IADR Abstract Archives
Power, Spectral-Distribution, and Beam-Homogeneity Characterization of 10 LED Light-Curing-Units
Objectives: The objective of this work was to characterize 10 LED light-curing-units(LCUs) with respect to power, spectral-distribution, and beam homogeneity.
Methods: Power and spectral-distribution measurements were obtained for 10 different LED LCUs(Table1) using a 6inch integrating-sphere(IS) connected to a miniature spectrometer(Flame, Ocean-Optics) through a 100µm fiber-optic cable. The system was calibrated using a NIST-traceable light-source(HL3plus-INT-CAL). A custom-made adapter was fabricated for each LCU to match its light-emitting-tip(LET) and the opening of the IS. The adapters were 3-D printed(Mojo) and coated with diffuse-reflectance-coating(Labsphere). For each LCU, power-values were combined with a camera-based beam-profiler-system(Ophir-Spiricon) with a 50-mm lens to measure beam-homogeneity(irradiance-distribution across the light-beam). For multi-peak LCUs, shortpass and longpass optical-filters(425nm cut-off wavelength) were used to compensate for differences in the spectral-response of the photo-diode within the CCD-camera.
Results: In Figure1, ChartsA and B each show 4 single-peak LCUs with average(avg.) peak-wavelengths(PWs) from 448 to 453nm and 453 to 475nm, respectively. ChartC shows the spectral-power-distribution for 2multi-peak LCUs with avg. PWs from 393 to 463nm. Table1 shows ValoGrand(XtraPower), Spec3(High), and Slimax-CPlus(High) had relatively high avg. power values of 2401, 1110, and 961mW, respectively; however, the 12mm LET of the ValoGrand resulted in an avg. radiant-exitance of 2123mW/cm2, while the smaller LETs of the SPEC3(7.5mm) and Slimax-CPlus(7mm) resulted in avg. radiant-exitance values of 2512 and 2490mW/cm2, respectively. Yet, Figure2A and 2B show that SPEC3 and Slimax-CPlus, respectively, exhibit highly inhomogeneous beam-profiles with regions exceeding 18,000mW/cm2 and lower than 900mW/cm2.
Conclusions: Ten LED LCUs were successfully characterized with respect to power, spectral-distribution, and beam homogeneity. Some LCUs had relatively-high radiant-power outputs; however, beam-profiles showed the existence of non-uniform irradiance distributions across the LETs of some of these LCUs. This factor combined with the large diameter range(6.8-12mm) of the LETs can result in single-irradiance-values that may be highly misrepresentative of the light-output from some LCUs.
Methods: Power and spectral-distribution measurements were obtained for 10 different LED LCUs(Table1) using a 6inch integrating-sphere(IS) connected to a miniature spectrometer(Flame, Ocean-Optics) through a 100µm fiber-optic cable. The system was calibrated using a NIST-traceable light-source(HL3plus-INT-CAL). A custom-made adapter was fabricated for each LCU to match its light-emitting-tip(LET) and the opening of the IS. The adapters were 3-D printed(Mojo) and coated with diffuse-reflectance-coating(Labsphere). For each LCU, power-values were combined with a camera-based beam-profiler-system(Ophir-Spiricon) with a 50-mm lens to measure beam-homogeneity(irradiance-distribution across the light-beam). For multi-peak LCUs, shortpass and longpass optical-filters(425nm cut-off wavelength) were used to compensate for differences in the spectral-response of the photo-diode within the CCD-camera.
Results: In Figure1, ChartsA and B each show 4 single-peak LCUs with average(avg.) peak-wavelengths(PWs) from 448 to 453nm and 453 to 475nm, respectively. ChartC shows the spectral-power-distribution for 2multi-peak LCUs with avg. PWs from 393 to 463nm. Table1 shows ValoGrand(XtraPower), Spec3(High), and Slimax-CPlus(High) had relatively high avg. power values of 2401, 1110, and 961mW, respectively; however, the 12mm LET of the ValoGrand resulted in an avg. radiant-exitance of 2123mW/cm2, while the smaller LETs of the SPEC3(7.5mm) and Slimax-CPlus(7mm) resulted in avg. radiant-exitance values of 2512 and 2490mW/cm2, respectively. Yet, Figure2A and 2B show that SPEC3 and Slimax-CPlus, respectively, exhibit highly inhomogeneous beam-profiles with regions exceeding 18,000mW/cm2 and lower than 900mW/cm2.
Conclusions: Ten LED LCUs were successfully characterized with respect to power, spectral-distribution, and beam homogeneity. Some LCUs had relatively-high radiant-power outputs; however, beam-profiles showed the existence of non-uniform irradiance distributions across the LETs of some of these LCUs. This factor combined with the large diameter range(6.8-12mm) of the LETs can result in single-irradiance-values that may be highly misrepresentative of the light-output from some LCUs.
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