A new spatial integration method for luminous flux determination of light-emitting diodes

Abstract

Spatial integrated measurement using an integrating sphere is usually used for the luminous flux determination of light sources. Devices using an integrating sphere are bulky for use on a production assembly line. This paper proposes an alternative spatial integration method for accurately measuring the total luminous flux of light-emitting diodes (LEDs) having no backward emission. A compound parabolic concentrator is introduced to collect the light from an LED in conjunction with a detector which in turn measures the luminous flux. The study reported here combines both modeling and experiment to show the applicability of this novel method. The uncertainty in the measurements is then evaluated for the total luminous flux measurement from an LED.

New LED Luminous Flux Test System and Its Error Analysis

“…The volume of the luminous flux test system is small, the CPC bowl is about 4cm in length and about 7mm in diameter. And the test is quickly, after the LED is stable, it can read the data immediately [3]. In contrast, the distribution of photometer needs a black chamber in the space.…”

“…Using a large area (48 * 48mm) silicon photovoltaic cells as a detector, and install the attenuator,   V  correction and cosine corrector in turn from the exit port to the light receiving surface of the detector. The output signal of the detector is subjected to current and voltage conversion, and the final display is amplified [3], and then amplified to get the final number. The parameters of the various parts of the actual system are consistent with those in section A.The new luminous flux tester CPC-01 is a rectangular box with a length of 374mm, a width of 206mm and a height of 70mm.…”

Fluorescence detections and directions

“…Originally operated at low (∼10 kHz) repetition rates Misawa 1995, Chithambo andGalloway 2000) and latterly at MHz pulse rates integrated into hand-held sources for sensing applications (O'Hagan et al 2002), LEDs have also been used in fluorescence lifetime imaging (FLIM) microscopy at repetition rates >100 kHz (Kennedy et al 2008). The flux/optical power of LEDs has been measured using integrating spheres (Hanselaer et al 2009) and other collection geometries (Zhou et al 2010) analogous to their use in quantum yield determination.…”