Luckiesh-Moss visibility meter

Luckiesh-Moss visibility meter

[lü′kēsh ′mȯs ‚viz·ə′bil·əd·ē ‚mēd·ər]
(engineering)
A type of photometer that consists of two variable-density filters (one for each eye) that are adjusted so that an object seen through them is just barely discernible; the reduction in visibility produced by the filters is read on a scale of relative visibility related to a standard task.