Apparatus and method for producing visible coherent light at a plurality of wavelengths

Claim 1

Pulsed tunable laser apparatus having outputs in the visible optical wavelengths comprising a laser having a lasing medium, means to excite said lasing medium whereby to produce a pump beam of coherent light having a wavelength λ p greater than 8000 A (near infrared), and first and second laser mirrors spaced from opposite sides respectively of said medium and traversing said beam whereby to define the laser cavity, switch means in said laser cavity operative on said beam, means to activate and deactivate said switch means whereby to produce a succession of pulses of said coherent light, a non-centrosymmetric crystal between said lasing medium and said second mirror and positioned to be traversed by said light pulses whereby to cause stimulated Raman scattering (SRS) of the light and thereby to produce Stokes wavelengths, said crystal having an optic axis and an angle θ with respect to the pulsed beam propagation direction within the crystal, means to adjustably support said crystal for movement relative to said pulsed beam whereby θ is selectively changeable, and means to cause said Raman scattered light to oscillate through said crystal comprising at least one of said mirrors whereby to produce visible light outputs having a plurality of wavelengths corresponding to a like plurality of values of θ, said mirrors being non-transmissive at λ p and at said Stokes wavelengths, at least one of said mirrors being transmissive at visible light wavelengths between 4000 and 7000 A whereby coherent light in the latter wavelength range is outputted from said apparatus.

Claim 9

The method of generating a coherent light beam at a plurality of wavelengths in the visible spectrum consisting of the steps of directing a laser pump beam having a wavelength λ p through a non-centrosymmetric crystal at an angle θ with the crystal optic axis and producing by stimulated Raman scattering (SRS) Stokes and Raman modes having wavelengths λ S and λ R , respectively, whereby to satisfy the conditions ω.sub.P =ω.sub.S +ω.sub.R and k.sub.P =k.sub.S +K.sub.R where ω P , ω S and ω R are the pump, Stokes and Raman frequencies, respectively, and k represents the wavevectors for said frequencies, causing said Stokes and Raman modes to oscillate through said crystal, selectively changing the angle θ through a plurality of different values, deriving spectrally spaced coherent light outputs from said crystal at a plurality of wavelengths in the visible spectrum corresponding to said plurality of different values, respectively, of θ, and separating said outputs from said laser pump beam and from said Stokes and Raman modes.

Claim 10

The method of generating a coherent light beam at a plurality of wavelengths in the visible spectrum consisting of the steps of directing a laser pump beam having a wavelength λ p through a non-centrosymmetric crystal at an angle θ with the crystal optic axis and producing by stimulated Raman scattering (SRS) Stokes and Raman modes having wavelengths λ S and λ R , respectively, whereby to satisfy the conditions ω.sub.P =ω.sub.S +ω.sub.R and k.sub.P =k.sub.S +K.sub.R where ω P , ω S and ω R are the pump, Stokes and Raman frequencies, respectively, and k represents the wavevectors for said frequencies, causing said Stokes and Raman modes to oscillate through said crystal, selectively changing the angle θ through a plurality of different values, deriving spectrally spaced coherent light outputs from said crystal at a plurality of wavelengths in the visible spectrum corresponding to said plurality of different values, respectively, of θ, and separating said outputs from said laser pump beam and from said Stokes and Raman modes.

Claim 11

The method of generating coherent light at a plurality of wavelengths in the visible spectrum consisting of the steps of directing a laser pump beam through a non-centrosymmetric crystal at an angle θ with the crystal optic axis, simultaneously producing stimulated Raman scattering (SRS) and phasematched second harmonic generation (SHG) in said crystal, selectively changing the angle θ through a plurality of different values and thereby producing outputs from said crystal at a plurality of wavelengths in the visible spectrum corresponding to said plurality of different values, respectively, of θ, and separating said outputs from coherent light at wavelengths outside the visible spectrum.

Claim 12

The method of generating coherent light at a plurality of wavelengths in the visible spectrum consisting of the steps of directing a laser pump beam through a non-centrosymmetric crystal at an angle θ with the crystal optic axis, simultaneously producing stimulated Raman scattering (SRS) and phasematched second harmonic generation (SHG) in said crystal, selectively changing the angle θ through a plurality of different values and thereby producing outputs from said crystal at a plurality of wavelengths in the visible spectrum corresponding to said plurality of different values, respectively, of θ, and separating said outputs from coherent light at wavelengths outside the visible spectrum.

Claim 13

The method of generating coherent light at a plurality of wavelengths in the visible spectrum consisting of the steps of directing a laser pump beam through a non-centrosymmetric crystal at an angle θ with the crystal optic axis, simultaneously producing stimulated Raman scattering (SRS) and phase matched sum frequency generation (SFG) in said crystal, selectively changing the angle θ through a plurality of different values and thereby producing outputs from said crystal at a plurality of wavelengths in the visible spectrum corresponding to said plurality of different values, respectively, of θ, and separating said outputs from coherent light at wavelengths outside the visible spectrum.

Claim 14

The method of generating coherent light at a plurality of wavelengths in the visible spectrum consisting of the steps of directing a laser pump beam through a non-centrosymmetric crystal at an angle θ with the crystal optic axis, simultaneously producing stimulated Raman scattering (SRS) and phase matched sum frequency generation (SFG) in said crystal, selectively changing the angle θ through a plurality of different values and thereby producing outputs from said crystal at a plurality of wavelengths in the visible spectrum corresponding to said plurality of different values, respectively, of θ, and separating said outputs from coherent light at wavelengths outside the visible spectrum.