A spectroradiometer is a device designed to measure the wavelengths of individual colors of light. The visible light spectrum is made up of six colors, each formed by a different wavelength which determines its color. The spectroradiometer measures spectral power distributions given off by a light source. This simply means it separates each wavelength, or color of light, it detects and then takes an individual reading for each color. The results tell how strong each color of light is and how strong the light source is as a whole.
The term spectroradiometer is closely related to radiometry. Radiometry is the study of electromagnetic radiation. Light is one form of electromagnetic radiation and thus included in the scientific field of radiometry. Both radiometry and spectroradiometry are used by astronomers to study objects in space. Spectroradiometry can help scientists measure visible light waves which, in turn, help determine factors such as temperature based on the color of the light.
Aside from its use in astronomy, the spectroradiometer is also useful for measuring the quality of light from common, household light bulbs. A manufacturer needs to test the light bulbs and label them according to how much power they produce, and what types of light they give off. Different bulbs cover different ranges of the color spectrum and can give off light that appears warm or cool in color. What the device is measuring when it tests the light bulbs is how much power it detects on each color, or wavelength, coming from the light. We see all the colors mixed together, but the spectroradiometer can break them into individual bands of color for a more accurate reading.
Light bulbs aren't the only items the spectroradiometer works on. It also helps when calibrating computer monitors or television screens. Specific types of displays, such as a CRT display or an LCD display, often require calibration to find the right color balance and settings. To ensure that the monitors give off the proper amount of color either individually or in relation to each other, spectroradiometers take a reading of what is referred to as CIE color.
CIE color readings are then compared to the ideal reading of the TV. Once this comparison is made, it is simple to determine what color adjustments to make. After adjusting, another reading may be taken to ensure that the color is balanced and at the desired setting. If not, the new reading can point out what adjustments are still required.