OPTICAL FILTER HAVING AT LEAST TWO DIFFERENTIABLE LIGHT TRANSMITTANCE REGIONS, AND INFRARED OPTICAL SYSTEM LOCATING THE FILTER AT FIELD STOP IN OPTICAL PATH

摘要

PURPOSE: An infrared ray optical system for an infrared camera is provided to differently control light intensity transferred to an image sensor of front monitoring equipment according to each viewing direction of an image. CONSTITUTION: An image is imaged on the field stop location between a most back side lens(10) of an object unit and a most front side lens(20) of an imaging unit. A viewing direction transmission ratio control filter(30) reduce the quantity of light transferred to an image sensor of front monitoring equipment to desire level according to viewing direction of an image. An infrared ray optical system for an infrared camera comprises a sunlight filter reducing the quantity of light of a specific wavelength band.