There are a number of techniques used to manipulate the readout of CCDs to achieve various effects. One of these techniques is ‘binning’. For sCMOS based cameras, such as the Andor Neo and Zyla models, the binning process differs from that of CCD’s due to the technical differences between the two sensor technologies. This technical note outlines the use of binning for sCMOS and the effect of frame rates on different Neo and Zyla sCMOS camera models at different resolutions. Binning for CCD camera models is explained in the Andor Technical Note CCD Binning- What does Binning mean?
What is Binning?
Binning is the procedure of combining the signal from a number of adjacent pixels into an output for a single pixel (super-pixel). For 2x2 binning, an array of 4 pixels becomes a single larger pixel, reducing the overall number of pixels that need to be readout and also reducing the resolution available. By combining the charge from 4 pixels into one super-pixel, the number of read events is reduced, therefore resulting in a lower read noise. Consequently, it is possible to use binning to increase the signal to noise ratio at the expense of lower resolution.
Binning and sCMOS
Figure 1: Andor Zyla and Neo sCMOS Cameras
In general, when binning is performed for CCD’s, fewer pixels are read-out so the acquisition speed can be increased. This provides benefits when a higher frame rate is desirable and the reduced resolution is not so critical.
Although the binning process is different to that of CCDs, binning in the Neo and Zyla sCMOS (Figure 1) also enables significant increases in frame rates. In the Andor Neo and Zyla sCMOS cameras, binning is performed in the FPGA after the image is read out from the sensor. Therefore, applying binning makes no difference to the number of pixels that are read-out from the sensor. Binning is performed after all other processing takes place and the binned image is then transmitted over the Camera-Link or USB 3.0 interface to the PC. The frame rates which can be achieved from the sensor are unaffected- but binning may enable higher frame rate transmission to PC.
It is important to note that the bit-depth does not scale with binning, 12-bit images will saturate at 4095 counts while 16- bit images will saturate at 65,000 whether binning is applied or not.
Neo 5.5, Zyla 5.5 and Zyla 4.2 (Camera-link and USB 3.0 variants)
Binning in the Neo 5.5 and Zyla 5.5 USB 3.0 and Zyla 4.2 USB 3.0 can have a significant effect on frame rates since the sensor read-off is the limiting factor and not the FPGA processing. This is illustrated in the following figures for Neo 5.5, Zyla 4.2 and Zyla 5.5 USB 3.0. This increase in speed with binning does not apply to the Zyla 5.5 or Zyla 4.2 10-tap since the maximum speeds are already being achieved with the 10-tap Camera Link interface; however there is a slight increase in acquisition speeds when using the 16-bit mode in Zyla 5.5 10-tap.
The effect of Binning on frame rates of the Neo 5.5, Zyla 5.5 and Zyla 4.2
Neo 5.5 RS= Rolling Shutter Mode, GS= Global Shutter Mode 12-bit (left), 16-bit (right)
Figure 2: The effect of binning on the frame rate of Neo 5.5 at 12-bit (left) and 16-bit (right)
Zyla 4.2 USB 3.0 RS= Rolling Shutter Mode, GS= Global Shutter Mode
Figure 3: The effect of binning on the frame rates of the Zyla 4.2 at 12-bit (left) and 16-bit (right).
Zyla 5.5 USB 3.0 RS= Rolling Shutter Mode, GS= Global Shutter Mode 12-bit (left), 16-bit (right)
Figure 4: The effect of binning on the frame rates of the Zyla 5.5 at 12-bit (left) and 16-bit (right).
Zyla 5.5 Camera Link RS= Rolling Shutter Mode, GS= Global Shutter Mode 12-bit (left), 16-bit (right)
Figure 5: The effect of binning on the frame rates of the Zyla 5.5 Camera Link at 12-bit (left) and 16-bit (right).
The binning process on sCMOS sensors differs from that of CCD’s, but as with CCDs binning may also be utilised to provide increased frames rates. In this technical note, the effects of binning on the frame rates achievable with the Neo, Zyla Camera Link and USB 3.0 models have been outlined- showing that in some cases the frame rates can be significantly increased. For more information on the Neo and Zyla sCMOS cameras please go to the following link: https://andor.oxinst.com/products/scmos-camera-series/
Data Tables for Andor sCMOS Neo and Zyla models showing the framerates (fps) attainable under different modes