Choosing the right geometry for your colour measurement needs
Instrument geometries play a pivotal role in accurate colour measurement, as they measure the interaction between light and the material from different, specific angles.
The two most commonly used geometries for reflection measurement are 45/0 and d/8 — the first number is the illumination angle or method, while the second number refers to the observation angle or method. Understanding these geometries will help you choose the right spectrophotometer for your colour measuring processes.
45°/0 Instrument Geometry (Closest to the eye)
A 45/0 geometry spectrophotometer illuminates the sample at a 45-degree angle and detects the reflection of light from 0 degrees, perpendicular to the sample. This setup provides results consistent with how humans perceive colour, making it ideal for assessing colour as it appears in real-world conditions.
It’s used for colour measurement of uniform or flat materials, such as inks, printed sheets of paper, plastic parts, etc.
Suitable applications: Packaging and printed materials, tissue towel. Essentially, any industry where the final appearance to the consumer is critical.
d/8 Instrument Geometry
For irregular surfaces where surface texture and gloss significantly affect the colour perception, a d/8 geometry spectrophotometer is preferred. It uses diffuse illumination (d refers to the diffuse angle) and measures the reflected light at an 8-degree angle, minimising the effects of surface texture and gloss.
Additionally, d/8 geometry can measure the performance of an object in two modes: Specular Component Included (SCI) and Specular Component Excluded (SCE). The latter includes the specular reflection, meaning colour and gloss are measured, while SCE opens the gloss trap so the colour is being measured without gloss. Use the SCI mode for glossy and textured surfaces, with the SCE mode is better suited for precise colour evaluations on smooth or matte surfaces.
Suitable applications: Used for colour formulation and is ideal for industrial and laboratory applications where uniformity is key across different substrates — paints, plastics, textiles, etc.
Spectrophotometers that meet customer expectations
AML Instruments offers a wide range of colour measurement devices that work on 45/0 or d/8 geometries to enhance the quality and precision of your colour assessments. Whether maintaining colour consistency and quality of appearance is key, or you need to ensure uniformity across samples with different textures, both 45/0 and d/8 spectrophotometers have their unique advantages and applications.
Thinking about the properties of the material surface, alongside your measurement requirements and industry standards will help you make the best decision. If you’re still unsure, we have over 40 years experience providing businesses with accurate, flexible, and versatile colour measurement solutions.
Talk to us today to find the right spectrophotometer for your application.
