geometrical and wear properties of PCD cutting tools to the specific applications (i.e. roughing, finishing) as opposed to the standard industrial approach to use microstructurally different PCDs (i.e. grain size and binder %) based on the type of operation.
关键词： Adhesion,Dry cutting,Nanosecond pulse,Laser milling,Polycrystalline diamond insert,Laser surface texturing,Cutting forces
更新于2025-09-16 10:30:52
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Nano-to-micro diamond formation by nanosecond pulsed laser annealing
摘要： Here, we report the synthesis and characterization of nano-, micro-, twinned, and lonsdaleite diamonds, which are formed after melting and quenching of amorphous carbon or Q-carbon essentially at room temperature and atmospheric pressure. These conversions depend on the degree of undercooling, which is controlled by the laser parameters and thermal conductivities of the amorphous carbon and the substrate. The laser melting and undercooling provide liquid-phase packing of atoms similar to high-pressure, which facilitate the conversion of amorphous carbon into diamond or Q-carbon without using any catalyst. By changing the nucleation and growth rates, we have synthesized a wide range of sizes (4 nm to 3 μm) of diamond crystals. The formation of twinned and lonsdaleite diamonds is controlled by the quenching rate. Therefore, we have created a “factory of diamonds” at ambient conditions by nanosecond laser annealing, which will pave the pathway to design high-speed mechanical and electrical devices.
关键词： diamond formation,nanosecond pulsed laser annealing,Q-carbon,nano-to-micro diamonds,undercooling
更新于2025-09-16 10:30:52
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Design and fabrication of three-dimensional single-mode waveguide arrays in bulk diamond through direct focused proton beam implantation
摘要： We demonstrate the feasibility of creating three-dimensional photonic devices through the realization of multi-level waveguides inside diamond by a series of systematic combined simulations grounded on Monte-Carlo statistics and Maxwell solver algorithms. Further, we have fabricated the counterparts of the multi-level waveguides buried in single crystalline diamond using a process based on several proton beam irradiation steps with different energies and fluences. On top of that, we draw a thorough comparison between the simulation results and the experimental observations, and find that they are in a good agreement with each other. Moreover, the simulation results also provide additional information such as the working fluence range of single-mode light (1550 nm) wave-guiding, the effective refractive index, and the polarization direction. The proof-of-concept of producing three-dimensional optical and photonic structures by direct focused proton beam implantation would open up a variety of new opportunities in designing and fabricating optical modulators, photonic components and quantum-computing related functional devices in bulk diamond, thus further promoting the development of three-dimensional diamond photonics.
关键词： FDE simulation,SRIM simulation,Ion implantation,Proton beam writing,3D diamond waveguide arrays
更新于2025-09-16 10:30:52
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Optical properties of laser-modified diamond: From visible to microwave range
摘要： We have measured the optical properties of a graphitised layer with dc conductivity of 305 W–1 cm–1 produced by excimer laser irradiation (KrF, t = 20 ns, l = 248 nm) of a polycrystalline diamond surface grown by chemical vapour deposition. Studies have been conducted in a wide range of wavelengths: from far-IR to visible spectral regions. The resulting constants of the Drude model are the basic parameters for calculating the electromagnetic response of diamond/graphite photon elements or metamaterials fabricated using the direct laser writing method.
关键词： optical properties,diamond,metamaterials,spectroscopy,nanocrystalline graphite,laser
更新于2025-09-16 10:30:52
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Laser heating setup for diamond anvil cells for <i>in situ</i> synchrotron and in house high and ultra-high pressure studies
摘要： The diamond anvil cell (DAC) technique combined with laser heating is one of the major methods for studying materials at high pressure and high temperature conditions. In this work, we present a transferable double-sided laser heating setup for DACs with in situ temperature determination. The setup allows precise heating of samples inside a DAC at pressures above 200 GPa and could be combined with synchrotron beamline equipment. It can be applied to X-ray diffraction and X-ray transmission microscopy experiments. In the setup, we use high-magnification and low working distance infinity corrected laser focusing objectives that enable us to decrease the size of the laser beam to less than 5 μm and achieve the maximum optical magnification of 320 times. All optical components of the setup were chosen to minimize chromatic and spatial aberrations for accurate in situ temperature determination by multiwavelength spectroscopy in the 570–830 nm spectral range. Flexible design of our setup allows simple interchange of laser sources and focusing optics for application in different types of studies. The setup was successfully tested in house and at the high-pressure diffraction beamline ID15B at the European Synchrotron Radiation Facility. We demonstrate an example of application of the setup for the high pressure–high temperature powder diffraction study of PdH and X-ray transmission microscopy of platinum at 22(1) GPa as a novel method of melting detection in DACs.
