ABSTRACT
The use of resolving power tests offers advantages of simplicity, convenience and low cost for some forms of evaluation of optical systems. The effect of contrast has been noted, and it was the observed change of modulation upon imaging that initially suggested an alternative and complementary means of image evaluation from consideration of the physical optics of image formation rather than geometrical optics. A linear scan across this ‘light mound’ by a micro-photometer equipped with a pinhole aperture will give an intensity profile representing the three-dimensional point spread function. The mathematical treatment of optical images has developed from audio theory, which is concerned with variation of signal amplitude with time, to the two-dimensional spatial variations of light intensity. Lens design by computer packages utilizes predicted modulation transfer function data to evaluate the effects of changes in design parameters.
