Technical Information

A spectrophotometer is a color measurement device used to capture and evaluate color. As part of a color control program, especially in global and distributed environments where components are manufactured in different locations and assembled together as a whole, brand owners, designers, suppliers, and manufacturers use spectrophotometers to specify and communicate color, and manufacturers use them to monitor color accuracy throughout the production process.

Each physical sample has its own reflectance, or the amount of light reflected, and transmittance, or the amount of light absorbed. A reflectance spectrophotometer emits a beam of light and measures the amount of light reflected from different wavelengths of the visible spectrum, while a transmittance spectrophotometer measures the amount of light that passes through the sample. Spectrophotometers can measure and quantitatively analyze almost anything, including liquids, plastics, paper, metals, fabrics, and painted samples to verify color consistency from conception to delivery.

There are three main types of spectrophotometers. Your choice depends on the application, required functionality, and portability. Spectrophotometers come in a variety of sizes, from portable devices to large benchtop instruments.

This instrument is the most common spectrophotometer, measuring the wavelengths of light reflected at a fixed angle to the sample, typically 45°. This type of spectrophotometer is compact and can exclude gloss to most closely replicate how the human eye sees color. It is commonly used to measure color on smooth or matte surfaces.

The first number refers to the illumination angle, and the second number refers to the detection angle. With a 45:0 spectrophotometer, the light source illuminates at a 45° angle to the normal of the sample, and the detector receives the reflected light at a 0° angle, or perpendicular to the object surface.

Sphere spectrophotometers measure light reflected at all angles to calculate color measurements that closely approximate those seen by the human eye. They are commonly used to measure the color of textured surfaces (such as textiles, carpets, and plastics) as well as shiny or specular surfaces (including metallic inks, foil printing, and other high-gloss surfaces). Some sphere spectrophotometers that support UV can assess UV light in the wavelength (185 - 400 nm) UV range.

With a sphere spectrophotometer, the object being measured is illuminated diffusely, or from all directions, and the detector receives the reflected light at an 8° angle from the surface of the object being measured. This is called "sphere geometry" because the instrument contains a sphere that provides diffuse illumination. In a sphere spectrophotometer, the inside of the sphere is lined with a highly reflective, low-gloss matte white material used to project and diffuse light, making it a near-perfect white reflector. When a beam of light strikes a point on the surface of the sphere, over 99% of the light is reflected. At the same time, the matte finish of the sphere causes the light to scatter randomly in all directions. This happens at every point on the surface and effectively makes the light inside the sphere appear to come from all directions simultaneously, making the inside of the sphere a light source.

Multi-angle spectrophotometers view the color of a sample as if it were being moved back and forth, much like you would twist a sample to view the color at different angles. Today's multi-angle instruments are used for special coating pigments and special effect colors with additives such as mica and pearlescence, such as nail polish and automotive coatings. These are commonly used in labs, production lines, QC operations, and shipping areas.

Multi-angle is very complex and requires the user to verify five or more sets of L*a*b* values or Delta E* values. Their aperture size is typically 12 mm, which is too large to measure the fine details that occur in many small industrial applications. While the main illumination is typically provided at a 45° angle, some models provide auxiliary illumination at a 15° angle. The latest generation of multi-angle spectrophotometers features up to 12 measurement angles for comprehensive characterization and measurement of effect finishes in various applications, including automotive paints, plastics, and metals.

Spectrophotometers come in single-beam and double-beam configurations. A double-beam spectrophotometer compares the light intensity between two light paths, one containing a reference sample and the other containing a test sample. A single-beam spectrophotometer measures the relative light intensity of the beam before and after inserting the test sample.

From cardboard packaging to laundry soap, carpets, and small plastic parts, X-Rite spectrophotometers help ensure that the color produced matches the color initially specified the first time, reducing waste and saving you time and money.

“We consider X-Rite to be a vital partner in our evolution and continued exceeding of customer expectations. Our past experiences with X-Rite and GretagMacBeth products have been excellent, and the new Ci7800 is no exception. Having this next-generation instrument as an integral part of our operations is critical to our ability to continue driving our color-critical business forward.”

As a global leader in color trends, science, and technology, we offer a full range of solutions from inspiration to final delivery, consistently and accurately controlling color. Whether you want to specify, communicate, formulate, and measure color, we help you make the right choice the first time, every time.

• Portable Spectrophotometers
  X-Rite portable devices are rugged, accurate, and comfortable to hold in your hand or pocket, allowing you to measure color anywhere in your operation. Browse solutions for a range of surface geometries and materials.

• Benchtop Spectrophotometers
  X-Rite benchtop displays are the choice for lab operations that require the highest level of color accuracy and control.