Contrast Reducing Visibility Meter
Original Publication Date: 1980-Jun-01
Included in the Prior Art Database: 2005-Feb-13
This optical measuring device makes use of the consensual pupillary response of the operator's eyes to establish the task luminance level. The device, shown here schematically only within the chain line 10, comprises a source of light, shown here as a lamp 12, a collimating lens 14 and a twin light spot generator comprising a pair of apertured plates 18 and 19, and a manual control 20. One of the plates 18 is stationary within the device, and the other 19 is moveable with respect to it. One of the plates has a pair of narrow slits arranged at an angle to one another, and the other plate has a single slit arranged to overlay both of the other slits in such manner that two light passages are arranged through the two disks and the distance between them is variable.