Diffractive optics allow achromatic correlation
Researchers at the Universitat de Valencia (Burjassot, Spain), the Universitat Jaume I (Castello, Spain), and the Universitat Erlangen-Nuremburg (Erlangen, Germany) have developed an all-incoherent optical correlator that produces a point-spread function (PSF) whose scale is independent of wavelength over much of the visible spectrum.