Ocean Optics spectrometers measure the chromaticity, or color, of a sample. Chromaticity is a photometric parameter (matching the response of the human eye), usually expressed in CIE standard coordinates. The human eye has cone cells that act as a red, green, and blue color sensor, and every color you "see" is the result of the combined response of these cells. Likewise, a spectrometer takes the photometric response of these sensors (based on its spectral output) and calculates the color of the sample to best match the color we see. The spectrometer can be further manipulated by quantifying the color of the sample as it sees, allowing the calculation of the following parameters:
• Correlated Color Temperature (CCT) - The temperature of a black body when the light emitted by the absolute black body is the same color as the sample. Different from "cold light source and hot light source" in the traditional sense, if the light source emits blue light, it can be described as a cold light source, and if it emits reddish light, it can be described as a warm light source. However, the black body changes from red light to yellow light to white light to green light. , the temperature gradually increased. A blue LED with a high correlated color temperature will look "cooler" than a red LED with a very low color temperature.
• Color Saturation – This is a measure of how rich the color of the sample is. Whiter samples, closer to the middle of the chromaticity diagram, have less "color saturation" than samples closer to the edge of the chromaticity diagram. This is different from saturation.
• Dominant Wavelength - At this wavelength, a straight line can be drawn from the white "center point" on the CIE color chart through the CIE sample coordinates, on the edge of the CIE chart. The dominant wavelength is not necessarily the wavelength of the highest peak in the spectrum.
Chromaticity is usually illustrated by the chart below, which includes every hue that the human eye can perceive. At the edges of the image (moving clockwise from the bottom corners), the wavelengths of visible light increase in sequence. Every visible color can be created by summing the colors of the wavelengths at the edges of the image. Samples are usually given CIE xyz coordinates (as seen by xy plots), although L*a*b* plots are often used.
The perceived color of a sample will vary with the incident light, so it is important to be able to express information about the light you are using to illuminate your sample when making color reflectance measurements.
