A two-dimensional intensified photodiode array is used to measure charge exchange recombination emission in the TFTR. The noise of this detector has been characterized to provide a better estimation of the error bars associated with ion temperature measurements. Contributions to the measured signal include a dc level offset, an integrated dark signal, and the actual photon signal. In addition to photon noise, there is a significant readout noise. The analysis was complicated by a nonlinear response of the readout circuitry. The detector output is linearized and the pixel-to-pixel gain variation is removed with a white field correction. The noise has been modeled over a range of integration times of the detector and gains of the intensifier, allowing an estimation of the uncertainty in the measurement at each pixel, and therefore its appropriate weight in the fitting function.
