REDUCED THICKNESS OF AN OPTICAL MODULE IN A HEAD-WORN DISPLAY
Aspects of the present disclosure relate to solid optical systems and methods for use in head-worn computing systems, including reduced thickness optical modules.
1 . An optical module for displaying an image in a head-worn display wherein the optical module has reduced thickness, comprising:
an image source providing image light; and
display optics including multiple elements with optical surfaces that are cemented together with a transparent adhesive to provide a solid display optic, wherein the solid display optic includes multiple internal optical surfaces comprising at least one refractive surface supplying optical power and at least two partially reflective surfaces, wherein after the image light has been refracted and reflected by the internal surfaces, it undergoes a refractive effect as it exits the solid display optics such that the subtended angle associated with the image light is increased after exit; and
a. the increased subtended angle of the image light after exit is associated with an increased display field of view, while the thickness of the solid display optic is reduced relative to the display field of view because the subtended angle of the image light is less while the image light is contained within the solid display optic.
2 . The optical module of claim 1 wherein at least one partially reflective surface is curved to provide optical power to the image light.
3 . The optical module of claim 2 wherein the at least one curved partially reflective surface has a larger radius so the curved partially reflective surface has less sag, because it is positioned internal to the solid display optic thereby reducing the thickness of the solid display optic.
4 . The optical module of claim 1 wherein at least one footprint of the image light on a partially reflective surface is reduced in area because the partially reflective surface is internal to the solid display optic.
5 . The optical module of claim 4 wherein one of the partially reflective surfaces is at an angle to the thickness of the solid display optic so that a reduction in the area of the image light footprint enables a reduction in the thickness of the solid display optic.
6 . The optical module of claim 1 wherein the display optics are arranged with a folded optical path to reduce the overall size.
7 . The optical module of claim 2 wherein the curved partially reflective surface is associated with a prismatic element.
8 . The optical module of claim 2 wherein the curved partially reflective surface is associated with a plano element that mates with a prismatic element.
9 . The optical module of claim 8 wherein curved partially reflective surface is a notch mirror.
10 . The optical module of claim 8 wherein the solid display optic includes at least four elements cemented together.
11 . The optical module of claim 1 wherein the solid display optic further comprises a separate optical element supported by one or more flanges so that an air gap separates the separate optical element the remaining elements in the solid display optic.
12 . The optical module of claim 11 wherein the flanges also align the separate optical element with the remaining elements in the solid display optic.