Abstract: Frequency conversion methods are taught wherein non-collinear phase matching configurations may be implemented in non-linear crystals used in three wave mixing processes such that the frequency conversion efficiency is enhanced through walk-off compensation while also maximizing conversion efficiency. The harmonic conversion techniques are especially applicable to sum frequency process, and in particular to third harmonic generation.

Abstract: A diode end-pumped solid state laser is provided which produces improved power output, long term stability and improved conversion efficiency from the pumping power, high as well as low power operation while maintaining certain desirable common characteristics such as TEM00 operation, circular outputs, readily aligned systems and compatibility with long lifetime for all components. The invention intracavity conversion to second, third and higher harmonics in several different spectral regimes. The invention also addresses the aspects of design flexibility, seeking in certain embodiments to provide a single platform for providing several harmonic beams.

Abstract: A method and system are described aimed at substantially increasing the lifetime of sensitive optical elements subjected to high power laser radiation. The lifetime enhancement is accomplished by spatially distributing the laser beam spots both globally and locally according to algorithms that are custom tailored to the subject element as well as the system and application needs. The methods of the invention are particularly well-suited to non-linear crystals used to convert radiation from high repetition rate, diode-pumped laser systems into the UV spectral range, where lifetime requirements are particularly challenging. The methods of the invention further enable effective utilization of available experimental data characterizing the element's performance in combination with a stored library of preferred spot scanning patterns that may be executed on the surface of the element according to the selected algorithm.

Abstract: A diode end-pumped solid state laser is provided which produces improved power output, long term stability and improved conversion efficiency from the pumping power, high as well as low power operation while maintaining certain desirable common characteristics such as TEM00 operation, circular outputs, readily aligned systems and compatibility with long lifetime for all components. The invention intracavity conversion to second, third and higher harmonics in several different spectral regimes. The invention also addresses the aspects of design flexibility, seeking in certain embodiments to provide a single platform for providing several harmonic beams.

Abstract: A method, apparatus and system for a transverse tracker is described that can greatly improve the accuracy, speed, range, reliability, versatility, safety, and efficacy of interventions such as laser microsurgery, particularly ophthalmic surgery, and industrial micromachining. The instrument and system disclosed are applicable to those situations wherein the positioning accuracy of laser lesions is critical, and/or whenever precise operations on a target or series of targets subject to random movement during a procedure are to be effected. The present invention provides means for stabilizing the motion of targets in a plane perpendicular to the axial direction, thus allowing an imaging system, diagnostics illumination, and/or laser beam to maintain a lock on the target area, regardless of its movement.

Abstract: An edge-pumped solid state thin slab laser apparatus is disclosed that is power scalable to well over 150 W for either multimode or near single transverse mode operation. A slab thickness is selected that is small enough to minimize thermal effects for a straight through beam yet large enough to allow efficient direct coupling of pump light from high power diode array stacks while also keeping the gain to within manageable levels for pulsed operation. Cooling of the slab is provided conductively, preferably by contact with metal blocks of high thermal conductivity. The edge-pumped solid state thin slab laser provides a near-one dimensional temperature gradient and heat flow direction that is perpendicular to the laser signal plane of propagation. The width of the slab is selected so as to maximize pump absorption length for a given laser material and both one and two-sided pumping schemes can be accommodated by the basic slab laser platform, depending on power, mode and beam quality requirements.

Abstract: A long wavelength infrared laser system is disclosed where radiation from laser sources such as frequency-doubled Nd:YAG or a Cr:LiSAF is used to resonantly pump a gain medium consisting of a holmium-doped fluoride crystal having a high active ion concentration. The laser pump source has a pulse duration that may be short enough to gain switch a particular transition or long enough to allow end-pumping with high energy densities without damage. The gain material has an absorption approximately resonant with the pump source wavelength, and the dopant concentration is selected to maximize absorption strength for a given excitation. The output radiation from the laser system consists of one or more wavelengths including, in particular 3.9 nm but also other infrared wavelengths such as 1.4 &mgr;m, 2.9 &mgr;m and 3.4 &mgr;m., several of which may be produced simultaneousely from the same laser material through the mechanism of cascade transitions.

Abstract: A solid state laser in which a slab of lasing material is held within an optical resonator is disclosed. The length of the slab in parallel to the optical axis of the resonator is between 5 and 1,000 mm, the width and thickness of the slab are 1-50 mm and 0.01-2 mm, respectively. The slab is designed in a way that causes the pump light to be confined when side- or end pumped by diode lasers. This is accomplished by either polishing the two largest area faces (referred to as upper and lower sides) of the slab and coating them with a material (dielectric or metallic) that is highly reflective at the emission wavelength, or by sandwiching the slab between dielectric materials that comprise a lower refractive index compared to the index of the slab. In alternative embodiments, the thin dimension of the slab may be selected so as to either guide the signal light or to allow free space propagation.

