Raspberry Pi Mono
Raspberry Pi V2 8 Megapixel Monochrome.
While we have been asked by a number of people if we can convert a Raspberry Pi camera, we hesitated on converting because the cost to convert a sensor to monochrome far exceeds the cost to buy a stock unit. But as we learned more about the camera, we found that there is some remarkable engineering in the Sony IMX219 sensor that the camera uses. Another thing that caught our attention is that the Raspberry Pi can save a RAW image which opens up the door to some higher end applications such as lenless imaging and scientific analysis. With a typical USB camera, the video output is a compressed format which means there are certain applications which the USB cameras can't do. While some people were successful in using toxic chemicals to remove the Color Filter Array (CFA) from the V1 camera, those chemicals did not work with the V2 camera.
Converting such a tiny sensor can be challenging, but we did figure out how to do an edge to edge removing the microlenses, CFA and then the 2nd microlens layer (this camera has microlenses above and below the CFA).
Some information about the sensor:
IMX219 is a diagonal 4.60mm (Type 1/4.0) CMOS active pixel type image sensor with a square pixel array and 8.08M effective pixels. This chip operates with three power supplies, analogue 2.8V, digital 1.2 V, and IF 1.8 V, and has low power consumption. High sensitivity, low dark current, and no smear. This chip features an electronic shutter with variable charge-storage time.
- Back-illuminated CMOS image sensor Exmor RTM
2-wire serial communication circuit on chip
CSI2 serial data output (selection of 4lane/2lane)
Timing generator, H and V driver circuits on chip
CDS/PGA on chip
10-bit A/D converter on chip
Automatic optical black (OB) clamp circuit on chip
PLL on chip (rectangular wave)
High sensitivity, low dark current, no smear
Excellent anti-blooming characteristics
Variable-speed shutter function (1 H units)
Max. 30frame/s in all-pixel scan mode
Pixel rate: 280 [Mpixel/s] (All-pixels mode)
180 frame/s @720p with 2x2 analog (special) binning, 60 frame/s @1080p with V-crop
Datarate: Max.755Mbps/lane (@4lane), 912Mbps/Lane(@2lane)
- CMOS image sensor
Image size : Diagonal 4.60mm (Type 1/4.0)
Total number of pixels : 3296(H) × 2512(V) approx. 8.28M pixels
Number of effective pixels : 3296(H) × 2480(V) approx. 8.17M pixels
Number of active pixels : 3280(H) × 2464(V) approx. 8.08M pixels
Chip size : 5.095mm (H) × 4.930mm (V) (w/ Scribe)
Unit cell size : 1.12m (H) × 1.12m (V)
Substrate material : Silicon
IMX219 Cross -Section