JAI SW-2000M-CL-65 User Manual

JAI SW-2000M-CL-65 User Manual Manual pdf 10 page image

SW-2000M-CL-65１０5 Operation and functions5.1 Introduction5.1.1 Image sensorThe SW-2000M-CL-65 is built around a high performance CMOS line scan image sensor, whichconverts the light collected by each pixel into electrical charge. The amount of chargegenerated in each of the individual pixels is basically directly proportional to the amount oflight they receive.The sensor has two options to store the charge of each pixel. These are called Quantum Wells.The smaller well can hold about 60,000 electrons (60 ke-), while the larger has capacity for 360ke-. The larger well should be used whenever feasible as it provides the best image quality dueto higher dynamic range and better signal-to-noise ratio (SNR).SNR is limited by the shot noise of the light itself and thus it is beneficial to collect as manyphotons (light) as possible. The smaller well can be used to provide about six times higherresponse to light, but with the cost of lower SNR and dynamic range.Correlated Double Sampling (CDS) is used for sampling the charge voltage and the reset levelto find the difference, which is then digitized into more than 12 bits and sent out of the sensorfor processing.Fig.5. Sensor block diagrame-PIXELSMALLLARGEVOLTAGE VOLTAGECDS A/D 12½ BITSQUANTUM WELLCOMMAND: SENSOR