Abstract: A method and system are described aimed at substantially increasing the lifetime of sensitive optical elements subjected to high power laser radiation. The lifetime enhancement is accomplished by spatially distributing the laser beam spots both globally and locally according to algorithms that are custom tailored to the subject element as well as the system and application needs. The methods of the invention are particularly well-suited to non-linear crystals used to convert radiation from high repetition rate, diode-pumped laser systems into the UV spectral range, where lifetime requirements are particularly challenging. The methods of the invention further enable effective utilization of available experimental data characterizing the element's performance in combination with a stored library of preferred spot scanning patterns that may be executed on the surface of the element according to the selected algorithm.

Abstract: A laser parametric generator for surgical applications is disclosed which utilizes short-pulse, mid-infrared radiation. The mid-infrared radiation may be produced by a pump laser source, such as a neodymium-doped laser, which is parametrically downconverted in a suitable nonlinear crystal to the desired mid-infrared range. The short pulses reduce unwanted thermal effects and changes in adjacent tissue to potentially submicron-levels. The parametrically converted radiation source preferably produces pulse durations shorter than 25 ns at or near 3.0 &mgr;m but preferably close to the water absorption maximum associated with the tissue. The down-conversion to the desired mid-infrared wavelength is preferably produced by a nonlinear crystal such as KTP or its isomorphs. In one embodiment, a non-critically phased-matched crystal is utilized to shift the wavelength from a near-infrared laser source emitting at or around 880 to 900 nm to the desired 2.9-3.0 &mgr;m wavelength range.

Abstract: A long wavelength infrared laser system is disclosed where radiation from laser sources such as frequency-doubled Nd:YAG or a Cr:LiSAF is used to resonantly pump a gain medium consisting of a holmium-doped fluoride crystal having a high active ion concentration. The laser pump source has a pulse duration that may be short enough to gain switch a particular transition or long enough to allow end-pumping with high energy densities without damage. The gain material has an absorption approximately resonant with the pump source wavelength, and the dopant concentration is selected to maximize absorption strength for a given excitation. The output radiation from the laser system consists of one or more wavelengths including, in particular 3.9 &mgr;m but also other infrared wavelgths such as 1.4 &mgr;m, 2.9 &mgr;m and 3.4 &mgr;m., several of which may be produced simultaneousely from the same laser material through the mechanism of cascade transitions.

Abstract: A long wavelength infrared laser system is disclosed where radiation from laser sources such as frequency-doubled Nd:YAG or a Cr:LiSAF is used to resonantly pump a gain medium consisting of a holmium-doped fluoride crystal having a high active ion concentration. The laser pump source has a pulse duration that may be short enough to gain switch a particular transition or long enough to allow end-pumping with high energy densities without damage. The gain material has an absorption approximately resonant with the pump source wavelength, and the dopant concentration is selected to maximize absorption strength for a given excitation. The output radiation from the laser system consists of one or more wavelengths including, in particular 3.9 nm but also other infrared wavelgths such as 1.4 &mgr;m, 2.9 &mgr;m and 3.4 &mgr;m., several of which may be produced simultaneousely from the same laser material through the mechanism of cascade transitions.

Abstract: A solid state laser source for surgical applications which produces short-pulse, mid-infrared radiation. Specifically, the laser preferably emits radiation near the absorption peak of water, with energy levels up to 20 mJ, pulse durations shorter than 50 ns and preferably shorter than 30 ns, with beam quality of less than 8 times the diffraction limit. The short pulses reduce unwanted thermal effects and changes in adjacent tissue to potentially sub-micron levels. The laser source produces pulse repetition rates in excess of 10 Hz when pumped by a flashlamp, but in a diode pumped embodiment, the repetition rate may exceed 30 Hz. Of particular interest is an erbium-doped YAG laser which is especially well suited to the needs of mid-infrared corneal ablation procedures for correcting refractive errors, when constructed according to principles disclosed by the invention.

Abstract: A method, apparatus and system for a transverse tracker is described that can greatly improve the accuracy, speed, range, reliability, versatility, safety, and efficacy of interventions such as laser microsurgery. The present invention provides means for stabilizing the motion of targets in a plane perpendicular to the axial direction, thus allowing an imaging system, diagnostics illumination, and/or laser beam to maintain a lock on the target area, regardless of its movement. Unique attributes provided in the tracking system include means for (1) sensing contrast in recognizable large scale boundaries such as the change between the cornea/sclera interface (limbus), thereby to determine the absolute location and orientation of these boundaries, all without having to resort to digital sampling techniques and (2) dual mode operation of an electronic control system compatible with all analog technologies, thereby substantially increasing the speed of operations over other, comparable digital method.

Abstract: A surgical technique for removing corneal tissue with scanned infrared radiation is disclosed which utilizes short mid-infrared laser pulses to provide a tissue removal mechanism based on photospallation. Photospallation is a photomechanical ablation mechanism which results from the absorption of incident radiation by the corneal tissue. Since photospallation is a mechanical ablation process, very little heat is generated in the unablated adjacent tissue. The disclosed surgical system includes a scanning beam delivery system which allows uniform irradiation of the treatment region and utilizes low energy outputs to achieve controlled tissue removal. A real-time servo-controlled dynamic eye tracker, based on a multiple-detector arrangement, is also disclosed which senses the motion of the eye and provides signals that are proportional to the errors in the lateral alignment of the eye relative to the axis of the laser beam.