Effects of wavefront aberration on visual instrument performance, and a consequential test technique.

Assessment of the visual image quality produced by afocal optical systems is complicated, by both the coherent coupling between eye and instrument and the general lack of correlation between the modulation transfer function and visual performance. This paper summarizes previous results obtained by the authors on simulating primary wavefront aberrations and extends the results to more typical higher-order aberrations, using the same image processor as before. The results strongly support the adoption of a form of Strehl ratio measurement as an outstandingly simple, yet visually appropriate assessment method for afocal systems. A possible test layout is suggested.