Since adaptive optics on large telescopes provides almost diffraction limited resolution, Nyquist sampling of moderate
fields requires large format arrays. Because of limited substrate sizes there is a tendency to shrink the pixel size to extend
the array format beyond 2Kx2K. However, with smaller pixel sizes the coupling capacitance between neighboring pixels
becomes more important and its effect on performance and basic parameters of large format arrays has to be analyzed.
Therefore, techniques to measure the effect of the coupling capacitance on the conversion gain will be presented. The
capacitance comparison method and the autocorrelation technique will be discussed and compared quantitatively. It will
be shown that the "noise squared versus signal" method which is in common use to obtain the conversion gain, can only
be applied for negligible interpixel capacitance. The X-ray decay of Fe55 is a well established calibrator for silicon and
can be applied to Si-PIN diode arrays in order to verify the different methods. Finally, a new technique called single
pixel reset will be presented, which directly measures the impulse response or point spread function generated by the
inter-pixel capacitance. The measured PSF impulse response can be used for the deconvolution of images to compensate
the degradation of spatial resolution induced by the interpixel capacitance. The difference of interpixel capacitance
measured in infrared hybrid arrays and Si-PIN diode arrays hybridized to the same multiplexer will be discussed.
Keywords:, interpixel capacitance, conversion gain, point spread function, single pixel reset, CMOS hybrid, Hawaii-
2RG, HgCdTe, Si-PIN, HyViSI.