The effect of aberrations on objectively assessed image quality and depth of focus

The effects of aberrations on image quality and the\udobjectively assessed depth of focus (DoF) were studied. Aberrometry data from 80 young subjects with a range of refractive errors was used for computing the visual Strehl ratio based on the optical transfer function(VSOTF), and then, through-focus simulations were performed in order to calculate the objective DoF (using two different relative thresholds of 50% and 80%; and\udtwo different pupil diameters) and the image quality (the\udpeak VSOTF). Both lower order astigmatism and higher\udorder aberration (HOA) terms up to the fifth radial order were considered. The results revealed that, of the HOAs, the comatic terms (third and fifth order) explained most of the variations of the DoF and the image quality in this population of subjects. Furthermore, computer\udsimulations demonstrated that the removal of these\udterms also had a significant impact on both DoF and the\udpeak VSOTF. Knowledge about the relationship between\udaberrations, DoF, image quality, and their interactions is\udessential in optical designs aiming to produce large\udvalues of DoF while maintaining an acceptable level of\udimage quality. Comatic aberration terms appear to\udcontribute strongly towards the configuration of both of\udthese visually important parameters