Compact achromatic optical Fourier transform system using geometric-phase lenses

In this work we present a new configuration to achieve an achromatic all-optical Fourier (FT) transform using two blazed diffractive lenses and one non-dispersive lens. Different configurations are identified by imposing constraints on the ray matrix of the optical system, minimizing the wavelength dependence of both the transversal location of the FT plane and the FT spatial scaling. Experimental verification is carried out using geometric-phase flat diffractive lenses and an achromatic refractive lens. Furthermore, one identified novel configuration is symmetric. This symmetric triplet configuration enables a straightforward implementation in a reflective geometry that reduces the number of elements to a single geometric-phase lens combined with a mirror, thus leading to a highly-compact implementation. Experimental results are presented that validate the proposed systems.