Laser systems

Claim 2

Apparatus for improving properties of a solid material by providing shock waves therein, comprising means for providing a plurality of pulses of coherent radiation; means for sharpening the leading edge of each pulse; means for directing each pulse as a beam having a predetermined diameter onto amplifying means comprising first and second laser amplifier rods in series; means for directing at least a major portion of the radiation amplified by the first amplifier rod to the second amplifier rod; means for directing the radiation amplified by the second amplifier rod to a surface of the solid material; and means for providing substantially uniform spatial amplitude in the radiation directed to the surface of the solid material.

Claim 3

Apparatus as in claim 1, wherein the means for providing substantially uniform spatial amplitude in the radiation comprises the amplifying means; the amplifying means includes with each laser amplifier rod a pair of flashlamps for pumping the rod, the axis of each flashlamp and the axis of the rod being substantially parallel to each other and substantially in the same plane; and the plane containing the axis of the second laser amplifier rod and the axes of its associated flashlamps is substantially perpendicular to the plane containing the axis of the first laser amplifier rod and the axes of its associated flashlamps.

Claim 4

Apparatus as in claim 1, comprising also means for directing a minor portion of the radiation amplified by the first amplifier rod to second amplifying means comprising third and fourth laser amplifier rods in series; means for directing at least a major portion of the radiation amplified by the third amplifier rod to the fourth amplifier rod; and means for directing the radiation amplified by the fourth amplifier rod to a surface of the solid material; and so on similarly for any desired number of additional similar amplifying means.

Claim 5

Apparatus as in claim 3, wherein each means for directing radiation to a surface of the solid material provides the radiation to the surface at an intensity of about 10 to 500 Joules per square centimeter.

Claim 6

Apparatus as in claim 3, wherein each means for directing radiation to a surface of the solid material directs its portion of the radiation substantially simultaneously to an area on the same surface that overlaps at least a portion of the area to which another said means directs its portion of the radiation.

Claim 7

Apparatus as in claim 5, wherein the optical path length of each beam is selected so as to provide the substantially simultaneous arrival at the surface by each portion of the radiation.

Claim 8

Apparatus as in claim 5, wherein each means for directing radiation to the same surface of the solid material directs its portion of the radiation to an area on the surface such that all of aid means together direct the total radiation approximately evenly over a continuous area.

Claim 9

Apparatus as in claim 3, wherein at least one of the means for directing radiation to a surface of the solid material directs its portion of the radiation substantially simultaneously to an area on a different surface of the solid material from the surface to which at least one other said means directs its portion of the radiation.

Claim 10

Apparatus as in claim 8, wherein said means for directing radiation to a surface of the solid material direct their respective portions of the radiation to areas that are substantially opposite to each other and on opposite sides of the solid material.

Claim 11

Apparatus as in claim 3, wherein the means for providing substantially uniform spatial amplitude in the radiation comprises the amplifying means; each amplifying means includes with each laser amplifier rod a pair of flashlamps for pumping the rod, the axis of each flashlamp and the axis of the rod being substantially parallel to each other and substantially in the same plane; the plane containing the axis of the second laser amplifier rod and the axes of its associated flashlamps is substantially perpendicular to the plane containing the axis of the first laser amplifier rod and the axes of its associated flashlamps; the plane containing the axis of the fourth laser amplifier rod and the axes of its associated flashlamps is substantially perpendicular to the plane containing the axis of the third laser amplifier rod and the axes of its associated flashlamps; and so on similarly for any additional similar amplifying means.

Claim 12

Apparatus as in claim 1, wherein the pulse providing means comprises a laser oscillator including a rod and a pair of flashlamps for pumping it, the axis of each flashlamp and the axis of the rod being substantially parallel to each other and substantially in the same plane; and a preamplifier including a rod and a pair of flashlamps for pumping it, the axis of each flashlamp and the axis of the rod being substantially parallel to each other and substantially in the same plane; the means for providing substantially uniform spatial amplitude in the radiation comprises the laser oscillator and the preamplifier; and the plane containing the axis of the preamplifier rod and the axes of its associated flashlamps is substantially perpendicular to the plane containing the axis of the oscillator rod and the axes of its associated flashlamps.

Claim 13

Apparatus as in claim 1, wherein the means for providing substantially uniform spatial amplitude in the radiation comprises the pulse providing means, and the pulse providing means comprises means for providing a beam of coherent radiation that is not polarized and in which each succeeding pulse is, in the spatial amplitude pattern of the beam, substantially a mirror image of the pattern in the pulse that preceded it.

Claim 14

Apparatus as in claim 12, wherein the means for providing a beam of coherent radiation comprises a. laser means for providing a beam of unpolarized coherent radiation in a predetermined first direction; b. polarizing means located in the path of the beam, for breaking down the radiation into two linearly polarized orthogonal components, transmitting one component through it in the first direction, and reflecting the other component from it in a predetermined second direction; c. means for reflecting the component that was transmitted through the polarizing means, along a first closed path that ends in directing it back to the polarizing means in a predetermined third direction, opposite to the second direction, and for reflecting the component that was reflected from the polarizing means, along a second closed path that is opposite to the first closed path, and ends in directing it back to the polarizing means in a predetermined fourth direction, opposite to the first direction; d. means located in the closed paths for retarding each component of the radiation by a predetermined fraction of a wavelength, a substantial fraction of the transmitted component being transformed into the opposite component before reaching the polarizing means, and a substantial fraction of the reflected component being transformed into the opposite component before again reaching the polarizing means; e. the transformed transmitted component being reflected from the polarizing means in the fourth direction to the laser means to maintain oscillation therein, and the transformed reflected component being transmitted through the polarizing means in the fourth direction to the laser means to maintain oscillation therein; f. the fraction of the transmitted component that remains not transformed being transmitted through the polarizing means in the third direction, and the fraction of the reflected component that remains not transformed being reflected from the polarizing means in the third direction; and g. the two last mentioned components combining to form a beam of unpolarized useful output radiation that is directed in the third direction.

