Achromatic lens including Fresnel optical element for near eye display
Aspects of the disclosure provide an achromatic lens. The achromatic lens can include a first lens and a second lens. The first lens with a negative focal length includes a first optically transparent member having a first surface and a second surface. The second lens is attached to the first lens at the second surface. The second lens having a positive focal length includes a second optically transparent member having a third surface and a fourth surface. A second chromatic aberration of the second lens is reduced by a first chromatic aberration of the first lens. The second surface of the first lens includes a first Fresnel structure.
1 . An achromatic lens, comprising:
a first lens with a negative focal length including a first optically transparent member having a first surface and a second surface, and
a second lens attached to the first lens at the second surface, the second lens having a positive focal length including a second optically transparent member having a third surface and a fourth surface, wherein
a second chromatic aberration of the second lens is reduced by a first chromatic aberration of the first lens,
the second surface of the first lens includes (i) a center region without a Fresnel structure and (ii) a first Fresnel structure that surrounds the center region, and
a size of the center region depends on a field of view (FOV) threshold of a light receiver and a distance between the light receiver and the first lens.
2 . The achromatic lens according to claim 1 , wherein
the second surface is an aspheric surface.
3 . The achromatic lens according to claim 1 , wherein
a first ratio of an edge thickness of the first lens over a center thickness of the first lens is between 1 to 1.2, and
a second ratio of an edge thickness of the second lens over a center thickness of the second lens is between 1/3 to 1.
4 . A lens system comprising:
an achromatic lens including
a first lens with a negative focal length including a first optically transparent member having a first surface and a second surface, and
a second lens attached to the first lens at the second surface, the second lens having a positive focal length including a second optically transparent member having a third surface and a fourth surface, and
a third lens with a positive focal length including a third optically transparent member having a fifth surface and a sixth surface, the sixth surface having a second Fresnel structure, wherein
a second chromatic aberration of the second lens is reduced by a first chromatic aberration of the first lens,
the second surface of the first lens includes (i) a center region without a Fresnel structure and (ii) a first Fresnel structure that surrounds the center region, and
a size of the center region depends on a field of view (FOV) threshold of a light receiver and a distance between the light receiver and the first lens.
5 . The lens system according to claim 4 , wherein
the sixth surface includes (i) a center region without a Fresnel structure and (ii) the second Fresnel structure that surrounds the center region of the sixth surface.
6 . The lens system according to claim 4 , wherein
a first ratio of an edge thickness of the first lens over a center thickness of the first lens is between 1 to 1.2,
a second ratio of an edge thickness of the second lens over a center thickness of the second lens is between 1/3 to 1, and
a third ratio of an edge thickness of the third lens over a center thickness of the third lens is between 1/3 to 1.
7 . An optical system, comprising:
the lens system according to claim 5 ,
a beam splitter configured to partially transmit and partially reflect light beams from a display device,
a reflective polarizer configured to pass through light having a first linear polarization state and reflect light having a second linear polarization state that is orthogonal to the first linear polarization state, and
a quarter waveplate (QWP) that is positioned between the beam splitter and the reflective polarizer, wherein
the QWP is on a surface of the first lens, the second lens, or the third lens,
the beam splitter is on the fifth surface of the third lens, and
the reflective polarizer is on the first surface of the first lens.
8 . The optical system according to claim 7 , wherein
the optical system includes the display device, a pixel array in the display device being configured to generate light beams, a polarization state of the light beams being a first circular polarization state,
the third lens is positioned between the display device and the achromatic lens, the fifth surface of the third lens being configured to face the display device, and
the second lens is positioned between the first lens and the third lens, the third surface of the second lens being configured to face the third lens.
9 . An optical system, comprising:
the lens system according to claim 5 ,
a beam splitter configured to partially transmit and partially reflect light beams from a display device,
a reflective polarizer configured to pass through light having a first linear polarization state and reflect light having a second linear polarization state that is orthogonal to the first linear polarization state, and
a quarter waveplate (QWP) that is positioned between the beam splitter and the reflective polarizer, wherein
the QWP is on a surface of the first lens, the second lens, or the third lens,
the reflective polarizer is on the fifth surface of the third lens, and
the beam splitter is on the first surface of the first lens.
10 . The optical system according to claim 9 , wherein
the optical system includes the display device, a pixel array in the display device being configured to generate light beams, a polarization state of the light beams being the first linear polarization state,
the third lens is positioned between the display device and the achromatic lens, the fifth surface of the third lens being configured to face the display device, and
the second lens is positioned between the first lens and the third lens, the third surface of the second lens being configured to face the third lens.
11 . An optical system, comprising:
a lens system including an achromatic lens, the achromatic lens including
a first lens with a negative focal length including a first optically transparent member having a first surface and a second surface, and
a second lens attached to the first lens at the second surface, the second lens having a positive focal length including a second optically transparent member having a third surface and a fourth surface, wherein
a second chromatic aberration of the second lens is reduced by a first chromatic aberration of the first lens,
the second surface of the first lens includes (i) a center region without a Fresnel structure and (ii) a first Fresnel structure that surrounds the center region,
the lens system is configured to direct light beams from a display device to a light receiver, and
a size of the center region depends on a field of view (FOV) threshold of the light receiver and a distance between the light receiver and the first lens.
12 . The optical system according to claim 11 , wherein
the second surface is an aspheric surface.
13 . The optical system according to claim 11 , wherein
a first ratio of an edge thickness of the first lens over a center thickness of the first lens is between 1 to 1.2, and
a second ratio of an edge thickness of the second lens over a center thickness of the second lens is between 1/3 to 1.
14 . The optical system according to claim 11 , wherein
the lens system includes a third lens with a positive focal length, and
the third lens includes a third optically transparent member having a fifth surface and a sixth surface, the sixth surface having a second Fresnel structure.
15 . The optical system according to claim 14 , wherein
the sixth surface includes (i) a center region without a Fresnel structure and (ii) the second Fresnel structure that surrounds the center region of the sixth surface.
16 . The optical system according to claim 14 , wherein
a first ratio of an edge thickness of the first lens over a center thickness of the first lens is between 1 to 1.2,
a second ratio of an edge thickness of the second lens over a center thickness of the second lens is between 1/3 to 1, and
a third ratio of an edge thickness of the third lens over a center thickness of the third lens is between 1/3 to 1.
17 . The optical system according to claim 14 , further comprising:
a beam splitter configured to partially transmit and partially reflect light beams from the display device,
a reflective polarizer configured to pass through light having a first linear polarization state and reflect light having a second linear polarization state that is orthogonal to the first linear polarization state, and
a quarter waveplate (QWP) that is positioned between the beam splitter and the reflective polarizer, wherein
the QWP is on a surface of the first lens, the second lens, or the third lens,
the beam splitter is on the fifth surface of the third lens, and
the reflective polarizer is on the first surface of the first lens.
18 . The achromatic lens according to claim 1 , wherein
the FOV threshold is approximately 70° along an axis that is perpendicular to an optical axis of the achromatic lens.
19 . The achromatic lens according to claim 1 , wherein
the first Fresnel structure is configured to refract light that is incident onto the first Fresnel structure.