Polarization maintaining multi-pass imaging system for thin-disk amplifiers and oscillators

An optical amplifier, comprising:

• a thin-disk gain-medium having a reflective backing;
• a source of optical pump radiation;
• an arrangement for causing a beam of pump-radiation from the source thereof to be incident one or more times on the thin-disk gain-medium for energizing the thin-disk gain-medium;
• a concave mirror having an optical axis, the thin disk gain medium being located on the optical axis of the concave mirror facing the concave mirror;
• a first retro-reflecting mirror arrangement located below the optical axis of the mirror and facing the concave mirror;
• a second retro-reflecting mirror arrangement located above the first retro-reflecting mirror arrangement, above the optical axis of the concave mirror, and facing the optical axis of the concave mirror;
• at least a first reflecting surface located between the first and second retro-reflecting mirror arrangements and inclined to the optical axis of the concave mirror;
• and
• wherein the positions and angular orientations of the surfaces of the concave mirror, the first and second retro-reflecting mirror arrangements, the at least first reflecting surface, and the thin-disk gain-medium are cooperatively arranged such that when a light-ray to be amplified enters the amplifier parallel to and spaced apart from the optical axis of the concave mirror and is incident on the concave mirror, the light-ray is caused to be incident on the thin-disk gain-medium at least four times, with each of the four incidences thereon being from a different direction, and with the light-ray being amplified on each incidence as a result of the energizing of the gain-medium by the pump radiation and wherein the polarization-orientation of the light-ray is about the same at each of the at least four incidences thereof on the thin-disk gain-medium.

A laser, comprising:

• a thin-disk gain-medium having a reflective backing;
• a source of optical pump radiation for providing a beam of pump-radiation for energizing the thin-disk gain-medium
• a laser resonator formed by the reflective backing of the thin disk gain medium and another resonator mirror;
• a concave mirror having an optical axis having a central aperture therein, the thin disk gain medium being located on the optical axis of the concave mirror facing the concave mirror, and the laser resonator having a longitudinal axis coaxial with the optical axis of the concave mirror and extending through the central aperture therein;
• a first retro-reflecting mirror arrangement located below the optical axis of the concave mirror and facing the concave mirror;
• a second retro-reflecting mirror arrangement located above the first retro-reflecting mirror arrangement, above the optical axis of the concave mirror, and facing the optical axis of the concave mirror;
• at least a first reflecting surface located between the first and second retro-reflecting mirror arrangements and inclined to the optical axis of the concave mirror;
• and
• wherein the positions and angular orientations of the surfaces of the concave mirror, the first and second retro-reflecting mirror arrangements, the at least first reflecting surface, and the thin-disk gain-medium are cooperatively arranged such that when a beam of pump radiation that is plane-polarized with a predetermined polarization-orientation enters the laser parallel to and spaced apart from the optical axis of the concave mirror and is incident on the concave mirror, the pump beam is caused to be incident on the thin-disk gain-medium at least four times, with each of the four incidences thereon being from a different direction, and with a portion of the pump-radiation beam being absorbed by the thin-disk gain medium on each of the four incidences and wherein the polarization-orientation of the light-ray is about the same at each of the at least four incidences thereof on the thin-disk gain-medium.

Optical apparatus, comprising:

• a concave mirror having an optical axis;
• a thin-disk gain-medium having a reflective backing, and located on the optical axis of the concave mirror facing the concave mirror;
• a first retro-reflecting mirror arrangement located below the optical axis of the concave mirror and facing the concave mirror;
• a second retro-reflecting mirror arrangement located above the first retro-reflecting mirror arrangement, above the optical axis of the concave mirror, and facing the optical axis of the concave mirror;
• at least a first reflecting surface located between the first and second retro-reflecting mirror arrangements and inclined to the optical axis of the concave mirror;
• and
• wherein the concave mirror, the first and second retro-reflecting mirror arrangements, the at least first reflecting surface, and the thin-disk gain-medium are cooperatively arranged such that a light-ray entering the apparatus parallel to and spaced apart from the optical axis of the concave mirror and incident on the concave mirror is caused to be incident on the thin-disk gain-medium at least four times, with each of the four incidences thereon being from a different direction and wherein the optical axis of the concave mirror defines the z-axis of Cartesian x-, y-, and z-axes with the y-axis being a nominally vertical-axis, the x-axis being a nominally lateral-axis, and the z-axis being a longitudinal-axis of the apparatus, wherein the first and second retro-reflecting mirror arrangements each include first and second reflecting surfaces inclined to each other, with adjacent edges thereof meeting at an apex of the arrangement, and wherein the apex of the first retro-reflecting mirror arrangement is located on the z-axis aligned with the y-axis, the apex of the second retro-reflecting mirror arrangement is laterally displaced from the z-axis in the x-axis direction one side thereof, and the at least a first reflecting surface between the retro-reflecting mirror arrangements is parallel to the x-axis and inclined to the y-axis and the z-axis and wherein there is defined a maximum x-axis displacement value x0 from the z-axis for the apex of the second retro-reflecting mirror arrangement, this displacement value equal in magnitude to an x-axis incidence coordinate x0, of opposite sign, of the light-ray on the mirror on the opposite side of the z-axis from the apex of the second retro-reflecting mirror pair, and wherein for a displacement x from the z-axis of the apex of the second retro-reflecting mirror pair given by an equation
• x
• =
• x
• 0
• (
• 2
• ⁢
• n
• -
• 1
• )
• if n is an integer, the number of incidences of the light-ray on the thin-disk gain-medium will be equal to 4n.

