Optical magnifier suitable for use with a microdisplay device
AssigneeEastman Kodak Company
InventorScott C. Cahall
Life of this patent
Estimating the term…
Abstract
An optical magnifier is provided. One general form of one example embodiment includes two lens elements, at least two aspheric surfaces, and at least one diffractive surface. Another general form of another example embodiment includes three lens elements, and at least three aspheric surfaces. At least two of the aspheric surfaces can be simple conics. The optical magnifier, suitable for use in an electronic display system, has an apparent field of view of at least +/−10 degrees; a magnification of at least 15×; a back focal length of at least 5 mm; and an eye relief greater than the effective focal length of the optical magnifier. The lens elements can be made from plastic.
Claims60
A magnifier lens comprising in order from an eye side:
- a first positive power meniscus lens element having an eye side surface and an object side surface, at least one of the eye side surface and the object side surface being aspheric;
- and
- a second positive power lens element having an aspheric object side surface convex toward the object side and an eye side surface, wherein at least one of the object side surface of the first positive power meniscus element and the eye side surface of the second positive power element is diffractive.
An optical system comprising in order from an eye side:
- a first positive power meniscus lens element having an eye side surface and an object side surface, at least one of the eye side surface and the object side surface being aspheric;
- a second positive power lens element having an aspheric object side surface convex toward the object side and an eye side surface, wherein at least one of the object side surface of the first positive power meniscus element and the eye side surface of the second positive power element is diffractive;
- and
- an object to be viewed.
A magnifier lens comprising in order from an eye side:
- a first positive power lens element having an aspheric surface;
- and
- a second positive power lens element having an aspheric surface, the second positive power lens element having an object side surface, the object side surface having a most object side point, the magnifier lens having an effective focal length, wherein a distance from the most object side point on the object side surface of the second positive power lens element to an object to be viewed is greater than 0.38 times the effective focal length of the magnifier lens.
A magnifier lens comprising in order from an eye side:
- a first positive power lens element having an aspheric surface and
- a second positive power lens element having an aspheric surface, the magnifier lens having a back focal length in air, wherein the back focal length of the magnifier lens in air is greater than 5 mm and at least one of the positive power lens elements includes a diffractive surface.
A magnifier lens comprising in order from an eye side:
- a first positive power lens element having an aspheric surface;
- and
- a second positive power lens element having an aspheric surface, the magnifier lens having a back focal length in air, an eye relief, and an effective focal length, wherein the back focal length of the magnifier lens in air is greater than 5 mm and the eye relief is greater than the effective focal length.
A magnifier lens comprising in order from an eye side:
- a first positive power lens element having an aspheric surface;
- and
- a second positive power lens element having an aspheric surface, the magnifier lens having a back focal length in air and an effective focal length, wherein the back focal length of the magnifier lens in air is greater than 5 mm and wherein the back focal length is greater than 0.3 8 times the effective focal length.
A magnifier lens comprising in order from an eye side:
- a first positive power lens element having an aspheric surface;
- a negative power lens element having an aspheric surface;
- and
- a second positive power lens element having an aspheric surface, the magnifier lens having a back focal length in air and an effective focal length, wherein the back focal length of the magnifier lens in air is greater than 5 mm and the back focal length is greater than 0.38 times the effective focal length.
A magnifier lens comprising in order from an eye side:
- a first positive power lens element having an aspheric surface;
- a negative power lens element having an aspheric surface;
- and
- a second positive power lens element having an aspheric surface, the magnifier lens having a back focal length in air, an effective focal length, and a total thickness from the eye side surface of the first lens element to a surface of a viewable object, wherein the back focal length of the magnifier lens in air is greater than 5 mm and the total thickness is less than 1.40 times the effective focal length.
A magnifier lens comprising in order from an eye side:
- a first positive power lens element having an aspheric surface;
- and
- a second positive power lens element having an aspheric surface, the magnifier lens having a back focal length in air, an effective focal length, and a total thickness from the eye side surface of the first lens element to a surface of a viewable object, wherein the back focal length of the magnifier lens in air is greater than 5 mm and the total thickness is less than 1.33 times the effective focal length.
Dependencies are inferred from the claim text.