Apparatus for monitoring the optical quality of a beam radiation

Abstract

An improved apparatus for monitoring the optical quality of a beam of coherent radiation or an image from an incoherent source is disclosed. The apparatus includes a disk capable of being rotated and having a plurality of rings of slit sets radially disposed within the disk symmetrically about a central axis at a plurality of radial positions wherein each ring of slit sets includes a plurality of slit sets, symmetrically disposed about the ring, each adapted for passing a focused beam of radiation therethrough. A suitable beam steering mechanism such as an adjustable mirror is adapted for directing focused radiation from a first ring to a second ring for varying the intensity of the radiation passing through the slits to detector means for improved signal processing and for varying the parameters of the slits passing the radiation for optimizing the measurement of various beam parameters for determining the optical quality of the radiation. Detector means positioned behind the disk in optical line-of-sight communication with the adjustable mirror through the slits in the plurality of slit sets in each ring are adapted for providing data signals which when combined with synchronization signals, passing through the same slit as the radiation producing the data signal, results in error signals proportional to beam jitter, defocus and astigmatism. The apparatus is adapted for measuring quickly the optical quality of a beam having a signal-to-noise ratio variable between a low and a high value.