Optical apparatus, comprising:

• a concave mirror having an optical axis;
• a thin-disk gain-medium having a reflective backing, and located on the optical axis of the concave mirror facing the concave mirror;
• a first retro-reflecting mirror arrangement located below the optical axis of the concave mirror and facing the concave mirror;
• a second retro-reflecting mirror arrangement located above the first retro-reflecting mirror arrangement, above the optical axis of the concave mirror, and facing the optical axis of the concave mirror;
• at least a first reflecting surface located between the first and second retro-reflecting mirror arrangements and inclined to the optical axis of the concave mirror;
• and
• wherein the concave mirror, the first and second retro-reflecting mirror arrangements, the at least first reflecting surface, and the thin-disk gain-medium are cooperatively arranged such that a light-ray entering the apparatus parallel to and spaced apart from the optical axis of the concave mirror and incident on the concave mirror is caused to be incident on the thin-disk gain-medium at least four times, with each of the four incidences thereon being from a different direction and wherein the light-ray entering the apparatus is incident first on the concave mirror at a first location thereon, then incident a first time the thin-disk gain-medium, is again incident on the concave mirror at a second location thereon, is then retro-reflected and laterally translated by the first retro-reflecting mirror arrangement back onto the concave mirror at a third location thereon, is then incident a second time on the thin-disk gain-medium, is again incident on the concave mirror at a fourth location thereon, is then incident on the first reflecting surface, is then incident on the second retro-reflecting mirror arrangement and is retro-reflected by the second retro-reflecting mirror arrangement making a further four incidences of the concave mirror and a further two incidences on the thin-disk gain medium and wherein the light-ray is retro-reflected by the second retro-reflection arrangement along the incident path thereof thereon and the further four incidences of the light-ray on the concave-mirror are at the original four locations in reverse sequence, whereby the light-ray is incident on the gain medium only four times, and the light-ray exits the apparatus back along the entrance path thereof.

Optical apparatus, comprising:

• a concave mirror having an optical axis;
• a thin-disk gain-medium having a reflective backing, and located on the optical axis of the concave mirror facing the concave mirror;
• a first retro-reflecting mirror arrangement located below the optical axis of the concave mirror and facing the concave mirror;
• a second retro-reflecting mirror arrangement located above the first retro-reflecting mirror arrangement, above the optical axis of the concave mirror, and facing the optical axis of the concave mirror;
• at least a first reflecting surface located between the first and second retro-reflecting mirror arrangements and inclined to the optical axis of the concave mirror;
• and
• wherein the concave mirror, the first and second retro-reflecting mirror arrangements, the at least first reflecting surface, and the thin-disk gain-medium are cooperatively arranged such that a light-ray entering the apparatus parallel to and spaced apart from the optical axis of the concave mirror and incident on the concave mirror is caused to be incident on the thin-disk gain-medium at least four times, with each of the four incidences thereon being from a different direction and wherein the light-ray entering the apparatus is incident first on the concave mirror at a first location thereon, then incident a first time the thin-disk gain-medium, is again incident on the concave mirror at a second location thereon, is then retro-reflected and laterally translated by the first retro-reflecting mirror arrangement back onto the concave mirror at a third location thereon, is then incident a second time on the thin-disk gain-medium, is again incident on the concave mirror at a fourth location thereon, is then incident on the first reflecting surface, is then incident on the second retro-reflecting mirror arrangement and is retro-reflected by the second retro-reflecting mirror arrangement making a further four incidences of the concave mirror and a further two incidences on the thin-disk gain medium and wherein, the light-ray is retro-reflected by the second retro-reflecting mirror arrangement and laterally translated by the second retro-reflecting mirror arrangement and makes a further four incidences on the concave mirror and a further two incidences on the thin-disk gain-medium, the further four incidences on the concave-mirror being at different locations from each other and from the original four locations on the concave mirror.