Claim 15

Apparatus as in claim 1, wherein the means for providing substantially uniform spatial amplitude in the radiation comprises the pulse providing means, and the pulse providing means comprises means for providing a beam of coherent radiation that is not polarized and in which each succeeding pulse is, in the spatial amplitude pattern of the beam, rotated about its axis by a predetermined angle from the pattern in the pulse that preceded it.

Claim 16

Apparatus as in claim 14, wherein the means for providing a beam of coherent radiation comprises a. laser means for providing a beam of unpolarized coherent radiation in a predetermined first direction; b. polarizing means located in the path of the beam, for breaking down the radiation into two linearly polarized orthogonal components, transmitting one component through it in the first direction, and reflecting the other component from it in a predetermined second direction; c. means for reflecting the component that was transmitted through the polarizing means, along a first closed path that ends in directing it back to the polarizing means in a predetermined third direction, opposite to the second direction, and for reflecting the component that was reflected from the polarizing means, along a second closed path that is opposite to the first closed path, and ends in directing it back to the polarizing means in a predetermined fourth direction, opposite to the first direction; d. means located in the closed paths for retarding each component of the radiation by a predetermined fraction of a wavelength, with a substantial fraction of the transmitted component being transformed into the opposite component before reaching the polarizing means, and a substantial fraction of the reflected component being transformed into the opposite component before again reaching the polarizing means; e. the transformed transmitted component being reflected from the polarizing means in the fourth direction to the laser means to maintain oscillation therein, and the transformed reflected component being transmitted through the polarizing means in the fourth direction to the laser means to maintain oscillation therein; f. the fraction of the transmitted component that remains not transformed being transmitted through the polarizing means in the third direction, and the fraction of the reflected component that remains not transformed being reflected from the polarizing means in the third direction; and g. the two last mentioned components combining to form a beam of unpolarized useful output radiation that is directed in the third direction; h. means located in the closed paths for rotating the beam of radiation about its axis; and i. means in the laser means for retarding the radiation beam from each pass through the closed paths to the next pass therethrough by a predetermined fraction of a wavelength; j. the radiation beam being thus rotated from each pass through the closed paths to the next pass therethrough by a predetermined angle.

Claim 17

Apparatus as in claim 1, wherein the means for sharpening the leading edge of each pulse comprises means for providing phase conjugation reflection of the radiation to limit the rise time of the pulse to not longer than about 5 nanoseconds.

Claim 18

Apparatus as in claim 16, wherein the means for providing phase conjugation reflection comprises a stimulated Brillouin scattering cell.

Claim 19

Apparatus as in claim 17, wherein the reflecting material in the stimulated Brillouin scattering cell comprises a liquid or a gas.

Claim 20

Apparatus as in claim 17, wherein the reflecting material in the stimulated Brillouin scattering cell comprises carbon tetrachloride, sulfur hexafluoride, methane, acetone, benzene, carbon disulfide, or ethylene glycol.

Claim 21

Apparatus as in claim 17, wherein the stimulated Brillouin scattering cell is in the oscillator cavity.

Claim 22

Apparatus as in claim 17, wherein the stimulated Brillouin scattering cell is external to the oscillator cavity.

Claim 23

Apparatus as in claim 21, wherein the means for providing phase conjugation reflecting comprises also means for providing Faraday rotation of the radiation.

Claim 24

Apparatus as in claim 16, wherein the means for providing phase conjugation reflection comprises a Faraday isolator and a stimulated Brillouin scattering cell.

Claim 25

Apparatus as in claim 1, wherein the diameter of each laser amplified rod is about 2 to 3 centimeters.

Claim 26

Apparatus as in claim 24, wherein the output fluence level in each amplifier rod is about 6 to 20 Joules per square centimeter.

Claim 27

Apparatus as in claim 1, wherein the components in the amplifier means affecting flashlamp efficiency, cavity transfer efficiency, quantum defect, quantum efficiency, and extraction efficiency are selected to provide substantially maximum overall efficiency therein.

Claim 28

Apparatus as in claim 26, wherein cerium is provided in the walls of the flashlamps to minimize the number of photons emitting with wavelengths substantially shorter than 0.85 micrometer, and krypton is provided in the flashlamps to minimize the number of photons emitting with wavelengths longer than about 0.85 micrometer, to confine the radiation from the flashlamps predominantly to a narrow range of wavelengths just less than about 0.85 micrometer.

Claim 29

Apparatus as in claim 26, wherein the amplifier rods comprise a material having an absorption cross-section of less than about 10 -3 per centimeter and a stimulated emission cross-section of greater than about 4×10 -20 square centimeters.

Claim 30

Apparatus as in claim 28, wherein the amplifier rods comprise neodymium-doped glass.

Claim 31

Apparatus as in claim 29, wherein the concentration of neodymium in the amplifier rods is about 1.5 to 2.5 percent by weight.