Laser resonator cavities with wavelength tuning arrangements

In a laser comprising an optical cavity defined by first and second reflecting optics, a first amplifying medium within the cavity and means to excite said medium to produce lasing conditions, said laser including means to restrict the laser beam to a common path for all wavelengths in the region of said first reflecting optics, the improvement comprising means including spectral dispersion apparatus disposed within the optical cavity, positioned to receive a beam of restricted cross section in said common path from said first reflecting optics and to disperse said beam to a plurality of paths in which rays of different wavelength are laterally spaced apart, said paths passing through said first amplifying medium whereby rays differing in wavelength can be subjected to amplification in different spatially separated portions of said first amplifying medium, said second reflecting optics constructed to reflect regeneratively said rays back along said paths, in laterally spaced apart condition through said portions of said first amplifying medium for further amplification, thence from said spectral dispersion apparatus along said common path to said first reflecting optics, said laser including a second amplifying medium disposed in the common beam path between said first reflecting optics and said spectral dispersion apparatus, in which path said rays are in a non-resolved, overlapping relation, and means to excite both said first and said second amplifying medium whereby a given wavelength amplified in a portion of said first amplifying medium can be present in said common beam path to cause excitation of laser oscillation at said wavelength in said second amplifying medium.