| The imaging properties of far infrared detector arrays are analyzed. An arbitrary optical system imaging partially coherent light is reviewed. The imaging and detection process is correlated to the coherence properties of the imaged light. A selection set of optical flux concentrator arrays is set forth with reference to a literature review. A selection procedure for the concentrators is outlined which includes a derived performance function.; Transverse and longitudinal detector geometries are frequently considered in far infrared imaging problems. A ray model is constructed to describe the optical-transverse detector system. The absorbed photon density in a transverse detector is computed with a Monte Carlo simulation. The subsequent transport of the photogenerated holes is evaluated by solving the steady state diffusion equation. With the evaluation of the steady state current density, transfer functions, point spread functions and diffusive cross talk are determined.; With a Boltzmann transport equation approach, the response of a longitudinal detector array is analyzed. Signal equations are derived which relate the signal current density to the absorbed photon distribution and other relevant parameters. The various parameters derive from scattering and recombination of the photogenerated charges. Each parameter is qualitatively discussed, mathematically analyzed and algebraicly modeled. The absorbed photon distribution is computed with the aid of an optical multilayer model. The absorptive efficiency and the spatial distribution of the absorbed photons is computed for various layers of the longitudinal detector. The imaging response of the detector array is evaluated from the derived signal equations. An analytical expression is derived for the transfer function of an arbitrary optical-longitudinal detector array system. The derived transfer function includes the effects of diffusion and recombination of the photogenerated charges. Alternate measures of the detector's imaging response are derived; the transfer function, the point response function, the diffusive cross talk and the responsivity are computed as a function of various detector operating and design parameters. Conclusions which relate the detector's imaging performance to several operating and design parameters are made. |
