Abstract: An energy-efficient method and system for processing target material such as microstructures in a microscopic region without causing undesirable changes in electrical and/or physical characteristics of material surrounding the target material is provided. The system includes a controller for generating a processing control signal and a signal generator for generating a modulated drive waveform based on the processing control signal. The waveform has a sub-nanosecond rise time. The system also includes a gain-switched, pulsed semiconductor seed laser for generating a laser pulse train at a repetition rate. The drive waveform pumps the laser so that each pulse of the pulse train has a predetermined shape. Further, the system includes a laser amplifier for optically amplifying the pulse train to obtain an amplified pulse train without significantly changing the predetermined shape of the pulses.

Abstract: A rotary bearing includes concentric radially spaced-apart inner, intermediate and outer rings whose opposing surfaces define inner and outer ball tracks. An inner array of balls roll along the inner track and an outer array of balls roll along the outer track and a viscous lubricant is present between the rings. When the inner and outer rings are angularly reciprocated relative to one another, the intermediate ring is moved intermittently in a selected direction about the rotation axis so that the balls recirculate about the axis and redistribute lubricant along the tracks. In a preferred embodiment, the relative angular excursion of the inner and outer rings is increased periodically beyond a selected maximum angle to effect the advancement of the intermediate ring using the lubricant as a ratcheting mechanism.

Abstract: A system including confocal and triangulation-based scanners or subsystems provides data which is both acquired and processed under the control of a control algorithm to obtain information such as dimensional information about microscopic targets which may be "non-cooperative." The "non-cooperative" targets are illuminated with a scanning beam of electromagnetic radiation such as laser light incident from a first direction. A confocal detector of the electromagnetic radiation is placed at a first location for receiving reflected radiation which is substantially optically collinear with the incident beam of electromagnetic radiation. The system includes a spatial filter for attenuating background energy. The triangulation-based subsystem also includes a detector of electromagnetic radiation which is placed at a second location which is non-collinear with respect to the incident beam. This detector has a position sensitive axis. Digital data is derived from signals produced by the detectors.

Abstract: A digital decorating system for transferring a selected image to a surface of an article includes a thermal printhead, an advancing mechanism for producing relative movement between the printhead and the surface of the article, and a force member for exerting a selected amount of pressure between the thermal line of pixels and the surface of the article. The thermal printhead includes a plurality of energizable heater elements constructed to deliver heat to a thermal line of pixels on a surface of the printhead. The digital decorating system also includes a microcontroller operatively connected to the printhead, the force member and the advancing mechanism to provide control signals selectively delivering heat to pixels of the thermal line and selectively causing the movement thereby thermally transferring, over a two dimensional array of pixels, a two dimensional image to the article surface.

Abstract: A multi-element, folded beam laser includes a plurality of laser medium elements, pumping means, a highly reflective reflector, an output coupler and one or more beam directors for redirecting the beam through the elements and between the reflector and the output coupler. An alternate folded beam ring laser and an alternate folded beam laser amplifier are also disclosed.

Abstract: A multi-element, uniformly pumped laser includes a plurality of laser medium elements, a pumping means, a highly reflective reflector and an output coupler. The pumping means includes at least one pumping element which simultaneously excites at least two of the laser medium elements. An alternate uniformly pumped ring laser and an alternate uniformly pumped laser amplifier are also disclosed.

Abstract: A laser machining (including marking) method that employs a diode laser pumped solid state laser is controlled by a computer that contains a program for the interaction of the laser beam with a workpiece. The pumping of the laser is synchronised with the action of the beam in a series of active machining periods alternating with inactive non-machining periods. In order to avoid overheating of the active element, the duty cycle of these periods is maintained below a chosen value and no active period is allowed to exceed a selected percentage of the thermal time constant of the active element.

Abstract: The energy of a series of output pulses of a solid state laser pumped by a diode array and triggered by a Q-switch is stabilized and rendered independent of the repetition rate by interrupting the pumping to allow the energy stored in the laser active element to fall at the commencement of an interval between a pair of Q-switch trigger signals that is longer than the interval corresponding to the chosen repetition rate. Before the second of this pair of Q-switch trigger signals occurs, the pumping is recommenced for a duration and at an input level that restore the stored energy to the value required for generating output pulses of the laser at the desired energy level.

Abstract: The cooling of the outer surface of the rod or other solid active element of a solid state laser is improved by causing coolant to travel in a plurality of, preferably streamline, helical flows extending around this surface in contact with it. The respective longitudinal components of a pair of the helical flows preferably extend in opposite directions along the surface to improve the uniformity of cooling.

Abstract: A laser machining system employs a perforated proximity mask placed on or near a generally planar workpiece surface. Holes in the mask define a pattern of holes in the workpiece or marks on its surface to be formed by laser beam pulses passing through the mask. The beam is indexed from hole to hole or between groups of holes in the mask, between the pulses (or groups of pulses) of the laser. This indexing can be carried out by a pair of rotatable mirrors that direct the beam to a series of different holes in the mask via an optical element, e.g. a concave mirror or a telecentric lens assembly. This optical element converts the beams received from the indexing mirrors to a series of parallel beams that are directed to strike the mask and hence the workpiece generally normal to the workpiece surface. The optical element also serves the purpose of focusing each beam.

