Optical device
With a simple configuration, an optical device having an in-coupling function to a lightguide is provided. The optical device includes a light guiding layer; and in-coupling optics provided integrally with the light guiding layer to couple light from a light source to an incident edge of the light guiding layer. The in-coupling optics include an optical element that is convex toward the incident edge and an air cavity provided between the optical element and the incident edge.
1. An optical device, comprising:
a non-patterned light guiding layer;
in-coupling optics provided integrally with the non-patterned light guiding layer to couple light from a light source to an incident edge of the non-patterned light guiding layer;
out-coupling optics through which light propagating in the light guiding layer is extracted to the outside, wherein
the in-coupling optics include a first optical element that is convex toward the incident edge and an air cavity provided between the optical element and the incident edge, and
the out-coupling optics include at least one embedded cavity to extract the light propagating in the light guiding layer to the outside via total internal reflection; and
a low-refractive index layer provided on a light-extracting side of the non-patterned light guiding layer,
wherein the out-coupling optics that includes the at least one embedded cavity is provided on the low-refractive index layer such that the low-refractive index layer is interposed between the at least one embedded cavity and a surface of the non-patterned light guiding layer on which the low-refractive index layer is provided.
2. The optical device of claim 1 , wherein the in-coupling optics include a second optical element, identical to the first optical element, the first and second optical elements comprising a plurality of optical elements arranged along the incident edge, and apices of bumps of the optical elements are in contact with the incident edge, the incident edge constituting a uniform plane.
3. The optical device of claim 2 , wherein surfaces of the plurality of optical elements that are on an opposite side to the bumps constitute a continuous plane.
4. The optical device of claim 1 , wherein the in-coupling optics are adhesively bonded to the incident edge with an optical adhesive, or integrally formed with the light guiding layer.
5. The optical device of claim 1 , wherein a refractive index of the first optical element is equal or close to a refractive index of the light guiding layer.
6. The optical device of claim 1 , wherein the out-coupling optics include optical patterns which are discrete or at least partially continuous.
7. The optical device of claim 1 , wherein the low-refractive index layer has at least one first portion having a refractive index lower than a refractive index of the non-patterned light guiding layer and at least one second portion having a refractive index higher than the refractive index of the at least one first portion.
8. The optical device of claim 7 , wherein the at least one second portion includes a plurality of second portions, and
the plurality of second portions are formed by burying apertures in the low-refractive index layer with a material having a refractive index higher than the refractive index of the at least one first portion.
9. Light in-coupling optics to be integrated with a non-patterned lightguide,
the light in-coupling optics comprising at least one optical cavity pattern to collimate light which is incident on the non-patterned lightguide in at least one of a transverse direction and a longitudinal direction within a two-dimensional plane, wherein uniformity of luminous flux along the transverse direction is adjusted in accordance with an out-coupling structure of the non-patterned lightguide, and
the out-coupling structure includes at least one embedded cavity to extract the light which is incident on the non-patterned lightguide to the outside via total internal reflection, and a low-refractive index layer provided on a light-extracting side of the non-patterned light guide,
wherein the out-coupling optics that includes the at least one embedded cavity is provided on the low-refractive index layer such that the low-refractive index layer is interposed between the at least one embedded cavity and a surface of the non-patterned light guide on which the low-refractive index layer is provided.
10. The light in-coupling optics of claim 9 , wherein the optical cavity pattern has a cross-sectional shape of flat ball lens-type, round edge-type, or round ball lens-type.
11. The light in-coupling optics of claim 9 , wherein the optical cavity pattern is integrally formed with or adhesively bonded to the lightguide.
12. The light in-coupling optics of claim 9 , wherein the low-refractive index layer has at least one first portion having a refractive index lower than a refractive index of the non-patterned light guide and at least one second portion having a refractive index higher than the refractive index of the at least one first portion.
13. The light in-coupling optics of claim 12 , wherein the at least one second portion includes a plurality of second portions, and
the plurality of second portions are formed by burying apertures in the low-refractive index layer with a material having a refractive index higher than the refractive index of the at least one first portion.