Fokalgrid
Fokalgrid, or focal grid, is a calibration feature used in optical instrumentation to project or imprint a regular grid pattern at the focal plane of a camera, spectrograph, or telescope imager. It provides a known reference geometry that enables precise assessment of the instrument’s optical performance, including alignment, scale, and distortion.
Construction and forms vary. A focal grid can be a physical mask with an etched grid inserted
Applications encompass astrometric calibration, distortion mapping, and plate-scale determination. By recording images of the illuminated grid,
Operation notes. The focal grid is usually placed at or near the focal plane and activated during