| CPC G02B 9/60 (2013.01) [G02B 13/0015 (2013.01); G02B 13/0045 (2013.01)] | 27 Claims |

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1. An imaging optical lens assembly, comprising five lens elements, the five lens elements being, in order from an object side to an image side: a first lens element, a second lens element, a third lens element, a fourth lens element and a fifth lens element; each of the five lens elements comprising an object-side surface facing toward the object side and an image-side surface facing toward the image side;
wherein a total number of lens elements of the imaging optical lens assembly is five, the first lens element has negative refractive power, the fourth lens element has positive refractive power, the fifth lens element has negative refractive power, a central thickness of the first lens element is larger than a central thickness of the third lens element, a curvature radius of the object-side surface of the second lens element and a curvature radius of the image-side surface of the second lens element have the same sign, the curvature radius of the image-side surface of the second lens element and a curvature radius of the image-side surface of the third lens element have different signs, a curvature radius of the object-side surface of the fourth lens element and a curvature radius of the image-side surface of the fifth lens element have different signs;
wherein a focal length of the first lens element is f1, a focal length of the third lens element is f3, the curvature radius of the object-side surface of the second lens element is R3, the curvature radius of the image-side surface of the second lens element is R4, and the following conditions are satisfied:
f1/f3<5.0; and
|R4/R3|<2.0.
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