OPTICAL SYSTEM WITH GRATING ELEMENT AND IMAGING DEVICE USING THE SAME

AN OPTICAL SYSTEM THAT CAN BE USED IN AN OPTICAL IMAGING SYSTEM AND DISPLAYS GOOD IMAGING PERFORMANCE WITH CORRECTED CHROMATIC ABERRATION WITHOUT INCREASING THE NUMBER OF LENSES IS PROVIDED BY EMPLOYING A LENS SURFACE WITH A DIFFRACTIVE EFFECT. THE OPTICAL SYSTEM USES A LENS (1) WITH A CONCAVE INCIDENT SURFACE AND POSITIVE REFRACTIVE POWER. A GRATING ELEMENT (40) SURFACE 40 WITH POSITIVE REFRACTIVE POWER IS FORMED ON AT LEAST ONE SURFACE OF THE LENS (1). THE SURFACE ON WHICH THE GRATING ELEMENT (40) IS FORMED IS AN ASPHERICAL SURFACE WITH A RADIUS OF CURVATURE THAT BECOMES BIGGER WITH INCREASING DISTANCE FROM THE OPTICAL AXIS. (FIG. 1)