Imaging system and method having extended depth of field

A method of controlling depth of field in an imaging system, comprising:

• providing an imaging lens with chromatic aberration for forming images of an object;
• and
• receiving the images of the object at a color image sensor, the color image sensor having a selected spectral response, wherein the selected spectral response of the color image sensor is a combined response of a color filter sensitivity and a sensor sensitivity of the color image sensor, wherein the selected spectral response, for each pixel of the color image sensor, is spectral response of electrical signals produced by the pixel from intensity of light at the pixel, and wherein the spectral response of the electrical signals is a function of wavelength of the light, the selected spectral response defining a selected first center wavelength, a selected second center wavelength and a selected third center wavelength, wherein the selected first center wavelength is larger than the selected second center wavelength and the selected second center wavelength is larger than the selected third center wavelength, the selected first center wavelength and the selected third center wavelength cooperatively defining a selected depth of field of the imaging system;
• wherein the selected spectral response of the color image sensor has a first response, a second response, and a third response, wherein the first response and the second response have overlapping wavelength area to cover a first wavelength, and the second response and the third response have overlapping wavelength area to cover a second wavelength, wherein the first response is a spectral response of a first type of pixel of the color image sensor corresponding to a first color filter, the second response is a spectral response of a second type of pixel of the color image sensor corresponding to a second color filter, and the third response is a spectral response of a third type of pixel of the color image sensor corresponding to a third color filter, wherein center wavelength of the first color filter is the selected first center wavelength, center wavelength of the second color filter is the selected second center wavelength, and center wavelength of the third color filter is the selected third center wavelength, and wherein difference between the selected first center wavelength and the selected second center wavelength is greater than 150 nm.

An imaging system, comprising:

• an imaging lens having chromatic aberration for forming color images of an object;
• a color image sensor having a selected spectral response for detecting images of a first center wavelength, a second center wavelength, and a third center wavelength of the object formed by the imaging lens;
• wherein the selected spectral response of the color image sensor is a combined response of a color filter sensitivity and a sensor sensitivity of the color image sensor, wherein the selected spectral response, for each pixel of the color image sensor, is spectral response of electrical signals produced by the pixel from intensity of light at the pixel, and wherein the spectral response of the electrical signals is a function of wavelength of the light;
• wherein the spectral response of the color image sensor determines the first, second, and third center wavelengths, the first center wavelength is larger than the second center wavelength and the second center wavelength is larger than the third center wavelength, the selected first center wavelength and the selected third center wavelength cooperatively defining the depth of field of the imaging system;
• wherein the selected spectral response of the color image sensor has a first response, a second response, and a third response, wherein the first response and the second response have overlapping wavelength area to cover a first wavelength, and the second response and the third response have overlapping wavelength area to cover a second wavelength, wherein the first response is a spectral response of a first type of pixel of the color image sensor corresponding to a first color filter, the second response is a spectral response of a second type of pixel of the color image sensor corresponding to a second color filter, and the third response is a spectral response of a third type of pixel of the color image sensor corresponding to a third color filter,
• wherein center wavelength of the first color filter is the selected first center wavelength, center wavelength of the second color filter is the selected second center wavelength, and center wavelength of the third color filter is the selected third center wavelength, and wherein difference between the selected first center wavelength and the selected second center wavelength is greater than 150 nm;
• wherein the imaging system has a first through focus curve having a first peak of the first center wavelength, a second through focus curve having a second peak of the second center wavelength, and a third through focus curve having a third peak of the third center wavelength, and wherein at least one of the through focus curves covers any position in a domain spanned from the first peak to the third peak;
• and a digital image processor that processes the detected images of the first, second, and third center wavelengths, restores the images of the first, second, and third center wavelengths, and produces sharp images of the first, second, and third center wavelengths.