关键词： high pressure,diamond anvil cell,X-ray transmission microscopy,X-ray diffraction,synchrotron,laser heating,high temperature
更新于2025-09-16 10:30:52
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Raman spectroscopy of poly (methyl methacrylate) under laser shock and static compression
摘要： Time-resolved Raman spectroscopy for visualizing molecular fingerprint snapshots at nanosecond time scale is a useful tool for detailed understanding of in situ shock behaviour of materials. This technique was applied to study the changes in molecular vibrations of poly (methyl methacrylate) (PMMA) under laser driven shock compression up to ~1.9 GPa in a confinement geometry. A layered target configuration is used to enhance the shock pressure. The vibrational modes are measured as a function of dynamic shock and static compression. The Grüneisen parameters and bond anharmonicities in PMMA are determined using compression behaviour of Raman modes. The deduced shock velocity (~3.5 ± 0.4 km/s) in PMMA based on the time evolution of shocked Raman mode at 1.9 GPa is in agreement with the one calculated (~3.7 km/s) from 1-D radiation hydrodynamic simulations. A comparative study on shock experiment and static high pressure Raman spectroscopic measurements is done. Static pressure measurement up to ~16 GPa show rapid blue shifting of C–H stretching modes.
关键词： Raman spectroscopy,PMMA,confinement geometry,Raman shift,laser shock,diamond anvil cell (DAC),static experiment
更新于2025-09-16 10:30:52
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High-efficiency Posture Pre-alignment Method for Large Component Assembly via iGPS and Laser Ranging
摘要： A model for controlling the two-dimensional distribution of negatively charged nitrogen-vacancy (NV?) fluorescent centers near the surface of a diamond crystal is presented, using only a microwave plasma-assisted chemical vapor deposition (CVD) method. In this approach, a CVD diamond layer is homoepitaxialy grown via microwave plasma-assisted CVD using an isotopically enriched methane (12CH4 ), hydrogen (H2 ), and nitrogen (N2 ) gas mixture on patterned diamond (0 0 1). When the surface is imaged by means of confocal microscope photoluminescence mapping, fine grooves are observed to have been generated artificially on the diamond surface. NV? centers are found to be distributed selectively into these grooves. These results demonstrate an effective means for the formation of NV? centers of selectable size and density via microwave plasma-assisted CVD, with potential application in the production of diamond quantum sensors.
关键词： doping,nitrogen-vacancy centers,homoepitaxial,groove structure,Diamond,microwave plasma-assisted chemical vapor deposition
更新于2025-09-16 10:30:52
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Residual Stresses in Ultrasonic-Assisted Laser Sintered Grinding Diamond Materials
摘要： Special processing, viz ultrasonic vibration-assisted laser sintering of diamonds was studied. This process would eliminate the drawbacks pertaining to existing super-hard grinding wheels. The composite process fully utilized the odds of laser sintering and ultrasonic vibration to homogenize the structure and reduce residual stresses. Diamond particles were added to a 45 steel matrix using a Ni–Cr alloy via ultrasonic vibration-assisted laser sintering in argon. Metallographic microscopy, and were used to examine the microstructure of a Ni–Cr alloy and abrasive diamond particle bonding interface microstructure, Raman spectrometry was applied to evaluate residual stresses. Acoustic flow and cavitation effects generated by ultrasonic vibration refine crystal grains in the cladding layer and the microstructure is more homogeneous than the microstructure without ultrasonic treatment. A Cr3C2 layer formed on the surface of abrasive diamond particles enhances the bonding ability of a Ni–Cr alloy to diamond, which ensures the diamond isolation and protection, ultrasonic vibration reduces residual stresses inside abrasive diamond particles.
关键词： diamond,laser sintering,ultrasonic vibration,interfacial microstructure,residual stress
更新于2025-09-12 10:27:22
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Fabrication of diamond diffractive optics for powerful CO2 lasers via replication of laser microstructures on silicon template
摘要： New approach to fabricate diamond diffractive optical elements (DOEs) with continuous relief for powerful CO2 lasers is proposed and tested. It involves short-pulse laser microstructuring of a silicon wafer, which further is used as a substrate for polycrystalline diamond growth in a microwave plasma-assisted CVD process. After fine mechanical polishing of the growth side of the diamond film, the silicon substrate is removed via chemical etching. Two different DOEs providing close to 100% diffraction efficiency were fabricated with this technique: cylindrical Fresnel lens with kinoform surface profile and three-beam splitter with continuous microrelief. Optimization of the laser processing conditions has made possible to reduce the final roughness of the structured diamond surface to 200-400 nm depending on the local relief depth (0-7 μm). Both DOEs tested with a CO2 laser have demonstrated high transparency and diffraction efficiency, as well as low radiation scattering of the IR radiation at the surface irregularities.
关键词： laser microstructuring,diffraction efficiency,CVD process,diamond diffractive optics,CO2 lasers,silicon template
更新于2025-09-12 10:27:22