What is a spectrophotometer
What is a spectrophotometer?
A spectrophotometer is a measurement product that brings a high-performance, easy-to-use colorimeter to the market in a lightweight and compact form. Portable spectrophotometer is a measurement product that brings excellent performance and easy-to-use colorimeter to the market in a lightweight and compact way. It can be used for color measurement in automotive, new materials, new energy, plastic, leather, hardware, textile, food, pharmaceutical R&D, aviation and other industries.
Features of spectrophotometer
- Can be measured in any position.
- Can simulate a variety of light sources.
- Can measure the “reflectance curve” of each color point (10nm or 20nm wavelength interval).
- The use of a xenon lamp allows the instrument to be placed anywhere on the sample surface.
- Highly accurate measurement of objects.
- Portable and stylish body with illuminated finder’s mirror.
The portable and stylish body with illuminated spotting scope allows the user to quickly and precisely position the instrument on the object.
What does a spectrophotometer do?
When it comes to spectrophotometer, not professionals, the first reaction must be “what is a spectrophotometer”, “what for ah”.
In fact, spectrophotometer is a high-performance, accurate test color detection instrument, which is often said that the colorimeter, of course, it is more advantageous than the simple colorimeter. Can be divided into portable spectrophotometer and desktop spectrophotometer.
Can meet the laboratory, factory floor and the operation of the work site, covering almost all applications of quality control in the color measurement link. Not only can accurately measure the absolute value of color, and support the exchange of color data, with the entire color management system, you can coordinate color matching, and finally complete the goal of color uniformity.
The principle of spectrophotometer
Spectrophotometer generally uses prisms, gratings, interference filters, adjustable or discontinuous series of monochromatic light sources to achieve spectrophotometry, and then analyze single color information according to the principle of dispersion to achieve color figures. Spectrophotometer can finally display chromaticity information according to the internal setting of chromaticity space and calculation formula, and output in the form of digital. In addition, spectrophotometers can also analyze potential spectral data information based on chromaticity data.
Spectrophotometer can measure any material: paper, plastic, fabric, metal, ceramic, liquid, etc. Depending on the principle of construction, it is generally composed of three types as follows.
0°/45° mechanism principle: the instrument irradiates the sample at a fixed angle, which can exclude gloss, in a way that is closest to the color seen by the human eye. They are usually used to measure the color of flat or rough surfaces.
Integrating sphere mechanism principle: A spherical instrument emits diffuse light and can measure both excluding specular (SCE) and including specular (SCI) data. They are typically used to measure colors that are applied to textiles, carpet and plastic surfaces, as well as shiny or mirrored surfaces, including metallic inks, printed on foil, and other high gloss surfaces.
Multi-Angle Mechanism Principle: Receives light at one angle, but measures from multiple angles. Essentially, the color of a sample moves back and forth as if you would tilt a sample to see the color at a different angle. Today’s multi-angle instruments are used for special coatings of pigments and effect coatings, such as mica and pearl powder, for applications such as applying nail polish and automotive coatings.
How to use a spectrophotometer?
Familiar with the role of spectrophotometer and the principle, then we have to start the real practical operation of. After all, the theory is accurate, the actual operation of the error is difficult to avoid, in order to come up with accurate color difference results, we have to strictly follow the spectrophotometer use specification operation.
1. Turn on the power switch (if it is a desktop spectrophotometer also need to be connected to the power supply first)
After the power is turned on, we can see that the power indicator is lit in green. If the light is not lit, then you need to check whether the power supply is not connected.
2. Calibration work of colorimeter
Not calibrated can not be measured normally. From the “Instrument” menu, select “Set Mode”, when the dialog box prompts, first select “Reflection” in the mode, click “Calibration When prompted, first select “Reflection” in the mode, click “Calibration” and follow the 2 steps to calibrate, then select the next mode (i.e. transmission mode) to calibrate, and follow the 2 steps to calibrate. After calibration, return the calibration supplies to their original position for use in the next calibration.
3. Select the database you need in the main menu interface and open it.
4. Select the required test method and light source and observation angle in the setup menu.
5. If the sample to be tested is a standard color card or standard sample, the surface to be tested will completely cover the light-transmitting hole of the shade, clip the sample and then tap the test specimen or press F2 to get the specimen data.
6. If there is already specimen data, call the data from the database, cover the translucent hole of the shading plate completely with the sample to be measured and clip the sample after tapping the test specimen or press F3 to get the specimen data.
