Optical device and manufacture thereof

The invention provides an optical device and manufacture thereof. The optical device of the invention includes a transparent substrate, a seeding layer, a plurality of nano-rods and a protection layer. The seeding layer is formed to overlay an entrance surface and an exit surface of the transparent substrate. The plurality of nano-rods are formed on the seeding layer. The protection layer is formed to completely overlay the plurality of nano-rods.

CROSS-REFERENCE TO RELATED APPLICATION

This utility application claims priority to Taiwan Application Serial Number 102142377, filed Nov. 21, 2013, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an optical device and a method of manufacturing the same, and particularly to an optical device with low reflectance for broadband light and being insensitive to incident angle of light and manufacture thereof.

2. Description of the Prior Art

Essential optical devices in various optical systems include, for example, protection covers in photovoltaic systems, light covers in illuminating systems, protection covers in photography systems, and so on. The reflectance of light-entrance surfaces and light-exit surfaces of these optical devices directly affect the effectivity of these systems.

The aforesaid optical devices should have low reflectance for broadband light. The prior art relating to the aforesaid optical devices has used an evaporation process or a sputtering process to repeatedly coat different films to constitute multi-film structures on surfaces of substrates. These multi-film structures all have low reflectance for broadband light. However, these multi-structures all are insensitive to incident angle of light, i.e., these multi-structures all have larger reflectance for the light with larger incident angle.

At present, there is no optical device, which has low reflectance for broadband light and is insensitive to incident angle of light, been developed.

SUMMARY OF THE INVENTION

Accordingly, one scope of the invention is to provide an optical device with low reflectance for broadband light and being insensitive to incident angle of light and manufacture thereof.

An optical device to a preferred embodiment of the invention includes a transparent substrate, a first seeding layer, a plurality of first nano-rods and a first protection layer. The first seeding layer is formed to overlay a light-entrance surface of the transparent substrate. The plurality of first nano-rods are formed on the first seeding layer. The first protection layer is formed to completely overlay the plurality of first nano-rods.

In one embodiment, the plurality of first nano-rods are substantially perpendicular to the light-entrance surface of the transparent substrate.

In another embodiment, the plurality of first nano-rods on the light-entrance surface of the transparent substrate are arranged into a plurality of clusters. Each cluster is composed of some first nano-rods which each tilts in a respective angle with respect to a normal direction of the light-entrance surface.

Further, the optical device of the invention also includes a second seeding layer, a plurality of second nano-rods and a second protection layer. The second seeding layer is formed to overlay a light-exist surface of the transparent substrate. The plurality of second nano-rods are formed on the second seeding layer. The second protection layer is formed to completely overlay the plurality of second nano-rods.

A method of manufacturing an optical device according to a preferred embodiment of the invention, firstly, is to prepare a transparent substrate. Then, the method of the invention is to form a first seeding layer to overlay a light-entrance surface of the transparent substrate. Afterward, the method of the invention is to form a plurality of first nano-rods on the first seeding layer. Finally, the method of the invention is to form a first protection layer to completely overlay the plurality of first nano-rods.

In one embodiment, the first seeding layer is formed of a first oxide, and can be formed by a hydrothermal process, an atomic layer deposition process, a sputtering process, a sol-gel process, an organic chemical vapor deposition process, a chemical vapor deposition process, an electrochemical deposition process, or other deposition process.

In one embodiment, the plurality of first nano-rods are formed of a second oxide, and can be formed by a hydrothermal process, a sol-gel process, an organic chemical vapor deposition process, a chemical vapor deposition process, an electrochemical deposition process, a template process, a vapor-liquid-solid growth process, a vapor transport deposition process, or other deposition process.

Distinguishable from the prior art, the optical device of the invention not only has low reflectance for broadband light, but also is insensitive to incident angle of light

DETAILED DESCRIPTION OF THE INVENTION

Referring toFIG. 1andFIG. 2,FIG. 1is a cross-sectional schematic drawing showing an optical device1according to a preferred embodiment.FIG. 2is a partially enlarged schematic drawing of a boding between a plurality first nano-rods14and a first seeding layers12shown inFIG. 1. The optical device1of the invention can be, but not limited to, a protection cover in a photovoltaic system, a light cover in an illuminating system, a protection cover in photography system and so on.

As shown inFIG. 1andFIG. 2, the optical device1to the preferred embodiment of the invention includes a transparent substrate10, the first seeding layer12, the plurality of first nano-rods14and a first protection layer16. In one embodiment, the transparent substrate10can be formed of glass, Acrylic, single crystal (e.g., sapphire etc.).

