Microdensitometer

[2] The granularity measurement[2] 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[2][3] of the measured transmission surface, optical film, or photographic film, in particular .

[3][4] This instrument can illuminate simultaneously an area a few centimeters wide with an ultra thin height, in the micrometer regime.

[4] Advantages include increased depth of focus, significant increases in data collection speed, and superior signal to noise ratios.

This measurement technique, using ultra-thin expanded laser beams, is particularly useful to detect microscopic imperfections in optical coatings or transmission optical surfaces.