Exploring the Inner Workings of Colorimeter: How They Measure Color Differences

Colorimeter, also known as chroma meter or portable colorimeter, is a color measurement device used to measure color differences in objects, capture and evaluate colors, and plays an important role in color control programs.

Brands and designers use them to specify and communicate colors, while manufacturers use them to monitor color accuracy throughout the entire production process.

Chromatic aberration, also known as chromatic aberration, is a serious defect of lens imaging. In simple terms, color difference refers to the difference between colors, which occurs when polychromatic light is used as the light source, and monochromatic light does not produce color difference. The wavelength range of visible light is approximately 400 to 700 nanometers, and different wavelengths of light have different colors.

The refractive index also varies when passing through the lens. Color difference generally includes positional color difference and magnification color difference. The positional color difference causes the image to have color spots or halos when observed at any position, making the image blurry. And the magnification chromatic aberration causes the image to have colored edges. One of the main functions of optical systems is achromatic.

Colorimeter classification:
Colorimeters can be divided into two categories based on their working principles: photoelectric integrated color difference meters and spectroscopic color difference meters. The photoelectric integrated colorimeter is commonly known as a precision colorimeter, and the spectrophotometer colorimeter is commonly known as a spectrophotometer. According to the volume size of colorimeters, they can be divided into portable color difference meters and desktop color difference meters.

The photoelectric integrated colorimeter has a simple structure, low accuracy, and is only portable. Due to the need for grating to split the spectrum, the spectrophotometer can be divided into portable spectrophotometer and desktop spectrophotometer.

Working principle of Colorimeter:
1. photoelectric integrated colorimeter
Using the standard light source inside the instrument to illuminate the measured object, an integral measurement is carried out within the entire visible wavelength range to directly measure the tristimulus values and chromaticity coordinates of the transmitted or reflected object color. The color difference values between the measured samples can be provided through a dedicated microcomputer system.

Automatically compare the color difference between the template and the inspected product, and output CIE_ Lab three sets of data and four sets of color difference data after color comparison, including △ E, △ L, △ a, and △ b, provide the basis for product factory quality inspection.

2. Spectrophotometer
The spectrophotometer measures the relative spectral power distribution of reflected light from an object to obtain the reflection spectrum of the object surface. It is then weighted and multiplied by the three stimulus values of the CIE spectrum, and integrated to obtain other parameters such as the three stimulus values, color coordinates, and color difference of the sample surface color.

The spectrophotometer designed for the system is mainly composed of lighting and observation systems, spectroscopic systems, photoelectric detection systems, and circuit control systems.

Reasons for color difference:
Light of various wavelengths will be dispersed to varying degrees. White light is dispersed into various wavelengths of light in the ultraviolet, visible, and infrared bands. When passing through a lens, the resulting image has colored edges, which is called chromatic aberration.

The difference between the actual and ideal imaging of an optical system is collectively referred to as aberration. Chromatic aberration is a type of aberration that occurs when the transmittance of a transmitting material varies with wavelength, and therefore only when it comes to polychromatic light.

Quantitative representation of color perception differences. Represented by the differences in the three color attributes of brightness, hue, and chromaticity. The difference in brightness represents the difference in depth, the difference in hue represents the difference in hue (i.e., redness or blueness), and the difference in color represents the difference in brightness.

The evaluation of color difference is very important in industry and commerce, mainly used for color matching in production and color quality control of products. Modern color difference assessment is based on the standard color difference formula recommended by the International Illumination Association (CIE) and calculated using a color difference meter and computer measurement, using accurate numbers to represent. Commonly used formulas such as CIE 1976L * a * b * and CIE 1976L * u * v * color difference.

The phenomenon of color inconsistency between batches of products dyed in the same color, and several color differences between products dyed in the same time, is called color difference. It can refer to the color difference between different parts of the same product, the color difference between the same batch of processed products, and the color difference between different batches of products originally dyed the same color.

In the industry, product color consistency is required. Due to the above reasons, there may be deviations in the color of the product, which can reduce the quality of the product, and in severe cases, it may lead to failure to accept and deliver. At this point, we need to use color measurement instruments such as color difference meters to control the color difference of the product.

1. Control the quality of our factory’s products
To ensure the color consistency of each batch of products, it is first necessary to establish a product color standard as the factory logo. A certain amount of samples can be taken from different batches of the same product (hereinafter referred to as A product) for measurement.

After measurement, select products with relatively large color differences from them, and use the remaining products with relatively close color differences as calibration samples for product A. Measure the color values of the calibration sample in sequence using a color difference meter and calculate the average value (the instrument can automatically calculate the average value).

Use the average value as the color label of product A and store it in the color difference meter. The storage sample number can be set to 001 for easy memory. If there are multiple products, they can be measured according to the above method and stored as 002, 003, etc.

In the future production process, to check whether the color of product A is qualified, the standard sample value (data 001) of product A can be retrieved from the color difference meter storage, and then positioned as the standard value. Sampling and measuring from each batch of A product, the measured color difference value is both the result of comparison with the factory standard.

Product color difference value（ Δ E) Currently, most manufacturers control the color difference within 0.5 or 1（ Δ E) If there is no color difference within 0.5 or 1, it is considered a non-conforming product. If it is greater than 0.5 or greater than 1, it is considered a non-conforming product. Other products use this method to call up corresponding product factory standards and set them as standard values for measurement and analysis.

2. Production according to standard samples
Many companies order and produce according to the samples provided by the ordering company. They can use a color difference meter to measure the samples provided by the other party, store the measurement results in the instrument, remember the stored sample number, and use it as a standard sample.

When applying, set the value of this standard sample as the measurement standard value, and then measure the produced products in sequence. Follow the steps of “Method One” to inspect the color difference value of the products and evaluate whether the product color is qualified.

Portable Colorimeter/Chroma Meter is an innovation color measuring tool with powerful configuration to make color measurement easier and more professional; It support Bluetooth to connect with Android and ISO devices, Portable Colorimeter/Chroma Meter will take you into a new world of color management; It can be widely used to measure color value, color difference value and find similar color from color cards for printing industry, paint industry, textile industry, etc.

Lisun Instruments Limited was found by LISUN GROUP in 2003. LISUN quality system has been strictly certified by ISO9001:2015. As a CIE Membership, LISUN products are designed based on CIE, IEC and other international or national standards. All products passed CE certificate and authenticated by the third party lab.

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