Panasonic to double sensor’s sensitivity with unique “micro color splitters”

Panasonic to increase sensor sensitivity with unique micro color splitters

Constitution and features compared with the conventional method

Panasonic Japan announced today that they have developed the technology for producing highly sensitive image sensors by using unique "micro color splitters". Read the attached press release for more details:

Conventional method using a color fileDeveloped method using a micro color splitter

Left image: conventional method using a color filer, right image: Developed method using a micro color splitter.

Osaka, Japan - Panasonic Corporation has developed unique "micro color splitters", which separate the light that falls on image sensors by exploiting light's wavelike properties. Applying them to actual image sensors allows bright color images to be achieved even under low-light conditions. This development makes color filters unnecessary by using the micro color splitters that control the diffraction1 of light at a microscopic level. Panasonic has achieved approximately double the color sensitivity in comparison with conventional sensors that use color filters.

Image sensors are used in devices like smartphones, digital still cameras and video cameras, as well in security, vehicle parking, office, and healthcare applications - anywhere, in fact, that digital imaging is needed. Conventional color image sensors use a Bayer array2, in which a red, green, or blue light-transmitting filter is placed above each sensor. These filters block 50 - 70% of the incoming light before it even reaches the sensor. Progress is being made in increasing the resolution of image sensors used in mobile and other devices by reducing pixel size, but demand for higher-sensitivity cameras is also increasing. Panasonic has developed a new technology that can be applied to existing or future sensors to enable them to capture uniquely vivid color images.

The developed technology has the following features.

  1. Using color alignment, which can use light more efficiently, instead of color filters, vivid color photographs can be taken at half the light levels needed by conventional sensors.
  2. Micro color splitters can simply replace the color filters in conventional image sensors, and are not dependent on the type of image sensor (CCD3or CMOS4) underneath.
  3. Micro color splitters can be fabricated using inorganic materials and existing semiconductor fabrication processes.

This development is based on the following new technology.

  1. A unique method of analysis and design based on wave optics that permits fast and precise computation of wave-optics phenomena.
  2. Device optimization technologies for creating micro color splitters that control the phase of the light passing through a transparent and highly-refractive plate-like structure to separate colors at a microscopic scale using diffraction.
  3. Layout technologies and unique algorithms that allow highly sensitive and precise color reproduction by combining the light that falls on detectors separated by the micro color splitters and processing the detected signals.

Panasonic holds 21 Japanese patents and 16 overseas patents, including pending applications, for this development.

This development is described in general terms in the Advance Online Publication version of Nature Photonics issued on February 3, 2013.

More on the Technology

1. Unique method of analysis and design based on wave optics permitting fast and precise computation of wave-optics phenomena

FDTD5 is widely used to analyze light in wave form, but its heavy computation workload has up to now made it impractical for designing micro color splitters. On the other hand, BPM6 is an effective method of fast computation, but it has lower precision than FDTD and cannot accurately simulate color splitting. This prompted Panasonic to develop a practical and original design method that permits fast and precise computation of wave-optics phenomena. This technology allows the precise modeling of optical phenomena such as reflection, refraction, and diffraction by modeling spaces in regions with different optical constants and applying BPM to the spaces. This method can be applied not only to the design of micro color splitters, but can be extended to the design of other nano-scale optical processing systems.

2. Device optimization technologies leading to the creation of micro color splitters that control the phase of the light passing through a transparent and highly-refractive plate-like structure and use diffraction to separate colors on a microscopic scale

Color separation of light in micro color splitters is caused by a difference in refractive index between a) the plate-like high refractive material that is thinner than the wavelength of the light and b) the surrounding material. Controlling the phase of traveling light by optimizing the shape parameters causes diffraction phenomena that are seen only on a microscopic scale and which cause color separation. Micro color splitters are fabricated using a conventional semiconductor manufacturing process. Fine-tuning their shapes causes the efficient separation of certain colors and their complementary colors, or the splitting of white light into blue, green, and red like a prism, with almost no loss of light.

3. Layout technologies and unique algorithms that enable highly sensitive and precise color reproduction by overlapping diffracted light on detectors separated by micro color splitters and processing the detected signals

Since light separated by micro color splitters falls on the detectors in an overlapping manner, a new pixel layout and design algorithm are needed. The layout scheme is combined and optimized using an arithmetic processing technique designed specifically for mixed color signals. The result is highly sensitive and precise color reproduction. For example, if the structure separates light into a certain color and its complementary color, color pixels of white + red, white - red, white + blue, and white - blue are obtained and, using the arithmetic processing technique, are translated into normal color images without any loss of resolution.

Notes:

1. Diffraction
Behavior of light as a wave on the wavelength (nanometer) scale. Various phenomena occur when a wave encounters an obstacle.
2. Bayer array
The arrangement of color filters used in most single-chip digital imaging sensors used in digital cameras, camcorders, and scanners to create a color image. The filter pattern is 50% green, 25% red and 25% blue.
3. Charge Coupled Device Image Sensor (CCD sensor)
A type of solid-state image sensing device for digital imaging, used in digital video cameras of all types. It has higher sensitivity and lower noise than other sensing devices.
4. Complementary Metal Oxide Semiconductor Image Sensor (CMOS sensor)
A solid-state image sensing device for digital imaging using CMOS.
5. Finite-Difference Time-Domain method (FDTD)
FDTD is a versatile modeling technique used to solve Maxwell's equations by spatial and temporal discretization.
6. Beam Propagation Method (BPM)
A numerical analysis technique in electromagnetics for solving the Helmholtz equation under conditions of a time-harmonic wave.

 

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  • http://www.facebook.com/people/Simon-Stucki/759448619 Simon Stucki

    hmm very interesting. hope this also helps dynamic range and color accuracy (or at least doesn’t make one of those worse).

