摘要 |
The average aperture width in a small area of an apertured member, such as a shadow mask for a cathode-ray tube, is determined by passing a beam of substantially monochromatic light through an area of the member to form an interference pattern, detecting the intensities of at least two light fringes of the interference pattern, generating electrical signals which are representative of the detected intensities and then deriving the average width of apertures in the lit area of the member from the generated signals. |