Optical device, module, apparatus, and system for fingerprint identification
The present disclosure provides an optical device, a module, an apparatus and a system for fingerprint identification. The optical device includes: a first lens array including a plurality of first lenses; a second lens array opposite to the first lens array, including a plurality of second lenses; and a light shielding element between the first lens array and the second lens array, the light shielding element including a plurality of light-transmitting apertures. 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. 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.
1. 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 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
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, n 1 is a refractive index of a material of the step, n 2 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.
2. The optical device according to claim 1 , wherein radii of annulus corresponding to the N steps of each phase grating of the M annular phase gratings are r j,1 and r j,2 , respectively, wherein
r
j
,
1
=
[
(
f
′
+
(
2
j
-
1
)
λ
/
2
n
1
)
2
-
f
′
2
]
1
/
2
=
(
2
j
-
1
)
f
′
λ
n
1
(
1
-
(
2
j
-
1
)
λ
4
n
1
f
′
)
1
/
2
,
r
j
,
2
=
[
(
f
′
+
j
λ
n
1
)
2
-
f
′
2
]
1
/
2
=
2
jf
′
λ
n
1
(
1
-
j
λ
2
n
1
f
′
)
1
/
2
,
wherein f′ represents a focal length value of the first lens array or the second lens array, and j represents a number of the phase grating.
3. The optical device according to claim 1 , wherein a center of each first lens of the plurality of first lenses, a center of a corresponding second lens of the plurality of second lenses, and a center of a corresponding light-transmitting aperture of the plurality of light-transmitting apertures are coaxial.
4. The optical device according to claim 1 , 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.
5. The optical device according to claim 1 , further comprising:
a first substrate;
a second substrate; and
an OCA optical adhesive layer,
wherein the first lens array is integrally formed with the first substrate,
wherein the second lens array is integrally formed with the second substrate, and
wherein the light shielding element and the OCA optical adhesive layer are between the first substrate and the second substrate.
6. A module for the fingerprint identification, comprising:
the optical device according to claim 1 ; and
a photosensitive element array on a side of the first lens array away from the light shielding element, the photosensitive element array comprising a plurality of photosensitive elements, the plurality of photosensitive elements and the plurality of first lenses being in one-to-one correspondence.
7. The module according to claim 6 , further comprising:
a transparent layer between the first lens array and the photosensitive element array.
8. A module for the fingerprint identification, comprising:
the optical device according to claim 1 ; and
a light source having a light emitting direction that is a same as a direction from the first lens array to the second lens array.
9. The module according to claim 8 , wherein the light source comprises an OLED panel, and the OLED panel is on a side of the second lens array away from the light shielding element.
10. The module according to claim 9 , wherein the OLED panel and the optical device are attached in a frame-to-frame or face-to-face manner.
11. An apparatus for the fingerprint identification, comprising:
the optical device according to claim 1 ;
a light source having a light emitting direction that is a same as a direction from the first lens array to the second lens array; and
a photosensitive element array on a side of the first lens array away from the light shielding element, the photosensitive element array comprising a plurality of photosensitive elements, the plurality of photosensitive elements and the plurality of first lenses being in one-to-one correspondence.
12. The apparatus according to claim 11 , wherein the light source comprises an OLED panel, and the OLED panel is on a side of the second lens array away from the light shielding element.
13. A fingerprint identification system comprising the apparatus according to claim 11 .
14. 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, n 1 is a refractive index of a material of the step, n 2 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.
15. The method according to claim 14 , wherein radii of annulus corresponding to the N steps of each phase grating of the M annular phase gratings are r j,1 and r j,2 , respectively, wherein
r
j
,
1
=
[
(
f
′
+
(
2
j
-
1
)
λ
/
2
n
1
)
2
-
f
′
2
]
1
/
2
=
(
2
j
-
1
)
f
′
λ
n
1
(
1
-
(
2
j
-
1
)
λ
4
n
1
f
′
)
1
/
2
,
r
j
,
2
=
[
(
f
′
+
j
λ
n
1
)
2
-
f
′
2
]
1
/
2
=
2
jf
′
λ
n
1
(
1
-
j
λ
2
n
1
f
′
)
1
/
2
,
wherein f′ represents a focal length value of the first lens array or the second lens array, and j represents a number of the phase grating.
16. The method according to claim 14 , wherein disposing the light shielding element between the first lens array and the second lens array comprises:
disposing the light shielding element between a first substrate and a second substrate;
bonding the first substrate and the second substrate using an OCA optical adhesive layer.
17. 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.