Coolable slab laser

Claim 2

A laser element comprising a slab of laser material in the form of an eight sided solid having a longitudinal axis and bounded by two spaced parallel nonspecular planes perpendicular to the longitudinal axis and forming first and second end surfaces of the laser element, two spaced parallel nonspecular planes parallel to the longitudinal axis and forming top and bottom surfaces of the laser element, first two nonparallel planes perpendicular to said top and bottom surfaces and intersecting, if extended, along a first line parallel to said first end surface and spaced a particular first distance from the first end surface in a direction away from the laser element, said first two nonparallel planes having coatings with a one hundred percent reflectance at the laser radiation wavelength for radiation incident substantially at normal angle, second two nonparallel planes shorter in length than said first two nonparallel planes and perpendicular to said top and bottom surfaces and intersecting, if extended, along a second line parallel to the second end surface and spaced a particular second distance, less than the particular first distance, from the second end surface in a direction away from the laser element, the first and second lines intersecting the longitudinal axis, one of said second two nonparallel planes having a one hundred percent mirror coating, the other of said second two nonparallel planes having a partial mirror coating, one of said first and second two nonparallel planes intersecting at a first obtuse angle and forming a first side surface of the laser element, and the other of said first and second two nonparallel planes intersecting at a second obtuse angle and forming a second side surface of the laser element, a beam of laser radiation which is produced in the laser element in response to optical pumping of the laser material being reflected between said first two nonparallel planes a plurality of times at a small angle of incidence less than that for total internal reflection in passing from the second end to the first end and back again to the second end of the laser element.

Claim 3

A laser element as set forth in claim 1 wherein said second two nonparallel planes have an anti-reflecting coating instead of one having a one hundred percent mirror and the other a partial mirror coating.

Claim 4

A coolable slab laser comprising a slab of laser material in the form of an eight-sided solid having a constant height rectangular cross section perpendicular to its longitudinal axis and two parallel end surfaces perpendicular to said longitudinal axis which define the longitudinal dimension of said slab, said rectangular cross section of constant height but increasing in width from one end surface of the slab to an intermediate point along said longitudinal axis and then decreasing in width continuing from said intermediate point to the other of said end surfaces, said increasing width portion defined by a first pair of side surfaces, said decreasing width portion defined by a second pair of side surfaces, said first and second pair of side surfaces intersecting at said intermediate point, the height of said rectangular cross section defined by parallel top and bottom surfaces, said parallel end and top and bottom surfaces having a non-specular finish, said first pair of side surfaces having a substantially one hundred percent mirror coating at laser wavelength adapted to reflect a beam of laser wavelength energy within the laser material but being transparent at pumping radiation wavelengths, optical pump means located adjacent said first pair of side surfaces for impinging pumping radiation only thereon and inducing a population inversion in a particular excited energy level characteristic of the laser material and thereby producing a laser wavelength energy beam Therein which is reflected between said first pair of side surfaces a plurality of times at a small angle of incidence less than that for total internal reflection while traveling longitudinally from a first of said end surfaces to a second of end surfaces and back again to said first end surface, and cooling means in contact with said first pair of side surfaces for withdrawing heat from said laser material during operation of said laser and inducing a thermal gradient in the laser material, the reflected laser wavelength energy beam traversing paths nearly parallel to the thermal gradient due to the reflection at small angle of incidence to thereby substantially reduce temperature induced distortions in the laser beam wavefront.

Claim 5

A coolable slab laser comprising a slab of laser material in the form of an eight-sided solid having a constant height rectangular cross section perpendicular to its longitudinal axis and two parallel end surfaces perpendicular to said longitudinal axis which define the longitudinal dimension of said slab, said rectangular cross section of constant height but increasing in width from one end surface of the slab to an intermediate point along said longitudinal axis and then decreasing in width continuing from said intermediate point to the other of said end surfaces, said increasing width portion defined by a first pair of side surfaces, said decreasing width portion defined by a second pair of side surfaces, said first and second pair of side surfaces intersecting at said intermediate point, the height of said rectangular cross section defined by parallel top and bottom surfaces, said parallel end and top and bottom surfaces having a non-specular finish, said first pair of side surfaces having a substantially one hundred percent mirror coating at laser wavelength adapted to reflect a beam of laser wavelength energy within the laser material but being transparent at pumping radiation wavelengths, optical pump means located adjacent said first pair of side surfaces for impinging pumping radiation only thereon and inducing a population inversion in a particular excited energy level characteristic of the laser material and thereby producing a laser wavelength energy beam Therein which is reflected between said first pair of side surfaces a plurality of times at a small angle of incidence less than that for total internal reflection while traveling longitudinally from a first of said end surfaces to a second of end surfaces and back again to said first end surface, and cooling means in contact with said first pair of side surfaces for withdrawing heat from said laser material during operation of said laser and inducing a thermal gradient in the laser material, the reflected laser wavelength energy beam traversing paths nearly parallel to the thermal gradient due to the reflection at small angle of incidence to thereby substantially reduce temperature induced distortions in the laser beam wavefront.

Claim 6

A coolable slab laser as set forth in claim 3 wherein said second pair of side surfaces having an anti-reflection coating, whereby said laser acts as an amplifier in which a beam of laser wavelength energy enters through one of said second pair of side surfaces, is reflected between said first pair of side surfaces, accumulating energy from the pumped laser material, and exits through the other of said second pair of side surfaces.

Claim 7

A coolable slab laser as set forth in claim 3 wherein one of said second pair of side surfaces has a substantially one hundred percent mirror coating and the other of said second pair of side surfaces has a partial mirror coating to form a Fabry-Perot laser cavity having a folded beam path, said folded beam path being contained by said first pair of side surfaces.

Claim 8

A coolable slab laser as set forth in claim 5 wherein the distance along said longitudinal axis from said one end surface to the intermediate point is greater than the distance along said longitudinal axis from said intermediate point to the other of said end surfaces.