Posted by Optical Solutions on September 24, 2021
New instruments and approaches to measuring bidirectional scattering distribution function (BSDF) data make it easier and faster to evaluate light scattering of electronic displays and determine their performance.
The BSDF formula is
L: Luminance on the sample surface at observer direction
E: Illuminance on the sample surface from source direction
The BSDF measurement of a display characterizes how the light is reflected from any display surface or material.
Synopsys offers multiple solutions for measuring the light scattering properties of displays. The results can be imported in optical design software, such as LightTools, for optical system ray tracing and virtual prototyping.
You can also purchase an instrument for high-resolution BSDF measurements, such as the Mini-Diff V2 or the REFLET 180S. In just a few steps, you can configure the instrument to measure the display’s BSDF and quickly provide results.
If you do not need an on-site instrument for scattering measurements, Synopsys also offers on-demand scattering measurements in its light- and temperature-controlled laboratory to provide the most accurate measurement environment for any sample.
The following example outlines how to take a BSDF measurement using the Synopsys Mini-Diff instrument.
First we calibrate the Mini-Diff for reflection prior to the measurement by measuring black and white reference samples, respectively. The reference samples are provided with the instrument.
Then we place the instrument over the sample, which in this case is the surface of the display. The screen is off in order to evaluate only reflected light and not emitted light.
We run an automatic measurement for angles of incidence 0°, 20°, 40° and 60° and for all colors (red, green, blue).
The measurement result shown in the following figure corresponds to the angle of incidence at 20° and with blue input light color. The result shows a narrow specular scattering lob, and is similar for each color and each angle of incidence. This corresponds to our visual observation that there is no color or angle dependence.
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