The first seeding layer12is formed to overlay an entrance surface102of the transparent substrate10. The plurality of first nano-rods14are formed on the first seeding layer12. The first protection layer16is formed to completely overlay the plurality of first nano-rods14. Because the scale of the first protection layer16is very small, the first protection layer16and the plurality of first nano-rods14are marked together inFIG. 1. InFIG. 2, it is clear that a gap is formed between one first nano-rod14and one adjacent first nano-rod14of the first nano-rods14, the first protection layer16completely overlays the surface of the plurality of first nano-rods14, find the first protection layer16is formed along the plurality of first nano-rods14and the exposed first seeding layer12without filling said gap between said one first nano-rod14and said one adjacent first nano-rod14.

The first seeding layer12assists in uniform distribution of the first nano-rods14subsequently formed on the first seeding layer12. If there is no first seeding layer12previously formed, the first nano-rods14directly formed on the light-entrance surface102of the transparent substrate10will distribute non-uniformly, and even there is no first nano-rods14formed on some regions of the light-entrance surface102of the transparent substrate10.

Referring toFIG. 3andFIG. 4, these pictures are SEM photographs of an optical device of an example of the invention to show the structure of the plurality of first nano-rods14. In the example shown inFIG. 3andFIG. 4, the plurality of first nano-rods14are formed of ZnO.FIG. 3is the side view of the first nano-rods14.FIG. 4is the top view of the first nano-rods14.FIG. 3andFIG. 4confirm that the first nano-rods14of the invention have high ratio of height to outer diameter. In practical application, the plurality of first nano-rods14have a ratio of height to outer diameter in a range of from 1 to 100. That is to say that the plurality of first nano-rods14have high ratio of depth to width inherently. By the first nano-rods14inherently having high ratio of depth to width, the optical device1of the invention is insensitive to incident angle of light. The reflectance of the optical device1of the invention for a broadband light will hereinafter be described by actual test data.

In one embodiment, the plurality of first nano-rods14are substantially perpendicular to the light-entrance surface102of the transparent substrate10.

In another embodiment, the plurality of first nano-rods14on the light-entrance surface102of the transparent substrate10are arranged into a plurality of clusters. Each cluster is composed of some first nano-rods14which each tilts in a respective angle with respect to a normal direction of the light-entrance surface102.

Further, as shown inFIG. 5andFIG. 6, the optical device1of the invention also includes a second seeding layer17, a plurality of second nano-rods18and a second protection layer19. The second seeding layer17is formed to overlay a light-exit surface104of the transparent substrate10. The plurality of second nano-rods18are formed on the second seeding layer17. The second protection layer19is formed to completely overlay the plurality of second nano-rods18. The second seeding layer17assists in uniform distribution of the second nano-rods18subsequently formed on the second seeding layer17. The components and devices inFIG. 5andFIG. 6identical to those shown inFIG. 1andFIG. 2are given the same numerical notations, and will be not described in detail herein. In practical application, the composition of the second seeding layer17and that of the first seeding layer12are the same. The composition of the second nano-rods18and that of the first nano-rods14are the same. The composition of the second protection layer19and that of the first protection layer16are the same. By the second nano-rods18, the haze of light exiting from the optical device1of the invention can be enhanced significantly.

Referring toFIGS. 7 through 9, these cross-sectional schematic drawings illustratively show a method of manufacturing an optical device1according to a preferred embodiment of the invention.

Firstly, as shown inFIG. 7, the method of the invention, is to prepare a transparent substrate10. In one embodiment, the transparent substrate10can be formed of glass, Acrylic, single crystal (e.g., sapphire etc.).

Then, as shown inFIG. 8, the method of the invention is to form a first seeding layer12to overlay a light-entrance surface102of the transparent substrate10.

In one embodiment, the first seeding layer12is formed of a first oxide, and can be formed by a hydrothermal process, an atomic layer deposition process, a sputtering process, a sol-gel process, an organic chemical vapor deposition process, a chemical vapor deposition process, an electrochemical deposition process, or other deposition process.

Afterward, as shown inFIG. 9, the method of the invention is to form a plurality of first nano-rods14on the first seeding layer12. The first seeding layer12assists in uniform distribution of the first nano-rods14subsequently formed on the first seeding layer12.

Finally, also as shown inFIG. 9, the method of the invention is to form a first protection layer16to completely overlay the plurality of first nano-rods14. Because the scale of the first protection layer16is very small, the first protection layer16and the plurality of first nano-rods14are marked together inFIG. 9.

