Total internal reflection micro lens array
View Patent ↗The invention relates to a total internal reflection micro lens array for a wide-angle lighting system. The micro lens array includes a plurality of Fresnel lens structures formed on a same optical incidence surface. Each of the Fresnel lens structure includes a plurality of grooves, each having a reflecting surface and a refractive surface. Incoming radiation incident through the incidence surface of the lens structure is internally totally reflected by the reflecting surface, refracted by the refractive surface and exits the lens structure.
1. A total internal reflection optical microstructure array comprising:
an optical incidence surface;
a plurality of optical microstructures formed on a surface opposite to the optical incidence surface, each of the optical microstructures comprising a plurality of concentric and annular outwardly-extending prismatic units, each of the prismatic units having a reflecting surface and a refractive surface,
wherein light incident from the optical incidence surface is totally internally reflected by the reflecting surface of the prismatic unit, and the reflected light is refracted by the refractive surface of the prismatic unit and exits,
wherein a first prismatic unit close to the center of the optical microstructure has a more elevated position than a second prismatic unit close to the edge of the optical microstructure with respect to the optical incidence surface.
2. The optical microstructure array according to claim 1 , wherein the central prismatic unit positioned in the center of the optical microstructure is configured in such a manner that light from the refractive surface of the central prismatic unit is directed to a wide-angle area, and the edge prismatic unit posit ioned in the edge of the optical microstructure is configured in such a manner that light from the refractive surface of the edge prismatic unit is directed to an angle area closer to the center than the wide-angle area.
3. The optical microstructure array according to claim 2 , each of the optical microstructures is designed in such a manner that any one of the prismatic units located closer to the center directs light to a wider angle area.
4. The optical microstructure array according to claim 1 , wherein each of the optical microstructures comprises two to ten grooves.
5. The optical microstructure array according to claim 1 , wherein the reflecting surface is calculated in such a manner that the incoming angle of light beam exceeds the angle for total internal reflection, and the maximum (utmost) angle is calculated by formula:
δ
=
γ
-
arcsin
(
n
1
n
2
·
sin
(
α
)
)
>
arcsin
(
n
1
n
2
)
where α is an input angle, γ is a slope of the reflecting surface, n 1 is the refractive index of air, and n 2 is the refractive index of the material of an optical microstructure.
6. The optical microstructure array according to claim 1 , wherein the functional dependence between the incoming beam, the outgoing beam and the optical microstructure parameters is pre-sented by the formula:
γ
=
0.5
·
[
(
(
π
2
+
arcsin
(
n
1
·
sin
(
π
2
-
β
-
ɛ
)
n
2
)
)
+
ɛ
)
+
arcsin
(
n
1
·
sin
(
α
)
n
2
)
]
where α is an input angle, β is an outgoing angle, γ is a slope of the reflecting surface, ε is a slope of the refractive surface, n 1 is the refractive index of air, and n 2 is the refractive index of the material of an optical microstructure.
7. The optical microstructure array according to claim 1 , wherein the incidence surface is planar.