Abstract: The known technique of marking (including machining) a workpiece by light energy, e.g. a pulsed laser beam, in order to create a pattern of marks on the workpiece is improved by converting a primary beam into a plurality of individual beamlets that are arranged in an array corresponding to the desired pattern and are each focused independently of the other beamlets. This independent focusing enables the size and energy density (and hence the marking effect) of each beamlet when it strikes the workpiece to be dependent on the relative location of the workpiece and the respective beamlet, while being independent of the size of the overall pattern. This feature enables variation of the ratio between the pitch between individual marks (which determines the size of the overall pattern) and the size of each mark, and hence selection of the optimum value of this ratio for a given situation.

Abstract: For separation of second and higher order second harmonics from a composite laser beam, a substrate is provided with a binary level relief structure that, in the preferred construction, consists of a regular series of parallel substantially rectangular grooves on one or both of its major surfaces. In a transmissive grating, which is traversed only once by the beam, the depth h of the grooves is chosen to be .lambda. divided by n.sub.1 -n.sub.0, where n.sub.0 is the refractive index external to the grating (assumed to be approximately unity for air), n.sub.1 is the refractive index of the substrate, and .lambda. is the wavelength that will pass directly through the grating, e.g. the second harmonic. Wavelengths greater than .lambda., e.g. the fundamental 2.lambda., will be diffracted away from the beam path. When a reflective coating is applied on the surface with the relief structure, the groove depth is chosen to be .lambda. divided by 2n.sub.0 or 2n.sub.

Abstract: To maintain substantially constant the temperature of a diode junction of a pulsed, cooled, diode laser and hence the wavelength of the optical output of the laser, which laser is used for optically pumping a main, pulsed, solid state laser, the diode junction is heated by an external source during inactive intervals between pulses of the diode laser. This heating, which preferably is achieved by passing a heating current through the diode junction, is adjusted to ensure that, per a unit time greater than the length of an inactive interval, the heat energy received by the diode junction from this external heating together with the heat energy generated in the diode junction itself by the pulses is substantially constant independent of the length of the inactive intervals. Preferably the heating current has a constant level except for a period after each pulse when the level is reduced, e.g. to zero.

Abstract: Dust in a gas laser, particularly an excimer laser, is removed from the gas charge by one or more electrostatic precipitators that are located inside the laser vessel in the path of gas circulation that is produced by a fan and passes through the discharge area defined by the main discharge electrodes. The gas is caused to travel rapidly past the precipitator so that only a minor proportion of the dust is removed at each pass, but a low background level of dust in the gas is soon achieved and maintained by repeated such passes. This technique of employing multiple passes, each removing only a small percentage of the dust in the gas at any given time, can also be applied to a system in which the precipitator is located outside the vessel and is connected thereto by conduits.

Abstract: The problems of maintaining proper alignment of the mirrors of an excimer laser in the face of thermal and pressure distortions of the ends of the laser vessel and when replacing the mirrors after removal for cleaning are overcome by mounting the mirrors on a separate, fixed supporting frame that is not influenced by movement of the vessel ends. The mounts nevertheless serve to connect the mirrors to the respective vessel ends so as to seal the pressurized gases in the vessel interior from the exterior. This sealing connection is a yielding one that permits relative movement between the vessel ends and the mirrors and hence avoids affecting the alignment of the mirrors. The mounts also include provision for ensuring that, after removal and replacement, wedge shaped mirrors are correctly realigned in respect of rotation about the axis of the laser beam, and that the mirrors can be replaced with their reference surfaces in exactly the original plane.

Abstract: Variable attenuation of a light beam is achieved by mounting a rotatable multilayer dielectric attenuator in the beam. A first portion of the beam is transmitted through the attenuator and a second portion is reflected. Rotation of the attenuator about an axis transverse to the beam varies the ratio between these portions. The main application of this attenutator is to control an output characteristic, e.g. output power, of a laser, and may include a feedback loop to maintain this characteristic constant.

Abstract: An excimer laser has a pair of main electrodes defining a lasing space, and a series of pairs of pre-ionization pins arranged alongside the main electrodes. These pins form preionization gaps for generating discharges that provide ultraviolet radiation to condition the gas in the lasing space. The invention consists of providing a tracker of insulating material between each pair of pins to bridge the gap and provide a tracking surface for the pre-ionization discharge.

Abstract: Purification of the gas mixture used in an excimer laser is carried out by cooling such mixture in a cryogenic trap to a temperature that is low enough that the lasting gas or gases (e.g. krypton, xenon, fluorine, hydrogen chloride) and the impurities are all substantially fully condensed. This temperature is nevertheless sufficiently high that the buffer gas (neon or helium or a mixture thereof) remains substantially all in gaseous form. The trap is then isolated from the laser vessel and the condensed gases therein are treated to remove at least the condensed impurities from the system. In a xenon chloride laser the condensed impurities can be effectively separated from the condensed laser gases by heating, i.e. differential distillation. After this has been done, the laser gases are returned to the laser vessel. In those instances in which such separation by differential distillation is not practicable, e.g.

Abstract: This invention describes a method and apparatus that can be used in optic quality monitoring of a gas laser. The method involves measuring the temperature of at least one of the optics in a gas laser, then subtracting the temperature of the laser enclosure from the optic temperature to obtain a temperature differential, and finally dividing the differential by a value proportional to the output power of the laser. The final value, termed "figure of merit", gives a quantitative measure of the condition of the optic. As a result appropriate cleaning and replacement decisions can be made for one or both of the optics in a gas laser.

Abstract: In an excimer laser system with wavelength bandwidth narrowing, a feedback loop for monitoring and correcting the tuning of the laser employs a wavelength calibration device in the form of a gas with an absorption peak at the desired narrow wavelength. A portion of the laser output received through the gas provides the information for generating the correction signal.