In one embodiment, the plurality of first nano-rods are formed of a second oxide, and can be formed by a hydrothermal process, a sol-gel process, an organic chemical vapor deposition process, a chemical vapor deposition process, an electrochemical deposition process, a template process, a vapor-liquid-solid growth process, a vapor transport deposition process, or other deposition process.

In practical application, the plurality of first nano-rods14have a ratio of height to outer diameter in a range of from 1 to 100. That is to say that the plurality of first nano-rods14have high ratio of depth to width inherently.

In one embodiment, the first protection layer16can be formed by an atomic layer deposition process. Due to high ratio of depth to width of the first nano-rods14, the first protection layer16cannot completely overlay the first nano-rods14by a general deposition process. The chemical reactions proceed only at the surface of the first nano-rods14during the atomic layer deposition process, leading to self-limiting and layer-by-layer growth. Therefore, the first protection layer16can completely overlay the first nano-rods14by an atomic layer deposition process. The atomic layer deposition process adopted by the invention has the following advantages: (1) the ability to control the formation of the material in atomic scale; (2) the ability to control the film thickness more precisely; (3) the ability to control the composition more precisely; (4) excellent uniformity; (5) excellent conformality and step coverage; (6) pinhole-free structure and low defect density; (7) mass production with large-area and large-batch capacity; and (8) low deposition temperatures, etc.

Referring toFIG. 10,FIG. 11andFIG. 12, these schematic side drawings show the structures of the first nano-rods12of three examples of the invention. InFIG. 10toFIG. 12, only portion of the first seeding layer12and a normal direction N of the transparent substrate10are illustrated. In the example shown inFIG. 10, the plurality of first nano-rods14are substantially perpendicular to the light-entrance surface102of the transparent substrate10, i.e., perpendicular to the normal direction N of the transparent substrate10. Herein, the first nano-rods14as shown inFIG. 10are called as the well-aligned first nano-rods14. In the example shown inFIG. 11, the plurality of first nano-rods14on the light-entrance surface102of the transparent substrate10are arranged into a plurality of clusters, and each cluster is composed of some first nano-rods14which each tilts in a respective angle with respect to the normal direction N of the light-entrance surface102. In the cluster shown inFIG. 11, the tilted angles of the first nano-rods14are small. Herein, the first nano-rods14as shown inFIG. 11are called as the quasi-aligned first nano-rods14. The arrangement of the first nano-rods14shown in the example ofFIG. 12is similar to that of the first nano-rods14shown in the example ofFIG. 11. Different from the example shown inFIG. 11, in the cluster shown inFIG. 12, the tilted angles of the first nano-rods14are larger so that each cluster of the first nano-rods14is like a blooming flower. Herein, the first nano-rods14as shown inFIG. 12are called as the flower-like first nano-rods14.

Referring toFIGS. 13 through 14, these cross-sectional schematic drawings illustratively show the further steps of the method of manufacturing the optical device1according to the invention.

Further, as shown inFIG. 13, the method of the invention is to form a second seeding layer17to overlay a light-exit surface104of the transparent substrate10.

Further, as shown inFIG. 14, the method of the invention is to form a plurality of second nano-rods18on the second seeding layer18. The second seeding layer17assists in uniform distribution of the second nano-rods18subsequently formed on the second seeding layer17.

Finally, also as shown inFIG. 14, the method of the invention is to a second protection layer19to completely overlay the plurality of second nano-rods18. By the second nano-rods18, the haze of light exiting from the optical device1of the invention can be enhanced significantly.

In practical application, the composition and manufacture process of the second seeding layer17and those of the first seeding layer12are the same. The composition and manufacture process of the second nano-rods18and those of the first nano-rods14are the same. The composition and manufacture process of the second protection layer19and those of the first protection layer16are the same. The second protective layer19and the first protective layer16may even be simultaneously formed with the same atomic layer deposition process, to reduce manufacturing cost. In addition, the second seeding layer17and the first seeding layer12may be simultaneously formed with the same process, to reduce manufacturing cost.

Referring toFIG. 15,FIG. 15shows the measured reflectance of ZnO first nano-rods14of an example of the invention for a broadband light. InFIG. 15, the measured reflectance of ZnO first nano-rods14further overlaid by 12 nm Al2O3first protection layer is also shown. The measured results ofFIG. 15confirm that the optical device1of the invention with the ZnO first nano-rods14has low reflectance for the broadband light. The Al2O3first protective layer16can further reduce the reflectance of the optical device1of the invention for the broadband light.