    • http://genotypewritings.blogspot.com/ genotypewriter

      Simon, the whole point of attempting to improve the sensitivity is to increase the dynamic range and therefore colour accuracy. When the sensor is more sensitive, it will gather more information from the same amount of provided information and therefore increase “what you get”.

      Also the getting rid of colour filter arrays may not be a bad thing because the article says “Panasonic has achieved approximately double the color sensitivity in comparison with conventional sensors that use color filters”

      • Jacques Lepignol

        Stop crapping on other’s posts, you’re irritating.

        • mozza

          +1

        • rkas

          Huh? What he says is true, so way are you crapping on him?

      • NRA Advocate

        +2

      • NRA Advocate

        +2

      • Nathaniel

        genotypewriter, why do you always have to be an as$ ?

      • Harry

        I found this answer very informative, not at all hostile. Don’t know about the past or this person, but I think this was a totally normal and good comment. If you disagree with the information, tell it. I think you are bulling this person now for some reason. Think what kind of attitude yourself have when reading? Thanks.

        • Errorrr

          Hm, I actually see how you read that, Harry. But I can see how others read it too. I think some more sensitive (in a good way) people here noticed that someone saying, “Simon, the whole point of..” to be condescending. As if he was petting a child on the head, essentially stating, “You’ve missed the whole point.” They found this offensive and worthy of defending the OP from basically being called an idiot by someone claiming he missed the whole point. They might read the “Also..” in the second paragraph as a second attack. As in “you ALSO missed this point..”.

          ON THE OTHER HAND, Geno could have just been restating the obvious (or at least what Geno believes to be obvious), which may have been better worded as “Simon, as I understand it, the designers are….” so as to move the conversation forward with a simplified premise in place (replacing the OP’s questioning-statement with a premise). As the second paragraph is much easier to read this way, especially if “Also..” is replaced with “I also think that…”

          As Geno did explain his thoughts on why he believed it to be a certain way (whether right or wrong on the facts), it lends credence to the second interpretation. It does not appear he was calling anyone any idiot, but that he simply tried to summarize his thoughts in a rather curt way that could “feel” insensitive if read from a particular angle. Engineers, politicians, police, and lawyers make those communication errors all the time. Its easy to forgive it in a blog.

      • AnthonyH

        You are incorrect. Increasing sensitivity means that less light is needed to obtain the same result, so one would expect even better high ISO performance. However, it doesn’t follow that dynamic range would improve, since the underlying sensor hasn’t changed. Notice how the sample doesn’t highlight DR, but exposure? Indeed, in some situations, the photo sites could be overwhelmed in much more dim lighting, so I think his concerns about DR are quite valid. Without the need for a Bayer array, resolution should be increased, but the graphic shows light being spread out by frequency, so the number of photosites overall will be reduced. It will be interesting to see exactly how this will be implemented and the real world effects. In the meantime, I agree with the other folks. Commenting just to look like you know something just makes you look foolish.

        • Marco Santa Cruz

          just saw this after i commented.

      • Marco Santa Cruz

        yeah, he is being a jerk.. cause #1… this doesn’t have to do with the sensor: regardless of what the title says (it should read something like “BAYERLESS color etc”)
        #2 to sum it up… this tech doesn’t need color filters (bayer) which to certain extent block light (isn’t that what filters do?)… therefore, whatever sensor you put under it would receive more light.
        #3 these micro whatever are like “micro prisms” which would then split the light up, and allow the sensor below it to ‘more accurately read the light.
        #4 as for dynamic range… that depends on the sensor. and as the article says, pretty much any sensor “with proper reworking (or whatever its called)” can go under these new “micro prisms” which would then give a better image… more color in the sense that it won’t be filtered out, but the sensor has the final say in how much range it can accept, and like all tech, it will work out…

        i’m sure this is all great, possibly better, but like the bayer system gives it’s own problems, who knows what kind we’ll encounter with these ‘micro prism’ tech.

        #5 if you take a photo with a graduated neutral density filter, you might notice a little weensy bit loss in sharpness (i guess depending on the filter)… well same goes for any filter. if this were to be done though, how big would the photosites have to be?…

  • aplusk

    That 2nd picture is what, a stop brighter than the first?

    If their current sensors fall behind Nikon/Canon say 2-3 stops in terms of high-ISO performance, they’ll still be inferior after this process…

  • http://alphacorner.eu/ Sky

    so… even more issues with color separation? As if Nikons ain’t bad enough already? Ehh… I really wish 3-layered sensors would grow up finally.

    • Sebastian

      Color separation is one of the weakest spots of current three-layered sensors.
      I’ll need to read the article they refer to but I wonder how they deal with light striking the sensor at an angle.

      • http://alphacorner.eu/ Sky

        But they are ahead of the others in color resolution and most likely have the highest chances from all technologies to get a correct colors. So as far as current Foveon in did can struggle with color separation – an overall image quality in terms of colors is ahead of competition and technology itself brings a lot of hope (especially in Canon and Sony implementations).

        Edges of the frame might in did be very interesting though, especially when people use 3rd party lenses through adapters which might be very, very demanding in that respect. So TBH: I’d laugh if it’d end up with “list of allowed lenses” to use with a camera running that sensor.

      • http://alphacorner.eu/ Sky

        But they are ahead of the others in color resolution and most likely have the highest chances from all technologies to get a correct colors. So as far as current Foveon in did can struggle with color separation – an overall image quality in terms of colors is ahead of competition and technology itself brings a lot of hope (especially in Canon and Sony implementations).

        Edges of the frame might in did be very interesting though, especially when people use 3rd party lenses through adapters which might be very, very demanding in that respect. So TBH: I’d laugh if it’d end up with “list of allowed lenses” to use with a camera running that sensor.

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