Andor Technology Neo sCMOS, Руководство по оборудованию

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FEATURES & FUNCTIONALITY
Neo
SECTION 2
Page 37
The dual column level amplifier/ADC pairs have independent gain settings, and the final image is reconstructed
by combining pixel readings from both the high gain and low gain readout channels to achieve a wide intra-
scene dynamic range, uniquely so considering the relatively small 6.5 μ m pixel pitch.
The method of combining signals from two 11-bit ADCs can be divided into four basic steps. The method of
combining signal from two 11-bit ADCs can be divided into four basic steps:
1. At the end of the analogue chain the “Signal” voltage is applied to two independent amplifiers: the high
gain amplifier (e.g. Gain 4) and the low gain amplifier (e.g. Gain 1). This results in two separate digital data
streams from the sensor
2. The camera selects which data stream to use on a pixel per pixel, frame by frame basis using a threshold
method
3. The data is then compensated for DC offset and gain. Again, this is done on a pixel by pixel basis using
the compensation data associated with the data stream. The gain corrects for pixel to pixel relative
sensitivity, pixel node amplifier and the high and low amplifier relative gains
4. The pixels are then combined into a single 16-bit image for transfer to the PC
The sensor has four available individual 11-bit gain settings and four dual amplifier 16-bit settings, as shown in
Table 3 in Section 2.6.1 . The user maintains the choice of opting to stay with 11-bit single gain channel data if
dynamic range is not critical, resulting in smaller file sizes. This in turn offers faster frame rates when
continuously spooling through the Camera Link interface and writing to hard disk.
Table 2: ‘Traditional’ limiting choice: the mutually exclusive effect of high vs low gain amplifier choice on noise floor and
effective well depth
Amplifier gain Electrons / count Noise Signal to noise ratio Effective well depth (limited by ADC)
High Fewer Lower Higher Lower
Low More Higher Lower Higher
Figure 13: High contrast image of fixed labelled cell. Intensity line profile through single row demonstrates pixel regions that were
sampled by high gain (low noise) and low gain (high capacity) amplifiers.