Compact head-mounted display system
There is provided an optical system, including a light-transmitting substrate ( 20 ) having at least two major surfaces ( 26 ) and edges, an optical prism ( 54 ) having at least a first ( 58 ), a second ( 56 ) and a third ( 60 ) surface, for coupling light waves having a given field-of-view into the substrate by total internal reflection, at least one partially reflecting surface located in the substrate, the partially reflecting surface being orientated non-parallelly with respect to the major surfaces of the substrate, for coupling light waves out of the substrate, at least one of the edges ( 50 ) of the substrate is slanted at an oblique angle with respect to the major surfaces, the second surface of the prism is located adjacent to the slanted edge of the substrate, and a part of the substrate located next to the slanted edge is substantially transparent, wherein the light waves enter the prism through the first surface of the prism, traverse the prism without any reflection and enter the substrate through the slanted edge.
1. An optical system, comprising:
a light-transmitting substrate having a plurality of surfaces including a planar first major surface and a planar second major surface parallel to said first major surface, said first and second surfaces defining, respectively, a first plane and a second plane, a dimension between, and perpendicular to, said first and second planes being defined as a substrate thickness, said plurality of surfaces further comprising a planar slanted edge surface slanted at an oblique angle to said major surfaces;
an optical prism optically integrated with said light-transmitting substrate by attachment to said planar slanted edge surface so as to form a planar interface between said optical prism and said planar slanted edge surface, said optical prism and said light-transmitting substrate together form a coupling-in region having a maximum thickness in a direction perpendicular to said first and second planes greater than said substrate thickness, said optical prism providing a coupling-in surface for coupling light waves having a given field-of-view into the substrate so as to propagate within the substrate by total internal reflection;
a coupling-out arrangement associated with the substrate and configured for coupling light waves out of the substrate;
wherein said coupling-in surface is at an orientation oblique to said first and second planes, said coupling-in surface being a continuous planar surface extending from outside said substrate thickness across at least part of said substrate thickness, said coupling-in surface being oriented such that the light waves enter the coupling-in region through said coupling-in surface and traverse the coupling-in region without any reflection prior to total internal reflection from one of said major surfaces,
and wherein the substrate is formed from a first material having a first refractive index, and wherein the prism is formed from a second material having a second refractive index different from said first refractive index.
2. The optical system according to claim 1 , wherein the field-of-view is defined by a lowest and a highest angle of the light waves coupled into the substrate.
3. The optical system according to claim 2 , wherein an angle between the planar slanted edge surface of the substrate and a normal to the major surfaces of the substrate is larger than the highest angle of the field-of-view.
4. The optical system according to claim 2 , wherein a third surface of said prism extends from an extremity of said coupling-in surface outside said substrate thickness to one of said major surfaces, the angle between the third surface of the prism and the normal to the major surfaces of the substrate being smaller than the lowest angle of the field-of-view.
5. The optical system according to claim 1 , wherein coupling-in surface is substantially normal to the central wave of the light waves.
6. The optical system according to claim 1 , wherein the coupled-in light waves from the field-of-view substantially cover the entire major surfaces of the substrate without forming any stripes or gaps.
7. The optical system according to claim 1 , further comprising a collimating module.
8. The optical system according to claim 7 , wherein the collimating module is composed of a light waves transmitting material, having at least one light waves entrance surface, at least one light waves exit surface and a plurality of external surfaces.
9. The optical system according to claim 8 , wherein said coupling-in surface is positioned adjacent to the exit surface of the collimating module.
10. The optical system according to claim 8 , wherein the collimating module comprising: at least one light waves reflecting surface carried by the optical device at one of said external surfaces;
at least one retardation plate carried by the optical device on at least a portion of an external surface;
at least one light waves collimating component covering at least a portion of at least one of the retardation plates, and at least one light waves polarizing beamsplitter, disposed at an angle to at least one of the light waves entrance or exit surfaces.
11. The optical system according to claim 7 , further comprising a display light source.
12. The optical system according to claim 11 , wherein light waves emerging from the display light source are collimated by the collimating module and coupled into the substrate through said coupling-in region.
13. The optical system according to claim 7 , wherein the refractive index of the prism is different than the refractive index of the collimating module.
14. The optical system according to claim 1 , wherein the light waves are coupled out from the substrate by said at least one partially reflecting surface into an eye of a viewer.
15. The optical system according to claim 14 , wherein the viewer's eye is located at the same side of the substrate as the side towards which said coupling-in surface extends outside said substrate thickness.
16. The optical system according to claim 14 , wherein the viewer's eye is located at the opposite side of the substrate as the side towards which said coupling-in surface extends outside said substrate thickness.
17. The optical system according to claim 7 , wherein the collimating module extends beyond the two major surfaces of the substrate.
18. The optical system according to claim 1 , wherein said coupling-out arrangement comprises at least one partially reflecting surface located in the substrate, the partially reflecting surface being orientated at an oblique angle to said first and second planes, for coupling light waves out of the substrate.
19. The optical system according to claim 2 , wherein a third surface of said prism extends from an extremity of said coupling-in surface outside said substrate thickness to one of said major surfaces, said third surface and said major surface meeting at a boundary line, said boundary line being illuminated both by direct illumination through said in-coupling surface and by illumination through said in-coupling surface that has been reflected from an opposing one of said major surfaces for both said highest angle and said lowest angle of the field-of-view.