Difference between 45/0 optical structure and d / 8 optical
The two most common optical structures for spectrocolorimeter are 45/0 (45 ° toroidal uniform illumination 0 ° reception) and d / 8 (diffuse illumination / 8 ° acceptance). We receive a lot of questions about which is the best choice. The following are guidelines for how these two devices measure color differences and when to use each color.
45/0
In a "fixed geometry" or "single-angle" setup, the first number is the start of the ray and the second is where the ray ends after being reflected from the sample surface. In the 45/0 instrument, the light source is set to 45 degrees and the detector is set directly above 0 degrees.
The 45/0 is ideal for measuring colors on smooth and matte surfaces because it captures the reflections in the sample just as the human eye sees it. Although using it to measure shiny or reflective surfaces is viable, it does not preclude the appearance of the surface and may cause the sample to measure deeper and more saturated than it is.
For example, suppose you have two black samples, one matte and one glossy. Although they are exactly the same black, the data will not match when measured with 45/0. Gloss samples appear darker and more saturated, while dull samples appear lighter. This is due to the difference between direct reflection (glossy sample) and diffuse reflection (matte sample).
d / 8
The d / 8 spectrophotometer's interior is actually spherical. By using a light source baffle and reflecting it off the original white matte surface inside the sphere, the detector receives the reflected light at an angle of 8 degrees to the surface of the object to accurately measure the color.
One of the keys to a sphere device is that it can measure with exclusion of specular reflection (SPIN, SCI) or specular reflection (SPEX, SCE) conditions. The inclusion of specular reflections eliminates the specular effect of surface reflections, which means that it measures only color - not appearance. Mirror exclusion includes the appearance of the surface under measurement.
As an example, let's return to our two black samples, Gloss and Matte, and if you measure two samples using a specular-containing mode, the resulting measurements should be similar. If you measure them with exclude specular reflection, these numbers will be more apart, similar to 45/0.
Which one is best for you?
When it comes to spectrophotometers, an optical structure is not suitable for all. To really identify the best instrument for your application, you must analyze your work portfolio and customer requirements. Contact our experienced color experts to choose the best solution for your workflow.