Convenience method for measuring the modulation transfer function of focal plane arrays

The modern trend in focal plane arrays (FPAs) implementation is to include an increasing amount of analog signal processing in micro technology circuitry embedded in the FPA construction. This technology includes such function as time-delayed integration (TDI). While such integration makes the FPA and its associated signal processing more compact and faster, it introduces new complications into the testing of the FPA, since the detector outputs, by themselves, are no longer directly accessible. The CdHgTe FPAs detectors with on-chip TDI have been successfully incorporated into infrared imagers. These impose requirements on the instrumentation to establish the modulation transfer function (MTF) of the integrated FPAs. This paper details a method for measuring the MTF for such arrays within 3-5μ+m and 8-14μ+m spectral band. A description of a test facility for testing and evaluating MTF of FPA is given. We use a knife-edge target to measure MTF. The Pentium III computer system takes the charge of controlling and calculating. Some other methods of MTF measurement will be mentioned.