Laser utilizing a negative branch instable cavity resonator
AssigneeQuanta System S.P.A.
InventorsPier G. Gobbi, Giancarlo Reali
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Abstract
The invention relates to a laser utilizing a negative branch unstable cavity resonator, comprising two opposed and aligned reflecting mirrors and a baffle aligned with the optic axis of the cavity and located in close proximity to the effective focal point of at least one of the mirrors as determined by the influence of the cavity's remaining optical components. The baffle is provided with an aperture of size such as to stop down the focal spot at its first minimum level of luminous intensity from center. The laser beam, which is out-coupled by conventional techniques, possesses optimum intensity-distribution spatial characteristics in space, and can be focused almost to the diffraction limits.
Claims15
A laser, utilizing a negative branch type unstable cavity resonator comprising at least two aligned and opposed reflecting mirrors, at least one active laser medium located along the optic axis of the resonator and interposed between said mirrors and means for intercepting and coupling a beam emitted from said active laser medium out of the resonator, wherein the effective focal point of at least one of the mirrors, the focusing mirror, as determined by the influence of all the optical components located in the resonator, including the other reflective mirror, said laser medium and said beam coupling means, falls within the cavity resonator itself;
- and wherein a baffle, aligned with the optic axis in close proximity to said effective focal point, is provided with a pin hole aperture dimensioned so as to stop down the light spot of the laser beam emitted by the active laser medium and reflected by the focusing mirror to thereby provide a first minimum level of its luminous intensity as measured transversely with respect to the optic axis and departing from it and wherein said dimensioning of the pinhole aperture, which effectively limits the intensity level of the laser beam at the effective focal point and produces a smooth intensity and phase beam profile, is calculated applying the formula:
- D=2.sqroot.m.multidot.f.multidot..lambda.
- for circular symmetry, side for rectangular symmetry), m equals 0.61 for circular symmetry and 0.5 for rectangular symmetry, f which is the distance of the pinhole aperture from the focusing mirror is also the equivalent focal length of said focusing mirror as determined by the influence of all the optical components located in the resonator, and .lambda. is the wavelength of the laser beam emitted by the laser medium.
Dependencies are inferred from the claim text.