The different domains of the point spread function ‐ Small angle vs large angle

Purpose The Point‐Spread‐Function peaks at 107, and drops off to 10‐2 at 90 degrees, a dynamic range of 109. Important changes in the PSF already occur within the first 1 minute of arc, so spatially the dynamic range is 105. Very different experimental techniques are needed to describe the small angle (aberrometry, double pass) and the large angle (straylight) domains. What optical irregularities achieve such PSF? Methods Literature models for the aberration structure of the human eye media, in particular Thibos et al. JOSA A 2002 were used to derive the PSF. The Thibos et al. model was extrapolated to allow inclusion of the high orders of aberration not normally included in aberrometry, but potentially visible with double pass, so as to encompass as much as possible from the PSF. Results The modeled aberration structures of the eye covers the central part of the PSF up till about 0.3 degrees if extreme high orders were included. For angles >1 degree predicted values were far below the actual values of the PSF. On the other hand, double pass techniques grossly overestimate PSF values at angles of 0.3 degree and above. Using an alternative model for the aberration structure of the eye the PSF could be described up till 1 degree. Small particle scattering was essential to predict the PSF for angles above 1 degree. Conclusion In the assessment of disturbances to the optical media two domains must be discriminated: the aberration domain and the small particle domain, with corresponding parts (small angle vs large angle) to the PSF. Straylight originates from irregularities of small characteristic size (10 micrometer and below), as opposed to disturbances to the central part of the psf (<0.3 degrees), originating from large scale irregularities.Commercial interest