Imaging systems having lens substrates with total internal reflection mitigation structures
View Patent ↗Imaging systems may include camera modules that include multiple image sensor pixel arrays. A transparent lens substrate may be formed over the image pixel arrays. Lenses may be formed in the lens substrate such that each lens transmits light to a corresponding image sensor pixel array. Total internal reflection mitigation structures such as groove structures may be formed in one or more surfaces of the lens substrate between each of the lenses. The groove structures may include concentric ring shaped grooves in a surface of the lens substrate so that each lens is surrounded by a respective group of concentric ring shaped grooves. The groove structures may have a depth, angle, shape, and spacing that prevents total internal reflection of image light between the lenses so that high incident angle image light incident on a given pixel array is not captured by an adjacent pixel array.
1. An imaging system, comprising:
a first image sensor comprising a first array of multiple adjacent image sensor pixels;
a second image sensor that is different from the first image sensor and comprises a second array of multiple adjacent image sensor pixels, wherein the first and second arrays each comprise over one hundred image sensor pixels;
row control circuitry, wherein the row control circuitry is configured to provide row control signals to the first array in the first image sensor and to the second array in the second image sensor;
a first lens formed directly over each of the over one hundred image sensor pixels in the first array;
a second lens formed directly over each of the over one hundred image sensor pixels in the second array, wherein the first and second lenses are formed from a lens substrate;
total internal reflection mitigation structures formed in the lens substrate between the first and second lenses, wherein the total internal reflection mitigation structures comprise at least one groove structure in the lens substrate, and wherein the total internal reflection mitigation structures are configured to prevent total internal reflection of high incident angle image light between the first and second image sensors; and light absorbing structures that fill the at least one groove structure, wherein the lens substrate has a first index of refraction and the light absorbing structures have a second index of refraction that is less than the first index of refraction.
2. The imaging system defined in claim 1 , wherein the lens substrate comprises a first lens portion on which the first lens is formed, a second lens portion on which the second lens is formed, and an inter-lens portion between the first and second lens portions, wherein the total internal reflection mitigation structures are formed on at least one surface of the inter-lens portion of the lens substrate.
3. The imaging system defined in claim 1 , wherein the lens substrate comprises plastic.
4. The imaging system defined in claim 1 , wherein the lens substrate comprises an upper surface and a lower surface that opposes the upper surface, wherein the lower surface is formed adjacent to the first and second arrays of multiple adjacent image sensor pixels, and wherein the at least one groove structure is formed in the upper surface of the lens substrate.
5. The imaging system defined in claim 1 , wherein the lens substrate comprises an upper surface and a lower surface that opposes the upper surface, wherein the lower surface is formed adjacent to the first and second arrays of multiple adjacent image sensor pixels, and wherein the at least one groove structure is formed in the lower surface of the lens substrate.
6. The imaging system defined in claim 1 , wherein the lens substrate comprises an upper surface and a lower surface that opposes the upper surface, wherein the lower surface is formed adjacent to the first and second arrays of multiple adjacent image sensor pixels, and wherein the total internal reflection mitigation structures comprise a first groove structure formed in the upper surface of the lens substrate and a second groove structure formed in the lower surface of the lens substrate.
7. The imaging system defined in claim 6 , wherein the total internal reflection mitigation structures further comprise a third groove structure formed in the upper surface of the lens substrate and a fourth groove structure formed in the lower surface of the lens substrate.
8. The imaging system defined in claim 7 , wherein the first and third groove structures in the upper surface of the lens substrate are offset with respect to the second and fourth groove structures in the lower surface of the lens substrate.
9. The imaging system defined in claim 6 , wherein the first and third groove structures have a selected depth and a selected angle for mitigating total internal reflection of image light between the first and second lenses.
10. The imaging system defined in claim 6 , wherein the first groove structure comprises a ring-shaped groove in the lens substrate formed around the first lens and the third groove structure comprises a ring-shaped groove in the lens substrate formed around the second lens.
11. A camera module, comprising:
a plurality of image sensor pixel arrays;
a lens substrate formed over the plurality of image sensor pixel arrays, wherein the lens substrate comprises a plurality of lenses that each transmits light onto a corresponding image sensor pixel array in the plurality of image sensor pixel arrays;
a plurality of groove structures formed in the lens substrate, wherein the plurality of groove structures is configured to prevent total internal reflection of image light in the lens substrate between the lenses; and
light absorbing structures that fill at least one groove structure of the plurality of groove structures, wherein the lens substrate has a first index of refraction, and the light absorbing structures have a second index of refraction that is less than the first index of refraction.
12. The camera module defined in claim 11 , wherein the plurality of groove structures comprises a plurality of concentric ring-shaped grooves in the lens substrate around a given lens of the plurality of lenses.
13. The camera module defined in claim 12 , wherein the plurality of groove structures further comprises an additional plurality of concentric ring-shaped grooves in the lens substrate around an additional lens of the plurality of lenses.
14. The camera module defined in claim 12 , wherein the lens substrate comprises first and second opposing surfaces, wherein the second surface is interposed between the first surface and the plurality of image sensor pixel arrays, and wherein the plurality of concentric ring-shaped grooves comprises a plurality of circular ring-shaped grooves in the second surface of the lens substrate.
15. The camera module defined in claim 11 , wherein the plurality of lenses comprises first and second rows of lenses, wherein the lenses in the first row of lenses are offset with respect to the lenses in the second row of lenses, and wherein at least one corresponding groove structure of the plurality of groove structures is formed between every pair of lenses in the plurality of lenses.
16. The camera module defined in claim 11 , wherein the plurality of image sensor pixel arrays are formed on a common semiconductor substrate and wherein the plurality of lenses comprises at least one multi-element lens.