What is a Spectrophotometer / color spectro?

How does a Spectrophotometer work?

Applications of Spectrophotometer in Industries

How to use a Spectrophotometer: Step-by-Step Guide

Classification of spectrophotometer

The differences between Spectrophotometer and Colorimeter

Precautions during the use of Spectrophotometer

How to Find the Right Spectrophotometer

What is a Spectrophotometer / color spectro?

A spectrophotometer (or color spectro ) is an instrument used to accurately measure the color of an object's surface. It uses the principle of spectroscopy to decompose the light emitted by a light source into beams of different wavelengths and measures the reflectance or transmittance of the object under test to these different wavelengths of light. With these data, the spectrophotometer can generate a spectral reflectance curve or spectral transmittance curve of the object to analyze the color of the object.

How does a Spectrophotometer work?

In simple terms, the working principle of a spectrophotometer includes the following steps:

1. Light source irradiation: The instrument emits a beam of light to the sample through the light source.

2. Decomposition of light: Light is decomposed into different wavelengths (usually within the visible range, between 380nm and 780nm).

3. Reflection/Transmission Measurement: The amount of light reflected or transmitted by the sample at each wavelength is measured.

4. Data processing: The instrument records these reflectances or transmittances and generates spectral data, which can then calculate the color data of the sample (such as CIELAB value).

A spectrophotometer works on the principle of measuring light as it passes through or reflects off a sample. The light source, which typically emits across the visible spectrum (400-700nm), strikes the sample, and the device captures the light that either transmits through the material or reflects off its surface.

This spectral data allows the device to assess the material's optical properties, such as color, reflectance, transmittance, and absorption. By analyzing the light's behavior across different wavelengths, spectrophotometers can measure more than just color—they offer a comprehensive understanding of how light interacts with materials.

Applications of Spectrophotometer in Industries

Spectrophotometers can measure the color performance of samples under different lighting conditions and geometric structures, so they have a wider range of application scenarios, especially for color management and quality control with high precision and strict color standards . Some of the main applications include :

Automotive Industry: Used for precise color matching in car paints and coatings, ensuring consistency across production lines.

Textile Industry: Helps measure and control fabric colors to meet industry standards, particularly for colorfastness.

Coating Industry: Used to check paint and coating quality by measuring how different coatings reflect or absorb light.

Food Industry: In food production, spectrophotometers analyze color consistency in products such as beverages, processed foods, and packaging materials.

Spectrophotometer in Color Measurement

In the realm of color measurement, a spectrophotometer goes beyond the capabilities of basic colorimeters. It provides detailed color data in various color spaces, such as CIE LAB and XYZ, which helps manufacturers maintain color consistency across products. This is particularly important in industries like printing, packaging, and textiles, where even the slightest color variation can affect product quality.

Spectrophotometer in Scientific Research

In scientific research, spectrophotometers play a critical role in analyzing materials' optical properties. Researchers use spectrophotometers to measure absorbance, transmittance, and reflectance across the UV, visible, and near-infrared spectra. This allows scientists to study chemical properties, concentration levels, and material composition.

Spectrophotometer in Field of Petrochemicals

In the field of petrochemicals, colorimeter can be used to detect common chromaticity indicators in the petrochemical industry, such as whiteness, yellowness, transmittance, platinum cobalt index APHA, Gardner index Gardner, Saybolt index Saybolt, oil chromaticity coordinates ASTM, etc.

How to use a Spectrophotometer: Step-by-Step Guide

Operating a spectrophotometer involves several precise steps to ensure accurate measurement. Here's a general guide:

1. Calibration : Before measurement, calibrate the device using a white or black standard to establish baseline readings.

2. Sample Preparation : Ensure the sample is clean and free of any imperfections. Proper sample placement in the spectrophotometer is crucial for reliable data.

3. Measurement Mode Selection : Choose the appropriate mode—reflection or transmission—depending on the sample's properties.

4. Data Collection : The spectrophotometer will emit light on the sample, and sensors will capture the reflected or transmitted light to generate a spectral curve.

5. Analysis : Use the device's built-in software to analyze and interpret the data based on the application's requirements. Or use the host computer software to manage and analyze color data.

Spectrophotometer Calibration and Setup Procedures

Proper calibration is key to ensuring accurate results. Calibration involves comparing the spectrophotometer's readings with a known standard to adjust for any discrepancies. Periodic recalibration helps maintain long-term measurement accuracy.

Spectrophotometer Measurement Techniques: Reflection Modes and Transmission Modes

Reflection Mode: Light reflects off the sample, and the spectrophotometer measures how much light is reflected at each wavelength. This mode is widely used for surface analysis in industries like automotive and textiles.

Transmission Mode: Light passes through the sample, and the device measures how much light is transmitted at each wavelength. This mode is essential for analyzing transparent or translucent materials, such as films or liquids.

Classification of spectrophotometer

The classification of spectrophotometers is mainly based on their optical system, lighting and observation geometry, measurement mode and application scenarios. The following are common classifications of spectrophotometers:

1. Classification by optical system

Single-beam Spectrophotometer : This type of spectrophotometer uses only one beam of light during measurement, and requires separate measurements of the sample and reference. Although the design is simple, it requires a lot of work before each measurement. A baseline calibration is required and the accuracy is relatively low.

