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Results for “LASER DRILLING”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

The reverse laser drilling of transparent materials

Within a limited range of incident laser-beam intensities, laser drilling of a sapphire wafer initiates on the surface of the wafer where the laser beam exits and proceeds upstream in the laser beam to the surface where the laser beam enters the wafer. This reverse laser drilling is the result of the constructive interference between the laser beam and its reflected component on the exit face of the wafer. Constructive interference occurs only at the exit face of the sapphire wafer because the internally reflected laser beam suffers no phase change there. A model describing reverse laser drilling predicts the ranges of incident laser-beam intensity where no drilling, reverse laser drilling, and forward laser drilling can be expected in various materials. The application of reverse laser drilling in fabricating feed-through conductors in silicon-on-sapphire wafers for a massively parallel processer is described.

Anthony, T. R.↗
DOE OSTI2014

Novel signal inversion of laser beam induced current for femtosecond-laser-drilling-induced junction on vacancy-doped p-type HgCdTe

In this paper, experimental results of temperature-dependent signal inversion of laser beam induced current (LBIC) for femtosecond-laser-drilling-induced junction on vacancy-doped p-type HgCdTe are reported. LBIC characterization shows that the traps induced by femtosecond laser drilling are sensitive to temperature. Theoretical models for trap-related p-n junction transformation are proposed and demonstrated using numerical simulations. The simulations are in good agreement with the experimental results. The effects of traps and mixed conduction are possibly the main reasons that result in the novel signal inversion of LBIC microscope at room temperature. The research results provide a theoretical guide for practical applications of large-scale array HgCdTe infrared photovoltaic detectors formed by femtosecond laser drilling, which may act as a potential new method for fabricating HgCdTe photodiodes.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

Laser Drilling Development Trial Final Report CRADA No. TSB-1538-98

This project performed various laser drilling tests to demonstrate femtosecond laser drilling of fuel injector nozzles with minimal recast, minimal heat affected zone and no collateral damage. LLNL had extensive experience in ultra short-pulse laser systems and developed specialized hardware for these applications.

36 MATERIALS SCIENCE↗
NASA NTRS1984

Reverse laser drilling

This invention provides a method for laser drilling small diameter, closely-spaced, and accurately located holes in a body of material which is transparent or substantially transparent to the laser radiation employed whereby the holes are drilled through the thickness of the body from the surface opposite to that on which the laser beam impinges to the surface of laser beam impingement.

Anthony, Thomas R.↗
DOE OSTI2024

In situ x-ray imaging to understand subsurface behavior during continuous wave laser drilling

A limited understanding regarding the underlying dynamics and mechanisms of material removal during continuous wave laser drilling has presented significant challenges in achieving precision and process control. Here, to address this, we employed high-fidelity, in situ synchrotron x-ray imaging to reveal previously unknown material behaviors during continuous wave laser drilling with power modulation. Our findings highlight that high-aspect ratio drill holes are achieved when the laser modulation frequency falls within the range of 8–12 kHz, provided that the laser average power and modulation amplitude levels meet the specified limits. Under these conditions, we identified a material removal mechanism driven by incremental accumulation of recoil pressure that gradually pushes material upward from deep within the substrate to the surface. This mechanism manifested as a low-frequency fluctuation in the vapor depression depth, resulting in periodic instances of material ejection. Furthermore, our study underscores that rapid expansion of the melt pool and the widening of the drill hole opening can impede effective material removal by redirecting energy from material ejection to increasing the melt pool size. This investigation contributes essential insights into the subsurface dynamics involved in the drilling of high-aspect ratio holes, furthering our fundamental understanding of this intricate process.

47 OTHER INSTRUMENTATION↗
DOE OSTI2022

FEMTOSECOND LASER DRILLING OF SILICON NITRIDE

Ceramics are employed in various engineering applications including electronics, semiconductors, automotive and aerospace industry, among others. Ceramics are desirable materials due to their high hardness, thermal resistance, chemical, thermal, and mechanical properties. A drawback of engineering ceramics is the manufacturing process. Ceramics are hard and brittle and conventional drilling or cutting methods can damage the material. These challenges in manufacturing have limited the application of ceramics in certain engineering applications. The non-contact machining of ceramics through ultrashort pulsed laser drilling offers a possible solution to the manufacturing issues. The advantage of laser drilling is the ability to machine hard and brittle materials. A laser, pulsed in the time regime of femtoseconds (fs), drills/machines sharp and well-defined holes and cuts. Additionally, the short pulse width results in limited melting, cracking, or heat transfer to the surrounding material, as well as no residual stresses. This non-contact process can greatly aid in the machining of hard materials. This study focuses on drilling into silicon nitride to produce zero-taper through holes. With this, other thicknesses can be explored, to achieve zero-taper holes.

