Diffractive focusing using multiple selectively light opaque elements

A diffractive focusing apparatus for focusing light from a subject onto a focal plane located a distance D from said device, said apparatus comprising a focusing device including:

• a light transmissive substrate;
• a plurality of selectively light opaque elements supported by said light transmissive substrate and being selectively controlled to be either substantially light opaque or substantially light transmissive;
• said plurality of selectively light opaque elements being controlled to form a focusing diffraction grating pattern of light transmissive channels separated by light opaque regions, said focusing diffraction grating pattern having a variable spacing between successive light transmissive channels, which spacing varies as a function of D, such that light from said subject passing through said focusing device is focused onto said focal plane;
• and
• a corrective device positioned substantially coaxially with said focusing device, said corrective device including
• a light transmissive substrate, a plurality of selectively light opaque elements supported by said light transmissive substrate and being selectively controlled to be either substantially light opaque or substantially light transmissive;
• said plurality of selectively light opaque elements of said corrective device being controlled to form a correcting diffraction grating pattern of light transmissive channels separated by light opaque regions, said correcting diffraction grating pattern having a spacing between successive light transmissive channels that is different from the spacing of said focusing diffraction grating pattern.

An image capturing apparatus, comprising:

• an image sensor;
• a diffractive focusing device for focusing light from a subject onto said image sensor located a distance D from said device, including
• a light transmissive substrate;
• a plurality of selectively light opaque elements supported by said light transmissive substrate and being selectively controlled to be either substantially light opaque or substantially light transmissive;
• said plurality of selectively light opaque elements being controlled to form a focusing diffraction grating pattern of light transmissive channels separated by light opaque regions, said focusing diffraction grating pattern having a variable spacing between successive light transmissive channels, which spacing varies as a function of D, such that light from said subject passing through said focusing device is focused onto said image sensor.