The invention relates to a device for generating a plurality of charged particle beamlets, and an inspection, imaging or processing apparatus and method for using the same. The device subsequently comprises a charged particle source, a first converging member, a lens array comprising a plurality of lenslets, wherein the lens array is configured for providing a plurality of separate focused charged particle beamlets, wherein each lenslet is configured for focusing one charged particle beamlet of said plurality of charged particle beamlets, a diverging member for refracting the plurality of charged particle beamlets, and a second converging member for refracting the plurality of charged particle beamlets. The diverging member is configured to provide a negative chromatic dispersion, which allows to at least partially compensate the chromatic dispersion of the first converging lens.