Fresnel lens with dynamic draft for variable gaze

A method of making a lens for directing light from an electronic display toward a first reference pupil through a first medium, comprising:

• configuring a lens that comprises an optically transparent substrate having a first lens surface and a second lens surface opposite to the first lens surface, wherein:
• the first lens surface includes a plurality of Fresnel structures, wherein a respective Fresnel structure of the plurality of Fresnel structures includes a slope facet and a draft facet, and the draft facet is characterized by a draft angle, relative to an optical axis of the lens, that is between a first angle for the respective Fresnel structure and a second angle for the respective Fresnel structure,
• the first angle for the respective Fresnel structure corresponding to an angle between the optical axis of the lens and a direction of a chief ray, in the first medium, incident upon the slope facet of the respective Fresnel structure, wherein the chief ray:
• is transmitted from a reference off-axis position on the electronic display, located away from the optical axis of the lens, and
• is transmitted through the slope facet of the respective Fresnel structure and propagates toward a center of a second reference pupil;
• and
• the second angle for the respective Fresnel structure corresponding to an angle between the optical axis of the lens and a direction of the chief ray, in the optically transparent substrate, that is transmitted through the slope facet of the respective Fresnel structure and propagates toward the center of the second reference pupil;
• the draft angle of the respective Fresnel structure is distinct from the first angle and the second angle for the respective Fresnel structure, and the draft angle of the respective Fresnel structure is a predefined weighted average of the first angle and the second angle;
• the first reference pupil is located at a first distance from the optically transparent substrate;
• the second reference pupil is located at a second distance from the optically transparent substrate;
• and
• the second distance is greater than the first distance.

A method for transmitting light with reduced optical artifacts to a first reference pupil, the method comprising:

• transmitting light from an electronic display through a first medium toward a lens comprising an optically transparent substrate having a first lens surface and a second lens surface opposite to the first lens surface, wherein:
• the first lens surface includes a plurality of Fresnel structures, wherein a respective Fresnel structure of the plurality of Fresnel structures includes a slope facet and a draft facet, and the draft facet is characterized by a draft angle, relative to an optical axis of the lens, that is between a first angle for the respective Fresnel structure and a second angle for the respective Fresnel structure,
• the first angle for the respective Fresnel structure corresponding to an angle between the optical axis of the lens and a direction of a chief ray, in the first medium, incident upon the slope facet of the respective Fresnel structure, wherein the chief ray:
• is transmitted from a reference off-axis position on the electronic display, located away from the optical axis of the lens, and
• is transmitted through the slope facet of the respective Fresnel structure and propagates toward a center of a second reference pupil;
• and
• the second angle for the respective Fresnel structure corresponding to an angle between the optical axis of the lens and a direction of the chief ray, in the optically transparent substrate, that is transmitted through the slope facet of the respective Fresnel structure and propagates toward the center of the second reference pupil;
• the draft angle of the respective Fresnel structure is distinct from the first angle and the second angle for the respective Fresnel structure, and the draft angle of the respective Fresnel structure is a predefined weighted average of the first angle and the second angle;
• the first reference pupil is located at a first distance from the optically transparent substrate;
• the second reference pupil is located at a second distance from the optically transparent substrate;
• and
• the second distance is greater than the first distance;
• and
• transmitting the light through the lens toward the second reference pupil.