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A UV spectrophotometer is a device used to study the interaction between radiation and matter in regards to the wavelength of photons. Specifically, it measures visible light and the close-to-visible range of ultraviolet and infrared spectrum ranges. The device allows a user to identify electronic transitions within the various regions of the electromagnetic spectrum.
UV light can be measured by a spectrophotometer most readily when it is in the 400 to 700 nanometer (nm) region to quantify and determine the features of color perception. Essentially, the device allows scientists to take measurements on the ability of the human eye and mind to isolate specific wavelengths that define colors. The study of the colors within human perceptive range is known as colorimetry.
Traditionally, a spectrophotometer cannot detect fluorescence. This requires an additional component known as a bi-spectral fluorescent mechanism. Without this ability, it is difficult to properly manage color imagery, specifically if the color contains some sort of fluorescence.
A UV spectrophotometer is set up in two different formats known as d/8, a spherical analysis, and 0/45, a straight line analysis. Both designations are geared towards identifying the specific geometric pattern of the light source, as well as the environment of the object. Additionally, it takes into account what an observer would see naturally when looking at the colorization.
One advantage to this device is the fact that it can identify the exact levels of compounds within a particular spectrum sample. For example, if it analyzes a photograph, it should be able to identify the different color components of each section of the image. Each color and the saturation of the color is identifiable.
The Beer-Lambert law states that different colors are also affected by the materials through which the light travels. This will have profound influence on the analytical data of the spectrophotometer. Due to this fact, the absorbency of light on specific materials can have divergent results.
The printing industry uses UV spectrophotometers extensively to guarantee the correct color is being placed on a product. Ink manufacturing relies on the technology to guarantee that the base ink composition will produce the correct color when placed on paper or boxes. The device also continues to monitor results when the actual printing occurs. By taking readings throughout the 10 to 20 nm spectrum in visible light, the spectrophotometer can identify the production of the spectral reflectance curve, radiation reflected from the surface of an object.
@SZapper - I've unfortunately had the experience of seeing printer ink spill out of a cartridge so I know exactly what you're talking about.
Printing the right color is very tricky, especially when you're printing from a digital file. Sometimes the color that prints looks much different from the color on the screen! I can only imagine what kind of problems would occur if the ink industry didn't use a UV spectroscopy to at least make sure the ink is the correct color.
Printer ink definitely looks like a different color in the cartridge versus when printed on the page. I've always wondered how the ink manufacturers make sure the ink will actually be the color it's supposed to be when it's used for something. Now I have my answer: uv spectrophotometry!