7. If you need to save the specimen and specimen data, you can choose to save in the current database in the drop-down menu.
What does spectrophotometer LAB refer to?
After some series of standardized operation, we can get the result of color difference between sample and standard, which is usually LAB value. So what does LAB refer to mean?
Color difference meter color measurement after the display of data results for analysis, we use color difference meter is to data control the color of our product appearance, to reduce disputes with customers, color difference meter test results show that:
- △E * the size of the total color difference
- △L*large indicates white bias, △L*small indicates black bias
- △a* large indicates red bias, △a* small indicates green bias
- △b* large indicates yellowish, △b* small indicates blueish
- L (brightness) axis, black and white, below 50 is black, above 50 is white
- A (red-green) axis, positive values for red, negative values for green, 0 for neutral color
- B (yellow-blue) axis, positive values for the yellow, negative values for the blue, 0 for the neutral color
Note: L*white and black, a*red and green, b*yellow and blue, C*saturation, h*hue angle
The data obtained by visual inspection is determined and quantified numerically, thus reducing potential color errors in the pre-production process. In order to ensure the accuracy of the measurement results, you will need to choose a professional spectrophotometer manufacturer.
How does spectrophotometer control the color difference?
The more advanced spectrophotometer in the more advanced spectrophotometric type, we often say spectrophotometer, this instrument contains an internal optical component that can be divided dispersion.
Spectrophotometer generally uses prisms, gratings, interference filters, adjustable or discontinuous series of monochromatic light sources to achieve spectrophotometry, and then analyze single color information according to the principle of dispersion to achieve color figures. Spectrophotometer can finally display chromaticity information according to the internal setting of chromaticity space and calculation formula, and output in the form of digital. In addition, spectrophotometer can also analyze potential spectral data information based on chromaticity data.
We know that ultraviolet light is not in the visible spectrum and cannot be pounced and observed by the naked eye, but it can affect the color change. There is a UV-resolved spectrophotometer for measuring chromaticity, which allows for more accurate color analysis.
However, more manufacturers now prefer to use test kits to accomplish this measurement. The kits help to measure more color information about the product while accuracy can be guaranteed, but the kits are easier to adjust than the spectrophotometer’s internal technology while also reducing the manufacturing cost of the instrument, making it affordable and accessible to more manufacturers.
Spectrophotometer is designed for visual colorimetric data comparison and simulation, while used as an important auxiliary tool for computer color matching, which can help major manufacturers to perfectly complete the analysis, processing and monitoring of spectral and colorimetric information. In the use of spectrophotometer, will involve a key data equation – color tolerance equation, in fact, we usually say tolerance range, in the industrial batch generation there are tolerances to control the product and qualified situation, both fast, but also reasonable.
Spectrophotometer wants to measure the color difference between products to control and ordinary colorimeter is the same, first to measure the information of the standard product, and then measure the sample color information, through comparison to get the color difference data. In fact, color measurement and color management in general is the same, but the spectrophotometer higher accuracy, more comprehensive functions.
Color envelops every moment of our lives, in large or small ways, or in conscious and unconscious ways that affect our emotions, behaviors and beliefs.
Color can set emotions, warn us of danger, provide important information, and even bring us joy.
Although color is universal, its description remains elusive, partly because of differences in human perception of color, and partly because of the lack of description of the millions of colors seen by the human eye.
Instrumental color measurement transcends the limits of human perception and vocabulary, allowing us to capture color information as objective data, thereby creating a common color language that is essential for communication within and between industries around the globe. Colorimeters and spectrophotometers are two types of color measurement instruments that accurately quantify and define color.
While these two instruments are closely related, they both have unique characteristics that may make one instrument more suitable for a particular measurement method than the other. Understanding the characteristics of colorimeters and spectrophotometers can help you choose the best tool for your application.
A colorimeter is designed to perform a type of psychophysical sample analysis by mimicking human eye-brain perception, which means that its measurements are correlated with human perception. In other words, it is designed to see color the way we do.
Its results are straightforward, reading tri-stimulus values. A tri-stimulus value is the identification of a color with characters that represent different dimensions of its visual appearance. A tri-stimulus value may contain values such as X, Y and Z or L, A and B. The “gold standard” for tri-stimulus colors is the CIE color system developed by the International Commission on Illumination, with the CIE in the title representing the French version of their name.
