reflectionsdensitometri

Reflectionsdensitometri is a measurement technique used to quantify the optical density of a surface by assessing reflected light. It is primarily employed for analyzing inks, coatings, dyes, and printed materials, where the amount of absorbing material on a substrate reduces the amount of light reflected back to the sensor.

Principle: A stable light source illuminates the sample while a photodetector records the reflected irradiance. The result is related to the amount of light absorbed by the surface; a common formulation defines optical density D = log10(I0/I), with I0 the incident and I the reflected light. In practice, densitometers report a density value or the corresponding reflectance (often as a percentage).

Instrumentation: Reflective densitometers typically comprise a light source, an optical path to a detector, a calibration standard (white and black references), and a measurement aperture. They can operate at specific wavelengths or color channels (for example red, green, blue) to evaluate process colors in printing. There are hand-held spot devices and larger table-top instruments used in labs and presses.

Applications: In the graphic arts and printing industries, reflectionsdensitometri is used to monitor ink densities, verify color balance, ensure consistency across runs, and diagnose printing defects. It also supports quality control in coatings, textiles, and other surface finishes where color density matters.

Limitations: Measurements reflect surface reflectance and are influenced by substrate color, gloss, and measurement geometry. Accurate results require standardized illumination, geometry, and calibration; multi-angle or multi-spectral devices may be needed for complex surfaces.

See also: densitometry, reflectance spectroscopy, color management.