Off-axis, slit based MTF measurements at PTB

Abstract

This article presents off-axis modulation transfer function (MTF) measurements in the image field covered by the azimuthal angle θ = ±20 deg and a defocus range of ∆z ∈ [−40 µm, +40 µm] with the slit based MTF measurement setup at PTB. The experimentally determined standard deviation of a set of N = 10 MTF repetition measurements under a certain set of repeatability conditions is employed to estimate the standard uncertainty u exp with respect to the repeatability of measurements in the setup. The importance of measurement repeatability and measurement reproducibility in the assessment of measurement accuracy and measurement uncertainty for interlaboratory comparisons is discussed.