Laser having a gas-filled fabry-perot etalon mode selector

Claim 2

A laser including within its optical cavity a prism and a Fabry-Perot etalon, saie etalon comprising two spaced parallel surfaces each slightly inclined to a normal to that part of the laser optical axis lying between the two surfaces, one of the parallel surfaces of the etalon being formed by a face of the prism and the space between the parallel surfaces being filled by a gaseous medium.

Claim 3

A laser as claimed in Claim 1 further including a block of optically transparent material, the other of the parallel surfaces of the etalon being formed by an adjacent surface of the block of optically transparent material, the remote surface of the block forming a resonator mirror of the laser.

Claim 4

A laser as claimed in claim 1 further including a second prism, the other of the parallel surfaces of the etalon being formed by a face of the second prism.

Claim 5

A laser as claimed in claim 1 including means between the parallel surfaces of the etalon for adjusting the spacing therebetween.

Claim 6

A laser as claimed in claim 4 in which the means between the two parallel surfaces of the etalon includes a common member of piezo-electric material separating said parallel surfaces, said member including conductive means for applying to the material a direct current potential difference of adjustable value thereby varying the extent of the separation between the said surfaces.

Claim 7

A laser as claimed in claim 5 wherein said means forms a seal for sealing the space between the parallel surfaces of the etalon.

Claim 8

A laser as claimed in claim 1 including a gaseous active medium, the space between the parallel surfaces of the etalon containing the same gaseous medium.

Claim 9

A laser as claimed in claim 1 in which the two spaced surfaces of the Fabry-Perot etalon are concentric spherical surfaces, and means for supporting the surfaces such that the tengent to each surface at the point of intersection of the surface and that part of the optical axis lying between the two surfaces being slightly inclined to a normal to the said part of the optical axis.

Claim 10

A laser as claimed in claim 1 including means for supporting the spaced surfaces such that the inclinatioN of each spaced surface of the etalon to a normal to that part of the optical axis lying between the spaced surfaces is of the order of a few milliradians.

Claim 11

A laser as claimed in claim 8 in which the spaced surfaces are supported such that the inclination of each said tangent to the said normal is of the order of a few milliradians.

Claim 12

A laser including within its optical cavity thermally stable mode selector means for selecting the wavelength of the output radiation from a number of closely spaced discrete wave lengths, said mode selector means comprising a first prism and a second prism spaced from each other, each prism having a first face inclined at an angle in the order of a few milliradians to a normal to that part of the laser optical axis lying between the two first faces of the prisms, said first faces being parallel to each other thereby forming a prism-Fabry/Perot etalon combination, each said prism having a second face inclined at an angle relative to a normal to the optical axis of the laser at said second face, said angle being approximately equal to the Brewster''s angle for the selected wavelength, said laser having a resonator mirror surface along its optical axis, means for adjusting the spacing between the parallel faces, said means including a common member of piezo-electric material extending between said parallel faces and supporting said faces such that only a desired relative movement between said faces is allowed, said member having spaced conductive surfaces thereon for applying across the thickness of said member a potential difference for causing a change in the length of said member.

Claim 13

A laser including within its optical cavity thermally stable mode selector means for selecting the wavelength of the output radiation from a number of closely spaced discrete wave lengths, said mode selector means comprising a first prism and a second prism spaced from each other, each prism having a first face inclined at an angle in the order of a few milliradians to a normal to that part of the laser optical axis lying between the two first faces of the prisms, said first faces being parallel to each other thereby forming a prism-Fabry/Perot etalon combination, each said prism having a second face inclined at an angle relative to a normal to the optical axis of the laser at said second face, said angle being approximately equal to the Brewster''s angle for the selected wavelength, said laser having a resonator mirror surface along its optical axis, means for adjusting the spacing between the parallel faces, said means including a common member of piezo-electric material extending between said parallel faces and supporting said faces such that only a desired relative movement between said faces is allowed, said member having spaced conductive surfaces thereon for applying across the thickness of said member a potential difference for causing a change in the length of said member.

Claim 14

A laser as set forth in claim 11 wherein said mirror surface is external to the prism etalon combination and said first faces are concentric spherical surface.