What would a curved image sensor change in camera and lens design?
Asked 2/21/2022
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I’ve read that many lenses naturally form a curved focal surface, and that projecting onto a flat sensor requires extra optical correction. Since digital cameras no longer need a flat recording medium like film strips or plates, would a curved sensor simplify lens design or improve performance? For example, could it reduce lens size, aberrations, or other design compromises? What practical challenges prevent curved sensors from being common today, and is this an area manufacturers or researchers are exploring?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
4y ago
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Digital image sensors used in modern cameras are essentially silicon chips:
Sensor dies are produced in large batches on silicon wafers. The wafers are cut into many pieces with each piece housing a single sensor die. The larger the sensor die size, the lower number of sensors per wafer.
The wafers are sawn with diamond saws from silicon ingots, which renders them flat. I can only imagine that trying to saw or otherwise cut a surface curved in two dimensions would be very hard or impossible. Consequently, the "natural state" of a digital sensor is flat.
Image of two such wafers
(Image by Hebbe at German Wikipedia, via Wikimedia Commons.)
However, the raw wafers undergo considerable "post-processing" like polishing which conceivably could be used to grind one surface into a concave shape; but of course the succeeding processes currently are expecting a plane surface, so one must expect all kinds of costly adaptations and problems down the road.
That said, Canon has filed a patent for a curved sensor. I suppose that if the chip is thin enough it is flexible enough for the purpose.
Originally by user37413. Source · Licensed CC BY-SA 4.0
user37413
4y ago
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A curved sensor could help because many simple lenses naturally focus onto a curved surface rather than a flat one. Matching that curvature can improve image quality and reduce the amount of optical correction needed, which may allow simpler lenses with lower aberrations.
This isn’t a new idea: curved film planes were used in many older low-cost cameras for exactly that reason, especially with simple meniscus-type lenses.
The main obstacle is sensor manufacturing. Modern image sensors are made as flat silicon dies cut from flat silicon wafers, so their “natural” form is flat. Making a sensor curved in two dimensions is much harder than making a conventional flat chip.
That said, research does exist. Experimental curved or hemispherical silicon sensor systems have been demonstrated, inspired by biological eyes, with potential benefits such as wider viewing angles, lower aberrations, and other optical advantages.
So: yes, curved sensors can simplify some lens-design problems, but they are limited mainly by fabrication and production practicality, not by lack of optical benefit.
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