The colorimeter has several unique components.
Light source: The light source represents a specific light source, such as an incandescent or white light, to project a consistent brightness onto the object. In a colorimeter, the light emitter is fixed.
Observer: A standard observer provides a specific field of view to analyze color. Colorimeters usually use a 2-degree standard observer and are suitable for color evaluation and quality control.
Triple Stimulus Absorption Filter: The absorption filter separates the specific wavelengths applied to the sample.
How does a colorimeter work?
The use of colorimeters is usually based on the beer-Lambert law, which tells us that the concentration of a solute is proportional to its absorbance. A colorimeter starts with a simple light source. With the help of a lens and a triple-stimulated absorption filter, the light beam becomes a single, focused wavelength and then moves into the sample solution. On the other side of the solution is a photocell detector, which determines how many wavelengths have been absorbed. The detector is connected to a processor and a digital display that provides a readable output of the results.
Now that you understand how a colorimeter works, let’s take a look at the pros and cons of colorimeters.
Advantages of colorimeters
- a. They are concerned with tri-stimulus values. If you don’t need the full range of spectral data, you can choose a colorimeter.
- b. They are more portable. Colorimeters are less complex, so they may be easier to move around or use in the field.
- c. They work quickly. Many applications of colorimeters require fast moving equipment, such as on an assembly line, and colorimeters can do this.
Disadvantages of colorimeters
- a. They do not provide complete spectral data. While colorimeters are great, they do not provide spectral information on your sample. A colorimeter does not have an adjustable light source and filter to make additional measurements. It will not be able to find colorant intensity or help with color formulation.
- b. They are not foolproof. Colorimeters lack versatility because their primary purpose is to compare a product to a pre-determined sample. They are not well suited for research or product development applications due to their lack of accuracy and adjustable components.
- c. They are unable to identify homochromatic spectra. The phenomenon of homochromatic heterogeneity is when colors look the same under one lighting condition but not under another. For example, a fluorescent light may make a product look completely different than it does in sunlight. A colorimeter cannot recognize and adjust for this condition.
Application of the colorimeter
Typically, a colorimeter compares the results to an existing sample.
Colorimeters are very accurate for simple color measurements and are well suited for color difference, fastness and strength measurements, as well as for routine comparisons of similar colors.
As such, they can color quality control and are primarily used in the production and inspection phases of manufacturing.
What are spectrophotometers?
Spectrophotometers are physical samples analysis instrument designed to measure color through the full spectrum.
By providing a wavelength-wavelength spectral analysis of the reflectance, absorbance or transmittance characteristics of a sample, it produces accurate data beyond what can be observed by the human eye. If desired, spectrophotometers can also be used to calculate psychophysical colorimetric information.
Spectrophotometers are incredibly accurate and offer a wide range of data.
They use components similar to colorimeters, but with slight differences.
Light source: The light source for spectrophotometers is versatile. You can use both standard and fluorescent light sources that represent various types of light.
Observer: The spectrophotometer’s observer is usually large, about 10 degrees.
CIE recommends it as the most suitable tool for industrial color applications.
Prism, Grating or Interference Filter: To separate specific wavelengths, spectrophotometers use a prism, grating or interference filter so that the selected wavelength can be changed.
- ▲ColorFlex EZ spectrophotometer
- ▲UltraScan PRO Spectrophotometer
How does a spectrophotometer work?
The basic layout of a spectrophotometer is similar to that of a colorimeter, but with more steps and variations, and a few different components.
The emitter projects a light source onto the object and divides the light through prisms and gratings.
The sensor detects the light not absorbed by the object and transmits the data to a processor or computer equipped with the appropriate software. It can detect reflectance, transparency and illumination by means of three stimulus values.
Next, we will discuss the pros and cons of spectrophotometer.
Advantages of spectrophotometer
Some of the advantages of spectrophotometers are as follows.
- a. They are very comprehensive. Spectrophotometers have more advanced hardware and can measure qualities than colorimeters can, including isochromatic and reflectance.
- b. They are versatile. You can usually adjust the illumination and observer settings to get the right options on a spectrophotometer.
- c. Work with powerful software.
- d. By integrating with software, spectrophotometers offer a new, comprehensive way to examine and analyze data outside of the built-in monitor.
- e. They are available in a wide variety of styles. Spectrophotometers are available for a wide range of sample types, including powders, liquids and transparent materials.
