Due to poor air quality related to fires in California, the Academy’s San Francisco offices will be closed Friday, Nov. 16. Member support staff will not be available by phone and responses to emails may be delayed.

  • Illustration by Edmond H. Thall, MD.
    File Size: 595 KB
    Refractive Mgmt/Intervention

    The electromagnetic (EM) spectrum. The spectrum is divided for practicality into regions in which the radiation is generated and detected by similar techniques and equipment; thus, various EM regions partially overlap. Notice the relatively small visible portion of the EM spectrum (red bar) compared with other portions.