Patent ID: 8576479

Claim:
An arrangement for up-converting incoming polychromatic electromagnetic radiation (EMR) in wavelength interval Δλ 1 into up-converted EMR in corresponding wavelength interval Δλ 3 of smaller wavelengths than the wavelength interval Δλ 1 , the arrangement comprising: a nonlinear crystal; a laser for providing a laser beam having a second wavelength, λ 2 , different from the first wavelengths; and a first zone plate for converging the incoming EMR inside the nonlinear crystal; wherein the nonlinear crystal is selected for producing up-converted EMR by sum frequency generation between the incoming EMR and the laser beam; and wherein the nonlinear crystal, the laser, and the first zone plate are arranged so that: the laser beam will be provided in the nonlinear crystal; the incoming EMR will be converged in the nonlinear crystal by the first zone plate and in spatial overlap with the laser beam; and the laser beam will not be converged in the nonlinear crystal by the first zone plate.