Optical guide and ocular vision optical system
The invention relates to optical guides and more precisely to guides for conveying an image without deforming the same. These guides can particularly be used in the production of ocular-vision optical systems more currently named informative spectacles. The optical guide includes an extraction section made of reflective microstructures at the surface of the guide. The microstructures define prisms having a calculated angle in order to send back the light beam at a given angle relative to the opposite surface enabling the exit thereof from the guide. Advantageously, the cut and the arrangement of said microstructures make them invisible to the eye while generating a large and comfortable image.
1. Device for the optical guidance of a light beam ( 1 . 3 ) transporting an image, comprising:
a material forming a guide ( 1 . 5 ) provided with two faces ( 2 . 3 , 2 . 4 );
an injection section ( 1 . 4 ) for entry of the light beam into the guide ( 1 . 5 ), the beam ( 1 . 6 ) propagating in the guide by successive reflections on the two faces ( 2 . 3 , 2 . 4 ) of the guide;
an extraction section ( 1 . 7 ) for exiting of the beam;
characterised in that the extraction section comprises a plurality of microstructures situated on the surface of one of the two faces ( 3 . 2 ) of the guide ( 1 . 5 ) and each microstructure comprising a flat surface ( 3 . 4 ) causing the exiting from the guide of the light rays ( 3 . 5 ) of the beam striking the said flat surface ( 3 . 4 ) and at least one transparent interstitial zone formed from a flat section parallel to the surface of the guide and disposed between the said microstructures.
2. Optical guidance device according to claim 1 , characterised by the fact that the two faces of the guide are parallel.
3. Optical guidance device according to claim 2 , characterised by the fact that the two faces of the guide are flat, the light beam transporting the image then being collimated.
4. Optical guidance device according to claim 3 , characterised in that, the flat surface ( 3 . 4 ) of each microstructure is reflective, such that the light rays ( 3 . 5 ) of the beam striking the said flat surface ( 3 . 4 ) leave the guide through the face of the guide opposite to the face ( 3 . 2 ) on which the said microstructure is situated.
5. Optical guidance device according to claim 4 , characterised in that each said microstructure is composed of a prism projecting on the face of the guide ( 3 . 2 ).
6. Optical guidance device according to claim 4 , characterised in that each said microstructure is composed of a hollow prism on the face of the guide ( 6 . 3 , 6 . 4 ).
7. Optical guidance device according to claim 1 , characterised in that the said extraction section is composed of several zones, each zone being characterised by a particular arrangement of the microstructures and interstitial zones.
8. Optical guidance device according to claim 1 , characterised in that each microstructure is a band over the entire length of the extraction zone.
9. Optical guidance device according to claim 1 , characterised in that, an exit image defines two extreme rays forming respectively angles ω− and ω+ with the normal to an extraction surface of the guide outside the guide and ω n− and ω n+ with the normal to the extraction surface of the guide inside the guide, and the angle μ formed by a mirror with the extraction surface has a value less than an angle
μ
-
=
π
/
2
-
ω
n
+
3
or greater than an angle
μ
+
=
π
/
2
-
ω
n
-
3
.
10. Method of manufacturing an optical guidance device according to claim 1 , characterised in that it comprises the following steps:
a step of generating a plurality of microstructures and at least one transparent interstitial zone formed from a flat section parallel to the surface of the guide and disposed between the said microstructures on the surface of one of the two faces of an optical guide by moulding the said guide;
a step of depositing a reflective thin film on one of the faces of each said microstructure.
11. Ocular vision optical system, characterised in that it comprises an optical guidance device according to claim 1 .
12. A device configured for the optical guidance of a light beam transporting an image, the device comprising:
a guide with two faces;
an injection section configured for entry of the light beam into the guide, with the beam propagating in the guide by successive reflections on the two faces of the guide;
an extraction section configured for exiting of the beam;
the extraction section comprising a plurality of microstructures situated on one of the two faces of the guide, each microstructure comprising a flat surface configured for causing the exiting from the guide of the light rays of the beam striking the flat surface, and at least one transparent interstitial zone formed from a flat section parallel to the one face of the guide and disposed between the microstructures.
13. The device according to claim 12 , wherein the two faces of the guide are parallel.
14. The device according to claim 13 , wherein the two faces of the guide are flat.
15. The device according to claim 14 , wherein the flat surface of each microstructure is reflective, such that the light rays of the beam striking the flat surface leave the guide through the face of the guide opposite to the face on which the microstructure is situated.
16. The device according to claim 15 , wherein each microstructure comprises a prism projecting on the face of the guide.
17. The device according to claim 15 , wherein each microstructure comprises a hollow prism on the face of the guide.
18. The device according to claim 12 , wherein the extraction section comprises several zones, each zone comprising a particular arrangement of the microstructures and interstitial zones.
19. The device according to claim 12 , wherein each microstructure is a band over the entire length of the extraction zone.
20. A device configured for the optical guidance of a light beam transporting an image, the device comprising:
a guide with two flat and parallel faces;
an injection section configured for entry of the light beam into the guide, with the beam propagating in the guide by successive reflections on the two faces of the guide;
an extraction section configured for exiting of the beam;
the extraction section comprising several zones, each zone comprising a plurality of microstructures and transparent interstitial zones situated on one of the two faces of the guide with each microstructure being over the entire length of the extraction zone, each microstructure comprising a hollow prism on the face of the guide with a reflective flat surface configured for causing the exiting from the guide of the light rays of the beam striking the flat surface, each interstitial zone formed from a flat section parallel to the one face of the guide and disposed between the microstructures.