After finishing the long series of PTC stories, I asked for new ideas and suggestions for this blog. I got several reactions through this blog, through the www.image-sensors-world.blogspot.com as well as through private mail communication. And the result is that for the time being I will continue for 6 or 7 more blogs around the PTC. As you should be aware of, I developed a software tool to simulate images and to study the influence of different noise sources and specification parameters on the image quality. I will use this software tool to illustrate the effect on the PTC analysis of the following parameters :
– Temperature at which the camera is running,
– Number of photons,
– Conversion gain,
– QE specification,
– Number of ADC bits,
– Non-linearity of the readout node and the source-follower.
Because I do not want to repeat over and over all the settings of the sensor and the camera, I will list the “standard” settings here that will be use in all further simulations (unless otherwise specified). Here they are :
– Sensor size : 640 x 480,
– Number of images generated : 25,
– Conversion gain : 40 µV/e–,
– Analog gain : 1,
– Temperature : 30oC,
– Exposure time changing from 0 s to 6.5 s,
– Number of ADC bits : 12,
– Dark current : 200 e–/s at 22oC,
– Dark random non-uniformity : 30 e–/s at 22oC,
– Dark current doubling temperature : 8oC,
– Saturation level : 17,500 e–,
– Number of photons : 150,000/s,
– QE : 33 %,
– Saturation level non-uniformity : 5 %,
– DC offset of the output : 125 mV,
– Output amplifier noise : 0.3 mV,
– Temporal row noise : 6 e–,
– Fixed pattern row noise : 3e–,
– Repetition frequency row FPN : 16 lines,
– Temporal column noise : 8 e–,
– Fixed pattern column noise : 12e–,
– Temporal pixel noise : 10 e–,
– Fixed pattern pixel noise (offset) : 3 e–,
– Defects : 100 pixels stuck at “1”, 100 pixels stuck at “0”,
– RTS pixels : 900 pixels, RTS chance : 20 %,
– Non-linearity SF : switched off,
– Non-linearity FD : switched off.
When studying the influence of the aforementioned parameters, the first measure taken is the correction of the defect pixels. With this knowledge in hand, the first exercise can start : what is the temperature influence on the PTC, or how can the temperature being used to generate a Photon Transfer Curve ? The answer will follow shortly.
Albert, 14-01-2011.