Phase transfer function determn. device for lens of optical system - measures position of focus of beam projected into aperture of system through spiral array of holes in rotary screen

摘要

Light with a well-defined wavefront is supplied from an illuminating device to the aperture of the system (100) with which a perforated screen (108) is associated. The screen is rotatable about an axis (118) parallel to that (114) of the system and contains nine holes arranged along a spiral so that only one hole faces the aperture in any angular position. The beam of light passing through the hole is focused on to a position-sensitive photodetector (112) at right angles to the optical axis. ADVANTAGE - The complete phase transfer function is found more quickly from simple appts.