Double-beam Spectrophotometer : This instrument divides the light beam into two parts during measurement, one for measuring the sample and the other as a reference. This design can measure the sample and the reference at the same time, reduce environmental interference, and have higher accuracy.

2. Classification according to brightness and observation geometry

Reflection Spectrophotometer : This spectrophotometer is mainly used to measure the color of the surface of opaque objects. The light emitted by the light source shines on the sample surface, and then the reflected light enters the detector. It is often used to measure the surface color of coatings, plastics, textiles, etc.

Transmission Spectrophotometer : This instrument is used to measure the color of transparent or translucent materials (such as plastic films, glass, liquids, etc.). The light emitted by the light source passes through the sample and then enters the detector to measure the sample's transmittance of light at different wavelengths.

Integrating Sphere Spectrophotometer : The integrating sphere is used to eliminate the influence of the reflection angle of the object surface. It can collect and evenly distribute the reflected light, making the measurement result more accurate. Integrating sphere spectrophotometer is often used to measure the diffuse reflection and total reflection of samples, and is suitable for materials with different surface characteristics.

3. Classification by measurement mode

 Static Spectrophotometer: Static spectrophotometers are usually used in laboratory or factory environments. They have high accuracy and stability and are suitable for measuring large quantities of samples.
They are mostly desktop devices suitable for fixed position measurements.

Portable Spectrophotometer: Portable spectrophotometer is light and small, which is convenient for on-site measurement in different occasions. It is often used for on-site color control in the textile, coating and food industries. Although its accuracy is slightly lower than that of desktop equipment, it is highly flexible and suitable for field or mobile measurement needs.

4. Classification by application field

Industrial spectrophotometer : Industrial spectrophotometer is specially designed for online detection in industrial production processes. It can monitor color changes on the production line in real time and is used for online color quality control in industries such as plastics, paints, and automobiles.

5. Classification by wavelength range

UV-Vis Spectrophotometer: This instrument can measure spectral data from ultraviolet to visible light. It is usually used in the fields of chemistry, materials and biology to measure the absorbance or reflectance of transparent substances.

Vis-NIR Spectrophotometer: This type of instrument covers the visible to near-infrared spectrum and is often used for material analysis in industry, such as testing agricultural products or monitoring food quality.

Summarize

Spectrophotometers can be divided into many types according to optical design, measurement geometry, application scenarios, etc. The selection of the appropriate instrument type needs to be based on specific measurement requirements and industry standards.

The differences between Spectrophotometer and Colorimeter

The main differences between a spectrophotometer and a colorimeter are as follows:

1. Working principle:

Spectrophotometer: Measures every wavelength of the light spectrum, providing detailed spectral data.

Colorimeter: measures color through RGB filters, simulating human eye perception.

2. Accuracy:

Spectrophotometer: higher precision, suitable for demanding color management.

Colorimeter: lower accuracy, suitable for general quality control.

3. Data output:

Spectrophotometer: Outputs spectral reflectance/transmittance curves and detailed color data (such as CIELAB).

Colorimeter: Provides direct color values (such as L*, a*, b*).

4. application:

Spectrophotometers: For precision color management and quality control (e.g. coatings, textiles, plastics).

Colorimeter: Used for daily color inspection and simple color comparison.

5. Price and usage:

Spectrophotometer: High price and complicated operation.

Colorimeter: low price and easy to operate.

In short, spectrophotometers are more accurate and suitable for complex color analysis, while colorimeters are used for simple and fast color measurement.

Precautions during the use of Spectrophotometer

When using a spectrophotometer, several factors should be considered to maintain accurate and consistent results:

Environmental Factors

Temperature, humidity, and light conditions can influence spectrophotometer measurements. For best results, use the device in a controlled environment with stable lighting and temperature.

Common Mistakes to Avoid

Improper Calibration: Failing to calibrate regularly can lead to inaccurate results.

Sample Handling: Ensure the sample is clean and properly placed to avoid measurement errors.

How to Find the Right Spectrophotometer

You can choose based on the usage scenario:

Desktop instruments are mostly used in fixed laboratory environments and can provide high-precision color data. Desktop spectrophotometers are available in two models: vertical and horizontal. You can choose the specific configuration of the desktop instrument according to the shape and size of your sample. .

Portable color measurement instruments can be easily moved around the work area and are suitable for quick quality control checks on the production floor.

In-line non-contact spectrophotometers are commonly used in the consumer retail market for color matching.

You can also choose by industry:

Coating and textile industries : desktop instruments are often used in combination with portable instruments. Desktop instruments are mostly used in fixed environments such as laboratories, while portable instruments are mostly used for color measurement in workshops.

Plastics industry: Because transparent or translucent samples often need to be measured, when selecting an instrument, it is necessary to consider whether the instrument can perform color measurement in reflection or transmission mode;

Retail paint industry: Customers often need customized colors, and the use of a desktop spectrophotometer with color matching software can be very helpful. In addition, an online non-contact spectrophotometer can match the color that the customer wants with the color in the color library, which is also a good choice.

Contact us and 3nh color experts will provide you with the solution that best matches your needs.