Hints and Tips Discussion The differences of the sensors for Phantom Pro./Adv. and Standard

Phantom Pro & Adv: Sony Exmor R BSI
Phantom Standard: Panasonic Smart FSI

The earliest CMOS sensor used FSI (Front Side Illumination) structure, then comes BSI (Back Side Illumination), the structure of these two have been shown in picture 1.

1. For FSI, light need to travel through the layer of metal wiring first, then arrive at the substrate where the conversion from light signal into electrical signal started. However part of the light signal has been missed caused by the scattering of the metal wiring. Such part of light just can’t reach substrate and of course cannot be used for the final picture.
2. For BSI, designer turned the metal wiring and substrate upside-down, so the light signal has been absorbed by the substrate first, thus there being more signal gathered than FSI structure. It is estimated that over 40% of the extra light can be absorbed when comparing BSI with FSI structure under the same circumstances.
3. Usually FSI can reach the same feature of BSI with lower expense, and it provide a better quality for the whole picture when the pixels required are big enough (mostly considered as 1.4um+). Under such case, for BSI having a bigger sensing size and different structure, it’s easier to get affected by irrelevant noise signal caused from things like induced current , while FSI can wipe out most of them with the help of its physical structure.

When it comes to talk about application, FSI has been mostly used for circumstances where quality comes more important than resolution. Technique like Aptina FSI has been used for Phantom 2 Vision+. And BSI is mostly used for smaller pixels (e.g 1.1um-) to get higher resolution, as we can find it on more and more high-end mobile phones and cameras.

Smart FSI used on Phantom 3 Standard

For both FSI and BSI, there will be a part of the light absorbed by other part of the sensor (not only wiring), and Smart FSI created a tunnel where light reflects inside and won’t lost info before reaching the substrate. It’s the same theory as optical fiber.

As sectional views shown below, traditional FSI to the left, and Smart FSI to the right.


In such case, it combines the advantages of both of the two sensors, avoid the effect from the sensor itself as much as possible, but also provide better imaging quality with less light signal lost.

At the moment, smart FSI sensor for Phantom 3 Standard should be the best sensor for aerial imaging among these three. It guarantees the quality of the picture, and get the resolution as high as possible. (However it’s still not that high as Phantom 3 Professional).

Based on the theories above, it’s easier to choose among these three. If you need higher resolution with clearer detail, circumstances like mining survey and real exploration, Pro & Adv are suggested. And if you’re planning to use drone for taking pictures for landscape and daily life, Standard will be a better choice. And of course, if you’re not that hurry, you can also wait and see which sensor has been used for the next generation of the products.