An optical system for conical vortex imaging comprising: a lens arranged to receive light from an object to be imaged; an imaging lens arranged to receive light from said lens; an optical device arranged after the imaging lens comprising: a biaxial crystal arranged to receive incoming incoherent or partially incoherent light and one or more polarization elements to modify the polarization of an incoming or outgoing beam of the biaxial crystal, wherein a geometrical axis of the incoming incoherent or partially incoherent light traverses the biaxial crystal and the one or more polarization elements characterized in that the biaxial crystal is provided with a vortex conical diffraction set up in which the optical axis of conical diffraction is aligned with the geometrical axis of the incoming incoherent or partially incoherent light, and in that the optical system further comprises: an optical detector arranged to receive light imaged by the imaging lens via the optical device and forming an image of the object, wherein the optical detector consists of at least one of a light detector, a pixelated detector, a pair of light detectors or a pair of pixelated detector a lens arranged to receive light from an object to be imaged; an imaging lens arranged to receive light from said lens; an optical device arranged after the imaging lens comprising: a biaxial crystal arranged to receive incoming incoherent or partially incoherent light and one or more polarization elements to modify the polarization of an incoming or outgoing beam of the biaxial crystal, wherein a geometrical axis of the incoming incoherent or partially incoherent light traverses the biaxial crystal and the one or more polarization elements characterized in that the biaxial crystal is provided with a vortex conical diffraction set up in which the optical axis of conical diffraction is aligned with the geometrical axis of the incoming incoherent or partially incoherent light, and in that the optical system further comprises: an optical detector arranged to receive light imaged by the imaging lens via the optical device and forming an image of the object, wherein the optical detector consists of at least one of a light detector, a pixelated detector, a pair of light detectors or a pair of pixelated detector a biaxial crystal arranged to receive incoming incoherent or partially incoherent light and one or more polarization elements to modify the polarization of an incoming or outgoing beam of the biaxial crystal, wherein a geometrical axis of the incoming incoherent or partially incoherent light traverses the biaxial crystal and the one or more polarization elements characterized in that the biaxial crystal is provided with a vortex conical diffraction set up in which the optical axis of conical diffraction is aligned with the geometrical axis of the incoming incoherent or partially incoherent light, and in that the optical system further comprises: an optical detector arranged to receive light imaged by the imaging lens via the optical device and forming an image of the object, wherein the optical detector consists of at least one of a light detector, a pixelated detector, a pair of light detectors or a pair of pixelated detector an optical detector arranged to receive light imaged by the imaging lens via the optical device and forming an image of the object, wherein the optical detector consists of at least one of a light detector, a pixelated detector, a pair of light detectors or a pair of pixelated detector