Let there be light meters
The Insight
The light bulb has come a long way since the incandescent globe which produces light via thermal radiation. With the introduction of light emitting diodes (a semiconductor that emits light when current flows through it), lighting has become stronger, more consistent and more energy efficient. This advancement in technology has made its way into our everyday lives, populating our TVs, buildings, and our outdoor environment.
As lighting has evolved, the tools we use to measure light have too. As electrical engineers, these tools are important in ensuring that the spaces we create meet the intended objectives and potentially tune the lighting in the space.
A handheld illuminance (light) meter is a useful instrument to measure lighting performance in real world conditions and compare the results against the design. However not all light meters are created equal and results can vary based on the meter selection and the light source.
The Impact
A handheld light meter traditionally contains four components:
An optical diffuser
A spectral filter
Photodiode electronics
A display
Industry speaking, the device is relatively basic so how can the produced results vary?
The quality of the componentry is generally important, particularly the spectral filter and photodiode. These components are fundamental to the measurement of light in the way that we perceive it. This lighting spectral response separates the more budget-grade light meters from the professional.
While budget-grade light meters may be accurate for traditional light sources such as fluorescent, metal halide and incandescent, they are unable to deliver the same accuracy for LED light sources.
Electrical engineers should be aware of these constraints when selecting a light meter. Our recommendation is to have a calibrated test report produced by a NATA-accredited laboratory… and don’t forget a spectral response curve!