Abstract: An optical communication system includes a free space optical transceiver within a housing to transmit and receive optical communication signals along an optical pathway through a window in the housing. Heating elements applied to the interior surface of the window substantially uniformly heat the window such that the window is kept free from condensation and ice without introducing significant distortions in the wavefront. Accordingly, the heating elements are designed and placed on the window such that the obscuration caused by the presence of the heating elements within the optical pathway and the wavefront distortion caused by temperature gradients within the cross-section of the window in the optical pathway cause less than 1 decibel (dB) in transmission loss as compared to the same system without the heating elements on the window.

Abstract: An optical communication system includes a free space optical transceiver within a housing to transmit and receive optical communication signals along an optical pathway through a window in the housing. Heating elements applied to the interior surface of the window substantially uniformly heat the window such that the window is kept free from condensation and ice without introducing significant distortions in the wavefront. Accordingly, the heating elements are designed and placed on the window such that the obscuration caused by the presence of the heating elements within the optical pathway and the wavefront distortion caused by temperature gradients within the cross-section of the window in the optical pathway cause less than 1 decibel (dB) in transmission loss as compared to the same system without the heating elements on the window.

Abstract: A low cost, high reliability system for correcting aberrations in optical signals is disclosed. A foreoptic assembly, such as a telescope, receives an incoming optical signal and directs it to an active optical element, such as a fast steering mirror. The incoming optical signal is diffracted by a diffractive optical element to shape the image that is formed at a wavefront sensor, such as a quad-cell. The wavefront sensor measures a tip-tilt aberration of the incoming optical signal and the active optical element is adjusted to correct the measured aberration. An outgoing optical signal can be transmitted along substantially the same optical path as the incoming optical signal, but in the opposite direction. Thus, the aberration measured from the incoming optical signal can be automatically accounted for in the outgoing optical signal.

Abstract: A Cassegrain telescope uses a pivoted corrector plate to reduce back-reflections. A converging lens is added to the optical path inside a housing of the telescope to focus the light within the telescope. The modified Cassegrain design may be used a hybrid radio frequency and free-space optical commercial communications network.

Abstract: A low cost, high reliability system for correcting aberrations in optical signals is disclosed. A foreoptic assembly, such as a telescope, receives an incoming optical signal and directs it to an active optical element, such as a fast steering mirror. The incoming optical signal is diffracted by a diffractive optical element to shape the image that is formed at a wavefront sensor, such as a quad-cell. The wavefront sensor measures a tip-tilt aberration of the incoming optical signal and the active optical element is adjusted to correct the measured aberration. An outgoing optical signal can be transmitted along substantially the same optical path as the incoming optical signal, but in the opposite direction. Thus, the aberration measured from the incoming optical signal can be automatically accounted for in the outgoing optical signal.

Abstract: Systems and methods for performing semiconductor laser annealing using dual loop control are disclosed. The first control loop operates at a first frequency and controls the output of the laser and controls the 1/f laser noise. The second control loop also controls the amount of output power in the laser and operates at second frequency lower than the first frequency. The second control loop measures the thermal emission of the wafer over an area the size of one or more die so that within-die emissivity variations are average out when determining the measured annealing temperature. The measured annealing temperature and an annealing temperature set point are used to generate the control signal for the second control loop.

Abstract: The present invention relates to a fluorine gas discharge laser system and control of replenishment of fluorine gas as the gas discharge laser operates and consumes fluorine.

Abstract: A method and apparatus are disclosed for controlling the output of a two chamber gas discharge laser comprising an oscillator gas discharge laser and an amplifier gas discharge laser that may comprise establishing a multidimensional variable state space comprising a coordinate system having at least two coordinates, each coordinate comprising a selected variable representing an operating parameter of the oscillator or the amplifier; tracking a multidimensional operating point in the multidimensional variable state space according to the variation of the selected variables in either or both of the oscillator or the amplifier to determine the position of the multidimensional operating point in the multidimensional state space; determining from the position of the multidimensional operating point in the multidimensional operating space a region from a plurality of defined regions in the multidimensional operating space in which the multidimensional operating point is located and identifying the region.

