Abstract: A hair removal device (22) includes a cooling surface (34) which is used to contact the skin (6) prior to exposure to hair tissue-damaging laser light (74) passing from a radiation source (36) through a recessed window (46). The window is laterally offset from the cooling surface and is spaced apart from the cooling surface in a direction away from the patient's skin to create a gap between the window and the skin. The window preferably includes both an inner window (46) and an outer, user-replaceable window (48). The laser-pulse duration is preferably selected according to the general diameter of the hair.

Abstract: A hair removal device (22) includes a cooling surface (34) which is used to contact the skin (6) prior to exposure to hair tissue-damaging laser light (74) passing from a radiation source (36) through a recessed window (46). The window is laterally offset from the cooling surface and is spaced apart from the cooling surface in a direction away from the patient's skin to create a gap between the window and the skin. The window preferably includes both an inner window (46) and an outer, user-replaceable window (48). The laser-pulse duration is preferably selected according to the general diameter of the hair.

Abstract: Fluence monitoring apparatus is disclosed for a system for modifying curvature of the cornea of an eye by selective laser photoablation of corneal tissue by delivery of pulses of laser radiation to the cornea in an overlapping pattern. The system includes a scanner for directing the pulses to form the overlapping pattern, the movement of which is modified by an eye-tracker. A beamsplitter is located between the scanner and the cornea for directing a fraction of each of the pulses to a fixed monitor plate, which emits fluorescent light on being irradiated by each pulse-fraction. A video camera 100 images the monitor plate. Processing circuitry periodically records the image which includes images of pulse-fractions delivered during the period between recordings. These recordings are electronically integrated and processed to form a composite image representative of spatial distribution of laser fluence on the cornea.

Abstract: Fluence monitoring apparatus is disclosed for a system for modifying curvature of a cornea by selective laser photoablation of corneal tissue by means of a succession of pulses of laser radiation delivered to the cornea in an overlapping pattern corresponding to a desired pattern of photoablation. The system includes a scanning arrangement for directing the pulses to form the overlapping pattern. The fluence monitoring apparatus includes a beamsplitter located between the scanning arrangement and the cornea for directing a fraction of each of the pulses to a monitor plate. The monitor plate emits fluorescent light on being irradiated by each pulse-fraction. A video camera provides an electronic image of the monitor plate. Processing circuitry periodically records the electronic image, and the periodic image recordings are integrated to form a composite image representative of spatial distribution of laser fluence on the cornea.

Abstract: A method and apparatus for determining the quality of a multimode laser beam (10). In the preferred embodiment, the apparatus includes a lens (32) for creating a transformed or imaged waist from the input beam. The location of the transformed beam waist and its diameter are then determined. These steps can be carried out by chopping the beam using a rotating hub (34) having apertures (36,38) for selectively passing the beam. Preferably, one of the apertures has a pair of 45.degree. knife edges 40,42). The transmission of the beam past the knife edge is monitored by a detector (30). In operation, the lens focal position is varied while the transmission of the beam past the knife edge is monitored in order to locate and measure the diameter of the transformed waist. The diameter of the beam at one other known location is measured. A processor then calculates beam quality by fitting these measurements to a mathematical model.

Abstract: A method and apparatus for determining the quality of a multimode laser beam (10). In the preferred embodiment, the apparatus includes a lens (32) for creating a transformed or imaged waist from the input beam. The location of the transformed beam waist and its diameter are then determined. These steps can be carried out by chopping the beam using a rotating hub (34) having apertures (36,38) for selectively passing the beam. Preferably, one of the apertures has a pair of 45.degree. knife edges (40,42). The transmission of the beam past the knife edge is monitored by a detector (30). In operation, the lens focal position is varied while the transmission of the beam past the knife edge is monitored in order to locate and measure the diameter of the transformed waist. The diameter of the beam at one other known location is measured. A processor then calculates beam quality by fitting these measurements to a mathematical model.

Abstract: A method and apparatus for determining the quality of a multimode laser beam (10). In the preferred embodiment, the apparatus includes a lens (32) for creating a transformed or imaged waist from the input beam. The location of the transformed beam waist and its diameter are then determined. These steps can be carried out by chopping the beam using a rotating hub (34) having apertures (36,38) for selectively passing the beam. Preferably, one of the apertures has a pair of 45.degree. knife edges (40,42). The transmission of the beam past the knife edge is monitored by a detector (30). In operation, the lens focal position is varied while the transmission of the beam past the knife edge is monitored in order to locate and measure the diameter of the transformed waist. The diameter of the beam at one other known location is measured. A processor then calculates beam quality by fitting these measurements to a mathematical model.

Abstract: A laser system employing one or more mirror sets having substantially astigmatism-free focusing power sufficient to maintain a desired laser beam diameter, for example, to compensate for thermally-induced distributed lensing. In one class of preferred embodiments, the invention is a high power gas laser system having a folded optical cavity with a periodic intracavity refocusing means to compensate for distributed negative thermal lensing in the hot plasma that comprises the active medium, and thus maintain a substantially constant beam diameter throughout the optical cavity. The periodic intracavity refocusing means preferably includes a corner mirror set (including at least one curved mirror and at least one other mirror) at each corner of the folded optical cavity. In one preferred embodiment, each corner mirror set is a mirror pair including a spherical mirror and cylindrical mirror.

