Is Measuring Led Illuminance With a Lux Meter Accurate?
Light measuring devices called lux meters can measure with high precision in a wide measuring range. But when it comes to LEDs things get a little more complicated. Different brands and models of lux meters may take different measurements at the same point.
LED technology is longer lasting and more economical than traditional lighting solutions. LEDs produce more light while using less energy. This means more lighting.
The illumination level is expressed in units of lux. The devices used to measure the illumination level are called lux meters. The higher the lux value measured at a certain point, the more illumination is made.
Light measuring devices called lux meters can measure with high precision in a wide measuring range. But when it comes to LEDs things get a little more complicated. Different brands and models of lux meters may take different measurements at the same point. In other words, one might show 100 lux while the others might show 120 or 150 lux. When you change lamps in an app, you can visually feel it’s darker, even though you read higher lux values.
In order to understand this emerging problem, it is necessary to look at the lux meter working principle. The light reaching the surface from the light source passes through the optical filter of the lux meter and reaches the photo diode inside. The light measured by the photodiode is converted to lux by the correction factor. The first part of the optical filter, which meets the light, imitates the human perception of brightness. It increases measurement accuracy by blocking ultraviolet and infrared rays that the human eye cannot see.
Conventional light sources such as halogen and incandescent can be measured with a very low margin of error (less than 1 percent) with the aid of ordinary lux meters. High error rates (20-30 percent) may occur in the measurement of other light sources. Because ordinary lux meters are usually calibrated for incandescent lights.
The spectral power distribution of incandescent light is clear and is the same for all lights. The spectral distribution of LEDs is quite variable. The spectral distribution of different LEDs is different from each other. Therefore, it is not possible to filter and measure accurately with cheap lux meters.
Quality lux meters make accurate measurement possible by properly filtering the LED light. On the other hand, an illuminance meter called a spectrometer can read the spectral power distribution of light. No optical filters are used in these devices and lux is calculated directly with the help of the software inside.
Lighting measurements should be made accurately to inform consumers that adequate lighting conditions are provided.