Abstract: A method and apparatus are disclosed for controlling the output of a two chamber gas discharge laser comprising an oscillator gas discharge laser and an amplifier gas discharge laser that may comprise establishing a multidimensional variable state space comprising a coordinate system having at least two coordinates, each coordinate comprising a selected variable representing an operating parameter of the oscillator or the amplifier; tracking a multidimensional operating point in the multidimensional variable state space according to the variation of the selected variables in either or both of the oscillator or the amplifier to determine the position of the multidimensional operating point in the multidimensional state space; determining from the position of the multidimensional operating point in the multidimensional operating space a region from a plurality of defined regions in the multidimensional operating space in which the multidimensional operating point is located and identifying the region; based upo

Abstract: The present invention relates to a fluorine gas discharge laser system and control of replenishment of fluorine gas as the gas discharge laser operates and consumes fluorine.

Abstract: A method and apparatus are disclosed for controlling the output of a two chamber gas discharge laser comprising an oscillator gas discharge laser and an amplifier gas discharge laser that may comprise establishing a multidimensional variable state space comprising a coordinate system having at least two coordinates, each coordinate comprising a selected variable representing an operating parameter of the oscillator or the amplifier; tracking a multidimensional operating point in the multidimensional variable state space according to the variation of the selected variables in either or both of the oscillator or the amplifier to determine the position of the multidimensional operating point in the multidimensional state space; determining from the position of the multidimensional operating point in the multidimensional operating space a region from a plurality of defined regions in the multidimensional operating space in which the multidimensional operating point is located and identifying the region; based upo

Abstract: A high power gas discharge laser for and method of producing laser output light pulses of high energy density is disclosed which may comprise a laser output light pulse beam optical track having a plurality of modular components arranged in order from a laser light source to a laser system output port and defining a laser output light pulse beam path having a single centerline axis; a first optical module and a second optical module in series in the optical track; a flexible interface element intermediate the first and the second optical module and rigidly attached to each of the first and second optical modules; and an optical element having a fixed position in the output laser pulse beam path comprising a rigid attachment to the first optical module, and extending within the flexible interface element. The optical element may comprise a beam expander, which may comprise a lensed beam expander.

Abstract: The present invention provides an excimer laser capable of producing a high quality pulsed laser beam at pulse rates of about 4,000 Hz at pulse energies of about 5 mJ or greater. A preferred embodiment is an ArF excimer laser specifically designed as a light source for integrated circuit lithography. An improved wavemeter with special software monitors output beam parameters and controls a very fast PZT driven tuning mirror and the pulse power charging voltage to maintain wavelength and pulse energy within desired limits. In a preferred embodiment two fan motors drive a single tangential fan which provides sufficient gas flow to clear discharge debris from the discharge region during the approximately 0.25 milliseconds between pulses.

Abstract: The present invention provides an excimer laser capable of producing a high quality pulsed laser beam at pulse rates of about 4,000 Hz at pulse energies of about 5 mJ or greater. A preferred embodiment is an ArF excimer laser specifically designed as a light source for integrated circuit lithography. An improved wavemeter with special software monitors output beam parameters and controls a very fast PZT driven tuning mirror and the pulse power charging voltage to maintain wavelength and pulse energy within desired limits. In a preferred embodiment two fan motors drive a single tangential fan which provides sufficient gas flow to clear discharge debris from the discharge region during the approximately 0.25 milliseconds between pulses.

Abstract: A lithograph quality optimization process for controlling laser beam parameters when changing operating modes. The laser is programmed to automatically conduct an optimization procedure preferably in less than one minute to adjust laser operating parameters such as blower speed, total gas pressure and F2 partial pressure in order to optimize beam quality parameters.

Abstract: An excimer laser system with an automatic fluorine control system to permit precise control of the fluorine concentration within an F2 “sweet spot” in a gas discharge laser chamber. This is done with a computer control system which monitors laser parameters, determines &Dgr;E/&Dgr;V, the change of pulse energy with voltage, and automatically and precisely controls the fluorine concentration based on &Dgr;E/&Dgr;V without the need to actually measure the fluorine concentration. The present invention is especially useful in lithography environments in which photo resist having a wide range of sensitivity are used. The present invention permits operation of the laser at substantially maximum efficiency over a wide range of pulse energy outputs.

Abstract: The present invention provides a reliable modular production quality excimer laser capable of producing 10 mJ laser pulses at 2000 Hz with a full width half, maximum bandwidth of about 0.6 pm or less. Replaceable modules include a laser chamber; a pulse power system comprised of three modules; an optical resonator comprised of a line narrowing module and an output coupler module; a wavemeter module, an electrical control module, a cooling water module and a gas control module. Improvements in the laser chamber permitting the higher pulse rates and improved bandwidth performance include a single upstream preionizer tube and a high efficiency chamber. The chamber is designed for operation at lower fluorine concentration. Important improvements have been provided in the pulse power unit to produce faster rise time and improved pulse energy control.