Femtosecond laser ablation, Ceramics, Silicon Nitr↗
DOE OSTI2016

Air-void embedded GaN-based light-emitting diodes grown on laser drilling patterned sapphire substrates

Air-void structure was introduced in GaN-based blue light-emitting diodes (LED) with one-step growth on periodic laser drilling patterned sapphire substrate, which free of any photolithography or wet/dry etching process. The influence of filling factors (FF) of air-void on crystal quality and optical performance were investigate. Transmission electron microscopy images and micro-Raman spectroscopy indicated that the dislocation was bended and the partially compressed strain was released. When FF was 55.43%, compared with the LED structure grown on flat sapphire substrate, the incorporation of air-void was observed to reduce the compressed stress of ∼20% and the luminance intensity has improved by 128%. Together with the simulated reflection intensity enhancement by finite difference time-domain (FDTD) method, we attribute the enhanced optical performance to the combined contribution of strong back-side light reflection of air-void and better GaN epitaxial quality. This approach provides a simple replacement to the conventional air-void embedded LED process.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1980

The random walk of a drilling laser beam

The disregistry of holes drilled with a pulse laser beam in 330-micron-thick single-crystal silicon-on-sapphire wafers is examined. The exit positions of the holes were displaced from the hole entrance positions on the opposing face of the wafer, and this random displacement increased with the number of laser pulses required. A model in which the bottom of the drill hole experiences small random displacements during each laser pulse is used to describe the experimental observations. It is shown that the average random displacement caused by each pulse is only a few percent of the hole diameter and can be reduced by using as few laser pulses as necessary while avoiding the cracking and spalling of the wafer that occur with a hole drilled with a single pulse.

Anthony, T. R.↗
DOE OSTI2016

Tracking of buried layers during plasma-assisted femtosecond laser drilling of compound targets

It was shown that drilling of multi-layered target placed in the air by tightly focused femtosecond laser radiation with high fluence (up to 1000 J/cm{sup 2}) can be monitored online using plasma-induced X-ray emission and second harmonic of incident laser radiation. The technique based on X-rays registration is appeared to be more flexible than the method based on detection of second harmonic since its accuracy depends crucially on the target type. We demonstrated that the X-ray signal clearly indicates the transition from one layer to another during the microdrilling of targets consisting of 2–4 layers of titanium foil when a laser beam is focused beneath the target surface at a depth comparable to the layer thickness. The diagnostics of microchannel production in the chicken eggshell was performed for the first time. It was found that the presence of albumen beneath the shell accounts for longtime generation of X-ray pulses.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

Laser drilling and machining enhancement using gated CW and short pulsed lasers

The present disclosure relates to a laser system for processing a material. The system may make use of a laser configured to intermittently generate a first laser pulse of a first duration and a first average power, at a spot on a surface of the material being processed, and a second laser pulse having a second duration and a second peak power. The second duration may be shorter than the first duration by a factor of at least 100, and directed at the spot. The second laser pulse is generated after the first laser pulse is generated. The first laser pulse is used to heat the spot on the surface of the material, while the second laser pulse induces a melt motion and material ejection of molten material from the melt pool.

Ly, Sonny S.↗
DOE OSTI2014

Methods and apparatus for removal and control of material in laser drilling of a borehole

The removal of material from the path of a high power laser beam during down hole laser operations including drilling of a borehole and removal of displaced laser effected borehole material from the borehole during laser operations. In particular, paths, dynamics and parameters of fluid flows for use in conjunction with a laser bottom hole assembly.

47 OTHER INSTRUMENTATION↗
DOE OSTI2016

Methods and apparatus for removal and control of material in laser drilling of a borehole

The removal of material from the path of a high power laser beam during down hole laser operations including drilling of a borehole and removal of displaced laser effected borehole material from the borehole during laser operations. In particular, paths, dynamics and parameters of fluid flows for use in conjunction with a laser bottom hole assembly.

15 GEOTHERMAL ENERGY↗
DOE OSTI2023

SR23012, A Pragmatic Approach to Laser Drilling and Rewelding of Fill Stems, SRNL-TR-2023-00551

The current approach to disposing unloaded reservoirs is to snap the remaining stem, and seal the hole with JB weld, a two-part epoxy mix that is messy to work with and that takes many hours to ensure it is property cured. During this time, reservoirs may be outgassing and cause higher than desired activity in the glovebox. This project will develop, characterize, and deploy a method to drill stems to unload the reservoirs (already in use in the facility, but may require some simple process / procedure modifications), demonstrate that the reservoirs are fully unloaded, and reweld stems by returning to the unloading station and firing the laser to weld the unloading hole closed.

Korinko, Paul S.↗
NASA NTRS1977

Laser drilling of vias in dielectric for high density multilayer LSHI thick film circuits

A design analysis of a high density multilevel thick film digital microcircuit used for large scale integration is presented. The circuit employs 4 mil lines, 4 mil spaces and requires 4 mil diameter vias. Present screened and fired thick film technology is limited on a production basis to 16 mil square vias. A process whereby 4 mil diameter vias can be fabricated in production using laser technology was described along with a process to produce 4 mil diameter vias for conductor patterns which have 4 mil lines and 4 mil spacings.

Cocca, T.↗
NASA NTRS1988

Protective Coating For Laser Drilling Of Silicon

Sodium silicate prevents spattered silicon from fusing with surrounding material. Sodium silicate solution applied to wafer by dipping and draining or by spinning; application by spraying also works. When dried in oven, solution leaves thin coating of sodium silicate glass.

Shlichta, Paul J.↗
DOE OSTI2015

Electric motor for laser-mechanical drilling

A high power laser drilling system utilizing an electric motor laser bottom hole assembly. A high power laser beam travels within the electric motor for advancing a borehole. High power laser drilling system includes a down hole electrical motor having a hollow rotor for conveying a high power laser beam through the electrical motor.

42 ENGINEERING↗
NASA NTRS1995

Carbon/Carbon Grids For Ion Sources

Ion-extraction grids made of carbon/carbon composites used in spacecraft ion engines and industrial ion sources in place of molybdenum grids. In principle, carbon/carbon grids offer greater extraction efficiency and longer life. Grid fabricated by mechanical drilling, laser drilling, or electrical-discharge machining of array of holes in sheet of carbon/carbon. Advantages; better alignment and slower erosion.

Garner, Charles E.↗