Color surrounds humans every moment of their lives and affects their behaviors, emotions, and beliefs in small and enormous, conscious and unconscious manner. A color is instrumental in setting a mood, warning of danger, providing vital information, and creating joy. Irrespective of its universal presence, color remains elusive, partly due to the differences in how we perceive it and due to the lack of descriptors for the millions of shades that the human eye sees.
The measurement of color goes past the limits of human vocabulary and perception and allows for capturing of color information as the objective data, establishing a common color language which is important for communication between and within various industries in the world. Today, color measurement is done by two main instruments namely the colorimeter and the spectrophotometer, which have always been confused for each other. These two devices utilize sophisticated technologies to precisely define and quantify color. Although the colorimeter and the spectrophotometer are somewhat related and somehow similar in how they function, the two have unique features which make each suitable for specific type of measurement. Knowing the characteristics of each of these devices can assist in selecting the right instrument for your intended application.
What is a colorimeter?
A colorimeter is a gadget that is used in measuring the amount of specific color of light that a solution absorbs. This device comes with either LED bulbs that produce certain colors of light or a set of colored filters. For you to use this instrument, you first need to select the appropriate color. After that, place a cuvette that contains the solution inside the device. The instrument will then provide an absorbance for the specific color selected. It’s imperative not to forget that a solution of particular color absorbs its color the least. For example, a solution that contains green chlorophyll will absorb the green color the least.
This instrument is designed to carry out a sort of psychophysical sample evaluation by mirroring the perception of the human eye. In other words, the colorimeter is meant to see color as humans do. By use of an illuminant observer combination and absorption filter which separates wavelengths’ broad band, the device distils information of color into tristimulus values to come up with objective color data. If you want, you can compare this data to a reference or standard to ascertain acceptability.
From the Beer’s Law, color absorbance is directly related to the solution’s concentration (as long as the solutions of a similar chemical are measured and the light’s path length remains unchanged). If you draw a graph of absorbance against concentration for solutions that have known concentrations, then you can use the graph to measure the concentration of unknown solutions.
• Usage: Colorimeters are amazingly suitable for measurement of color and ideal for differentiating color, strength, fastness and routine comparisons of colors. For this reason, colorimeters can be useful for quality control. They are utilized in the production as well as assessment stages of manufacturing.
• Drawbacks: While these instruments can produce color measurements of high accuracy, the colorimeters also have a few drawbacks; they aren’t suitable for color formulation, they can’t identify metamerism and are ineffective under variable observer/illuminant conditions.
What is spectrophotometer?
This is a device meant for sample evaluation through the measurement of full color spectrum. This instrument is used for measuring reflectance and transmittance of light as a function of light’s wavelength. This implies that a spectrophotometer is used for measuring reflectance and transmittance for all light colors, and depicts how the reflectance/transmittance differ as the light’s color is changed. Unlike the colorimeter, the wavelengths measured by this instrument goes past the visible into infrared and UV regions. If desired, this device can also be used in calculating psychophysical colorimetric information.
• Usage: These devices give a high level of versatility and flexibility compared to colorimeters as a result of the fact that they provide different observer/illuminant combinations and can function in various geometric arrangements. As such, they are able to measure metamerism, identify colorant strength, assess a wide range of samples, and offer the users the choice between excluding and incorporating specular reflectance so as to account for the geometric attributes. The spectrophotometer’s full spectrum analysis offers greater specificity by identifying differences in color that were not identified by the colorimeters. These instruments are for a wide range of usage during the research and development stage, including formulation of color and color system development. It can also be used for quality control during the time of production.
• Drawbacks – Although the spectrophotometers have been complex devices, technological advances have today made it possible to design smaller and user-friendly gadgets, getting rid of the size and complexity concerns. Nonetheless, not every person needs the capabilities of the spectrophotometers and may find their requirements are met by the colorimeter.
Choosing a spectrophotometer or colorimeter
Selecting a color measurement device requires you to understand the merits and demerits of these instruments as highlighted above. If you are not sure about which device is best suited for your purpose, the questions below can help give you an idea of what you require when considering either of the two options .
• The geometry of the instrument – Does the device have the geometry needed for your application?
• The type of data needed – Does the application need tristimulus values or spectral data?
• Accuracy and precision – What are the levels of accuracy and precision necessary to obtain satisfactory outcomes?
• Light source – Does the device have a light source for the application?
• Ease of use – Has the device been manufactured with the user in mind? How easy is it to operate?
• The rapidity of measurement – How fast can you obtain data? What sort of preparation is required?
• Robustness – Is the device suitable for environmental in which it’ll be used? Is it able to withstand extreme factory conditions?
• Product quality – Not all instruments used in measuring color are the same, irrespective of whether they’re spectrophotometers or colorimeters. By choosing the best instrument, you are confident you’ll be able to get the best results.
• Software interface – Does the software accompanying the instrument make it possible for you to gather, analyze, and share information with ease?
So what are the differences?
A table highlighting the difference between the colorimeter and the spectrophotometer is shown below.
|This instrument quantifies color through the measurement of three main color components of light i.e. green, red, and blue.||This device measures a precise color in the visible light wavelength|
|The colorimeter utilizes fixed wavelengths that are only in the visible range||The spectrophotometer utilizes wavelengths in wider range i.e. IR and UV|
|The colorimeter measure light absorbance||The spectrophotometer measures the quantity of light passing through the sample. It measures the reflectance or transmittance of colors as the function of wavelength|
|The colorimeter works with the light in visible part of an electromagnetic system only||The spectrophotometer works with the ultraviolet and infrared light, and the visible light as well.|
|The Colorimeter is relatively cheaper||The Spectrophotometer is relatively costly. This device has a wider range of functions including those found in the colorimeter. Thus, the spectrophotometer is more costly compared to the colorimeter|