Coherent Patent Grants

Mode-locked laser using non-linear self-focusing element

Granted: November 10, 1992
Patent Number: 5163059
A passively mode-locked laser (110) is disclosed that includes a resonant cavity (112, 114) having a gain medium (116) therein. A transmissive element (116), which may be the gain medium, is also located in the cavity and is formed from a material which varies the two-dimensional, lateral spatial profile of the beam with respect to intensity due to the Kerr effect. The resonator is arranged such that the round trip gain of the system increases with respect to the intensity of the beam so…

Residual echo elimination with proportionate noise injection

Granted: October 20, 1992
Patent Number: 5157653
An echo canceller with an adaptive convolution processor for computing and subtracting an anticipated echo has a nonlinear processor coupled to the error signal and to the send output. The nonlinear processor is responsive to average values and attenuates the error signal over a continuous range as a function of presence of send and receive signals, rather than coupling and decoupling the error signal to the output in the manner of a center clipper. Attenuation is altered rapidly when…

RF excited CO.sub.2 slab waveguide laser

Granted: October 13, 1992
Patent Number: 5155739
A CO.sub.2 slab waveguide laser (10) is disclosed including a pair of spaced apart electrodes (36,38) having opposed light reflecting surfaces. The electrodes are dimensioned in a manner to guide light in a plane perpendicular to the reflecting surfaces. Light parallel to the reflecting surfaces is not constrained other than by the resonator mirrors (30,32). The resonator structure includes a negative branch unstable resonator in the nonwaveguide dimension. A stable resonator is used in…

Laser resonators employing diffractive optical elements

Granted: September 29, 1992
Patent Number: 5151917
A laser 10 is disclosed in which there are incorporated one or more diffractive optical elements (DOE's) 20. The DOE's can be used in place of conventional optics to save costs and allow design of resonators not heretofore possible. The ability to vary the reflectivity of the surface of a DOE in any desired pattern allows unprecedented control of both the intracavity mode as well as the mode of the output beam.

Mid-infrared laser endoscope

Granted: September 15, 1992
Patent Number: 5147354
A Ho:YAG laser is coupled to a needle tip through a flexible, fiber optical cable for performing endoscopic and arthroscopic surgery.

Laser with actively stabilized etalon for single frequency operation

Granted: September 1, 1992
Patent Number: 5144632
An actively stabilized laser is disclosed which includes a temperature tunable etalon in the laser cavity for single frequency operation. The operation of the laser is actively monitored to detect variations induced by changes in the length of the resonator. These changes tend to cause the frequency of the selected longitudinal mode to shift so that it is no longer aligned with the peak of the transmission curve of the etalon. When this misalignment occurs, operation deteriorates. By…

Method and apparatus for controlling the power supply of a laser operating in a pulse mode

Granted: August 25, 1992
Patent Number: 5142544
An electronics controller for controlling the power supply of a laser operating in a pulse mode is disclosed. The power supply is of the type having resonant DC converter, charging a capacitive storage means with an inverter stage driving the laser discharge tube. The current supplied to the laser discharge tube is monitored. In addition, the voltage of the capacitive storage means is also measured. Set points for the current, the voltage, and on/off are provided to the electronics…

RF excited CO.sub.2 slab waveguide laser

Granted: August 18, 1992
Patent Number: 5140606
A CO.sub.2 slab waveguide laser (10) is disclosed including a pair of spaced apart electrodes (36,38) having opposed light reflecting surfaces. The electrodes are dimensioned in a manner to guide light in a plane perpendicular to the reflecting surfaces. Light parallel to the reflecting surfaces is not constrained other than by the resonator mirrors (30,32). The resonator structure includes a negative branch unstable resonator in the nonwaveguide dimension. A stable resonator is used in…

Poynting vector walk-off compensation in type II phasematching

Granted: August 4, 1992
Patent Number: 5136597
An improved geometry is disclosed for enhancing the efficiency of second harmonic conversion in a Type II phasematching material. In this approach, the effects of wave vector double refraction are used to compensate for the effects of Poynting vector walk-off. To achieve this goal, the input fundamental beam 32 is arranged to enter the doubling crystal 30 at an oblique angle of incidence. This angle is selected so that the wave vector double refraction angle is equal to the Poynting…

Coupler for a laser delivery system

Granted: August 4, 1992
Patent Number: 5136676
A coupler 30 for use with medical laser delivery systems is disclosed. The delivery system includes an articulated arm and an endoscope 42. The coupler 30 connects the arm to the endoscope. The coupler includes an axially extending tube 46 receivable in the bore 48 of the endoscope. The tube facilitates alignment of the coupler with the endoscope. The coupler is also provided with a telescope optical system (50, 52) for adjusting the diameter of the beam at the entrance to the endoscope…

Method and device for preconditioning a laser having a solid state gain medium

Granted: July 21, 1992
Patent Number: 5132980
A method and device for preventing premature optics burn-out in a laser having a solid gain medium is provided. The invention involves preheating the gain medium by supplying power at a level which is sufficient to set up a thermal lens, yet insufficient to cause substantial production of laser light. In one approach, a simmer routine is overlaid on a ramp routine, so that the power supplied to the gain medium is gradually increased during the warm-up period.

