We talked about the improved sensitivity of latest generation CMOS image sensors compared to CCD – see here for the details. For the CCD and CMOS image sensors we measured quantum efficiency and read noise, we also collected video and images at various light levels from our subsequent cameras.
The CMOS image sensor has both improved Quantum Efficiency (QE) and almost half the read noise (about 9 electrons for the CCD and 4 electrons for the CMOS image sensor).
The images below show how this translates to the image information you can obtain. Both images are stills from real time video at Full HD and 60 frames per second. The light level of 0.3 Lux is just an example; it doesn’t show the limiting light levels of these image sensors. The CCD camera uses a top quality image sensor. Both images are color-processed; lower light levels can be achieved with monochrome image sensors. We wanted to compare real life situations so the cameras are uncooled and running at full speed around room temperature. The scene, well that’s just something our engineers setup with “hard to photograph” package materials to show off what can be done.
Image from CCD camera (9 electrons of read noise) at 0.3 Lux
Image from CMOS camera (4 electrons of read noise) at 0.3 Lux
For outdoor applications, this means a better signal to noise ration (SNR) in low light extending the operational envelope of the daylight camera into more challenging lighting conditions.
In measurement and machine vision applications this can open up possibilities for improved accuracy with better fill factors at the same light levels or improved SNR. If there are motion artifacts, lower integration time can then be used…
So what can you do with 4 electrons of read noise?