When the bias-subtracted linearity data in Figure 29 are plotted as signal rates (Figure 30), it is apparent that the CASPIR array has a quadratic non-linearity that must be allowed for during data reduction. The best description of this non-linearity is currently given by the equation:
It is possible that different quadratic coefficients apply to different pixels. Further investigation of this effect is required.
Figure 30: Raw linearity data for readout method 2 plotted as signal rate versus
raw counts. The signal rates for the four output amplifiers are plotted
separately. The raw data show a quadratic non-linearity.