Apple invention uses spherically curved photosensor for smaller, better iPhone camera
In its quest for high-performing, flexible and -- most importantly -- small imaging systems, Apple on Tuesday was granted a patent for a spherical photosensor and lens array that provides high-resolution capture in an incredibly compact package.
Source: USPTO
As published by the U.S. Patent and Trademark Office, Apple's U.S. Patent No. 9,244,253 for a "Small form factor high-resolution camera" marries cutting edge sensor technology with similarly complex optics to create a compact, high-performance digital shooter suitable for deployment in iPhone and iPad.
In some embodiments Apple describes a photosensor that is spherically curved to receive incoming light, refracted through specially crafted lenses, onto a concave surface. An apt analogy would be a bowl filled with water; the bowl represents a spherically curved image sensor and the water a fitted lens system.
To correct for diffraction and visual aberrations that propagate within miniature cameras, the proposed lens system includes three lenses, two of which are convex or substantially convex. A third meniscus lens, or a lens with opposing convex and concave surfaces, is situated between the first two lens elements and the spherical photosensor. The meniscus lens' concave surface faces the first two lens elements, and thus incoming light rays, while the convex surface interfaces with the sensor, focusing light onto the sensing surface.
This unique arrangement provides a comparatively small ray fan spot size for all field heights at the image plane, allowing for sharp, low-distortion images. Apple says that employing a curved array limits diffraction across the image field (it scores high in point spread function and modulation transfer function metrics), thereby allowing for a smaller photosensor with equally tiny pixels. Further, with an axial length of two millimeters or less, the total camera package is incredibly compact.
The setup does come with a few drawbacks, however, the most prominent being native barrel distortion, or a bubble-like warping. Apple proposes a software solution for correcting such unwanted effects, which can appear in varying degrees of severity depending on focal length, aperture and other system settings.
It is unclear if Apple intends to apply its curved photosensor patent in future iPhones, as the company has long relied on Sony's stellar backside-illuminated modules for its imaging needs. The technology could, however, delay the inevitable as Apple races to cram more components into an ever-shrinking device lineup.
Apple's curved spherical photosensor patent was first filed for in 2013 and credits Xi Chen, David S. Gere and Matthew C. Waldon as its inventors.
Source: USPTO
As published by the U.S. Patent and Trademark Office, Apple's U.S. Patent No. 9,244,253 for a "Small form factor high-resolution camera" marries cutting edge sensor technology with similarly complex optics to create a compact, high-performance digital shooter suitable for deployment in iPhone and iPad.
In some embodiments Apple describes a photosensor that is spherically curved to receive incoming light, refracted through specially crafted lenses, onto a concave surface. An apt analogy would be a bowl filled with water; the bowl represents a spherically curved image sensor and the water a fitted lens system.
To correct for diffraction and visual aberrations that propagate within miniature cameras, the proposed lens system includes three lenses, two of which are convex or substantially convex. A third meniscus lens, or a lens with opposing convex and concave surfaces, is situated between the first two lens elements and the spherical photosensor. The meniscus lens' concave surface faces the first two lens elements, and thus incoming light rays, while the convex surface interfaces with the sensor, focusing light onto the sensing surface.
This unique arrangement provides a comparatively small ray fan spot size for all field heights at the image plane, allowing for sharp, low-distortion images. Apple says that employing a curved array limits diffraction across the image field (it scores high in point spread function and modulation transfer function metrics), thereby allowing for a smaller photosensor with equally tiny pixels. Further, with an axial length of two millimeters or less, the total camera package is incredibly compact.
The setup does come with a few drawbacks, however, the most prominent being native barrel distortion, or a bubble-like warping. Apple proposes a software solution for correcting such unwanted effects, which can appear in varying degrees of severity depending on focal length, aperture and other system settings.
It is unclear if Apple intends to apply its curved photosensor patent in future iPhones, as the company has long relied on Sony's stellar backside-illuminated modules for its imaging needs. The technology could, however, delay the inevitable as Apple races to cram more components into an ever-shrinking device lineup.
Apple's curved spherical photosensor patent was first filed for in 2013 and credits Xi Chen, David S. Gere and Matthew C. Waldon as its inventors.
Comments
Ah - looks like Sony might be able to make them if they can put that much stress on the wafer to bend it that much, which I doubt.
In 2013, Sony was awarded a patent for a number of lens designs, including the rather simple 35mm f/1.8 lens paired with a curved image sensor shown above.
To keep the light gathering capacity up, they accept a lot of of predictable distortion, which can then be fixed in software (because it is predictable).
This introduces slight softness on the periphery in the widest end of the zoom, but it's a good
tradeoff for being able to stick those large sensors and bright zooms in a small body.
I don't see the relevance.
Now the smartphone industry can get back on track to thinner and lighter, and I mean the in the best possible way; that's what the market wants, and its just waiting for battery tech to leap forward.
The good thing is that a patent prevents anybody else from using it, even if they could solve the engineering problems themselves. And I bet that they are all working on such designs, and will now have to abandon them, no matter how close they were to perfection.
Way to go Apple!
They could have made it much thinner if they used a smaller sensor (like in a smartphone). But, past a certain point in thinness, focusing on a flat surface becomes nearly impossible without introducing distortion that can't be corrected; that is what limits the max size a flat sensor can be for a certain thinness.
Here they get more light, with less depth (2mm) through optics and since they got so little space to work with, the distortion needed is so severe they need to curve the sensor too to partially correct for it. with the result barrel distortion that still needs to be corrected (The curved sensor wasn't able to fix everything).
That's the parallel; that's the point,
These compact bright zooms with weird optics of Canon is their main advantage over Sony, which is tops in sensors.
That's what they say in the article:
"The setup does come with a few drawbacks, however, the most prominent being native barrel distortion, or a bubble-like warping. Apple proposes a software solution for correcting such unwanted effects, which can appear in varying degrees of severity depending on focal length, aperture and other system settings"
They can use just part of the image (use a slightly bigger sensor) to compensate. That's what my Canon G7X does; the distortion which is corrected, creates a slight peripheral softness when in the 24-30mm range (but, unless doing architectural shots it's not noticeable).