摘要:
A laser device which may be used as an oscillator or amplifier comprising a chamber having a volume formed therein and a gain medium within the volume. The gain medium comprises solid-state elements containing active laser ion distributed within the volume. A cooling fluid flows about the solid-state elements and a semiconductor laser diode provides optical pump radiation into the volume of the laser chamber such that laser emission from the device passes through the gain medium and the fluid. The laser device provides the advantages of a solid-state gain medium laser (e.g., diode-pumping, high power density, etc), but enables operation at higher average power and beam quality than would be achievable from a pure solid-state medium.
摘要:
A laser device which may be used as an oscillator or amplifier comprising a chamber having a volume formed therein and a gain medium within the volume. The gain medium comprises a solid-state element containing active laser ion within the volume. A cooling fluid flows about the solid-state element and a semiconductor laser diode provides optical pump radiation into the volume of the laser chamber such that laser emission from the device passes through the gain medium and the fluid. The laser device provides the advantages of a solid-state gain medium laser (e.g., diode-pumping, high power density, etc), but enables operation at higher average power and beam quality than would be achievable from a pure solid-state medium.
摘要:
A laser device which may be used as an oscillator or amplifier comprising a chamber having a volume formed therein and a gain medium within the volume. The gain medium comprises solid-state elements containing active laser ion distributed within the volume. A cooling fluid flows about the solid-state elements and a semiconductor laser diode provides optical pump radiation into the volume of the laser chamber such that laser emission from the device passes through the gain medium and the fluid. The laser device provides the advantages of a solid-state gain medium laser (e.g., diode-pumping, high power density, etc), but enables operation at higher average power and beam quality than would be achievable from a pure solid-state medium.
摘要:
Short pulse PLD is a viable technique of producing high quality films with properties very close to that of crystalline diamond. The plasma generated using femtosecond lasers is composed of single atom ions with no clusters producing films with high Sp3/Sp2 ratios. Using a high average power femtosecond laser system, the present invention dramatically increases deposition rates to up to 25 &mgr;m/hr (which exceeds many CVD processes) while growing particulate-free films. In the present invention, deposition rates is a function of laser wavelength, laser fluence, laser spot size, and target/substrate separation. The relevant laser parameters are shown to ensure particulate-free growth, and characterizations of the films grown are made using several diagnostic techniques including electron energy loss spectroscopy (EELS) and Raman spectroscopy.
摘要:
Methods and apparatus for material modification using laser bursts including appropriately timed laser pulses to enhance material modification. In one implementation, a method for material modification comprises the steps of: providing bursts of laser pulses, wherein each burst comprises at least two laser pulses, wherein each laser pulse has a pulse duration within a range of between approximately 10 ps and 100 ns, wherein a time between each laser pulse of each burst is within a range of between approximately 5 ns and 5 &mgr;s; a time between successive bursts is greater than the time between each laser pulse comprising each burst; and directing the bursts upon a workpiece, wherein an intensity of a primary laser pulse of each burst exceeds a damage threshold of the workpiece.
摘要:
A solid-state laser device consists of a gain medium in the shape of a polyhedron. A beam enters the gain medium at one surface of the polyhedron and is reflected internally at one or more surfaces with each reflection occurring in approximate the same plane as the plane of incidence of the incident beam. The beam enters and exits the gain medium at different locations. Pump radiation enters the polyhedron through one or more faces. The laser device may be used as the gain medium for a laser oscillator or a laser amplifier. In one variation, the polyhedron contains an internal core section in which there is no gain material. In another variation, the gain medium further includes one or more surfaces oriented to achieve a 90 degree internal reflection of the beam.
摘要:
The present invention is a method for penetrating a workpiece using an ultra-short pulse laser beam without causing damage to subsequent surfaces facing the laser. Several embodiments are shown which place holes in fuel injectors without damaging the back surface of the sack in which the fuel is ejected. In one embodiment, pulses from an ultra short pulse laser remove about 10 nm to 1000 nm of material per pulse. In one embodiment, a plasma source is attached to the fuel injector and initiated by common methods such as microwave energy. In another embodiment of the invention, the sack void is filled with a solid. In one other embodiment, a high viscosity liquid is placed within the sack. In general, high-viscosity liquids preferably used in this invention should have a high damage threshold and have a diffusing property.
摘要:
The invention consists of a method for machining (cutting, drilling, sculpting) of explosives (e.g., TNT, TATB, PETN, RDX, etc.). By using pulses of a duration in the range of 5 femtoseconds to 50 picoseconds, extremely precise and rapid machining can be achieved with essentially no heat or shock affected zone. In this method, material is removed by a nonthermal mechanism. A combination of multiphoton and collisional ionization creates a critical density plasma in a time scale much shorter than electron kinetic energy is transferred to the lattice. The resulting plasma is far from thermal equilibrium. The material is in essence converted from its initial solid-state directly into a fully ionized plasma on a time scale too short for thermal equilibrium to be established with the lattice. As a result, there is negligible heat conduction beyond the region removed resulting in negligible thermal stress or shock to the material beyond a few microns from the laser machined surface. Hydrodynamic expansion of the plasma eliminates the need for any ancillary techniques to remove material and produces extremely high quality machined surfaces. There is no detonation or deflagration of the explosive in the process and the material which is removed is rendered inert.
摘要:
An all-reflective pulse stretcher for laser systems employing chirped-pulse amplification enables on-axis use of the focusing mirror which results in ease of use, significantly decreased sensitivity to alignment and near aberration-free performance. By using a new type of diffraction grating which contains a mirror incorporated into the grating, the stretcher contains only three elements: 1) the grating, 2) a spherical or parabolic focusing mirror, and 3) a flat mirror. Addition of a fourth component, a retro-reflector, enables multiple passes of the same stretcher resulting in stretching ratios beyond the current state of the art in a simple and compact design. The pulse stretcher has been used to stretch pulses from 20 fsec to over 600 psec (a stretching ratio in excess of 30,000).
摘要:
A method for removing material via a laser so as to reduce the formation of channels comprising the steps of emitting a laser pulse comprising a pulse energy, a pulse duration, and a fluence towards a surface of a drilling material the fluence of a value sufficient to avoid the formation of a channel in the drilling material at the surface to form a hole comprising a side wall and a bottom, shaping a spatial profile of the laser pulse such that the fluence is substantially uniform across the spatial profile; and emitting at least one subsequent laser pulse having a pulse energy, a pulse duration, and a fluence sufficient to avoid the formation of a channel at the bottom of the hole.