Exact Transfer Function Research Articles

Properties of a Defocused Optical System*

The optical properties of an aberration-free defocused optical system used to image incoherently illuminated objects are analyzed. The exact diffraction optical transfer function (OTF) and point spread function (PSF) are compared to the geometrical OTF and PSF, respectively, for both small and large amounts of defocusing. It follows that geometrical optics does not describe diffraction optics very well for any reasonable amount of defocusing. Calculation of the diffraction OTF is complicated and time consuming, even with a large computer. An empirically derived analytic approximation to the diffraction OTF which is much easier to calculate, is formulated. It is also shown, and examples are presented to demonstrate, that the exact OTF and PSF are different in planes at equal distances on the two sides of the in-focus plane.

State variable feedback decoupling and design of multivariable systems

State variable feedback design of m-input, m- output time invariant linear systems requiring noninteraction and exact transfer functions, considering coupled core nuclear reactor

Solution of a Transistor Transient Response Problem

The transient response of the exact current transfer function, \alpha(\omega) , of a grounded-base junction transistor operating in the short-circuited output condition is compared with the transient response derived from the conventional approximate form for \alpha(\omega) . The response to both a unit impulse and a unit step is calculated, and it is shown how the results may be readily adapted to yield a rapid oscilloscope method of determining the \alpha cutoff frequency and several of the transistor material and dimensional constants.