案例十一：反射顏色測(cè)量

2019/08/07

Sample Setup: Reflected Color

Overview

Color measurement involves determining the reflection spectrum of a sample and applying it to a standard illuminant. The amount of light energy the sample reflects is manipulated and reduced to tristimulus values X, Y and Z. These values correspond to the physiological response of the three types of color receptors in the human eye. X, Y and Z values are combined into uniform colorspace values such as L*, a* and b*.

Spectrometer

A USB4000 with a 25 m Slit and Grating #2 (350-1000 nm) works well for color analysis. For those using an integrating sphere as the sampling optic, we recommend an L4 Detector Collection Lens to improve sensitivity.

Sampling Optics

When taking reflective-color measurements, your data depends on sampling geometry. The R400-7-VIS-NIR Reflection Probe provides illumination and detection from the same direction. If you use the probe at a 45? it measures diffuse reflection. If you use the probe at a 90? it measures specular reflection. The distance from the probe to the surface determines the sample size. An alternative is the ISP-REF Integrating Sphere, which provides 180?illumination and detection from flat surfaces for measuring specular and diffuse reflection.

Measurements

Reflectivity is measured against a reference standard such as the WS-1 Diffuse Reflectance Standard. SpectraSuite Spectroscopy Operating Software calculates a variety of colorspace values from the reflection spectra.

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