Patent ID: 8482738

Claim:
A method of generating a non-linear optical signal ( 17 ) on a material ( 16 ) excited by an excitation field ( 2 ), wherein with the excitation field ( 2 ) coherent fields of first and second optical pulses of differing frequency are overlapped in the material ( 16 ) in temporal and spatial relationship, wherein the first pulses of a first frequency are generated in a first beam ( 3 ) of a first optical generator unit ( 1 ), and the second pulses of a second frequency are generated in a second beam ( 8 ) of a second optical generator unit ( 7 ) synchronously pumped by the first optical generator unit ( 1 ), wherein with the first pulses of the first frequency as a fundamental frequency pulses of a higher harmonic frequency thereof are generated (SHG) and the second optical generator unit is pumped with the pulses ( 5 ) of the higher harmonic frequency, and wherein the second optical generator unit ( 7 ) as an optical parametric generator unit generates pulses of an idler frequency in an idler beam for providing the second pulses of the second frequency in the second beam ( 8 ), wherein the second frequency is smaller than the first frequency, and the second optical generator unit ( 7 ) generates pulses of a signal frequency in a signal beam ( 9 ), wherein the second frequency is smaller than the signal frequency, and wherein the non-linear optical signal ( 17 ) is overlapped for detection heterodynely in interfering relationship with the signal beam ( 9 ).