Microdensitometer

thumb|right|Microdensitometer

A microdensitometer is an optical instrument used to measure optical densities in the microscopic domain. A well-known microdensitometer, used in the photographic industry, is a granularity instrument or granularity machine. The granularity measurement involves the use of an optical aperture, 10-50 micrometers in diameter, and in the recording of thousands of optical density readings. The standard deviation of this series of measurements is known as the granularity of the measured transmission surface, optical film, or photographic film, in particular .