Method to design ultra-wide angle miniature lens
Miniature optical lenses are disclosed having a ratio of the optical image diameter divided by the total track length that is greater than 0.85. These thin optical lenses are often used in applications requiring large image sensors and small thickness like in consumer electronic applications. The miniature optical lenses presented have fields of view between 130° and 170° or more specifically inside the well-desired 140° to 160° field of view range in order to cover the ultra-wide-angle field of view range. The optical lenses presented also respect some dimensionless ratios in order to maximize the optical performance of the lenses.
1 . An optical imaging system comprising a plurality of optical elements configured to form an optical image having an image diameter in an image plane, the optical system having a field of view between 140° and 160° and the following characteristics:
a. a ratio of the image diameter divided by a total track length of the optical system is between 0.85 and 1.3,
b. a ratio of the image diameter divided by a clear aperture diameter of a first optical element of the plurality of optical elements is between 1.4 and 3.4,
c. a ratio of the image diameter divided by a focal length of the optical system is between 2.5 and 4.5,
d. a ratio of the image diameter divided by a focal length of the first optical element is between −2.2 and −1.3, and
e. a ratio of the total track length of the optical system divided by the focal length of the optical system is between 2.1 and 4.8.
2 . The optical system of claim 1 , wherein the plurality of optical elements comprises one of six, seven, or eight optical elements.
3 . The optical system of claim 1 , wherein an image side surface of the first optical element is of concave shape.
4 . The optical system of claim 1 , wherein a second optical element of the plurality of optical elements has a positive optical power in a central paraxial region.
5 . The optical system of claim 1 , wherein a last optical element of the plurality of optical elements before the image plane has a convex shape in a central paraxial region surrounded by a concave shape around the central convex shape on an object side thereof.
6 . The optical system of claim 1 , wherein a last optical element of the plurality of optical elements before the image plane has a concave shape in the central paraxial region surrounded by a convex shape around the central concave shape on an image side thereof.
7 . The optical system of claim 1 , wherein the plurality of optical elements are refractive aspherical elements made of plastic material.
8 . The optical system of claim 1 , wherein an image sensor is located at the image plane, the image sensor being configured to convert the optical image into a digital image.
9 . The optical system of claim 8 , wherein the digital image is configured to be processed by an algorithm.
10 . A method for designing an optical imaging system, the method comprising providing a plurality of optical elements configured to form an optical image having an image diameter in an image plane, the optical system having a field of view between 140° and 160° and the following characteristics:
a. a ratio of the image diameter divided by a total track length of the optical system is between 0.85 and 1.3,
b. a ratio of the image diameter divided by a clear aperture diameter of a first optical element of the plurality of optical elements is between 1.4 and 3.4,
c. a ratio of the image diameter divided by a focal length of the optical system is between 2.5 and 4.5,
d. a ratio of the image diameter divided by a focal length of the first optical element is between −2.2 and −1.3, and
e. a ratio of the total track length of the optical system divided by the focal length of the optical system is between 2.1 and 4.8.
11 . The method of claim 10 , wherein the plurality of optical elements comprises one of six, seven, or eight optical elements.
12 . The method of claim 10 , wherein an image side surface of the first optical element is of concave shape.
13 . The method of claim 10 , wherein a second optical element of the plurality of optical elements has a positive optical power in a central paraxial region.
14 . The method of claim 10 , wherein a last optical element of the plurality of optical elements before the image plane has a convex shape in a central paraxial region surrounded by a concave shape around the central convex shape on an object side thereof.
15 . The method of claim 10 , wherein a last optical element of the plurality of optical elements before the image plane has a concave shape in the central paraxial region surrounded by a convex shape around the central concave shape on an image side thereof.
16 . The method of claim 10 , wherein the plurality of optical elements are refractive aspherical elements made of plastic material.
17 . The method of claim 10 , further comprising locating an image sensor at the image plane, the image sensor being configured to convert the optical image into a digital image.
18 . The method of claim 17 , wherein the digital image is configured to be processed by an algorithm.
19 . An optical imaging system comprising a plurality of optical elements having an optical power and configured to form an optical image having an image diameter in an image plane, the optical system having a field of view between 130° and 170° and the following characteristics:
a. a ratio of the image diameter divided by a total track length of the optical system is between 0.85 and 1.3,
b. a ratio of the image diameter divided by a clear aperture diameter of a first optical element of the plurality of optical elements is between 1.4 and 3.4,
c. a ratio of the image diameter divided by a focal length of the optical system is between 2.5 and 4.5,
d. a ratio of the image diameter divided by a focal length of the first optical element is between −2.2 and −1.3, and
e. a ratio of the total track length of the optical system divided by the focal length of the optical system is between 2.1 and 4.8,
wherein the plurality of optical elements comprises seven or eight optical elements having an optical power.