EFFECT OF INSTRUMENTAL SPHERICAL-ABERRATION ON VISUAL IMAGE QUALITY

The effect of instrumental spherical aberration has been examined thro ugh the construction of telescopes with approximately 1, 2, and 3 wave s of aberration. Contrast sensitivity and resolution results have been obtained, as well as information on the preferred focus in the presen ce of aberration. The results show that an appropriately defined integ ral of the instrumental modulation transfer function (MTF), called MTF a, is the best candidate among objective image quality metrics for des cribing the observed degradation in performance as well as the preferr ed focus. For pupil diameters less than approximately 3 mm the results support the assertion that the monochromatic aberrations of a normal eye are of little importance in visual instrument optical design and t esting. (C) 1996 Optical Society of America