Systems and methods for manufacturing camera modules using active alignment of lens stack arrays and sensors

A method for actively aligning a lens stack array with a sensor that includes a plurality of focal planes, where each focal plane comprises a plurality of rows of pixels that also form a plurality of columns of pixels and each focal plane is contained within a region of the imager array that does not contain pixels from another focal plane, the method comprising:

• aligning the lens stack array relative to the sensor in an initial position, where the lens stack array comprises a plurality of lens stacks and the plurality of lens stacks forms separate optical channels for each focal plane in the sensor;
• varying the spatial relationship between the lens stack array and the sensor;
• capturing images of a known target using a plurality of active focal planes at different spatial relationships between the lens stack array and the sensor, where the known target includes a central region of interest and at least one peripheral region of interest;
• scoring the images captured by the plurality of active focal planes, where the resulting scores provide a direct comparison of the extent to which at least one region of interest is focused in the images;
• wherein the images are scored such that a score is provided for each region of interest visible in each image, the score being indicative of the extent to which the respective region of interest is focused in the image;
• selecting a spatial relationship between the lens stack array and the sensor based upon a comparison of the scores of images captured by a plurality of the active focal planes;
• wherein the comparison of scores comprises:
• determining mathematical relationships for each of a plurality of active focal planes that characterize the relationships between:
• the scores of the extent to which the central region of interest is focused in the images captured by the respective active focal plane and the spatial relationship between the lens stack array and the sensor;
• and
• the scores of the extent to which the at least one peripheral region of interest is focused in the images captured by the respective active focal plane and the spatial relationship between the lens stack array and the sensor;
• and
• computing, using the determined mathematical relationships:
• a first best-fit plane that defines a spatial relationship between the lens stack array and the sensor based on each active focal plane's ability to focus on a central region of interest according to predetermined criterion;
• a second best-fit plane that defines a spatial relationship between the lens stack array and the sensor based on each active focal plane's ability to focus on the at least one peripheral region of interest according to predetermined criterion;
• and
• a plurality of planes incrementally spaced that lie between the first and second best-fit planes
• forming an array camera subassembly in which the lens stack array and the sensor are fixed in the selected spatial relationship.

A method for actively aligning a lens stack array with a sensor that includes a plurality of focal planes, where each focal plane comprises a plurality of rows of pixels that also form a plurality of columns of pixels and each focal plane is contained within a region of the imager array that does not contain pixels from another focal plane, the method comprising:

• aligning the lens stack array relative to the sensor in an initial position, where the lens stack array comprises a plurality of lens stacks and the plurality of lens stacks forms separate optical channels for each focal plane in the sensor;
• varying the spatial relationship between the lens stack array and the sensor;
• capturing images of a known target using a plurality of active focal planes at different spatial relationships between the lens stack array and the sensor, where the known target includes at least one region of interest;
• scoring the images captured by the plurality of active focal planes, where the resulting scores provide a direct comparison of the extent to which at least one region of interest is focused in the images, wherein scoring the images captured by the plurality of active focal planes comprises:
• determining preliminary scores for the captured images in accordance with a first criterion;
• determining scores for a related set of captured images in accordance with a second criterion;
• and
• extrapolating the preliminary scores as a function of the spatial relationship between the lens stack array and the sensor based on the scores determined for the related set of captured images;
• selecting a spatial relationship between the lens stack array and the sensor based upon a comparison of the scores of images captured by a plurality of the active focal planes;
• and
• forming an array camera subassembly in which the lens stack array and the sensor are fixed in the selected spatial relationship.