- f. Portability options are also available.
Disadvantages of spectrophotometers
Of course, no technology is without its drawbacks. Here are some of the disadvantages of spectrophotometry.
- a. They are more complex. Complexity brings sensitivity, and they may not be well suited to factory environments.
- b. They can be more expensive. While prices vary by model, spectrophotometers and their accurate, extensive information are usually more expensive than colorimeters.
- c. They may have more technology than needed. If you only need the simple color measurements that a colorimeter can provide, a spectrophotometer may be more than you need.
In the past, spectrophotometers were large and complex, but modern technology has made them smaller and easier to use.
Applications of spectrophotometers
Spectrophotometers offer a higher level of flexibility and versatility than colorimeters, in part because they offer multiple light source/observer combinations and can operate in a variety of geometric arrangements, including 45°/0° and d/8°.
As a result, spectrophotometers are able to measure isochromatic spectra, identify colorant intensities, analyze a full range of sample types, and allow the user to choose whether to include specular reflectance to account for geometric properties.
Full-spectrum analysis also provides greater specificity, with the potential to identify color differences missed by colorimeters.
Spectrophotometer instruments are ideally suited for a wide range of applications in the research and development phase, including color formulation and color system development, as well as color quality control throughout the production process.
What is the main difference between a colorimeter and a spectrophotometer?
A colorimeter is used to measure the difference in color between two samples. Generally cannot give the value of the color coordinate space of the color (L,a,b value), but can give the color difference value (ΔE) between two samples (usually between the standard and the sample), this kind of colorimeter does not have the value data of the color, there is no way to exchange data with others, and can not establish and manage their own color standard database.
Spectrophotometer, spectrophotometer is designed according to the principle of spectrophotometric type, it can measure the reflectance curve at each wavelength, but also accurately measure the L, a, b value, more accurate than the general colorimeter, better stability. The built-in software is powerful and contains all the necessary color equations, standard light sources for different tasks, and a large number of industry- and application-specific indicators.
The colorimeter is designed according to the tri-stimulus value type principle, and the spectrophotometer is designed according to the spectrophotometric principle.
Spectrophotometers offer high accuracy and increasing versatility.
Spectrophotometer can measure both SCI (a method that includes specular reflection for measurement, which reduces the influence of the sample surface to a small degree and is particularly suitable for color quality monitoring and computer matching) and SCE (a measurement method that excludes specular reflection, and the results obtained from this type of measurement are more similar to those observed by the naked eye). Because it can measure the reflectance at each wavelength, it is suitable for complex color analysis, and of course relatively expensive.
Colorimeter has a relatively low price, compact size, outstanding flexibility and easy to operate.
Colorimeters and spectrophotometers have some similarities, but they are still very different.
The biggest difference is in capability and use.
Spectrophotometers are incredibly powerful and can provide much more in-depth measurements than colorimeters, such as spectral data.
This is why they are primarily used in research and development or for precise measurements for laboratory use.
In contrast, colorimeters are simpler and are common in production and manufacturing, such as for quality control.
Some other differences include
Versatility: Spectrophotometers have many adjustable options that work well for different types of samples and measurements.
Cost: As mentioned above, spectrophotometers tend to be more expensive than colorimeters due to their powerful technology.
Accuracy: Colorimeters are not as accurate as spectrophotometers.
Choosing a color measurement instrument requires an understanding of the advantages and disadvantages of colorimeters and spectrophotometers, as described above. If you are still unsure which instrument is best for your purposes, these questions, inspired by David R. Wyble of the Rochester Institute of Technology, can help you choose the right instrumentation
Type of data required: Does the application require only spectral data or tri-stimulus values?
Instrument geometry: Does the instrument have the geometry you need?
Precision and Accuracy: What level of precision and accuracy is required to obtain satisfactory results?
Light source: Does the instrument have the right light source for your use?
Speed of measurement: How quickly can data be obtained? What kind of sample preparation is required?
Ease of use: Is the instrument designed with the user in mind for easy and fast operation?
Robustness: Is the tool suitable for the environment in which it will be used? Can it withstand harsh plant conditions?
Software interface: Does the companion software allow you to easily collect, analyze and share data?
Product Quality: Not all color measurement instruments are created equal, whether they are colorimeters or spectrophotometers.
By choosing the best quality instrument, you can be assured that you will get the highest quality results