Practical method for evaluating optical image defects caused by center artifacts

Abstract

Abstract. In modern optical element manufacturing, center artifacts are a common problem. A center artifact is a shape error that is rotationally symmetrical, steep, and localized at the center. These properties cause characteristic image defects different from those caused by ordinary irregularities. However, tolerancing center artifacts has not been fully discussed or properly carried out. We propose a simple mathematical model for center artifacts using normal distribution function as a figure model and showing that this function can be represented by a polynomial including odd-order terms. Our method enables appropriate optical simulation and tolerancing for center artifacts using general optical design software.

Updating the peak-to-valley (PV) irregularity specification for the modern world

“…Often inadequate tolerances are discovered "the hard way"; that is after all the manufactured optical components are assembled but the completed optical system fails to perform to its overall optical performance specifications. Some published examples include a 300x zoom system that needed a tolerance on local slope for key aspheric elements [4], optics for the National Ignition Facility (NIF) laser system that required power-spectral density (PSD) specifications [5], and wide-field aspheric camera lens suffering from localized artifacts in the center of the lens [6]. Surface form errors of the sort shown in figures 5 and 6 are often termed "mid-spatial frequency" (MSF) errors, and PV irregularity will often be…”