If you thin a silicon die enough it becomes flexible. I suspect they're using a standard planar fab then thinning the die and mounting it on some curved substrate.
They may even just be using relief cuts in the die to produce the effect. Reliefs have a number of advantages, including reducing twisting and buckling.
Take a sheet of paper and wrap it around a ball. Notice how it folds?
If you could take a flat surface and have it represent the surface of a sphere without warping (or vice-versa), we wouldn't have constant debates about what kind of map projections are best.
Maybe you could make it like an orange peel and bend it mostly sideways? Depends on how rigid it is. Or cut ridges like a fresnel lens? Or like lasik? All depends on the material properties.
Good question. I don't know but I know from another effort that was at Sun way back in the day it is really difficult to create curvature in a system that wants flat optical masks and flat processing.
There are at least two challenges, one is curve itself, and the other is laying out the sensor to be linear across the curved surface. I'm wondering if they are going to do a Hot Chips presentation, that has been where most of the coolest advances in chip making have been detailed.
A friend speculated they might be doing a mems sort of thing where they make a 'thick' chip and then etch down to the layers of sensors, perhaps polishing, as a glass lens might be made, but for me that seems like it would be too risky. Thinning and bending is a possibility of course you need to account for the final topology in your layout.
there are lenses in the lens assembly that flattens the image. Thus if you wanted to make curved wafers you could remove these. But then the curve would be across the water itself and maybe not what you want on the individual chip level.
By the way, this brings back thoughts how astronomy used to be done with thin glass plates, doing wide area sky surveys. The plates would be placed into the plate holder, and some pressure was necessary to deform the plate to match the curvature desired.
They said you knew when you'd gone to far because you'd hear the tinkle of broken glass...
(they also baked the plates in hydrogen to increase their light sensitivity)
This is from a reply they made to a comment on the article: "Hi, you are right, we take available sensors and just change their shape before packaging. It makes it a plug-and play product, with no need to have a specific PCB development."
Right but the Sony one is a small 1/2.3-inch, this one looks like a Full Frame 35mm sensors.
Edit: I think "the first one" is the claim for "very first commercial curved sensor for a scientific application"..."for a scientific application" they said, Sony was a selfie camera :-)
Sensor size designations are very confusing. The 1/2.3 is based on the diameter of an old tube sensor, of which a large portion couldn't be used for imaging. The 35mm is based on 35mm film, which was actually 24mm x 36mm. The only way to make sense of it is to use a table showing actual dimensions, such as https://en.wikipedia.org/wiki/Image_sensor_format#Table_of_s....
As someone who have designed lenses (with Zemax et al), this means I can get by with fewer lens elements, making it less expensive. That's one aberration type I can stop worrying about.
One interesting challenge I assume they faced here is that the properties of Silicon that are relevant for transistors can be (significantly?) affected by stress/strain.
So while it seems reasonable that you could thin down a digital circuit and have it continue to function correctly when bent, a CMOS sensor is a very analog device. I wonder if noise / dark current / other properties vary depending on where the stresses are applied.
The curvature goes in the opposite direction of what I would have thought. I would've thought the orientation of the curve was in the sense of maintaining a "constant radius" from the end of the lens stack. (exit pupil?) I.e. the curve helps bring in the distant parts of the sensor closer and more orthogonal to the light rays.
But the diagram shows the opposite kind of curve! That makes even less intuitive sense to me.
(I can't imagine someone not involved with the company creating this diagram, or it being so wrong and not being caught by some review process? I figure the diagram is legit? Someone drawing ray tracing level details would get it so wrong?)
The image of the sensor held by the fingers looks concave.
The illustration with simplified optics shows a convex sensor.
Hard to figure it out.
I would imagine chromatic abberation and light dropoff is due to flat sensors and concave sensors would help. But I might not understand modern lens design.
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[ 2.6 ms ] story [ 91.2 ms ] threadYet submitting a design to a commercial fab and saying "make it curved plz" isn't likely to work either.
So how is this done?
(Ie. You can curve it around a cylinder, but not around a sphere)
If you could take a flat surface and have it represent the surface of a sphere without warping (or vice-versa), we wouldn't have constant debates about what kind of map projections are best.
There are at least two challenges, one is curve itself, and the other is laying out the sensor to be linear across the curved surface. I'm wondering if they are going to do a Hot Chips presentation, that has been where most of the coolest advances in chip making have been detailed.
A friend speculated they might be doing a mems sort of thing where they make a 'thick' chip and then etch down to the layers of sensors, perhaps polishing, as a glass lens might be made, but for me that seems like it would be too risky. Thinning and bending is a possibility of course you need to account for the final topology in your layout.
Definitely a fun puzzle to speculate about.
Do they start with a curved piece of silicon and do the fabbing on that? Or is it initially flat and then bent during the process?
Will this be generally isolated to very specialty wide-field imaging? And expensive, custom runs?
It looks like their US patent is here: https://patentimages.storage.googleapis.com/10/b3/ee/69d396b...
By the way, this brings back thoughts how astronomy used to be done with thin glass plates, doing wide area sky surveys. The plates would be placed into the plate holder, and some pressure was necessary to deform the plate to match the curvature desired.
They said you knew when you'd gone to far because you'd hear the tinkle of broken glass...
(they also baked the plates in hydrogen to increase their light sensitivity)
We may be back to vacuum tubes again soon:
https://spectrum.ieee.org/semiconductors/devices/introducing...
https://news.ycombinator.com/item?id=25113755
Edit: I think "the first one" is the claim for "very first commercial curved sensor for a scientific application"..."for a scientific application" they said, Sony was a selfie camera :-)
Source: https://en.wikipedia.org/wiki/Image_sensor_format#Table_of_s...
EDIT: I don’t mean this in a negative manner, I just don’t know about this kind of stuff so I’m curious about what settings this is useful.
A curved sensor should improve optics by limiting distortion. So basically it can take better pictures.
So while it seems reasonable that you could thin down a digital circuit and have it continue to function correctly when bent, a CMOS sensor is a very analog device. I wonder if noise / dark current / other properties vary depending on where the stresses are applied.
The curvature goes in the opposite direction of what I would have thought. I would've thought the orientation of the curve was in the sense of maintaining a "constant radius" from the end of the lens stack. (exit pupil?) I.e. the curve helps bring in the distant parts of the sensor closer and more orthogonal to the light rays.
But the diagram shows the opposite kind of curve! That makes even less intuitive sense to me.
(I can't imagine someone not involved with the company creating this diagram, or it being so wrong and not being caught by some review process? I figure the diagram is legit? Someone drawing ray tracing level details would get it so wrong?)
[0]: https://en.wikipedia.org/wiki/Microlens
The illustration with simplified optics shows a convex sensor.
Hard to figure it out.
I would imagine chromatic abberation and light dropoff is due to flat sensors and concave sensors would help. But I might not understand modern lens design.