The amount of light emitted by LED is independent of distance
LED manufacturers need to ensure that the lights they manufacture are truly bright as designed. To achieve this, calibrate these lamps with a photometer, which is a tool that can measure the brightness of all wavelengths while considering the natural sensitivity of the human eye to different colors. For decades, NIST’s photometric laboratory has been meeting industry demands by providing LED brightness and photometer calibration services. This service involves measuring the brightness of customers’ LEDs and other solid-state lamps, as well as calibrating customers’ own photometers. Until now, the NIST laboratory has been measuring bulb brightness with relatively low uncertainty, with errors ranging from 0.5% to 1.0%, comparable to mainstream calibration services.
Now, thanks to the laboratory renovation, the NIST team has tripled these uncertainties to 0.2% or lower. This achievement makes the new LED brightness and photometer calibration service one of the best in the world. Scientists have also significantly reduced calibration time, as in old systems, it took almost a whole day to calibrate for a customer. NIST researcher Cameron Miller stated that most of the work involves setting up each measurement, replacing the light source or detector, manually checking the distance between the two, and then reconfiguring the equipment for the next measurement.
But now, the laboratory consists of two automated equipment tables, one for the light source and the other for the detector. The table moves on the track system, placing the detector anywhere from 0 to 5 meters away from the light. The distance can be controlled within 50 millionths of a meter (micrometer), which is approximately half the width of a human hair. Zong and Miller can program the table to move relative to each other without the need for continuous human intervention. It used to take a day, but now it can be completed within a few hours. No longer need to replace any equipment, everything is here and can be used anytime, giving researchers a lot of freedom to do many things at the same time because it is fully automated.
You can return to the office to do other work while it is running. NIST researchers indicate that the customer base is expected to expand as the laboratory has added several additional features. For example, the new device can calibrate hyperspectral cameras that measure much more wavelengths of light than typical cameras that typically only capture three to four colors. From medical imaging to analyzing satellite images of the Earth, hyperspectral cameras are becoming increasingly popular. The information provided by space-based hyperspectral cameras about Earth’s weather and vegetation enables scientists to predict famines and floods, and can help communities plan emergency and disaster relief efforts. The new laboratory can also make it easier and more efficient for researchers to calibrate smartphone displays, as well as TV and computer displays.
