Abstract A laser oscillator provided with a reflection-type laser resonator constituted of an output coupling mirror (4), a rear mirror (10), and one or more reflecting mirrors (11, 12). The rear mirror (10) exhibits a maximum reflective index for the linearly polarized component having vector E in parallel with the direction that is turned by π/4 relative to the incident surface of a reflecting mirror (11) positioned at the shortest distance on the optical axis, and the whole reflecting mirrors (11, 12) work as a π/2 phase retarder for the parallel and perpendicularly polarized components. Therefore, a circularly polarized beam is emitted directly from the output coupling mirror (4).
A laser oscillator for oscillating a laser beam, said oscillator comprising: an output coupling mirror; at least one folding mirror operating as a whole as a phase retarder imposing π /2 phase delay with respect to a parallel and perpendicular polarization components of said laser beam; and a rear mirror having a maximum reflectivity with respect to a linear polarization component of said laser beam, said linear polarization component having an E vector a direction of which rotated by a τ /4 phase from an incident plane of the nearest one of said folding mirror.
Claim 2
Dependent Claim
95 words
A laser oscillator for oscillating a laser beam, said oscillator comprising: an output coupling mirror; at least one folding mirror operating as a whole as a phase retarder imposing π /2 phase delay with respect to a parallel and perpendicular polarization components of said laser beam; and a rear mirror having a maximum reflectivity with respect to a linear polarization component of said laser beam, said linear polarization component having an E vector a direction of which rotated by a τ /4 phase from an incident plane of the nearest one of said folding mirror.
Claim 3
Dependent Claim
35 words
The laser oscillator as defined in claim 1, wherein said rear mirror has a surface on which an array of grooves is formed, said grooves being oriented in parallel with one another in one direction.
Claim 4
Dependent Claim
43 words
The laser oscillator as defined in claim 2, wherein said grooves have a depth falling within the range between a wavelength of said laser beam and a skin depth on said coupling mirror or said folding mirrors at a wavelength of said laser.
Claim 5
Dependent Claim
24 words
The laser oscillator as defined in claim 2, wherein the depth of said grooves falls within the range between 60 A and 10 µm.
Claim 6
Dependent Claim
23 words
The laser oscillator as defined in claim 2, wherein said rear mirror has a mirror surface cut by machining with a diamond lathe.
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