Patent ID: 8331030

Claim:
An optical system processing incoherent light divided into at least a first and a second spectral bands, a center wavelength value of one spectral band being different from a center wavelength value of other spectral band, comprising: a modulation translation transfer function (MTF); a lens to focus the incoherent light received from an object onto an image plane; a storage device to store a representation of light images due to said at least first and second spectral bands received at the image plane; and a device to increase a depth of field of the optical system, said device comprising: an optical phase mask interposed between the object and the image plane, said optical phase mask having a quality of increasing the depth of field of the optical system having the effect of-modifying the modulation transfer function of the optical system such that the modified modulation transfer function is sensitive to a distance between the object and the lens; wherein the modified modulation transfer function has a value higher than a first threshold for an object located in a first distance range near the lens and for the first spectral band; wherein the modified modulation transfer function has a value higher than a second threshold for an object located in a second distance range far from the lens and for the second spectral band; wherein the first and second distance ranges being larger with the presence of the optical phase mask than if the optical phase mask was not present in the optical system; and a processor to measure or correct all or part of a longitudinal chromatic aberration effect on an image, the processor being connected to the storage device to restore the representation of a light image received at the image plane.