Backscatter haze measurement using a distributed light source

Abstract

System and method for in situ measurement of haze in a transparency, such as an aircraft windscreen, canopies, windows or the like are described which comprise an annular light source for illuminating a selected test area of the transparency along a selected optical axis, a photodetector, and a lens for projecting an image of the illuminated test area along the axis onto the photodetector.

I claim: 
     
       1. A system for measuring haze in a transparency, comprising: (a) a substantially light tight housing having an open end for placement against a transparency surface;   (b) a substantially circular light source disposed within said housing for projecting light along an optical axis onto said transparency and substantially uniformly illuminating a selected region of said transparency;   (c) an optical detector disposed within said housing substantially coaxially with said circular light source for measuring the luminance of said selected region of said transparency; and   (d) light baffle means between said light source and said detector for blocking direct projection of light from said source to said detector.   
     
     
       2. The system of claim 1 .wherein said housing further includes means for selectively spacing said light source from said transparency. 
     
     
       3. The system of claim 1 wherein said optical detector comprises a photodiode, phototransistor, selenium cell or photoresistor.