Application Difference between Chromometer and Spectrophotometer

How do you establish color standards, improve product appearance, color quality control, and then computerize color matching? Here we have to mention a color detection tool - the colorimeter.

At present, there are many types of the colorimeter, brands, and vendors, and some customers do not have a deep understanding of colorimetry, and there is a big price gap between all kinds of instruments. Why are the measurements different? Why are some called colorimeter and some called spectrophotometer? What is the difference between these instruments, and what are they used for?

The following is our detailed description:

1. What is a "colorimeter" and what is a "spectrophotometer"?

As the name implies, a "colorimeter" is used to measure the color difference between two samples. It is less precise and generally does not accurately give the absolute value of the color coordinate space (L, a, b values), but it does give the value of the color difference (ΔE) between two samples (usually between standard and sample). This kind of colorimeter has no absolute color data, no way to exchange data with others, and no way to create and manage its own color standard database.

The spectrophotometer is highly accurate and uses pre-determined plate settings, eliminating the need for standard black and white plates in the calibration of conventional colorimeters and aberrometer. The built-in software is powerful and includes all the necessary color equations, standard light sources for different tasks, and a large number of industry- and application-specific metrics.

2. Design Principles

Spectrophotometers are designed based on the spectrophotometer principle, while ordinary colorimeter is designed based on the three-stimulus value principle. Colorimetric colorimetry offers high accuracy and increasing versatility. Color Spectrophotometry can measure SCI simultaneously (a method that includes specular reflection for measurement.) For this reason, it reduces the influence of the sample surface and is particularly suitable for color quality monitoring and computer color matching) and SCE (which is a measurement method that excludes specular reflections. The results obtained from this type of measurement are similar to those observed by the naked eye). Because it measures reflectance at each wavelength, it is suitable for complex color analysis and, of course, is relatively expensive. The three-stimulus colorimeter is relatively inexpensive, small in size, outstandingly flexible, and easy to operate.

3. Measurement Principle

The colorimeter can automatically compare the color difference between the sample and the inspected product and output CIE L, a, b three groups of data and four groups of color difference data of △E, △L, △a, △b after color comparison. Unlike colorimetric colorimetry alone, spectrophotometers can measure the "reflectance curve" of each color point (10nm or 20nm wavelength interval), while chromatic aberrometer cannot. A spectrophotometer can simulate multiple light sources, whereas a colorimeter typically simulates only one or two light sources.

4. Light Source

In a color measurement instrument, the primary considerations in choosing a light source are stability, light source orientation, longevity, and the validity of the spectral curve obtained. Most of the current light sources are LED and Xenon lamps.

Xenon lamps, which are primarily used for UV measurements, emit brief, high-intensity arcs but are difficult to produce repeated arcs of equal intensity. In addition, the xenon light source requires a complex high-voltage oscillation excitation circuit, and maintenance is very complicated.

The application of LED lights is technically and economically appropriate for the current standard color measuring instruments. Especially for portable instruments, they need to be lightweight, energy-efficient, and easy to maintain and operate. Color spectroscopy instruments use long-life CLEDs (full-band balanced Led light sources), eliminating the need for frequent light source changes.

In general, a colorimeter is used to measure color differences between samples for comparison. Spectrophotometers contain all the necessary color equations, standard light sources for different tasks, and a large number of industries- and application-specific metrics that are particularly well suited for color quality monitoring and computer color matching and are sufficient for color measurement in quality control in almost all applications.