RF excited CO.sub.2 slab waveguide laser

Granted: July 14, 1992
Patent Number: 5131003
A CO.sub.2 slab waveguide laser (10) is disclosed including a pair of spaced apart electrodes (36,38) having opposed light reflecting surfaces. The electrodes are dimensioned in a manner to guide light in a plane perpendicular to the reflecting surfaces. Light parallel to the reflecting surfaces is not constrained other than by the resonator mirrors (30,32). The resonator structure includes a negative branch unstable resonator in the nonwaveguide dimension. A stable resonator is used in…

RF excited CO.sub.2 slab waveguide laser

Granted: July 14, 1992
Patent Number: 5131004
A CO.sub.2 slab waveguide laser (10) is disclosed including a pair of spaced apart electrodes (36,38) having opposed light reflecting surfaces. The electrodes are dimensioned in a manner to guide light in a plane perpendicular to the reflecting surfaces. Light parallel to the reflecting surfaces is not constrained other than by the resonator mirrors (30,32). The resonator structure includes a negative branch unstable resonator in the nonwaveguide dimension. A stable resonator is used in…

Laser plasma tube having a window sealed end and a mirror sealed end

Granted: June 23, 1992
Patent Number: 5124998
A sealed laser plasma tube for use in a gas laser system. A Brewster window seals one end of the tube (the cathode end, in a preferred embodiment), and an end mirror which seals the opposite tube end (the anode end, in a preferred embodiment). In a laser system embodying the invention, a second end mirror is positioned adjacent to, but spaced from, the Brewster window. Intra-cavity elements may conveniently be inserted and replaced in the region between the sealed Brewster window and the…

RF Excited CO.sub.2 slab waveguide laser

Granted: June 16, 1992
Patent Number: 5123028
A CO.sub.2 slab waveguide laser (10) disclosed including a pair of spaced apart electrodes (36,38) having exposed light reflecting surfaces. The electrodes are dimensioned in a manner to guide light in a plane perpendicular to the reflecting surfaces. Light parallel to the reflecting surfaces is not constrained other than by the resonator mirrors (30,32). The resonator structure includes a negative branch unstable resonator in the nonwaveguide dimension. A stable resonator is used in the…

Alignment control system for lasers

Granted: June 9, 1992
Patent Number: 5121405
Control systems for stabilizing the position of a beam from a laser are disclosed. In one aspect, lateral alignment deviations created by varying thermal effects in a solid state gain medium are compensated. A system is also disclosed which can isolate and the correct both lateral and angular alignment errors.

Pressure regulation system for gas laser based on temperature of anode stem

Granted: May 26, 1992
Patent Number: 5117435
A gas laser includes a housing containing a lasing gas. Means are provided for electrically exciting the gas including a cathode mounted at one end of the housing and an anode mounted at the other end. The temperature of the anode is monitored and a control signal is generated which is indicative of the temperature that is measured. An automatic gas supply apparatus is activated to vary the gas pressure in the housing in response to the control signal. Additionally, the temperature that…

Apparatus for measuring the mode quality of a laser beam

Granted: March 31, 1992
Patent Number: 5100231
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…

Laser resonator mirror with wavelength selective coatings on two surfaces

Granted: March 31, 1992
Patent Number: 5101415
An improved laser mirror (22) is disclosed with wavelength selective coatings on the inner and outer surfaces (32) and (34) thereof. The coating on the inner surface (32) is reflective of light in a first wavelength region (36) and transmissive of light in a second wavelength region (38). The outer surface (34) is reflective of light in the second wavelength region ( 38). In the preferred embodiment, one of the surfaces of the mirror is planar and the other is curved to facilitate…

Mode-locked laser using non-linear self-focusing element

Granted: March 17, 1992
Patent Number: 5097471
A passively mode-locked laser (110) is disclosed that includes a resonant cavity (112, 114) having a gain medium (116) therein. A transmissive element (116), which may be the gain medium, is also located in the cavity and is formed from a material which varies the two-dimensional, lateral spatial profile of the beam with respect to intensity due to the Kerr effect. The resonator is arranged such that the round trip gain of the system increases with respect to the intensity of the beam so…