Goggle lens with compound curvature for downward field of view enhancement

An apparatus comprising:

• a lens configured to be worn by a user, the lens having an upper portion and a lower portion, wherein the upper portion is separated from the lower portion by a longitudinal line,
• wherein the upper portion has a substantially constant radius of curvature in a vertical direction, such that any two meridians perpendicular to the longitudinal line have a same constant radius of curvature in the upper portion,
• wherein the lower portion has a variable radius of curvature in the vertical direction such that at least two of the meridians have respective radii of curvature in the lower portion which are different from each other and different from the radius of curvature of the at least two of the meridians in the upper portion, and
• wherein, when worn by the user, an optical axis of the upper portion is aligned with a forward viewing direction of the user and a downward field of view is viewed through the lower portion.

An apparatus comprising:

• a lens configured to be worn by a user, the lens having an upper portion and a lower portion separated by a longitudinal line, wherein when worn by the user the upper portion is positioned in front of a main field of view of the user and the lower portion is positioned in a downward field of view of the user,
• wherein a first meridian extending along the lens perpendicular to the longitudinal line has a radius of curvature which is constant along the first meridian in the upper portion and varies along the first meridian in the lower portion,
• wherein a second meridian extending along the lens perpendicular to the longitudinal line has a radius of curvature which is constant along the second meridian in the upper portion and varies along the second meridian in the lower portion, and
• wherein the radius of curvature of the first meridian varies along the lower portion in a manner different to how the radius of curvature of the second meridian varies along the lower portion.

An apparatus comprising:

• a frame configured to be worn on a user's face, the frame configured to form an opening which encircles the user's eyes when worn;
• and
• a lens comprising an upper portion and a lower portion, wherein the upper portion is separated from the lower portion by a longitudinal line, and wherein the lens is configured to be coupled to the frame;
• wherein the upper portion has a substantially constant radius of curvature in a vertical direction, such that any two meridians perpendicular to the longitudinal line have a same constant radius of curvature in the upper portion,
• wherein the lower portion has a variable radius of curvature in the vertical direction such that at least two of the meridians have respective radii of curvature in the lower portion which are different from each other and different from the radius of curvature of the at least two of the meridians in the upper portion, and
• wherein, when worn by the user, an optical axis of the upper portion is aligned with a forward viewing direction of the user and a downward field of view is viewed through the lower portion.