Measuring Instruments

Giving Shape to Ideas

Precise Color Communication

As described in , the tristimulus colorimeter has features such as comparatively low price, compact size, superior mobility and simple operation. Colorimeters can determine tristimulus values easily. However, a colorimeter is not appropriate for complex color analysis such as metamerism and colorant strength.
A spectrophotometer has high precision and increased versatility. It is suitable for more complex color analysis because it can determine the spectral reflectance at each wavelength. However spectrophotometers can be more expensive than colorimeters. Always consider how accurately each color must be measured before selecting the type of instrument to use in a specific application.

The colorimeter is mainly used in production and inspection applications for color difference measurements and color chart measurement.
The spectrophotometer is used for high-precision analysis and accurate color management mainly in laboratories and research and development applications.

It was explained that the object color varies depending on the viewing conditions, the observation angle and illumination angle as discussed in Part I-2 . When an instrument measures a sample, the angle at which a beam of light from a source strikes the sample and the angle at which the light is received by a detector is called the optical geometry.

Unidirectional Illumination System
This is a method which provides illumination from one direction. With a geometry of 45/0, the specimen surface is illuminated from an angle of 452 degrees to the normal line and the light is received in the normal direction (010 degrees). With a geometry of 0/45, the specimen surface is illuminated from the normal line direction (010 degrees) and the light is received at the angle of 452 degrees from the normal line.
Diffused Illumination Integrating Sphere System
This system uses an integrating sphere for illuminating or viewing a specimen uniformly from all directions. (An integrating sphere is a spherical device with internal surfaces coated with a white material such as barium sulfate so that the light is uniformly diffused). An instrument with d/0 optical geometry illuminates the sample diffusely and detects the light at the normal direction (0 degrees). An instrument with 0/d optical geometry illuminates the sample at the normal angle (0 degrees) and collects the light reflected in all directions. (Reflected light within +/- 5 degrees from the specular angle can be included or excluded using the SCE/SCI function.)


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