Dye laser with pump cavity mode matched to laser resonator

Claim 1

A laser comprising in combination a first active laser medium capable of providing the stimulated emission of a first beam of optical radiation, means coupled to said first medium for creating a population inversion therein, resonator means coupled to at least said first medium for stimulating the emission of said first beam from said first medium, a second active laser medium capable of providing the stimulated emission of a second beam of optical radiation of lower frequency than the frequency of said first beam upon being pumped by said first beam, said second medium comprising a cell containing a dye in solution, the concentration of the dye in said cell being adjusted to transmit a substantial portion of said first beam upon incidence, said dye being selected to make the difference of said frequencies substantially less than either of said frequencies, wherein said resonator means comprises first and second end reflectors encompassing both of said media and a third reflector disposed between said first and second media, said third reflector being tilted with respect to the respective axes of said first and second reflectors to define a folded path along which said beams can oscillate, said resonator being capable of simultaneously resonating said beams, said second and third reflectors being curved reflectors with respective curvatures to provide said first beam with a minimum cross-sectional diameter in the region between said second and third reflectors, said second medium being positioned between said second and third reflectors in the path of said first beam at the minimum cross-sectiOnal diameter thereof to be pumped thereby, so that said first and second beams are substantially matched in beam shape and share a common path throughout said resonator.