Patent ID: 6917635

Claim:
A system for producing radiation of a desired frequency with temperature invariance comprising: a first source producing a first output having a first frequency; a first temperature sensor connected to said first source, said first temperature sensor sensing a first operating temperature of said first source and producing a first temperature signal proportional to said first operating temperature; a second source producing a second output having a second frequency; a second temperature sensor connected to said second source, said second temperature sensor sensing a second operating temperature of said second source and producing a second temperature signal proportional to said second operating temperature; a comparator, connected to said first temperature sensor and said second temperature sensor, said comparator producing a temperature difference signal from said first temperature signal and said second temperature signal; a control unit receiving said difference control signal from said comparator, said control unit producing a temperature difference control signal; a heater/cooler connected to said first radiation source, said heater/cooler receiving said temperature difference control signal from said control unit, said heater/cooler operative to adjust said temperature of said first radiation source as a function of said temperature difference control signal, wherein said temperature difference between said first and second sources is maintained at a predetermined level; and a nonlinear medium receiving said first output and said second output, wherein a plurality of beat frequencies are produced.