How Is Light Measured?

Many people wonder the same thought: how is light measured? To understand the answer, you need to know a little bit about science and measurement techniques. Light is measured one of two ways - photometry or radiometry. Photometry assesses light based on how bright something is perceived as being when seen with the naked eye. Radiometry calculates light on all the wavelengths, both non-visible and visible. They both offer important and differing data when it comes to light measurement.

Photometry

Light seen by the naked eye is measured by photometry. How sensitive the human eye is to light depends on the wavelength of the light. The practice of photometrics does not evaluate the way in which we distinguish colors. Light measured by this method is either monochromatic or falls somewhere in a progression of colors. Since the human eye is not sensitive to all of the light wavelengths equally, photometrics gauges the measured power at every wavelength with a specific feature that represents the sensitivity of the eye to brightness. This is critical in photography by helping to find the right lighting for photographers taking pictures. The strength of the brightness coming from an item is called "candlepower," referring to how much brighter an item is than the light from a regular candle. Tools that are employed to assess visible light are known as photometers. These devices create a contrast from an unknown brightness to a known brightness. Because of these contrasts, the evaluations of brightness measured in photometrics are not very precise.

Radiometry

In radiometry, measurements of the entire spectrum of wavelengths are taken. This includes ultraviolet, infrared and visible rays. Radiometry is linked with physics and entails mathematical definitions along with relationships as they pertain to light in the universe. Radiometry uses precise measurements of light by employing devices like vacuum photo-tubes, radiation thermocouples, and bolometers. Radiometry is broken into various areas of the light spectrum. The study of ultraviolet radiometry is one area, and the infrared radiometry is another area. The variation is due to the method in which light is evaluated in the different regions of the spectrum. A thermal detector measures light that reacts to a change in temperature. Light that makes or reacts to electrical charges is measured with radiation thermocouples. A bolometer gauges the resistance present in radiant light. Since radiometry gives such exact measurements, it is a better way to measure light when there is a need for precision in the results, compared to the photometric version of measuring.

There are different ways to measure light. Photometry is a method that works for some circumstances; when accurate results are required, radiometry gives far better and more exact measurements.