3521940

Information

• Patent Grant
• 3521940

• References
• Source

• Patent Number

  3,521,940

• Date Filed

  Not available

• Date Issued

  Tuesday, July 28, 1970
  54 years ago

• CPC

  • A61F9/062 - with movable polarising filter discs
  • A61F9/022 - Use of special optical filters
  • G02B27/281 - used for attenuating light intensity

• US Classifications

  • 359 - Optical: systems and elements