Optical device, module, apparatus, and system for fingerprint identification

A method for fabricating an optical device, the method comprising:

• providing a first lens array, the first lens array comprising a plurality of first lenses;
• providing a second lens array opposite to the first lens array, the second lens array comprising a plurality of second lenses;
• and
• disposing a light shielding element between the first lens array and the second lens array, the light shielding element comprising a plurality of light-transmitting apertures,
• wherein image focal planes of the plurality of second lenses, object focal planes of the plurality of first lenses, and the light shielding element are coplanar,
• wherein the plurality of first lenses are in one-to-one correspondence with the plurality of second lenses and the plurality of light-transmitting apertures, respectively, and
• each first lens of the plurality of first lenses or each second lens of the plurality of second lenses comprises M annular phase gratings, wherein M is a natural number;
• and
• wherein each phase grating of the M annular phase gratings comprises N steps, and a height of a step of the N steps is:
• h
• =
• λ
• /
• N
• n
• 1
• -
• n
• 2
• ,
• wherein λ is a wavelength of incident light, n1 is a refractive index of a material of the step, n2 is a refractive index of a dielectric on a side of the step away from the light shielding element, and N is an even number.

An optical device for fingerprint identification, comprising:

• a first lens array comprising a plurality of first lenses;
• a second lens array opposite to the first lens array, comprising a plurality of second lenses;
• and
• a light shielding element between the first lens array and the second lens array, the light shielding element comprising a plurality of light-transmitting apertures,
• wherein image focal planes of the plurality of second lenses, object focal planes of the plurality of first lenses, and the light shielding element are coplanar,
• wherein the plurality of first lenses are in one-to-one correspondence with the plurality of second lenses and the plurality of light-transmitting apertures, respectively, and
• wherein a shape of each second lens of the plurality of second lenses comprises a square or a regular hexagon;
• a shape of each first lens of the plurality of first lenses comprises a circle or a square, and an aperture of the each first lens is smaller than an aperture of the each second lens.