Method and apparatus for reducing microlens surface reflection
First Claim
1. A pixel array comprising:
- a plurality of pixels; and
an array of microlenses over said plurality of pixels, wherein each of said microlenses has a first index of refraction at a bumpy outer layer of said microlens and a second index of refraction inside said microlens, medial to said outer layer, said outer layer of each microlens including a plurality of bumps protruding from the surface of the microlens.
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Accused Products
Abstract
A microlens has a surface with an effective index of refraction close to the index of air to reduce reflection caused by change in indices of refraction from microlens to air. The microlens having an index of refraction approximately the same as that of air is obtained by providing a rough or bumpy lens-air surface on the microlens. Features protrude from the surface of a microlens to create the rough surface and preferably have a length of greater or equal to a wavelength of light and a width of less than a sub-wavelength of light, from about 1/10 to ¼ of the wavelength of light. The features may be of any suitable shape, including but not limited to triangular, cylindrical, rectangular, trapezoidal, or spherical and may be formed by a variety of suitable processes, including but not limited to mask and etching, lithography, spray-on beads, sputtering, and growing.
12 Citations
32 Claims
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1. A pixel array comprising:
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a plurality of pixels; and an array of microlenses over said plurality of pixels, wherein each of said microlenses has a first index of refraction at a bumpy outer layer of said microlens and a second index of refraction inside said microlens, medial to said outer layer, said outer layer of each microlens including a plurality of bumps protruding from the surface of the microlens. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An imager device comprising:
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a plurality of pixels; and an array of microlenses over said plurality of pixels, wherein each of said microlenses has a surface from which protrudes a plurality of bumps. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. An imager structure comprising:
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a plurality of pixels formed in a substrate; at least one planar layer formed over said plurality of pixels; and a plurality of microlenses over said plurality of pixels having a first index of refraction, each microlens having a bumpy refractive layer at a top surface of said microlenses having a second index of refraction, the bumpy refractive layer comprising a plurality of bumps protruding from the top surface of each microlens. - View Dependent Claims (19, 20, 21)
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22. A method of making a pixel array comprising:
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forming a plurality of pixels in a substrate; forming a plurality of microlenses over said plurality of pixels; and forming a plurality of bumps on protruding from a top surface of each of said microlenses. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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Specification