title: Experimental evaluation of geometric accuracy and stability of the image orthicon for astronomical applications.
abstract: Distortions were measured at thirty-six positions over the photocathodes of four different types of image orthicon tubes operated in a high precision camera system designed for astronomical use. Rms values of distortion for these tubes were found to be of the order of 0.2% to 0.3% of the picture width. Changes in distortion over 16-26-h periods of operation were measured for three tubes and were found to be of the order of 0.02% to 0.03% of the picture width, making it possible to correct astronomical TV images for distortion to within a few parts in 10(4).
authors.forename: W T
authors.initials: WT
authors.lastname: Powers
authors.forename: J
authors.initials: J
authors.lastname: Burns