Abstract: A laser system employing one or more mirror sets having substantially astigmatism-free focusing power sufficient to maintain a desired laser beam diameter, for example, to compensate for thermally-induced distributed lensing. In one class of preferred embodiments, the invention is a high power gas laser system having a folded optical cavity with a periodic intracavity refocusing means to compensate for distributed negative thermal lensing in the hot plasma that comprises the active medium, and thus maintain a substantially constant beam diameter throughout the optical cavity. The periodic intracavity refocusing means preferably includes a corner mirror set (including at least one curved mirror and at least one other mirror) at each corner of the folded optical cavity. In one preferred embodiment, each corner mirror set is a mirror pair including a spherical mirror and cylindrical mirror.

Abstract: An apparatus (12) for providing information about the power and position of a high laser beam includes a heat absorbing body (46) having a target area within which the laser beam is directed. Position information is provided by a plurality of thermocouples (46) connected in series in a circular array and located radially outward of the target area. In the preferred embodiment, the thermocouple array is divided into four quadrants (60-66), each quadrant generating a voltage proportional to the heat flow in the body at that location. A comparison of the voltages generated by each of the quadrants will provide information about the position of the laser beam with respect to the quadrants. In addition, by summing the output of the quadrants, information about the total power of the beam can be derived.

Abstract: A laser resonator system including an optical resonator whose side wall has an orifice through which gas may enter the resonator's interior, and may subsequently flow along the resonator's longitudinal axis. An elongated electrode (which preferably is an anode) is positioned at the orifice in electrical communication with the entering gas so that the projection of the electrode's tip on the plane of the orifice does not coincide with the center of the orifice. In a preferred embodiment, the electrode's longitudinal axis is aligned generally perpendicular to the plane of the orifice. In another preferred embodiment, two such electrode-orifice pairs are provided and are separated by a small distance along the resonator's axis. The orifice positions are preferably on opposite sides of the resonator, so that they are separated by an azimuthal angle substantially equal to 180.degree. with respect to the resonator tube's longitudinal axis.

Abstract: An improved gas laser is disclosed. The laser has a support tube to support and to maintain the alignment of the optical resonator structure. The gas lasing medium is used within the support tube to maintain the tube at a substantially constant temperature above the ambient. Furthermore, an active temperature controller is disclosed. The temperature controller maintains the gas lasing medium in the support tube at a substantially constant temperature. An active pressure controller is also disclosed. The active pressure controller uses a pressure sensor, an electronic processor, and a motor-driven needle valve to maintain the pressure of the gas lasing medium in the laser within the desired operating pressure range. The laser can also be switched in operation from a continuous mode to a pulsing mode. An active power control system is disclosed wherein the power output of the laser, through an active feedback loop is maintained at the desired level.

Abstract: A high voltage power supply for energizing a gas discharge laser in either an enhanced pulse mode or a continuous mode, which power supply is simple to manufacture and minimizes the voltage that other parts of the energizing circuit are required to withstand. The voltage provided by a high voltage DC power supply is boosted by the interaction of first and second reactive components. A first reactance is provided which stores charges at the boosted potential. This charge is provided to the laser to initiate electrical breakdown. The second reactance generates a potential which is additive with respect to the potential provided by the high voltage DC power supply so that the first reactance is charged to a potential equal to the generated potential plus the potential of the high voltage power supply.

Abstract: A high power, fundamental (TEMoo) mode gaseous laser is described having a discharge-confining bore tube which is provided with spaced-apart annular, inwardly-extending, radial projections or rings, which have inside diameters which match the fundamental mode diameter along the tube.

Abstract: A laser system adapted for a high power laser beam thermally reacting with a target of a rigid material to remove a portion of the rigid material, has a laser generating a high power beam of electromagnetic coherent radiation. The beam is aligned to impinge the material and is controlled by a controlling means such that the portion removed is symmetrically shaped.

Abstract: A starter element for a high power gas transport laser having cathode and anode electrodes connected across a constant current DC power supply comprises a wire-like conductor connected in parallel with the cathode to the negative terminal of the power supply and extending between the cathode and anode parallel to the gas flow transversely of and spaced closely to the middle of the cathode. The free end of the starter element extends approximately 1 cm. beyond the downstream edge of the cathode and, when the output potential of the DC power supply is applied, causes a breakdown of the gas due to the high field strength at the starter end, producing an electrical discharge between that end and the central portion of the cathode. This induces the main electric discharge between the cathode and anode.

Abstract: The method of reducing arcing in a high power gas transport laser consists of introducing molecular oxygen into the carbon dioxide mixture in which the glow discharge takes place. The oxygen may be in pure form or may be mixed with nitrogen as in air and is admitted to the recirculating gas mixture in predetermined quantities during operation of the laser. The effect of this addition of oxygen to the circulating gas mixture is to prevent the formation of oxide coatings on the copper electrode surfaces, and specifically on the cathode, thereby eliminating this cause of arcing in the laser.

Abstract: Arc detection and control apparatus for a high power high voltage gas laser with a constant current power supply comprises a circuit responsive to changes in voltage across the laser electrodes for disconnecting the power supply when the voltage change exceeds a predetermined limit. The circuit monitors a small proportional value of the interelectrode voltage through an optical coupler and has a multiplier circuit for converting detected voltage changes and the differential thereof into pulses with a constant amplitude for fixed percentage changes of the electrode voltage and into pulses with increasing amplitudes for proportionally greater electrode voltage changes. This circuit normalizes and filters the resultant pulses and permits them to be compared to a reference voltage in a comparator circuit. When the pulse amplitude exceeds the value of the reference voltage a control apparatus is actuated which disconnects the power supply from the laser electrodes.