VISIBILITY MEASURING APPARATUS

摘要

PURPOSE:To obtain the results of measurement near the results of observation by naked eyes with direct measurement of visibility, by forming an image of a pattern formed on a target at a light receiving section to perform a signal processing of an output of a photoelectric converter. CONSTITUTION:A pattern 2 formed on a flat target 1 is made up of five parallel black bands and four white bands. Light emitted from a light source 3 is turned to a parallel luminous flux with a lens 4 to irradiate the target 1 from the back 1b thereof and a photo sensor 5 detects the intensity of the emission light 6 from the target 1 to control the intensity of the emission light to a fixed value. A telescope system 12 comprising an objective lens 10 and an eyepiece lens 11 receives the emission light 6 of a projector section 9 to form a real image of the target 1 on a planar light receiving surface 15a through a magnifying lens 14. An output of a photoelectric converter 15 is inputted into a control arithmetic unit 13 through an A/D converter 22 to compute visibility at a space between an installation point of the target and that of a light receiving section.